BP Oil Spill 2010 Draft

8/11/2019 BP Oil Spill 2010 Draft

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Deepwater Horizon Oil Spill 2010

(AKA BP Oil Spill)

ME 111

Professor: Jinny Rhee

Contemporary Fluid Mechanics Research Project

Jaypee Bauzon

Kevin Yoshihara

Megan GilmoreCherise Chang


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Introduction

On April 20, 2010 at about 21:56, an explosion rocks the Deepwater Horizon, an oil

drilling rig operating in the Gulf of Mexico. The explosion and subsequent fire kills 11 workersand injures 16 more. After a day of constant burning and firefighting by supply boats and the US

Coast Guard, Deepwater Horizon sank on April 22 at 10:21am. The disaster was far from overhowever as a sea-floor oil gusher flowed and dumped crude oil for 87 days until it was cappedfully on July 15. According to the Flow Rate Technical Group, the estimated volume of leaked

oil was approximated to 4.9 million barrels making it the largest oil spill in history. Spilled oil,

tar balls, and containment chemicals were found washed ashore along 1074 miles of coastlineaffecting five states. To this day, oil continues to be found from time to time and cleanup efforts

are still ongoing.

Previous Oil Spills

Events like the Deepwater Horizon oil spill (more commonly known as the BP oil spill),are by no means a rare occurrence, although the scope may be on the larger end. Failure to

provide adequate and sufficient safety functionality to oil pipelines and drilling rigs have

consequently led to large oil spills, resulting in great environmental damage and high costs toclean up the spills. One hypothesis as to why the spill occurred is that the shearing rams, backup

equipment used to forcefully cap a drill pipe in the event that events escalate out of control,

failed to operate properly due to a portion of the drill pipe failing to be severed properly betweenthe shearing blocks. (Enghaug) Additional information about the failure in the Deepwater

Horizon oil spill of the blowout preventer (BOP), which includes the shearing rams, surfaced not

long after the initial failure. According to a report by the New York Times, information

concerning the federally mandated and required testing of the BOP that was shared within the

company was used to lower the pressure at which the BOP was to be tested at; 6500 pounds persquare inch, compared to 10,000 pounds per square inch, the latter being the pressure the BOP

was tested at before initial problems occurred. (Urbina) The reduction in pressure at which the

BOP was tested may have well led to the BOP being cited as 'safe' and in proper workingcondition, but the buckling of the pipe between the shearing rams and failure to close the pipe

stated otherwise.

Although not related directly to British Petroleum (BP), another event that occurred on asimilarly large scale was the oil spill created by the Sedco 135-F semi-submersible drilling rig

when drilling an exploratory bore down towards the pocket of oil. The drill bit encountered a

region where material was less dense, and resulted in a loss of hydrostatic pressure when the

drilling mud could no longer be circulated. (Restrepo, Lamphear, and et al) The shearing rams

that were in place to cut the pipe and cap the well, however, failed to do so when the drill collarswere brought line with the rams, as the drilling collars' walls were too thick to be severed by the

shearing rams, leading to an uncontrolled leakage from the ocean floor. In both cases, safetymeasures meant to contain and handle any failures did not operate correctly, and as a result,

thousands up on thousands of gallons of crude were spilled into the ocean, requiring high

cleanup costs and months of time before wells were capped.


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Events Leading to the BP Oil Spill Failure

There were three main reasons for the BP oil spill that occurred in 2010. First of all, the

BP oil rig failed a pressure test. The pressure test was conducted to verify the integrity of the

mechanical barriers. However, the results of the test proved that that the integrity of the barrierswas not achieved. Despite this, the BP and Transocean companies stated that the test wassuccessful and continued drilling. The second reason for the failure is that the cement barrier did

not isolate the hydrocarbons like it should have. On the day preceding the explosion, cement was

pumped into the drilling space to prevent hydrocarbons from entering the well. Due toweaknesses in the cement design, the cement had a nitrogen breakout, which in turn allowed

hydrocarbons to enter the well. The leaking hydrocarbons reached electronic areas of the rig,

where they ignited and caused the explosion on the rig. The third reason for the oil spill was that,

in addition to everything else, the blow out preventer failed to activate. A blow out is anuncontrolled flow of fluid. The blow out preventer was meant to seal off the oil once the spill

started in order to minimize the damage done. The preventer was later shown to have been

improperly manufactured, allowing the oil to continue to escape into the ocean.

