Deepwater Horizon Well Blowout Mass Balance

Deepwater Horizon Well Blowout Mass Balance

Chapter 15 Deepwater Horizon Well Blowout Mass Balance M. Fingas Spill Science, Edmonton, AB, Canada Chapter Outline 15.1 Introduction 15.2 Scientif...

2MB Sizes 0 Downloads 29 Views

Chapter 15

Deepwater Horizon Well Blowout Mass Balance M. Fingas Spill Science, Edmonton, AB, Canada

Chapter Outline 15.1 Introduction 15.2 Scientific Background 15.2.1 Ixtoc I 15.2.2 Deepwater Joint Industry Project Results 15.2.3 Subsequent Spill Modeling 15.2.4 Studies on Underwater Emulsion Formation 15.2.5 Density Gradients 15.3 The Macondo Blowout 15.3.1 Overview 15.3.2 The Discharge Amount 15.3.3 Modeling Studies 15.3.4 Chemical Behavior at Exit 15.3.4.1 Solubility 15.3.4.2 Weathering 15.3.4.3 Effect on Oil Composition 15.3.5 Physical Behavior at Exit 15.3.6 In-Sea Weathering 15.4 The Fate and Removals of Oil on the Sea Surface 15.4.1 Skimming 15.4.2 Vessel-of-Opportunity Removal System

806 806 806 807 808 808 809 809 809 810 812 812 812 817 817 818 818 819 819

15.4.3 15.4.4 15.4.5 15.4.6

In Situ Burning Oil on the Shoreline Residual Oil Surface Chemical Dispersion 15.4.7 Additional Surface Weathering 15.4.8 Marine Snow Formation 15.4.9 Sinking 15.4.10 Oil Moving out of Area 15.5 Subsurface Fate and Losses 15.5.1 Oil Sunken Near the Accident Site 15.5.2 Dissolution and Plumes 15.5.3 Subsea Chemical Dispersion 15.5.4 Marine Snow 15.5.5 Summary of Losses From the Surface and Subsurface 15.6 Timing of the Losses and Additions 15.7 Calculation of Mass Balance 15.8 Conclusion References

820 821 824 824 824 828 828 828 828 828 829 829 830

830 831 832 842 843

819

Oil Spill Science and Technology. http://dx.doi.org/10.1016/B978-0-12-809413-6.00015-1 Copyright © 2017 Elsevier Inc. All rights reserved.

805

806

Oil Spill Science and Technology

15.1 INTRODUCTION The mass balance of the Deepwater Horizon (DWH) was proposed as a calculator program federal interagency solutions group (FISG) in late 2010 [1]. At the time, there was important information that was unavailable. Examination of this study in the light of further information now available, shows that there are several points that should be re-evaluated: 1. The oil discharge was a maximum of 4,080,000 barrels (649,000 m3) as 820,000 barrels were siphoned off and taken away. The court-ruled scenario was that 3,190,000 barrels were released (507,000 m3) and is used here as a minimum discharge case. The average used here is 578,000 m3 or 3,635,000 barrels. 2. The weathering of the oil upon surfacing, by several analyses, was about 50%. 3. The amount of recovery was initially proposed to be 20% oil and 80% water. A check on the field operations showed that this was unreasonably low. Decanting was allowed and some discharges were estimated to be as large as 90% oil. Further, some of the vessels had oil-water separators. A reasonable estimate is then 70e90%. This increases the amount of physical recovery threefold or more from the FISG estimate. 4. The amount of oil recovery by the vessel-of-opportunity program, which had up to 400 vessels and more than 500 skimmers at the end. 5. The amount of oil that was sunken to the bottom by either physical or biological means, 6. Much oil arrived on shore at later times than when the FISG was carried out. Shoreline oiling was never counted into the FISG calculator. 7. Radar satellite measurements of the oil on the water have been recently published. 8. Several subsequent studies showed additional data such as sedimentation [2e5]. Recalculation of mass balance scenarios can show why there was so little oil remaining on the water shortly after the time the well was capped.

15.2 SCIENTIFIC BACKGROUND There are several studies and incidents that preceded the DWH spill that provide information on the fate of oil from underwater blowouts.

15.2.1 Ixtoc I In June 1979, the Ixtoc I exploratory well in the Bay of Campeche blew out, releasing oil for 290 days. It was the largest spill in history at that time, totaling approximately 3.5 million barrels. The oil released at the well was saturated with gas and formed an emulsion. The depth of the Ixtoc I oil release

Deepwater Horizon Well Blowout Mass Balance Chapter j 15

807

point was approximately 51 m (165 ft.) below the water surface [6]. The loss to evaporation of the Ixtoc I oil was reported as 50%. Studies of the emulsion formation by several parties concluded that the volatile loss and the emulsion formation occurred at the well head [7e10]. This was the result of several studies using video as well as sampling analysis. All of the oil rose in emulsified form, having already been weathered. Interestingly an underwater oil plume, estimated that about 3% of the oil was measured up to 80 km away [8]. The oil at Ixtoc was initially a medium oil with a density of about 0.86. The oil was prone to form emulsions once weathered. The findings from the Ixtoc blowout should have raised concerns among scientists about the “instant” volatilization of oil when released under water and under high pressure conditions. This knowledge should have been applied to the DWH spill.

15.2.2 Deepwater Joint Industry Project Results The DeepSpill joint industry project (JIP) and Offshore Operators Committee carried out various projects and six activities including three experimental studies and three model comparison exercises [11,12]. These further included several studies and model comparisons. It is important to note that in the 18 years of studies, the following points were made [11e16]: 1. The oil did not always shatter into small droplets. Droplets as large as the pipe opening were sometimes observed. The spectrum of droplets is much greater than those used by models. 2. The oil always rose on the surface faster than predicted. This is due to the fact that large particles, as large as the discharge orifice, were among the stream of particles. Further, it was observed that small bubbles of gas were entrained in some of the rising oil particles, increasing their buoyancy. 3. The chemical changes to the oil were not observed, nor even was notice paid to emulsion formation. Analysis of the oil before and after release was not carried out. 4. Some of the oil during the DeepBlow experiments rose to the surface as emulsion. 5. The models and experiments did not agree. Further, the models did not agree well among themselves. The differences between the models and the experiments were largely because the models assumed that oil broke into very fine droplets while the experiments showed that the oil broke into particles of the size of the orifice and some into small droplets. A wider spectrum of sizes was actually observed experimentally. 6. The models incorrectly used single-phase flow when in most cases there is two-phase flow. This results in quite different behavior initially, but later on both flow model types show similar behavior.

808

Oil Spill Science and Technology

7. The rise in fluid with a two-phase flow always drags much water upward and mixes this with the rising plume. The water and gases will “foldout” (peel off) either continuously or episodicallydtypically up to about 180 m above the release point. This is similar to a nuclear mushroom cloud. The foldout may be only one-sided. Cross-flows will move some of this material off horizontally. This phenomenon is the origin of the underwater plumes noted during both the Ixtoc and Macondo well blowouts [8,17].

15.2.3 Subsequent Spill Modeling The more recent modeling (since 2002) should have yielded some insights into the DWH spill; however, the models have not included some of the essential features to provide prediction. These essential features should have included (in perceived order of importance to the current situation): 1. 2. 3. 4. 5. 6.

foldout or peel off of water and gases and the depth at which this occurs, full two-phase flow modeling, separation of gases (not just methane), chemical effects such as increased solubility at depth, weathering and emulsion formation, inclusion of a wide spectrum of droplets, including those as large as the opening itself, and 7. movement of the gas and water plumes which have peeled off. Review of the models shows that only methane separation of the above seven elements has been included in the Comprehensive Deepwater Oil and Gas model and this separation occurs if the plume is “bent” by underwater currents [18e24]. The other model, DeepSpill, includes similar calculations [25e31]. The point is that models do not include gas dilution in the sea, which is an important part of blowout behavior. Thermodynamic modeling by Gros et al. shows that many of the smaller hydrocarbon compounds (
15.2.4 Studies on Underwater Emulsion Formation In late 1998 and early 1999, Environment Canada carried out some preliminary experiments in the release of high pressure oil into water [33]. These experiments were carried out in connection with a joint industry group to investigate the behavior of deep-sea blowouts. The preliminary experiments involved discharge of a light oil into a small lab vessel. The process of injection from high pressure to low pressure immediately resulted in rapid

Deepwater Horizon Well Blowout Mass Balance Chapter j 15

809

weathering and sometimes emulsion formation. About 20 runs were performed with similar findings. The preliminary experiments indicated that the oil injected from high pressure into water at lower pressure will be instantly weathered and will immediately form emulsions, if the oil is prone to emulsion formation. These results are consistent with the Ixtoc blowout and deep-sea experiments.

15.2.5 Density Gradients The densities of the Gulf waters near the Macondo well blowout are known for their variations. Beegle-Krause et al. reviewed this and noted that with this density gradient the dissolved oil and small particles would not rise, but rather would move off with bottom currents at about 1100 m level [34]. This effect could assist in the formation of subsea plumes.

15.3 THE MACONDO BLOWOUT 15.3.1 Overview The best-known information is summarized in Fig. 15.1. This figure shows that there are indeed many processes underway as a result of the release. The key

FIGURE 15.1 Overall schematic of the plume behavior.

810

Oil Spill Science and Technology

driving force is the pressure of release which is very high compared to the pressure at the sea floor. As a result of this, there are many chemical changes that occur including solubilization in methane and water. An important fact is that the oil composition as well as the amount of methane changes as the flow continues. This results in changes to the behavior and composition of the oil dissolving and rising to the surface. This was noted during the spill when some oil rose as emulsion and other times as highly weathered and unemulsified oil. As the oil hit the water at 81 MPa, it was reduced rapidly to 15 MPa, and the energy is transformed into velocity and the jet region of the plume forms [35]. This jet entrains much water which will be mixed with the oil and will dissolve both, the gases and some of the oil. At about 180 m above the blowout entry point, foldout(s) will occur [11]. These foldouts will discharge water, gases, and oil. These substances will then move off with crosscurrents. In the water entrained with the plume, there is a large amount of dissolved gas and oil components. These will gradually separate into discrete plumes with some material possibly rising, depending on oceanographic conditions. Once the jet plume phase ends, the velocity of the particles is reduced and the energy is dissipated with water entrainment and energy transfer to the water column. The remaining oil, after the foldout(s), undergoes massive weathering by loss of volatiles to water dissolution as well as to the gas bubbles which are separating. Because of the rapid pressure reduction, asphaltenes are precipitated into the oil mass and when conditions are right, water-in-oil emulsions are formed. The weathered and sometimes emulsified oil rises slowly to the surface in particle sizes varying from cm to mm sizes. The smaller droplets/ particles can take a very long time to rise to the surface.