Purpose

Our goal was to analyze and hypothesize possible reasons as to what caused the oil rigsfailure that led to the Deepwater Horizon Oil Spill. With this paper, we hope to assist BP and

other oil companies in preventing future oil spills from occurring. This information will benefit

not only the oil companies, but the public and the environment.We decided to analyze the BP Oil Spill, also known as the Deepwater Horizon Oil Spill,

because of three reasons. One, this event had a significant negative impact on society locally

(the United States) and globally. Two, the media extensively covered this event, so there was a

sufficient amount of research, information, and data about the oil spill that was available to us toutilize. Three, this event provides us with a real world application of fluid mechanics that we

can study and apply the knowledge we learned in ME111. We demonstrate this by analyzing

and hypothesizing the reasons why BPs oil rig failed.Our group analyzed this disaster by applying Fluid Mechanics equations discussed in

class such as the dispersion rate, flow rates, pressure conditions, and hydrostatic forces to our

hypotheses. Using the data we obtain from our calculations, we hope to provide answers andrecommendations to help prevent potential oil rig and oil pipe failures.


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Research Question 1Could the signs of influx infiltrating the drill pipe be seen and then reacted to before any possible

accident?

Hypothesis

In the BP Deepwater Horizon Accident Investigation presentation, Key Finding #4 was that The

influx was not recognized until hydrocarbons were in the riser. Had there been carefulmonitoring of flow rates and pressures, the presence of influx would have been caught and

emergency procedures enacted.

AnalysisThe Deepwater Horizon semi-submersible drilling rig used the long string casing piping

method of drilling which involved embedding a series of smaller diameter pipes in descending

fashion through the bedrock and into the reservoir. The pipes are then cemented in by [filling]

the space between the outside of the pipe and surrounding rock, allowing a more uniform cementsheath to form around the pipe, while preventing any gas from flowing up the sides." (Ingersoll,

Locke, Reavis, 2012) This is where the major problem arises for the basis of my researchquestion. The annulus cement barrier at the bottom of the piping failed to prevent the flow of

hydrocarbons from the reservoir due to faulty slurry mixture and improper installation. When the

cement failed, a mix of mud and hydrocarbons forced their way into the pipe, up the derrick, and

out at the surface, resulting in the explosive accident. Below is a Flow Rate-Pressure-TimelineGraph that tracks the flow rate of the pumps, the pressure of the pipe, and points out the

estimated amount of influx at a given time.

Source: BP Deepwater Horizon Investigation Report


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From 20:45 to 20:52, flow rates of both pumps in and out (blue and green lines respectively) and

the drill pipe pressure (orange line) are acting normally. The actual formulas used to calculate the

pressures and other parameters are beyond the scope of this research paper but we can use theContinuity Equation (eq. 1) and infer from the results whether pressure increase is apparent or

not.

Eq. 1

Breaking down Eq. 1 and rearranging it, we have...

Eq. 2

We have three flow rates to account for. During normal operations, there are just pumps Flow In

and Flow Out. During the time of the cement failure, the influx flow rate is taken into account.

As a control, we will calculate at time 20:45, the change in storage.

The two Q's used are:

The densities are:

Inputting the values into Eq. 2, we have...

Calcs. 1

This shows proof of pressure as shown on the graph by the orange line.

At 20:52, the aforementioned annulus cement barrier begins to fail and proceeds to start leaking

hydrocarbon laced mud into the pipe. The influx flow rate at time 20:59 is 2.74cfs. As seen in

Indication #1, Flow Rate Out increases by is increased by the influx flow rate in order tomaintain pressure within the pipe. In response to this sudden erratic behavior, both pumps areshut down at ~21:10 as shown in Indication #2. Despite the shutdown of the Flow In Pump, there

is evidence that pressure is continuing to rise due to the influx. It is slightly mitigated by the

small flow rate of the Flow Out Pump, which indicates pump control failure due to it beingshutdown yet still flowing. By implementing Eq. 2 again below, we can see that the change in

storage signifies pressure build up.


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Inputting this into Eq. 2, we get...

Calcs. 2

Compared to the control calculations, there is a significant difference showing that there is

possibly a significant pressure build up.

From 21:14 to 21:31, Flow In Pump runs for about 15 minutes as part of a routine procedure to

fill the pipe and equalize the pressure inside the pipe with the outside pressure. This creates the

increase in pressure shown. Considering how consistent the pressure and Flow In Rate aretogether, no signs of problems are shown at first glance. Yet by the time of the complete pump

shutdown at 21:31, pressure doesnt completely drop off and as shown by Indication #3, pressure

continues to climb in step with the now 9450 gpm or 21.1cfs of influx. In the calculations below,it is shown that the pressure is indeed rising through the influx flow rate alone.

Inputting this into Eq. 2, we get...

Calcs. 3

From the indications on the graph supported by my calculations [Calcs-1/2/3], at times 21:10 to

21:14 and times 21:31 to 21:35, personnel should have caught and been alerted of the influx

flowing into the pipe.


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Research Question 2In the case of the IXTOC I event, Deepwater Horizons spiritual predecessor, the shearing rams

activated but failed to cut the pipe and close it off completely. Could the pressure produced bythe oil and natural gas filling the well have helped prevent the shearing rams from closing

properly? And how will the results shown by an analysis of IXTOC I be related to the Deepwater

Horizon event?

Hypothesis:

Oil and natural gas being allowed to fill a lower pressure zone by moving from a higher pressurezone may have applied force to the walls of the bore, helping prevent the shearing rams from

closing off the pipe.

Analysis:Calculations have been done to determine how much potential force there could have been in the

drill well, how it compares to the pressure outside of the well at the same depth, and how much

force a shearing ram could have applied to the pipe to cut it.

An estimation by Paul Shrivastava and Charles Perrow of the pressure in the 9 5/8 inch bore at

the time when mud, oil and gas surged up the drill pipe was placed at 350 kg/cm2, and

recalculated to be 3.43 * 107kg/ms

s(calculations provided below). The corresponding pressure

at the surface of the ocean floor 50 m below sea level was calculated to be 5.03 * 105kg/ms

2.

The sheer pressure buildup inside the pipe was larger than the pressure outside of the pipe by an

order of almost 70 times, perhaps opposing any potential operation by the shearing rams.Unfortunately, information about the shearing rams, be it size of the shears, the maker of the

shears, or the pressure applied by the shears, is sparse, so comparisons and speculation about the

force utilized by the shearing rams has not been calculated in this report.

Estimated pressure inside of the bore:

Calculated pressure at ocean floor, 50 m below sea level:

Force exerted upon pipe wall at ocean floor, 50 m below sea level:

Conclusion:As has been iterated above, information on the shearing rams used on the Sedco 135-F drilling

rig could not be found, so no solid conclusions as to how much force the shearing rigs could

have theoretically applied have been drawn. Pressure due to static fluid may have acted againstany shearing force the shearing rams may have used, but by the time the shearing rams were

activated, the fluid in the pipe was flowing from deep in the ocean floor to the surface. Static

fluid no longer played a part as a force resisting the shearing rams, and it is more likely that the


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walls of the drill bore were what prevented the shearing rams from closing completely than any

pressure generated by liquid would have been.

Research Question 3By the time that engineers were able to seal the well, 4.9 million barrels (or 205.8 million

gallons) had leaked into the Gulf of Mexico. Based on the dispersion rate of oil on water, how farcould the oil spread had it not been collected and removed?

Hypothesis:

Because the oil would have spread itself thinly across the surface of the water, it is likely that it

would have spread over an area of 10 thousand square miles had there not been effort to clean up

the spill as it continued to leak.