15.3.2 The Discharge Amount Several studies were initiated to actually measure the flow rate using various techniques, mostly velocimetry [36e38]. Some of these are shown in Table 15.1. Many of the velocimetry results were thought to be a failure as they yielded low numbers. Some of the explanation given for this was that the scientists used too small a field of view which resulted in a much lower flow because the particles being tracked were out of the image by the next frame. Professor Paul Bommer was commissioned by National Oceanic and Atmospheric Administration to study the Macondo well blowout and appraise the pressures and calculate the release rate [39]. Bommer noted that the reservoir is a critical fluid. This is at a point where vapor and liquid are at equilibrium and indistinguishable. The pressure in the reservoir is 45 MPa (6504 psi) and at 117 C. Also, a point of note is that most substances are soluble in each other and therefore little can be done to distinguish various components. This critical fluid characteristic is important in that once the liquid is released and lowered to different pressures, various components will separate or precipitate. This is what will occur in the plume just after the

Deepwater Horizon Well Blowout Mass Balance Chapter j 15

811

TABLE 15.1 Flow Rate Estimates From In Situ Observations [36] 2010 Date Event Day

Method

Flow Rate (1000 BPD)

May 13e16 ED 24e27

Large eddy tracking

30  12

May 13e16 ED 24e27

Particle image velocimetry

23  9

May 13e16 ED 24e27

Particle image velocimetry

25  8

May 13e16 ED 24e27

Feature tracking

55  14

May 14 ED 25

Optical plume velocimetry

56  12

May 31 ED 42

Acoustic Doppler velocity þ sonar

57  12

June 3 ED 45

Large eddy tracking

46  4

June 3 ED 45

Particle image velocimetry

35  5

June 3 ED 45

Particle image velocimetry

32  8

June 3 ED 45

Digital image velocimetry

62  58

June 3 ED 45

Feature tracking velocimetry

61  15

June 3 ED 45

Optical plume velocimetry

68  14

Near final settlement

Court estimation

37

Preriser Cut Estimates

Postriser Cut Estimates

release at the sea floor. Bommer calculated the pressure drops though various zones of the flow conduits from the reservoir to the blowout, giving some alternate paths. The exit pressure at the sea floor was calculated to be 15 MPa (2250 psi). The various paths yielded blowout volumes ranging from 9000 to 22,000 barrels (1400e3500 m3) per day. The value of the outflow proposed and widely accepted was 4,200,000 barrels (667,800 m3) [36]. This was based on a calculated value of 5,000,000 barrels less the captured amount of 800,000 barrels. The consensus among certain scientists was that the discharge ranged from 62,000 barrels per day down to 53,000 bbd (99,000 to 89,000 m3) by the time the well was shut down 83 days later. This was because of the degradation of the producing formation.

812

Oil Spill Science and Technology

A court ruling on the discharge was issued in 2014 that the discharge was determined to be 3,190,000 barrels (507,000 m3) [40]. This amount is taken as the minimum and the maximum as 4,080,000 barrels. This is 3,635,000 barrels over the entire period or 578,000 m3. With the 87-day discharge this is 6600 m3/day on averagedas the geological studies showed this was tapered, a rate of 7500 m3/day on the first day to 5780 m3/day on the last day was assumed. This is in line with the data presented in the literature [36].

15.3.3 Modeling Studies Several modeling studies have been carried out on the Macondo well spill. Mariano et al. concluded that at least 50% of the oil had to have evaporated or lost to the water column to correspond to the remaining surface oil [41]. Mariano et al. carried out several runs of two types of models concluding that at least 25% of the oil remained in the water column and that at least 30% was evaporated [41]. Similarly, Paris et al. carried out modeling studies on the plume and rise as it relates to the dispersants applied subsurface [42]. They found that the rapid rise in oil could not be related to dispersant application and was contradictory to that. In fact, they predicted that only 1e2% may not have risen to the surface as a result of dispersant use. North et al. noted that droplet size had a very large effect on the fate of oil and if biodegradation of the oil was included, the loss of oil was very large [43]. Poje et al. used surface drifter buoys and models to examine the currents in the vicinity of the DWH spill [44]. All these studies point to the complexity of the discharge physics and subsequent movement of the oil.

15.3.4 Chemical Behavior at Exit 15.3.4.1 Solubility The solubility of oil components in water, and water-in-oil components as well as methane and other gases, is vastly increased at high pressures. [32] [45e47], This can be seen in Table 15.2 which shows some selected high pressure values. Generally, the solubility of compounds in each other is about 50 times what they are at atmospheric pressure. The result of this is that many of the lighter oil components are soluble either in the gas component or in the water. Further, the methane and other light gases are also more soluble both in water and oil. This is illustrated in Fig. 15.2 which shows a schematic of this solubility. The gas bubbles not only contain methane but also contain ethane and hydrocarbons as large as C15. The end result is that the lighter components of the oil are removed by both, the gases and the entrained water. This is equivalent to extreme weathering. This is supported by the studies of Reddy et al. [48]. This group took a sample of the oil directly before it went into the top hat. This oil was analyzed

At High Pressure (15 MPa)

At Ambient Pressure

References

Reference

Increase (By Factor)

Values in mole percent In water Methane

0.2813

[107]

0.00126

[107]

223

Ethane

0.0926

[107]

Butane

0.0093

[107]

Methane þ ethane

0.1127

[107]

Methane þ butane

0.0799

[107]

Methane (pure water)

0.0564

[108]

0.00126

[107]

45

Methane (1 mol/kg)

0.04315

[108]

0.00097

[107]

44

Methane (2 mol/kg)

0.02001

[108]

0.00046

[107]

44

Methane (6 mol/kg)

0.01235

[108]

0.00029

[107]

43

In mol/kg

Deepwater Horizon Well Blowout Mass Balance Chapter j 15

TABLE 15.2 High Pressure Solubilities

Continued

813

814

TABLE 15.2 High Pressure Solubilitiesdcont’d At High Pressure (15 MPa)

At Ambient Pressure Reference

Increase (By Factor)

In methane (þ water) Crude oil

1

[109]a

0.02

[110]

0

>100

7.84

[110]

0

>100

Completely in parts

[111]

0.35

[112]

mole/L Decalin Methane with water has a great carrying capacity In decalin Methane In liquid methane C24 to C32 In naphthalene Methane

[111] a

Noted that condensate would be enriched with C5 to C15 hydrocarbons as well as C15þ

0.008

44

Oil Spill Science and Technology

References g/L methane

Deepwater Horizon Well Blowout Mass Balance Chapter j 15

815

FIGURE 15.2 Schematic of the blowout and the solubility situation.

carefully. The results are presented in Table 15.3. This shows that there was abundant cross-mixing of hydrocarbon materials and perhaps water as well. The gas-to-oil ratio was found to be 1600 to 1700 which allowed ample opportunity for various components to separate. The sample analyzed in Table 15.3 contained only 5% water, however, a sample slightly above at the top hat vent had 23% water. This shows rapid water entrainment into the plume. Reddy et al. also compared the results of a previous paper and noted that the concentrations of hydrocarbons decreased in the plume away from the well site, the plume at 1050 m ranged from 1 to 30 mg/L in benzene, toluene, ethylbenzene and xylenes (BTEX) from 2.3 to 27 km away [48]. A fractionation index was compiled and it was noted that compounds above BTEX such as toluene, naphthalene, phenanthrene, and pyrene would also partition into the water to some extent. It was noted that methane stayed entirely at depth.

816

Oil Spill Science and Technology

TABLE 15.3 Composition of the Deepwater Horizon Discharge Analyte

Sample Result

Oil Density

820 g/L

Carbon

86.60%

Hydrogen

12.60%

Nitrogen

0.38%

Sulfur

0.39%

Saturated hydrocarbons

74%

Aromatic hydrocarbons

16%

Polar hydrocarbons

10%

Gas Methane

82.50%

Ethane

8.30%

Propane

5.30%

Isobutane

0.97%

n-butane

1.90%

Isopentane

0.52%

n-pentane

0.52%

Methane/ethane

9.9

Methane/propane

15.5

GORdmeasured

1730 (S. ft3/bbl)

GORdestimated

1600 (S. ft3/bbl)

From Reddy, CM, Arey, JS, Seewald, JS, Sylva, SP, Lemkau, KL, Nelson, RK, Carmichael, CA, McIntyre, CP, Fenwick, J, Ventura, GT, Van Mooy, BAS, Camilli R. Composition and fate of gas and oil released to the water column during the Deepwater Horizon oil spill. Proceedings of the National Academy of Sciences of the United States of America 2012;109(50), 20229.

Gros et al. studied the thermodynamics of the DWH and noted that many of the gases would be liquid at these pressures and temperatures [32]. Further, they noted that the solubility under high pressure would dominate the fate of the oil once released. This is the source of the hydrocarbon plume, consisting mainly of dispersed and dissolved hydrocarbons. This plume extended more

Deepwater Horizon Well Blowout Mass Balance Chapter j 15

817

than 200 km from the blowout at a depth of 1100 m. Several reports from cruises during the blowout showed the plume consisted primarily of soluble compounds [49]. Studies by Ryerson et al. showed that the soluble compounds made up about 70% of the subsea oil, while these soluble compounds only made up about 25% of the starting oil composition [50]. This indicates about a threefold enrichment in the subsea plume of soluble components and a threefold increase in the amount of nonsoluble components rising to the surface. This would imply that the oil was weathered by loss of the soluble compounds amounting to about 50%. It was noted further that little of the subsurface oil was trapped as small oil droplets and then only initially. Most was in the form of dissolved components as one progressed away from the blowout.

15.3.4.2 Weathering A few of the questions asked during the recent DWH incident include whether the oil was weathered and whether it formed emulsions. The immediate but incorrect presumption was that it occurred on the surface after it hit. Reflection upon this, however, reveals that most of the oil that came up was emulsified and all of it was already highly weathered [51e53]. This means that these weathering processes occurred in the water column or more likely, near the well head as described in the solubility section above. This also occurred at Ixtoc. Aeppli et al. studied the subsequent weathering of the Macondo oil, which occurred after the discharge [54]. This oxidation was found to be significant. Liu et al. studied the post-weathering emulsion on the sea as well as in the marshes and in sediments [55]. They concluded that the emulsion was still weathering on the sea surface, primarily by evaporation. They also concluded that little weathering occurred in the marshes and in the sediments. These studies show that oil was extensively weathered, especially once it encountered the shore. 15.3.4.3 Effect on Oil Composition The resulting effect of the above processes as well as the physical mixing and the inclusion of water is the formation of three components (gas, rising weathered oil, and dissolved material in water), all of which have different compositions. The end results are highly weathered oil, which largely rises to the surface, gas plume, and a separate oil-laden water plume. The latter two plumes may separate further and travel with currents. Some of the material in these plumes may also rise. The oil in the water plume is composed of compounds up to C15, especially aromatics. The oil in the gas plume is more abundant and may contain more of the larger substances up to at least C15.