Analysis:

In order to discover how far the oil spread across the Gulf of Mexico, one must first figure out

the thickness of the oil slick, or layer of oil floating on the water. According to a table presented,the appearance of the slick is directly correlated to the layer thickness (Leifer 189). The oil had

different thicknesses in different locations due to the water movement in the gulf, therefore the

difference in area can be calculated based on whether the layer thickness was thin (0.1m) or

thick (50m).

The total volume (V) of oil that was released into the ocean was 205.8 million gallons, or

m3. By using the value for the slick thickness (T), one can calculate the area that thevolume of oil would cover.

Case 1:

Case 2:


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If the thin layer is assumed, then the area that the oil covers would be over 3 million square

miles, whereas if the thicker layer is assumed, the area is only about 6000 square miles.

According to Jimoh, the oil dispersion rate in water is as followed:

Qdisp= cdispe0.57fbwfdisp

Where cdisp is the empirical dispersion constant,eis the dissipation of wave energy per unit

area (J/m2), fbwis the fraction of breaking wave of water per second (s

-1), fdispis the volume of oil

entrained per unit water volume (Jimoh). The symbol,e, represents the dissipation of wave

energy per unit area.

e= 0.0017gwHs2

In this equation, g, w, and Hsrepresent gravity, density of water, and wave height respectively.In the Gulf of Mexico, the average wave height is 1ft, or 0.3048 m. Typical seawater density is

1026kg/m3. Using these numbers,ecan be calculated.

e= 0.0017(9.81)(1026)(.3048)

2

e= 1.5896 kg/s

2

Jimoh gives the values of fbwand fdispas (max10/3

min10/3

)3/10, where is oil droplet diameter

and as the fraction of water surface covered by oil (fw) over the time of dispersion (tp). Thus, the

equation becomes

Qdisp= cdispfwc(1.302)(max10/3

min10/3

)/(10tp)

Using this and the viscosity of the oil (oil), the distance that the oil disperses (Ddisp) is as

follows:

Then, depending on the values of cdisp, fwc, and tp, the distance that the oil disperses over a certain

amount of time may be calculated.

Conclusion:

Depending on the thickness that the oil layer lay on the surface of the water, the area that the oil

could have spread over ranged from 6097 square miles to about 3 million square miles.

Research Question 4Once the Deepwater Horizon oil rig failed due to the numerous problems listed above, what was

the volume flow rate of the oil spilled into the Gulf of Mexico as a function of time?

Hypothesis:

The flow rate of oil varied over time, but at the end of the accident, the volume flow rate taperedoff at 50,000 bpd and spilled around 5 million barrels of oil into the ocean, causing permanent

damage to the surrounding environment.


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Analysis:Determining the flow rate is very important because it helps predict the likelihood for the success

of various well intervention strategies, plan containment capacity to capture the flow while reliefwells are drilled, and inform the public about the crisis.

Initially, the flow rate of oil from the disaster was announced as 1,000 bpd. However, thisestimate was immediately challenged by the NOAA hydrocarbon scientists who claimed that itwas at least 5,000 bpd. As different research groups used particle image velocimetry techniques

for video flow-rate analysis and observing oil on the surface, the estimated flow rate kept on

increasing until BP started to make temporary caps to stop the oil flow (McNutt , 2012). Theflow rate of the oil leakage decreased over time because of the various methods conducted to try

and cap the pipe to reduce the amount of oil spilled per day. This can be seen in figure 1.

However, around 5.4 million barrels of oil was discharged from the well and 4.6 million barrels

entered the Gulf. Eventually, the well was final capped after 86 days. The oil was spilling out ofthe well at around 6E-2 ft/s and the oil well was approximately 4.28 ft

2. Using this information,

we are able to calculate the volume flow rate (Q) of oil flowing out of the well (Griffiths, 2012)

Even though we have calculated the volume flow rate, we want to have it units commonly used

to describe oil spills such as barrels per day.

( )

Using our calculated volume flow rate, we can calculate the amount of oil spilled in total over

the course of 86 days.