818

Oil Spill Science and Technology

15.3.5 Physical Behavior at Exit The high velocity jet causes several physical effects, droplet shattering, mixing, and water entrainment. Once the velocity is slowed, there is a small inversion or foldout. This is analogous to the mushroom cloud of an explosion. This foldout results in a large amount of water, soluble oil compounds, and gases leaving the plume. Adams and Socolofsky noted that this foldout may occur at about 180 m, depending, of course, on many conditions such as release pressure [13]. The rising plume after a foldout still has sufficient energy to form water-in-oil emulsions, and it may be that they are formed at or above the height of the foldout. Several other researchers confirmed the behavior of oil at blowout release points [56,57].

15.3.6 In-Sea Weathering The surfaced oil was weathered between 45% and 60%, assumed here to be 50%. This is consistent with the physics and chemistry explained in Section 15.3. The process of weathering happens to be the single-largest remover of oil during the Gulf oil spill. Several workers noted that studies of the water column showed extensive dissolution [58]. Most of the hydrocarbons found in subsea plumes were soluble compounds and a strong soluble preference was found in the measured compounds. McNutt et al. noted that by all calculations only about 50% of the oil rose to the surface [36,59]. This was counted as 14% evaporation and 33% dissolution. In another part of the study it was noted that at least 50% did not rise counting all the various losses of the oil. It was further noted that surface calculations showed less than 50% of the oil calculated to be discharged, appeared on the surface. The amount in the sea was found to range between 33,000 and 48,000 barrels per day. This would correspond to about 60e70% [59]. There are several indications that weathering was 50% or more including: 1. the fact that much of the oil formed stable emulsions, which by tests only occurs at about 50% weathering or more; 2. measurements of weathered oil on the surface near the surfacing zone showed this amount of weathering; 3. several other studies on the amount of oil weathered are summarized in this paper; 4. several other modeling studies also showed about 50% weathering before the oil reached the surface; and 5. analysis of the oil by Lewan et al. showed that the oil on the surface was generally weathered by 50% [60]. The nominal weathering amount can then be taken as 50% in the water.

Deepwater Horizon Well Blowout Mass Balance Chapter j 15

819

15.4 THE FATE AND REMOVALS OF OIL ON THE SEA SURFACE There was direct and quantified removal of the oil by skimmers and by in situ burning. One can then consider the amount of oil that came ashore and the amount weathered before it came to the surface. This section will also summarize the estimations of losses on the surface as noted in the behavior section above.

15.4.1 Skimming Skimmers were used to remove oil from the Gulf water surface. These skimmers varied greatly in size, application, and capacity, as well as in recovery efficiency and water pickup. In the particular case of the Gulf oil spill the major issue was the amount of water recovered. It is known that 735,000 barrels of liquid were recovered [1]. The question to remains is how much of this was oil. The most important fact about this is that decanting was allowed for the first time in a major spill [61]. This meant that for those oils recovered as weathered oil there was little water in the mixdperhaps as little as 1e5%. For those oils recovered as emulsion, the water content was typically 60%. A mix of the weathered and emulsified oil was recovered. Many of the recovery vessels also had oilewater separators. Unfortunately, the water content in most of the recovered liquids was not measured. A conservative value of recovery would be 75% oil, and the maximum value would be 95%. Thus, a median value of 85% can be taken as oil. Performing the calculation, 99,000 m3 (735,000 barrels liquid recovered X .85 X .159 barrels to m3 = 99,000 m3) of oil was recovered by this group. This value appears to be much higher than that of the federal interagency solutions group (FISC) report, though that value was based on 100% oil, and not 50% as here. The remaining difference is that of the water content as noted above. The timing of this was that this group began about one week after the blowout and worked a few days after the blowout was capped. Daily recovery amounts were not released.

15.4.2 Vessel-of-Opportunity Removal System An extensive system of nearshore recovery was put in place using local fishing fleet vessels or vessels-of-opportunity. There were three groups organized for three geographical areas. Each group had five task forces and each task force consisted of five vessels [62e65]. Each group had 125 vessels for 375 fishing vessels total that were dedicated to skimming. There were other vessels (safety, shuttle, berthing, etc.) and barges. The assembly of the groups did not occur at the same time and progressed through the cleanup time. Although the group started early in the spill, it was not fully operational and equipped until about a month after the spill. At first many of the boats worked with sorbents and boom until they received skimmers. Near the end of

820

Oil Spill Science and Technology

FIGURE 15.3 Vessel-of-opportunity system depicted at work.

the operation they had more than 500 skimmers. A vessel-of-opportunity recovery system is shown in Fig. 15.3. Volume records were not kept, however on some days, estimates of particular vessels were made verbally. Often the estimates of 0e3 barrels/day (0e0.5 m3) were given. An average of 1.5 barrels/day/vessel or 0.25 m3/day/ vessel was used for this study. Given a total operating time of 113 days and an average of 220 vessels, this yields a total recovery of 5720 m3 or 36,000 barrels.

15.4.3 In Situ Burning An oil slick burns at a rate of 2e4 mm/min. The amount burned can be estimated using this range, the area of the slick on fire, and the total time of the burn. The best estimate is that 44,000 m3 or 275,000 barrels of oil were burned [66e69]. Fig. 15.4 shows one of the DWH burns.

FIGURE 15.4

One of the burns during the Deepwater Horizon spill.

Deepwater Horizon Well Blowout Mass Balance Chapter j 15

821

15.4.4 Oil on the Shoreline Oil appeared on the shoreline over a long distance from Florida to Louisiana [70e78]. Table 15.4 shows an older estimate of the amounts of shoreline oiled based on literature available in 2013 [3,70]. The widths of oiling used as shoreline criteria are shown in Table 15.5 [79]. The amount of oil on the shoreline was estimated by noting the thickness as an average 1 cm. Table 15.4 shows the estimations of shoreline oiling using this tactic. It was noted that the eastern states were oiled less frequently than the Louisiana coast which was probably oiled between 3 and 12 times. If one takes the least-oiled case, e.g., a thickness of 0.8 cm, it yields a total oiling of 215,000 barrels; the nominal or most probable situation would be a thickness of 1 cm, yielding an oiling of 390,000 barrels (62,000 m3). The heaviest oiling case would be if the thickness was 2 cm and a fivefold oiling of Louisiana, yielding 780,000 barrels (125,000 m3). A newer estimate of shoreline oiling was published by Nixon et al. [80] This used extensive ground surveys plus satellite imagery to yield a more accurate picture of the oiling. It was further noted that the amounts of oiling were more frequent than noted in the paper above. These data are summarized in Table 15.6. Values analogous to that mentioned above are obtained. If one takes the least-oiled case, e.g., a thickness of 0.8 cm, it yields a total oiling of 30,500 m3, the nominal or most probable situation would be a thickness of 1 cm, yielding an oiling of 54,000 m3 (340,000 barrels). The heaviest oiling case would be if the thickness was 2 cm yielding 108,000 m3. The value used here is the most probable case of 54,000 m3. These estimates are also more poignant when one considers that some of the oil was retained in salt marshes [81,82]. Nixon et al. estimated that by 2011, 626 million pounds (284,000,000 kg) of contaminated shoreline material had been gathered and by 2015 this total was 642 million pounds (290,000,000 kg) [83]. Given that 54,000 m3 was on shore or about 50,000,000 kg of oil, this would yield an average oil content in the gathered debris of about 18%. This appears to be reasonable. A saturated soil would hold about 500% of its weight in oil, so the appearance of 18% would be that of soil with a tinge of oil color. Tar mats became exposed nearshore for years after the spill and some very large ones were exposed by hurricanes. This adds to the estimates of the amount of oil on the beaches. There were a number of episodes of massive reoiling, mostly the exposure of tar mats [84e88]. These episodes occurred mostly in Louisiana, but also as far as Florida and Texas. Most of these were the exposure of tar mats containing 5e20% oil, typically about 10%. In the five referenced incidents, the oil amount is about 10,000 tons alone. These exposures occurred in the first year of the spill and still continued 5 years later. Continuous shoreline cleanup continued for 4 years after the spill. After that, monitoring continues with cleanup of episodic oiling.

822

Oil on Shoreline Type (m3)

Contaminated Shorelines (km) Shore Type

Heavy

Moderate

Light

Very Light

Trace

Heavy

Moderate

Light

Very Light

Trace

Total

Beach

85.8

52.3

100

59.1

13.4

2145

523

500

89.8

2

3259.8

Wetland

129.6

153

184.7

202.2

23.7

3240

1530

923.5

307.3

3.6

6004.4

Man-made

4.8

2.3

3.7

2.6

4.7

120

23

18.5

4

0.7

166.2

Total

220.2

207.5

288.4

263.9

41.7

5505

2075

1442

401.1

6.3

9429.4

Beach

126.5

7.7

318.8

28.7

118.5

3162.5

77

1594

43.6

17.8

4894.9

Wetland

1.1

5.6

26.9

16.9

5.5

27.5

56

134.5

25.7

0.8

244.5

Man-made

0.2

0.5

6.6

4.5

4.7

5

5

33

6.8

0.7

50.5

Total

127.8

13.8

352.3

50.1

128.6

3195

138

1761.5

76.2

19.3

5190

0

0

8700

5532.5

3203.5

477.3

25.6

14,619.4

Louisiana

Eastern States

Total

348

221.3

640.7

314

170.3

92,000 bbl

Oil Spill Science and Technology

TABLE 15.4 Calculations of Oil Arriving at Shorelines

Nominal oiling

Heavier oiling (2 cm average)

42,908 (270,000 barrels)

Single oiling of eastern states plus 5 oilings of Louisiana

61,766 (390,000 barrels)

Nominal

Single oiling of eastern states plus 3 oilings of Louisiana

34,326 (215,000 barrels)

Least

Single oiling of eastern states plus 5 oilings of Louisiana

49,413 (310,000 barrels)

Single oiling of eastern states plus 3 oilings of Louisiana

85,816 (540,000 barrels)

Single oiling of eastern states plus 5 oilings of Louisiana

123,532 (780,000 barrels)

Most

Deepwater Horizon Well Blowout Mass Balance Chapter j 15

Light oiling (0.8 cm average)

Single oiling of eastern states plus 3 oilings of Louisiana

823

824

Oil Spill Science and Technology

TABLE 15.5 Surface Cover Calculations Category

DWH Standard Width

Chosen Width (m)

Estimateda Oil/km (m3)

Heavy

>1.8 m

2.5

25

Moderate

0.9e1.8

1

10

Light

0.3e0.9

0.5

5

Very light

<0.3

0.15

1.5

0.015

0.15

Trace a

Presuming average thickness of 1 cm.

15.4.5 Residual Oil As noted above several of the shorelines retained oil that was not observed during and after the cleanup [81]. It is estimated that 2000 m3 of oil was retained in this manner.

15.4.6 Surface Chemical Dispersion Bejarano et al. reported on a dispersant-effectiveness sampling program during the DWH spill using the Special Monitoring of Applied Response Technologies (SMART) monitoring protocol [89]. The effort was to compare results from a sampling program with the results obtained using SMART. During the DWH, all three tiers of SMART were implemented: Tier-I visual observation; Tier-II in situ fluorometry monitoring at 1 m depth; and Tier-III in situ fluorometry monitoring at 1 and 10 m depths with collection of water samples for chemical analyses. The effectiveness of aerial application was not monitored for safety reasons, instead a boat spray system was used. It was found that 3 of more than 30 slicks sampled were effective using the SMART criteria.

15.4.7 Additional Surface Weathering After the oil rose to the surface it was subject to further weathering [48,60]. Specific studies using asphaltenes as a marker, compensating for photooxidation, were conducted on surface samples in the Gulf. It was found that the average weathering of the oil was 61% by volume or 55.2% by weight. The values ranged from 48 to 63.9% by weight. It is suspected that the values would range that much due to exposure. The additional weathering value of 11% by weight was taken for oil that was not skimmed near the release. The value of weathering for oil skimmed near the release was taken as 3% above the 50% subsurface weathering, because it was not exposed long enough to achieve a greater weathering.

Oil on Shoreline Type (m3)

Contaminated Shorelines (km) Shore Type

Heavier, Lit. Per.

Heavier

Lighter. Persistent

Lighter

Heavier, Persistent

Heavier, Lit. Per.

Heavier

Lighter. Persistent

Lighter

Total

Beach

86

90

15

39

63

2150

900

75

59.3

9.5

3193.8

Wetland

72

276

707

1800

0

1380

0

106.1

3286.1

Other

2

4

0

10

50

0

20

0

1.5

71.5

Total

160

90

295

39

780

4000

900

1475

59.3

117

6551.3

Beach

1

69

1

60

6

25

690

5

91.2

0.9

812.1

Wetland

0

0

7

0

0

0

0

1.1

1.1

Other

0

1

0

9

0

0

5

0

1.4

6.4

Total

1

69

2

60

22

25

690

10

91.2

3.3

819.5

Beach

1

60

0

123

101

25

600

0

187

15.2

827.2

Wetland

0

0

0

0

0

0

0

0

Louisiana

Alabama

Florida

0

Continued

825

Heavier, Persistent

Deepwater Horizon Well Blowout Mass Balance Chapter j 15

TABLE 15.6 Shoreline Oiling Calculator Based on 2016 Information

826

Oil on Shoreline Type (m3)

Contaminated Shorelines (km) Shore Type

Heavier, Persistent

Heavier, Lit. Per.

Heavier

Lighter. Persistent

Lighter

Heavier, Persistent

Heavier, Lit. Per.

Heavier

Lighter. Persistent

Lighter

Total

Other

0

1

0

2

0

0

5

0

0.3

5.3

Total

1

60

1

123

103

25

600

5

187

15.5

832.5

Beach

18

39

1

118

22

450

390

5

179.4

3.3

1027.7

Wetland

0

3

41

0

0

15

0

6.2

21.2

Other

0

0

0

15

0

0

0

0

2.3

2.3

Total

18

39

4

118

78

450

390

20

179.4

11.7

1051.1

Beach

0

0

0

0

57

0

0

0

0

8.6

8.6

Wetland

0

3

41

0

0

15

0

6.2

21.2

Other

0

0

0

15

0

0

0

0

2.3

2.3

Total

0

3

0

113

0

0

15

0

17

32

Mississippi

Texas

0

Total other states 2703.1

Oil Spill Science and Technology

TABLE 15.6 Shoreline Oiling Calculator Based on 2016 Informationdcont’d

Nominal oiling

Heavier oiling (2 cm average)

38,163 (240,000 barrels)

Triple oiling of eastern states plus 7 oilings of Louisiana

53,968 (340,000 barrels)

Nominal

Single oiling of eastern states plus 3 oilings of Louisiana

30,530 (192,000 barrels)

Least

Single oiling of eastern states plus 5 oilings of Louisiana

43,174 (270,000 barrels)

Single oiling of eastern states plus 3 oilings of Louisiana

76,326 (480,000 barrels)

Single oiling of eastern states plus 5 oilings of Louisiana

107,936 (680,000 barrels)

Most

Deepwater Horizon Well Blowout Mass Balance Chapter j 15

Light oiling (0.8 cm ave.)

Double oiling of others plus 5 oilings of Louisiana

827

828

Oil Spill Science and Technology

15.4.8 Marine Snow Formation There are two types of marine snow: microbial-derived marine oil snow : Produced by microorganisms as a by-product of oil biodegradation; and phytoplanktonderived marine oil snow (PDOS): Phytoplankton exposed to oil increase production of transparent exopolymer particles (TEP) as a protective mechanism [90,91]. This TEP emulsifies oil and produces PDOS [92]. The planktonic (microbial and phytoplankton) communities exposed to oil produce more TEP, which facilitates the formation of marine snow, which sinks as a result of flocculation processes, and can scavenge other suspended materials in the water column [92,93]. Both processes have been found to result in significant oil removal. Joye estimated that 2e15% of the surface or near-surface oil was sedimented as marine snow [2,94]. Vonk et al. also studied the occurrence of marine snow at DWH and other spills [95]. They found that the extensive marine snow at DWH was not unique and that it had also been shown at other spills, such as at Ixtoc. For this study, a value of 8% and 20,000 m3 will be used.

15.4.9 Sinking Oil interacts with mineral particles to form aggregates which may be prone to sinking. This is especially true in nearshore areas. It is estimated that 3500 m3 was lost in this manner [96].

15.4.10 Oil Moving out of Area Some of the oil was known to move out of the prime study area toward Mexico or Cuba [97]. The fate of this oil is unknown. An estimate of this amount is 10,000 m3.

15.5 SUBSURFACE FATE AND LOSSES 15.5.1 Oil Sunken Near the Accident Site Several surveys of the benthic environment were conducted near the accident site [98]. These surveys found petroleum-derived hydrocarbons associated with the Macondo blowout on the surface. Chanton et al. used sample data in the blowout area of 2.4  1010 m2 (2.4  103 km2) to calculate average deposition in this area [98]. This calculation results in an estimate of between 24,000 and 40,000 m3 (150,000 to 245,000 barrels) of oil on the sediment. Taking the average of this, it is estimated that 31,000 m3 of oil was deposited on the bottom area near the accident site. Similarly, Valentine et al. used sample results from 534 locations in an area of 3200 km2 around the Macondo blowout [99]. Using hopane as a surrogate and the estimate that 2,000,000 barrels (320,000 m3) of oil were trapped in

Deepwater Horizon Well Blowout Mass Balance Chapter j 15

829

deep water, it was estimated that 4e31% of this oil was deposited on or with the sediments. This yields between 80,000 and 620,000 barrels of oil with an average of 350,000 barrels or 56,000 m3 of oil. This is similar to the above estimate in that the area is somewhat larger. Valentine et al. noted that oil was certainly deposited outside this area but results were very heterogeneous [99]. One could estimate that about the same amount was deposited outside the immediate area. Fisher et al. noted that coral on the sea floor was extensively affected at around 6 km distance from the well head [100]. The effects, although less severe, were detected as far as 24 km from the well site. Similar coral damage was found by others [101]. Others noted that segmented worms within 6e9 km of the wellhead were impacted by the oil [102]. Examination of the sedimentation near the well site shows that up to several centimeters of sedimentation occurred within the time period the well was in blowout mode, whereas in other time periods this sedimentation was orders of magnitude lower for the same 6 months [103]. The mechanism behind this sinking was not investigated fully; however, Gros et al. noted that separation of dissolved components alone would not be sufficient to cause sinking by itself and that particle adhesion or marine-snow mechanisms must be involved [32]. Using the value of Valentine et al., the estimated value of oil sedimented near the blowout site is 56,000 m3. The estimate for the oil outside this area is that the same amount was also precipitated outside the area near the well site.

15.5.2 Dissolution and Plumes As was shown above, much of the subsea oil was dissolved components derived from the oil that rose [50]. This was covered in earlier in this chapter. It is important to distinguish between oil in the plumes and general dissolution. Both contained dissolved oil, however, plumes also contain droplets, at least for a short distance, and were largely derived from the blowout foldout. General dissolution occurred around the blowout plume as it rose through the water column. Indications are that 50% of the subsurface oil was in dissolved form [99]. Similarly, it was estimated that the main plume contained 320,000 m3 of oil [17,99]. It was estimated that a similar amount of oil was in other minor plumes.

15.5.3 Subsea Chemical Dispersion Chemical dispersant was injected into the oil near the discharge initially and later into the well hardware [104,105]. The effectiveness of this was not measured quantitatively. Gros et al. concluded that the level of dioctyl sodium sulfosuccinate, a dispersant ingredient, was found to be at concentrations up to 12 mg/L of oil [32]. This was noted by Gros et al. to be four orders of

830

Oil Spill Science and Technology

magnitude below critical micelle concentrations and thus would not influence the partitioning of hydrocarbons into water.

15.5.4 Marine Snow As noted above marine-snow formation was shown to sediment some of the oil subsurface, as well as at or near the surface [85,86]. The same estimate as the surface estimate or 8%, and 125,800 m3 was used.

15.5.5 Summary of Losses From the Surface and Subsurface Table 15.7 shows the summary of the above discussion on the losses or disposition of oil both on the surface and the subsurface. The volume of the oil discharges was divided equally between the surface and subsurface, in

TABLE 15.7 Losses and Removals From the Deepwater Horizon Blowout Surface Disposition of 2,88,980 m3

Subsurface Disposition of 2,88,980 m3

Process

Volume

%

Est. Error

Process

Volume

%

Est. Error

Skimming

99,375

34

10

Dissolved

500,000

28

50

On shore

54,060

19

50

Subsurface plume

320,000

18

50

Burning

43,730

15

10

Dispersed outside plume

320,000

18

50

Weathering

31,010

11

2

Marine snow

125,800

7

20

Sunken snow

20,000

7

5

Bath tub ring

56,000

3

10

Out of area

10,000

3

5

Other sedimentation

56,000

3

10

VOSS

5720

2

20

Sunken

3500

1

5

Residual

2000

1

5

Nearshore sunken

2000

1

5

Sum

271,395

94

Sum

1,377,800

76

Unaccounted for

17,585

6

Unaccounted for

4,39,700

24

All volumes in m3.

Deepwater Horizon Well Blowout Mass Balance Chapter j 15

831

accordance with the literature. The oil on the surface is consumed largely by countermeasures and by shoreline oiling. The major skimming over the blowout accounts for 34%, the shoreline losses account for 19%, and burning accounts for 15% of the oil. There are a number of documented losses of lesser percentage. About 6% of the surface oil was not accounted for in this calculation. The subsurface oil is largely accounted for by dissolution of the oil and the plumes of dispersed oil. The plumes of dispersed oil were as far as 250 km away from the blowout site. These three items were estimated to account for 64% of the oil. Other minor items account for about 13% of the oil. For the subsurface, about 24% of the oil cannot be accounted for.

15.6 TIMING OF THE LOSSES AND ADDITIONS There are some data available to calculate the approximate time scale of mass gains and losses. MacDonald et al. used synthetic aperture radar data over the DWH spill and neural network analysis of satellite synthetic aperture radar images to quantify the magnitude and distribution of surface oil in the Gulf of Mexico from persistent, natural seeps, and from the DWH discharge [106]. This analysis was able to separate the seeps from oil in the DWH blowout. This analysis showed that the 87-day DWH discharge produced a surface-oil footprint fundamentally different from background seepage, with an average ocean area of 11,200 km2 and a volume of 22,600 m3. Peak magnitudes of oil were detected during equivalent, w14 day intervals around May 23 and June 18, when wind speeds remained <5 m s1. Over this interval, aggregated volume of floating oil decreased by 21%; however, the area covered increased by 49%. These data then can be used in this paper to compare these to the other information known about the spill. The values of some oil losses or disposition presented in this chapter can be calculated as a time series and based on some information on timing. For example, the amounts burned are both given volume estimates and dates. This is shown in Fig. 15.5. These data were easy to obtain, however, skimmer recovery amounts and dates, and the amounts deposited on shorelines were not. In every case, removals were estimated to be initiated slowly and occur over a broad time scale. Daily recovery or shoreline oiling rates were not obtained but in many cases they would not be available. These fate data were accumulated in a spread sheet and totaled to estimate the amount of oil on the surface as shown in Table 15.8. Fig. 15.6 and 15.7 show the overlay of both the MacDonald areas and the calculated volume with the times of losses or countermeasures counted here. These figures show a great deal of correspondence between the various areas and surface amounts. Fig. 15.6 and 15.7 show similar trends between the estimated removals calculated in this paper and the areas, and surface volumes estimated by MacDonald et al. using remote sensing. In both cases the volume on the surface peaks on

832

Oil Spill Science and Technology

FIGURE 15.5

Graph of the oil burned and the day number after the blowout.

about day-35 after the blowout (about May 18e25), and then the surface volume declines. The declines are probably due to the intensification of countermeasures as well as the extensive shoreline oiling that took place at these times. Fig. 15.7 also shows the estimated daily removal rate and how it increases as the spill progresses and gradually reduces the amount of oil on the surface. Fig. 15.8 shows the overall average of oil on the surface calculated by averaging the estimated surface volume here and the amount estimated by MacDonald et al. [106]. This shows major events versus an average amount of oil on the surface. There appears to be in correspondence to events such as the reported major shoreline oiling on day-30 (May 19) and a reduction of surface oil. Similarly, the absence of surface countermeasures during hurricane Alex shows a small rise in surface-oil amount, and resumption of countermeasures shows a decrease. It must be reemphasized that the countermeasures except for burning were just estimated and spread out over the time period that they were active.

15.7 CALCULATION OF MASS BALANCE Table 15.7 presents a summary of the losses and removals from the blowout as it was estimated both on the surface and the subsurface. The graph of the average estimated mass balance of the surface oil is shown in Fig. 15.9. This is marked by the predominance of four factors: The skimming of an estimated 34%, the amount on shore of 19%, the burning of 15%, and the surface weathering amount of 11%.

TABLE 15.8 Table of Dates, Events, and Fate Amounts #

Blowout to Top Weathered

0

Events

m3

Blowout

8,397

m3

Oil

Removals or Losses From the Surface

Skimming

Burning

VOSS

Shoreline

Sunken/ Snow

Total

Others

Surface Losses

Left on Surface

1

20 Apr

2

21 Apr

8,372

840

800

800

3

22 Apr

8,347

2,517

2,370

2,370

4

23 Apr

8,322

5,868

5,480

5,480

5

24 Apr

8,297

10,049

9,320

9,320

8,272

14,217

13,080

13,080 16,780

2

6

25 Apr

Slick 1500 km

7

26 Apr

8,247

18,373

16,780

8

27 Apr

8,222

22,517

20,440

1,105

1,105

19,340

9

28 Apr

8,197

26,648

24,050

1,105

1,105

21,840

10

29 Apr

8,172

30,766

27,610

2,215

2,215

23,190

11

30 Apr

8,147

34,872

31,130

2,215

12

01 May

8,122

38,966

34,770

2,215

13

02 May

8,097

43,047

38,400

14

03 May

8,072

47,115

42,010

First shoreline contact

45

13

13

2,286

24,420

3

45

13

13

2,289

25,770

2,215

3

45

13

13

2,289

27,110

2,215

3

45

13

13

2,289

28,430 Continued

TABLE 15.8 Table of Dates, Events, and Fate Amountsdcont’d #

Blowout to Top Weathered

0

Events

Removals or Losses From the Surface

Total

VOSS

Shoreline

Sunken/ Snow

Others

Surface Losses

Left on Surface

5

45

13

13

2,291

29,720

170

5

45

13

13

2,461

30,810

1,105

1,180

7

45

13

13

2,363

31,980

56,170

2,215

320

8

45

13

13

2,614

32,860

67,270

59,700

2,215

9

45

13

13

2,295

34,100

7,922

71,264

63,200

45

13

13

71

37,530

m3

m3

Oil

Skimming

8,047

51,171

45,590

2,215

8,022

55,215

49,140

2,215

7,997

59,246

52,670

7,972

63,264

7,947

Burning

15

04 May

16

05 May

17

06 May

18

07 May

19

08 May

20

09 May

21

10 May

7,897

75,245

66,670

45

13

13

71

40,930

22

11 May

7,872

79,213

70,150

45

13

13

71

44,340

23

12 May

7,847

83,169

73,640

45

13

13

71

47,750

24

13 May

7,822

87,113

77,410

45

13

13

71

51,450

25

14 May

7,797

91,044

81,170

45

13

13

71

55,140

26

15 May

94,962

84,870

45

13

13

80

58,760

First burns

First container dome

Oil reported in Alabama

Riser tube inserted

9

27

16 May

15,000 barrels/ day

98,091

87,710

1,105

9

45

13

13

1,185

60,420

28

17 May

Start of sub-surf ops

100,433

89,730

1,105

540

11

45

13

13

1,727

60,710

29

18 May

101,213

90,270

1,105

170

13

45

13

13

1,359

59,890

30

19 May

101,213

90,130

1,105

4,530

13

360

161

88

6,257

53,490

31

20 May

101,213

90,030

1,105

18

360

161

88

1,732

51,660

32

21 May

101,213

89,940

1,105

18

360

161

88

1,732

49,840

33

22 May

101,213

89,850

1,105

18

360

161

88

1,732

48,020

34

23 May

101,213

89,760

2,215

1,880

18

360

161

88

4,722

43,210

35

24 May

101,213

89,670

2,215

210

18

360

161

88

3,052

40,060

36

25 May

7,775

101,213

89,580

1,105

380

36

360

161

88

2,130

37,840

37

26 May

7,753

101,990

90,240

2,215

80

36

360

161

88

2,940

35,560

38

27 May

7,731

103,543

91,620

2,215

100

36

720

309

174

3,554

33,390

39

28 May

7,709

106,646

94,280

2,215

42

720

309

174

3,460

32,590

40

29 May

7,687

110,518

97,670

2,215

130

42

720

309

174

3,590

32,390

41

30 May

7,665

114,379

101,030

2,215

210

42

720

309

174

3,670

32,080

42

31 May

7,643

118,230

104,360

2,215

330

42

720

309

174

3,790

31,620

Major shoreline oiling

Riser tube removed

Continued

TABLE 15.8 Table of Dates, Events, and Fate Amountsdcont’d #

Blowout to Top Weathered

0

Removals or Losses From the Surface

Total

Events

m3

m3

Oil

Skimming

Burning

VOSS

Shoreline

Sunken/ Snow

Others

Surface Losses

Left on Surface

Oil on Florida

7,621

122,069

107,670

2,215

2,480

42

720

309

174

5,940

28,990

43

01 Jun

44

02 Jun

7,599

125,897

110,990

2,215

1,180

42

720

309

174

4,640

27,670

45

03 Jun

7,577

129,714

114,640

2,215

170

42

720

309

174

3,630

27,690

46

04 Jun

7,555

133,520

118,270

57

720

309

174

1,260

30,060

47

05 Jun

7,533

137,315

121,890

57

720

309

174

1,260

32,420

48

06 Jun

7,511

141,099

125,490

57

720

309

174

1,260

34,760

49

07 Jun

7,489

144,872

129,080

2,215

190

57

720

632

310

4,124

34,230

50

08 Jun

7,467

148,634

132,650

2,215

760

57

720

632

310

4,694

33,100

51

09 Jun

7,445

152,385

136,210

1,105

520

57

720

632

310

3,344

33,320

52

10 Jun

7,423

156,126

139,750

1,105

100

57

720

726

350

3,058

33,800

53

11 Jun

7,401

159,855

143,280

1,105

1,160

74

300

632

286

3,557

33,770

54

12 Jun

7,379

163,573

146,590

1,105

2,690

74

300

632

286

5,087

32,000

55

13 Jun

7,357

167,280

149,890

1,105

620

74

300

632

286

3,017

32,280

56

14 Jun

7,335

170,976

153,180

1,105

160

74

300

632

286

2,557

33,010

57

15 Jun

7,313

174,661

156,460

1,105

3180

74

300

632

286

5,577

30,720

58

16 Jun

7,291

178,335

159,730

1,105

2100

74

300

632

286

4,497

29,490

59

17 Jun

7,269

181,998

162,990

1,105

10,560

74

300

632

286

12,957

19,790

60

18 Jun

7,247

185,650

166,240

1,105

350

74

300

161

286

2,276

20,770

61

19 Jun

7,225

189,291

169,480

1,105

80

74

300

161

150

1,870

22,140

62

20 Jun

7,203

192,922

172,710

1,105

74

740

161

176

2,256

23,110

63

21 Jun

7,181

196,541

175,930

1,105

74

740

161

176

2,256

24,070

64

22 Jun

7,159

200,149

179,140

1,105

74

740

161

176

5,056

22,230

65

23 Jun

7,137

203,746

182,340

1,105

74

740

161

176

2,256

23,170

66

24 Jun

7,115

207,332

185,530

740

161

176

1,077

25,280

67

25 Jun

7,093

210,907

188,710

740

632

176

1,548

26,920

68

26 Jun

7,071

214,471

191,880

740

632

176

1,548

28,540

69

27 Jun

7,049

218,024

195,040

740

632

176

1,548

30,150

70

28 Jun

7,027

221,566

198,190

740

632

176

1,548

31,750

71

29 Jun

7,005

225,097

201,330

740

632

176

1,548

33,340

72

30 Jun

6,983

228,618

204,460

740

632

176

1,548

34,930

73

01 Jul

6,961

232,127

207,580

1105

81

740

840

176

2,942

35,100

74

02 Jul

6,939

235,625

210,690

1105

81

1440

940

152

3,718

34,500

Very large burn

Hurricane Alex

Activity resumes

2800

Continued

TABLE 15.8 Table of Dates, Events, and Fate Amountsdcont’d #

Blowout to Top Weathered

0

Events

Removals or Losses From the Surface

Total

m3

m3

Oil

Skimming

Burning

VOSS

Shoreline

Sunken/ Snow

Others

Surface Losses

Left on Surface

1,400

81

1,440

632

152

4,810

32,790

75

03 Jul

6,917

239,112

213,790

1,105

76

04 Jul

6,895

242,588

216,880

1,105

81

1,440

632

152

3,410

32,470

77

05 Jul

6,873

246,053

219,960

1,105

81

1,440

632

152

3,410

32,140

78

06 Jul

6,851

249,507

223,030

1,105

81

1,440

632

152

3,410

31,800

79

07 Jul

6,829

252,950

226,090

1,105

81

1,440

161

152

2,939

31,920

80

08 Jul

6,807

256,382

229,140

1,105

81

1,440

161

152

2,939

32,030

81

09 Jul

6,785

259,803

232,180

1,105

81

1,440

161

152

2,939

32,130

82

10 Jul

6,763

263,214

235,210

1,105

1,560

81

1,440

161

152

4,499

30,660

83

11 Jul

6,741

266,613

238,240

1,105

840

75

1,440

161

152

3,773

29,920

84

12 Jul

6,719

270,001

241,260

1,105

75

1,440

161

152

2,933

30,000

85

13 Jul

6,697

273,378

244,270

1,105

220

75

1,440

81

152

3,073

29,940

86

14 Jul

6,675

276,744

247,270

1,105

140

75

1,440

81

152

2,993

29,950

87

15 Jul

6,653

280,099

250,260

1,105

100

75

1,440

81

152

2,953

29,990

88

16 Jul

283,443

253,240

1105

170

75

1,440

81

152

3,023

29,940

Blowout end

89

17 Jul

90

18 Jul

91

19 Jul

92

20 Jul

93

End of most surface measures

286,113

255,620

1105

75

1,440

81

152

2,853

29,470

288,111

257,400

1105

75

1,440

81

152

2,853

28,400

288,777

257,990

1105

75

1,440

81

152

2,853

26,130

1105

75

1,440

81

152

2,853

23,280

21 Jul

75

1,440

81

152

1,748

21,530

94

22 Jul

75

1,440

81

152

1,748

19,780

95

23 Jul

75

1,440

81

152

1,748

18,030

96

24 Jul

75

1,440

81

152

1,748

16,280

97

25 Jul

75

740

81

111

1,007

15,270

98

26 Jul

75

740

81

111

1,007

14,260

99

27 Jul

75

740

81

111

1,007

13,250

100

28 Jul

75

740

81

111

1,007

12,240

End of surface disposition

840

Oil Spill Science and Technology

FIGURE 15.6 Graph of the volumes and areas measured by MacDonald et al., compared to the volume values estimated in this chapter.

FIGURE 15.7 Graph of the input to the surface from the blowout compared to the estimated amount on the surface, the volume measured by MacDonald et al., and the daily spill countermeasures.

Deepwater Horizon Well Blowout Mass Balance Chapter j 15

FIGURE 15.8 the surface.

841

Chart of the spill events compared to an average amount of oil estimated to be on

FIGURE 15.9 Summary of the estimated mass balance items for oil on the sea surface.

842

Oil Spill Science and Technology

FIGURE 15.10 Summary of the estimations of the subsea oil.

Fig. 15.10 shows the estimated fate of the subsurface oil. The fate of the subsea is estimated to be dominated by dissolution, 28%, and dispersion in and out of plumes, 18% for both. The estimated errors are listed in Table 15.7. For the surface component, the errors for the shoreline are greatest and amount to about 50% of the particular value considered. The errors for burning and skimming are thought to be about 10% of that particular item. Errors for the amount of oil remaining in the water column are also similar. The errors for the subsea components are very large with 50% assigned to the largest components of dissolution and dispersion.

15.8 CONCLUSION A reexamination of the mass balance of the Macondo well at about the end of the capping of the well shows that there are several factors that should be considered, such as: 1. The oil discharge was a maximum of 4,080,000 barrels (649,000 m3) as 820,000 barrels were siphoned off and taken away. The court-ruling scenario with 3,190,000 barrels released (507,000 m3) was included to provide a minimum discharge case. The average used here was 578,000 m3 or 363,500 barrels. 2. The about 50% oil was weathered before surfacing. 3. The amount of oil in the recovered liquid from skimming was most likely about 85% as decanting and/or separation was carried out on most recovery systems. 4. The amounts of oil recovered from the shoreline, amounts as estimated in Section 15.4.3, were included in the scenario. These amounts are significant and vary from 15% to 23% of the total amount of the oil released. It is thought that 19% (of the total surface oil) is the best estimate of the amount of oil on the shoreline. The actual calculation was based on the average width and depth of oil, the length of shoreline oiled and finally the number of estimated oiling.

Deepwater Horizon Well Blowout Mass Balance Chapter j 15

843

5. The amount of oil removed by skimming and burning on the surface were significant and in total were estimated to be 49% of the surface oil. 6. Other transformations that occurred on the surface such as dispersion were not accounted for. These transformations are difficult to estimate and very little quantitative study of them was made. In summary, of the oil that came to the surface (about 50% of the oil), about 34% was skimmed near the upwelling point, 15% was burned, and about 19% went on shore. It was estimated that the oil weathered by another 11%. Other fate mechanisms such as the formation of marine snow, stranding, sinking, and small boat recovery accounted for another 15% leaving the fate of about 6% unknown. For the subsurface oil, 28% was estimated to have dissolved, 18% was in the dispersed plume, and 18% dispersed in other directions. Both dissolved oil and dispersed oil were present in the plumes near the well site, however further out, most of the plumes were dissolved oil. Other mechanisms including marine snow and sedimentation account for about 13% of the oil with about 24% being unaccounted for. The errors of the estimations for the subsurface fate are large (about 50%). A time analysis of the oil on the surface compared to the estimations carried out in this study and compared to remote sensing measurements shows correspondence. It should be noted that timing information on many of the countermeasures was unavailable. This time analysis shows that the major influences on the amounts surface oil were the skimming, shoreline encounter, and burning.

REFERENCES [1] [2] [3] [4]

[5]

[6] [7]

[8]

FISG. Oil budget calculator: Deepwater Horizon, the Federal Interagency Solutions Group. A report to the Incident Command. U.S. Government; November, 2010. Joye SB. Deepwater Horizon, 5 years on. Science 2015;349(6248):592. Fingas M. MACONDO well blowout mass balance: a chemical view. AMOP 2013;75. Ramseur JL. Deepwater Horizon oil spill: the fate of the oil, fate of the oil from the Deepwater Horizon spill. Congressional research service report 7-5700. 2011. www.crs. gov. 1, 20. Liu Y, MacFadyen A, Ji ZG, Weisberg RH, editors. Monitoring and modeling the Deepwater Horizon oil spill: a record breaking enterprise. Geophysical monograph series, vol. 195; 2011. Washington, D.C. Jernelov A, Linden O. Ixtoc I: a case study of the World’s largest oil spill. Ambio 1981;10(6):299. Boehm PD, Fiest DL, Mackay D, Paterson S. Physical-chemical weathering of petroleum hydrocarbons from the IXTOC I blowout: chemical measurements and a weathering model. Environmental Science & Technology 1982;16(8):498. Boehm PD, Fiest DL. Subsurface distributions of petroleum from an offshore well blowout. The Ixtoc I blowout, bay of campeche. Environmental Science & Technology 1982;16(2):67.

844

Oil Spill Science and Technology

[9] Macko SA, Winters JK, Parker PL. Gulf of Mexico dissolved hydrocarbons associated with the IXTOC I mousse. Marine Pollution Bulletin 1982;13(5):174. [10] Patton JS, Rigler MW, Boehm PD, Fiest DL. Ixtoc 1 oil spill: flaking of surface mousse in the Gulf of Mexico. Nature 1981;290(5803):235. [11] Adams EE, Socolofsky SA. Review of deep oil spill modeling activity supported by the DeepSpill JIP and offshore operators committee. Technical report, submitted to C. Cooper and the U.S. Dept. Interior. Minerals Management Service; February, 2005 (Last revision). [12] Masutani SM, Adams EE. Experimental study of multiphase plumes with application to deep ocean oil spills. Final report to U.S. Dept. of the Interior. Minerals Management Service; 2001. Contract No., 1435-01-98-CT-30946. [13] Adams EE, Socolofsky SA. Expected behavior of SINTEF’s oil/gas release experiments based on MIT laboratory experiments. Technical report, submitted to C. Cooper and the U.S. Dept. Interior. Minerals Management Service; February, 2001. [14] Socolofsky S, Adams EE. Multiphase plumes in uniform and stratified crossflow. Journal of Hydraulic Research 2002;40(6):661. [15] Socolofsky S, Adams EE. Liquid volume fluxes in stratified multiphase plumes. Journal of Hydraulic Engineering 2003;129(11):905. [16] Socolofsky SA, Dissanayake AL, Jun I, Gros J, Arey JS, Reddy CM. Texas A&M oilspill calculator (TAMOC): modeling suite for subsea spills. AMOP 2015;153. [17] Camilli R, Reddy CM, Yoerger DR, Van Mooy BAS, Jakuba MV, Kinsey JC, McIntyre CP, Sylva SP, Maloney JV. Tracking hydrocarbon plume transport and biodegradation at Deepwater Horizon. Science 2010;330(6001):201. [18] Dasanayaka LK, Yapa PD. Role of plume dynamics phase in a Deepwater oil and gas release model. Journal of Hydro-environment Research 2009:243. [19] Chen FH, Yapa PD. A model for simulating Deepwater oil and gas blowoutsdpart II: comparison of numerical simulations with “DeepSpill” field experiments. Journal of Hydraulic Research 2003;41(4):353. [20] Yapa PD, Zheng L. Simulation of oil spills from underwater accidents I: model development. Journal of Hydraulic Research 1997;35(5):673. [21] Yapa PD, Zheng L. Modeling underwater oil/gas jets and plumes. Journal of Hydraulic Engineering 1999;125:481e91. [22] Yapa PD, Zheng L, Chen F. A model for Deepwater oil/gas blowouts. Marine Pollution Bulletin 2001;45:234. [23] Yapa PD, Johansen O, Xie H. Comparison of CDOG and DEEPBLOW. Report submitted to Chevron Texaco Energy Technology Co. December, 2003. [24] Zheng L, Yapa PD, Chen FH. A model for simulating Deepwater oil and gas blowoutsdpart I: theory and model formulation. Journal of Hydraulic Research 2003;41(4):339. [25] Johansen O. DeepBlowda Lagrangian plume model for deep water blowouts. Spill Science & Technology Bulletin 2000;6(2):103. [26] Johansen O. Development and verification of deep-water blowout models. Marine Pollution Bulletin 2003;47:360. [27] Johansen Ø, Jensen HV, Daling P. Deep spill JIP. Experimental discharges of gas and oil at Helland Hansen e June 2000. Cruise report, technical report. Trondheim, Norway: SINTEF Applied Chemistry; 2000. [28] Johansen Ø, Jensen HV, Melbye A. Rov sonar and visual pictures from the field trial ‘deep spill’, June 2000. Technical report. Trondheim, Norway: SINTEF Applied Chemistry; 2000.

Deepwater Horizon Well Blowout Mass Balance Chapter j 15

845

[29] Johansen Ø, Rye H, Melbye AG, Jensen HV, Serigstad B, Knutsen T. Deep spill JIP. Experimental discharges of gas and oil at Helland Hansen e June 2000. Technical report, technical report. Trondheim, Norway: SINTEF Applied Chemistry; 2001. [30] Johansen Ø, Rye H, Cooper C. DeepSpill e field study of a simulated oil and gas blowout in deep water. Spill Science & Technology Bulletin 2003;8(5/6):425. [31] Johansen Ø, Rye H, Durgut I. Generalized integral plume model for simulations of marine discharges. AMOP 2010;863. [32] Gros J, Reddy C, Nelson RK, Socolofsky SA, Arey JS. Simulating gas e liquid e water partitioning and fluid properties of petroleum under pressure: implications for deep-sea blowouts. Environmental Science & Technology 2016;50(14):7397. [33] Fingas M, Li K. A high-to-low pressure oil release: an overview of an oil fate experiment, internal report to spill science and environment Canada. March, 2011. 10 pp. [34] Beegle-Krause CJ, Boyer TP, Garcia HE. Deepwater Horizon MC252: understanding the spill below the surface. AMOP 2011;177. [35] Hickman SH, Hsieh PA, Mooney WD, Enomoto CB, Nelson PH, Mayer LA, Weber TC, Moran K, Flemings PB, McNutt MK. Scientific basis for safely shutting in the Macondo well after the April 20, 2010 Deepwater Horizon blowout. Proceedings of the National Academy of Sciences of the United States of America 2012;109(50):20268. [36] McNutt MK, Camilli R, Crone TJ, Guthrie GD, Hsieh PA, Ryerson TB, Savas O, Shaffer F. Review of flow rate estimates of the Deepwater Horizon oil spill. Proceedings of the National Academy of Sciences of the United States of America 2012;109(50):20260. [37] ISPR - Incident - Specific Preparedness Review, United States Coast Guard, March 18, 2011, 112, 2011. [38] Plume Calculation Team. Deepwater Horizon release, estimate of rate by PIV. Report to the FRTG. July, 2010. [39] Bommer P. Reservoir fluid study and oil flow rate from the BP mission canyon 252 I-01 blowout. Department of Petroleum and Geosystems Engineering, The University of Texas at Austin; June 2, 2010. Report submitted to NOAA. [40] Judge’s Ruling. BP Gulf Spill Totaled 3.19 million barrels of oil. Science 2015;347(6220):356. [41] Mariano AJ, Kourafalou VH, Srinivasan A, Kang H, Halliwell GR, Ryan EH, Roffer M. On the modeling of the 2010 Gulf of Mexico oil spill. Dynamics of Atmospheres and Oceans 2011;52:322. 02-Jan. [42] Paris CB, He´naff ML, Aman ZM, Subramaniam A, Helgers J, Wang D-P, Kourafalou VH, Srinivasan A. Evolution of the Macondo well blowout: simulating the effects of the circulation and synthetic dispersants on the subsea oil transport. Environmental Science & Technology 2012;46(24):13293. [43] North EW, Adams EE, Thessen AE, Schlag Z, He R, Socolofsky SA, Masutani SM, Peckham SD. The influence of droplet size and biodegradation on the transport of subsurface oil droplets during the Deepwater Horizon spill: a model sensitivity study. Environmental Research Letters 2015;10(2):24016. ¨ zgo¨kmen TM, Lipphardt Jr BL, Haus BK, Ryan EH, Haza AC, Jacobs GA, [44] Poje AC, O Reniers AJHM, Olascoaga MJ, Novelli G, Griffa A, Beron-Vera FJ, Chen SS, Coelho E, Hogan PJ, Kirwan Jr AD, Huntley HS, Mariano AJ. Submesoscale dispersion in the vicinity of the Deepwater Horizon spill. Proceedings of the National Academy of Sciences of the United States of America 2014;11(35):12693.

846

Oil Spill Science and Technology

[45] Dohrn R, Peper S, Fonseca JM. High-pressure fluid-phase equilibria: experimental methods and systems investigated. Fluid Phase Equilibria 2000-2004;1:2010. [46] Sawamura S. High pressure investigations of solubility. Pure and Applied Chemistry 2007;79:861. [47] Fonseca JMS, Dohrn R, Peper S. High-pressure fluid-phase equilibria: experimental methods and systems investigated. Fluid Phase Equilibria 2005-2008;1:2011. [48] Reddy CM, Arey JS, Seewald JS, Sylva SP, Lemkau KL, Nelson RK, Carmichael CA, McIntyre CP, Fenwick J, Ventura GT, Van Mooy BAS, Camilli R. Composition and fate of gas and oil released to the water column during the Deepwater Horizon oil spill. Proceedings of the National Academy of Sciences of the United States of America 2012;109(50):20229. [49] Diercks A-R, Asper VL, Highsmith R, Woolsey M, Lohrenz S, McLetchie K, Gossett A, Teske A. NIUST e Deepwater Horizon oil spill response cruise, MTS/IEEE seattle. OCEANS 2010;2010. [50] Ryerson TB, Camilli R, Kessler JD, Kujawinski EB, Reddy CM, Valentine DL, Atlas E, Blake DR, De Gouw J, Meinardi S, Parrish DD, Peischl J, Seewald JS, Warneke C. Chemical data quantify Deepwater Horizon hydrocarbon flow rate and environmental distribution. Proceedings of the National Academy of Sciences of the United States of America 2012;109(50):20246. [51] Ross SL, Environmental Research Ltd. Spill related properties of MC 252 crude oil, sample ENT-052210-178. 2010. [52] Leirvik F, Daling P. Assessment of dispersibility of DWH oil at different stages of weathering. SINTEF. Marine Environmental Technology; 2010. [53] Leifer I, Lehr WJ, Simecek-Beatty D, Bradley E, Clark R, Dennison P, Hu Y, Matheson S, Jones CE, Holt B, Reif M, Roberts DA, Svejkovsky J, Swayze G, Wozencraft J. State of the art satellite and airborne marine oil spill remote sensing: application to the BP Deepwater Horizon oil spill. Remote Sensing of Environment 2012;124:185. [54] Aeppli C, Carmichael CA, Nelson RK, Lemkau KL, Graham WM, Redmond MC, Valentine DL, Reddy CM. Oil weathering after the Deepwater Horizon disaster led to the formation of oxygenated residues. Environmental Science & Technology 2012;46(16):8799. [55] Liu Z, Liu J, Zhu Q, Wu W. The weathering of oil after the Deepwater Horizon oil spill: insights from the chemical composition of the oil from the sea surface, salt marshes and sediments. Environmental Research Letters 2012;7(3):35302. [56] Davidson MJ, Pun KL. Weakly advected jets in crossflow. J. Hydr. Eng 1999;125(1):47. [57] Weber TC, De Robertis A, Greenaway SF, Smith S, Mayer L, Rice G. Estimating oil concentration and flow rate with calibrated vessel-mounted acoustic echo sensors. Proceedings of the National Academy of Sciences of the United States of America 2012;109(50):20240. [58] Spier C, Stringfellow WT, Hazen TC, Conrad M. Distribution of hydrocarbons released during the 2010 MC252 oil spill in deep offshore waters. Environmental Pollution 2013;173:224. [59] McNutt MK, Chu S, Lubchenco J, Hunter T, Dreyfus G, Murawski SA, Kennedy DM. Applications of science and engineering to quantify and control the Deepwater Horizon oil spill. Proceedings of the National Academy of Sciences of the United States of America 2012;109(50):20222. [60] Lewan MD, Warden A, Dias RF, Lowry ZK, Hannah TL, Lillis PG, Kokaly RF, Hoefen TM, Swayze GA, Mills CT, Harris SH, Plumlee GS. Asphaltene content and composition as a measure of Deepwater Horizon oil spill losses within the first 80 days. Organic Geochemistry 2014;75(54):60.

Deepwater Horizon Well Blowout Mass Balance Chapter j 15

847

[61] CLWMMP. Deepwater Horizon MC252 comprehensive liquids waste and materials management plan, BP, approved by EPA. 2010. [62] Hall CJ, Henry WJ, Hyder CR. Hopedale branch: a vessel of opportunity success story. IOSC 2011;407. [63] Baccigalopi MJ, Jensen D. Fishing communities assisting in A response: MC 252 vessel of opportunity e the mobile, Alabama model. IOSC 2011;365. [64] Mitchell V. Private communication. October, 2015. [65] Mitchell V. Private communication. February, 2016. [66] Allen A, Mabile N, Jaeger D, Costanzo D. The use of controlled burning during the Gulf of Mexico Deepwater Horizon MC-252 oil spill response. IOSC 2011. Portland, OR. [67] Mabile N. Controlled in-situ burning: transition from alternative technology to conventional spill response option. AMOP 2012;584. [68] Mabile NJ, Abou-Hamdan A. Burn volume estimating protocol: refined during the Deepwater Horizon response, SPE Americas E and P health. In: Safety, security, and environmental conference proceedings (Galveston, TX, 3/18e20/2013); 2013. p. 12. [69] Mabile NJ, Abou-Hamdan A. Burn volume estimating protocol: refined during the Deepwater Horizon response, society of petroleum engineers e SPE Americas E and P health. In: Safety, security, and environmental conference 2013; 2013. p. 48. [70] Owens EH, Santner R, Cocklan-Vendl M, Michel J, Reimer PD, Stong B. Shoreline treatment during the Deepwater Horizon-Macondo response. IOSC 2011. [71] PEIS. Programmatic environmental impact statement. NOAA; 2012-2017. http://www. gulfspillrestoration.noaa.gov/restoration/early-restoration/phase-iii/, downloaded March, 2016. [72] Shapiro K, Khanna S, Ustin SJ. Vegetation impact and recovery from oil-induced stress on three ecologically distinct wetland sites in the Gulf of Mexico. Journal of Marine Science and Engineering 2016;4(2):33. http://dx.doi.org/10.3390/jmse4020033. [73] McDaniel LD, Basso J, Pulster E, Paul JH. Sand patties provide evidence for the presence of Deepwater Horizon oil on the beaches of the west Florida Shelf. Marine Pollution Bulletin 2015;97:67. 02-Jan. [74] Boufadel MC, Abdollahi-Nasab A, Geng X, Galt J, Torlapati J. Simulation of the landfall of the Deepwater Horizon oil on the shorelines of the Gulf of Mexico. Environmental Science & Technology 2014;48(16):9496. [75] Michel J, Owens EH, Zengel S, Graham A, Nixon Z, Allard T, Holton W, Reimer PD, Lamarche A, White M, Rutherford N, Childs C, Mauseth G, Challenger G, Taylor E. Extent and degree of shoreline oiling: Deepwater Horizon oil spill, Gulf of Mexico, USA. PLoS One 2013;8(6):e65087. [76] Turner RE, Overton EB, Meyer BM, Miles MS, McClenachan G, Hooper-Bui L, Engel AS, Swenson EM, Lee JM, Milan CS, Gao H. Distribution and recovery Trajectory of Macondo (Mississippi Canyon 252) oil in Louisiana coastal Wetlands. Marine Pollution Bulletin 2014;87(1):57. [77] Zengel S, Bernik BM, Rutherford N, Nixon Z, Michel J. Heavily oiled salt marsh following the Deepwater Horizon oil spill, ecological comparisons of shoreline cleanup treatments and recovery. PLoS One 2015;10(7):e0132324. [78] Zengel S, Montague CL, Pennings SC, Powers SP, Steinhoff M, Fricano G, Schlemme C, Zhang M, Oehrig J, Nixon Z, Rouhani S, Michel J. Impacts of the Deepwater Horizon oil spill on salt marsh periwinkles (Littoraria irrorata). Environmental Science & Technology 2016;50(2):643. [79] Owens E. Private communication. October, 2013.

848

Oil Spill Science and Technology

[80] Nixon Z, Zengel S, Baker M, Steinhoff M, Fricano G, Rouhani S, Michel J. Shoreline oiling from the Deepwater Horizon oil spill. Marine Pollution Bulletin 2016. in press. [81] Lin Q, Mendelssohn IA. Impacts and recovery of the Deepwater Horizon oil spill on vegetation structure and function of coastal salt marshes in the Northern Gulf of Mexico. Environmental Science & Technology 2012;46(7):3737. [82] Lin Q, Mendelssohn IA, Graham SA, Hou A, Fleeger JW, Deis DR. Response of salt marshes to oiling from the Deepwater Horizon spill: implications for plant growth, soil surface-erosion, and shoreline stability. Science of the Total Environment 2016;557e558:369. [83] Nixon Z, Zengel SA, Michel J. Shoreline oiling from the Deepwater Horizon oil spill. DWH Shoreline NRDA technical working group report. 2015. [84] More massive tar mats from BP oil spill discovered on Louisiana beaches, https://www. thelensnola.org_2013_12_18_more-massive-tar-mats-from-bp-oil-spill-discovered-onlouisiana-beaches_htm. [85] Despite rosy report, BP still cleaning up oil, https://www.usatoday.com_story_news_ nation_2015_03_19_despite-rosy-report-bp-still-cleaning-up-oil_25001431_htm. [86] New mass of tar on Louisiana coast linked to 2010 BP oil spill, https://www.rt.com_usa_ bp-oil-tar-mat-328_htm. [87] BP acknowledges existence of 25,000-Pound “Tar Mat” on Louisiana Coast, Louisiana tar mat BP says cleanup continues.htm. [88] Oil still being found 3 years later from rig explosion, Oil still being found 3 years later from rig explosion _ WPMT FOX43.htm. [89] Bejarano AC, Levine E, Mearns AJ. Effectiveness and potential ecological effects of offshore surface dispersant use during the Deepwater Horizon oil spill: a retrospective analysis of monitoring data. Environmental Monitoring and Assessment 2013;185(12):10281. [90] Ziervogel K, McKay L, Rhodes B, Osburn CL, Others. Microbial activities and dissolved organic matter dynamics in oil-contaminated surface Seawater from the Deepwater Horizon oil spill site. PLoS One 2012;7(4):e34816. 1. [91] Passow U, Ziervogel K, Asper V, Diercks A. Marine snow formation in the aftermath of the Deepwater Horizon oil spill in the Gulf of Mexico. Environmental Research Letters 2012;7. 035301, 1, 552. [92] Passow U. Formation of rapidly-sinking, oil-associated marine snow, deep sea research part II: topical studies in oceanography. 2014. p. 1e9. [93] Baelum J, Borglin S, Chakraborty R, Fortney JL, 11 other authors. Deep-sea bacteria enriched by oil and dispersant from the Deepwater Horizon spill. Environmental Microbiology 2012;14(9):2405. [94] Kinner NE, Belden L, Kinner P. Unexpected sink for Deepwater Horizon oil may influence future spill response. Town hall: marine oil snow sedimentation and flocculent accumulation (MOSSFA); Mobile, Alabama, 27 January 2014 Eos 2014;95(21):176. [95] Vonk SM, Hollander DJ, Murk AJ. Was the extreme and wide-spread marine oil-snow sedimentation and flocculent accumulation (MOSSFA) event during the Deepwater Horizon Blow-out unique? Marine Pollution Bulletin 2015;100(1):5. [96] Romero IC, Schwing PT, Brooks GR, Larson RA, Hastings DW, Ellis G, Goddard EA, Hollander DJ. Hydrocarbons in deep-sea sediments following the 2010 Deepwater Horizon blowout in the northeast Gulf of Mexico. PLoS One 2015;105:e0128371. [97] Kolian SR, Porter SA, Sammarco PW, Birkholz D, Cake Jr EW, Subra WA. Oil in the Gulf of Mexico after the capping of the BP/Deepwater Horizon Mississippi Canyon (MC-252) well. Environmental Science and Pollution Research 2015;22(16):12073.

Deepwater Horizon Well Blowout Mass Balance Chapter j 15

849

[98] Chanton J, Zhao T, Rosenheim BE, Joye S, Bosman S, Brunner C, Yeager KM, Diercks AR, Hollander D. Using natural abundance radiocarbon to trace the flux of petrocarbon to the seafloor following the Deepwater Horizon oil spill. Environmental Science & Technology 2015;49(2):847. [99] Valentine DL, Fisher GB, Bagby SC, Nelson RK, Reddy CM, Sylva SP, Wood MA. Fallout plume of submerged oil from Deepwater Horizon. Proceedings of the National Academy of Sciences of the United States of America 2014;111(45):15906. [100] Fisher CR, Hsing P-Y, Kaiser CL, Yoerger DR, Roberts HH, Shedd WW, Cordes EE, Shank TM, Berlet SP, Saunders MG, Larcom EA, Brooks JM. Footprint of Deepwater Horizon blowout impact to deep-water coral communities. Proceedings of the National Academy of Sciences of the United States of America 2014;111(32):11744. [101] Etnoyer PJ, Wickes LN, Silva M, Dubick JD, Balthis L, Salgado E, MacDonald IR. Decline in condition of gorgonian octocorals on mesophotic reefs in the northern Gulf of Mexico: before and after the Deepwater Horizon oil spill. Coral Reefs 2016;35(1):77. [102] Qu F, Nunnally CC, Lemanski JR, Wade TL, Amon RMW, Rowe GT. Polychaete Annelid (segmented worms) abundance and species composition in the proximity (6e9 km) of the Deepwater Horizon (DWH) oil spill in the deep Gulf of Mexico. Deep-Sea Research Part II: Topical Studies in Oceanography 2016. [103] Brooks GR, Larson RA, Schwing PT, Romero I, Moore C, Reichart G-J, Jilbert T, Chanton JP, Hastings DW, Overholt WA, Marks KP, Kostka JE, Holmes CW, Hollander D. Sedimentation pulse in the NE Gulf of Mexico following the 2010 DWH blowout. PLoS One 2015;10(7):e0132341. [104] Nedwed T, Coolbaugh T, Tidwell A. Subsea dispersant use during the Deepwater Horizon incident. AMOP 2012;506. [105] Kujawinski EB, Kido Soule MC, Valentine DL, Boysen AK, Longnecker K, Redmond MC. Fate of dispersants associated with the Deepwater Horizon oil spill. Environmental Science & Technology 2011;45(4):1298. [106] MacDonald IR, Garcia-Pineda O, Beet A, Daneshgar Asl S, Feng L, Graettinger G, French-McCay D, Holmes J, Hu C, Huffer F, Leifer I, Muller-Karger F, Solow A, Silva M, Swayze G. Natural and unnatural oil slicks in the Gulf of Mexico. Journal of Geophysical Research 2015;120(12):8364. [107] Dhima A, De Hemptinne J-C, Moracchini G. Solubility of light hydrocarbons and their mixtures in pure water under high pressure. Fluid Phase Equilibria 1998:129e50. [108] Duan Z, Mao S. A thermodynamic model for calculating methane solubility, density and gas phase composition of methane-bearing aqueous fluids from 273 to 523 K and from 1 to 2000 bar. Geochimia et Cosmochimica Acta 2006:3369e86. [109] Price LC, Wanger LM, Ging T, Blount CW. Solubility of crude oil in methane as a function of pressure and temperature. Organic Geochemistry 1983:201e21. [110] Tobaly P, Marteau P, Ruffier-Meray V. High-pressure phase diagrams of methane + decahydronaphthalene and methane. Journal of Chemical Engineering Data 2001:1269e73. [111] Davenport AJ, Rowlinson JS. The solubilities of hydrocarbons in liquid methane. Pure and Applied Chemistry 1963:78e84. [112] Darwish NA, Gasem KAM, Robinson RL. Solubility of methane in benzene, naphthalene, phenanthrene and pyrene at temperatures from 323 to 433 K and pressures to 11.3 MPA. Journal of Chemical Engineering Data 1994:781e4.