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Figure 1: Time (s) vs. Stock Tank barrels per day (stbd)

Figure 2: Schematic diagram of damaged riser at the well spill site

Conclusion:From our calculations and figures, we can infer that around 53,000 bpd of oil was being spilled

over the course of 86 days.


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Conclusion

From our research we can conclude that the oil rig failed due to four reasons. First, equipment

used to build the rig failed standard pressure tests. Second, the cement barrier did not isolate the

hydrocarbons as intended. Third, the blow out preventer (BOP) failed to activate. Fourth, theshearing rams failed to operate. If all of the equipment operated their purpose, damage on theenvironment would have been less extensive in the case of a disaster.

Based on our hypotheses and analysis we determined several conclusions. First, BP could haveprevented the oil spill had there been careful monitoring of flow rates and pressures for signs of

influx infiltrating the drill pipe. Once abnormalities were detected emergency procedures could

have been enacted, therefore saving the lives that were lost. Second, the large amount of oil that

covered the ocean within the Gulf and the amount of oil spilled made this one of the worst oilspills in history. Third, pressure may have affected the shearing rams.

Overall, we can infer that this disaster could have been prevented if regulations and requirementswere followed. However, since this was not the case citizens lives were lost, the environment

and its habitants were damaged, and the lives of many people negatively impacted. We hope

further research into this disaster will help companies, who invest in oil rigs, take more

precautions and be wary of these potential scenarios that could occur and cause similar disasterssuch as the BP oil spill.


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References:

An internal BP incident investigation teamsDeepwater Horizon Accident Investigation Report.

(September 8, 2010).

Enghaug, Aage Andreas. "DNV report on Deepwater Horizon BOP concluded."Det NorskeVeritas. Det Norske Veritas, 23 Mar 2011. Web. 8 May 2013.

.

Griffiths, S.K. (2012). Oil Release from Macondo Well MC252 Following the Deepwater

Horizon Accident.Environ. Science and Technology, 2012, 46 (10), pp 56165622. doi:

10.1021/es204569t

Hebert, H., and Frederic Frommer. "What Went Wrong at Oil Rig? A Lot, Probers Find - ABC

News."ABCNews.com - Breaking News, Politics, Online News, World News, Feature

Stories, Celebrity Interviews and More - ABC News. The Associated Press-Washington.Web. 6 May 2013. .

Mayer, Emmett and Shea, Dan.What Happened on the Deepwater Horizon. The Times-

Picayune. Web. 6 May 2013.http://media.nola.com/news_impact/other/oil-cause-050710.pdf

McNutt, M. K., Camilli, R., Crone, T. J., Guthrie, G. D., Hsieh, P. A., Ryerson, T. B., . . .

Shaffer, F. (2012). Review of flow rate estimates of the deepwater horizon oil spill.

Proceedings of the National Academy of Sciences of the United States of America,

109(50), 20260-20267. doi:10.1073/pnas.1112139108

Restrepo, Carlos, F. Charles Lamphear, and et al. "IXTOC I OIL SPILL ECONOMIC IMPACT

STUDY."Bureau of Ocean Energy Management. Restrepo & Associates, 27 Aug 1979.Web. 8 May 2013. .

Urbina, Ian. "Documents Show Early Worries About Safety of Rig."New York Times. 29 May2010: n. page. Web. 8 May. 2013.

.


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Responsible For:

Jaypee Bauzon: Research Question 1, Introduction, and the following articles

Deepwater horizon incident investigation presentation. (n.d.). Retrieved fromhttp://www.bp.com/liveassets/bp_internet/globalbp/globalbp_uk_english/incident_respon

se/STAGING/local_assets/downloads_pdfs/Deepwater_Horizon_Accident_Investigation

_static_presentation.pdf

Ingersoll, C., Locke, R., & Reavis, C. (2012, April 03).Bp and the deepwater horizon disaster of

2010. Retrieved from https://mitsloan.mit.edu/LearningEdge/CaseDocs/10 110 BPDeepwater Horizon Locke.Review.pdf

Kevin Yoshihara: Research Question 2, Previous Oil Spills, and the following articles

Enghaug, Aage Andreas. "DNV report on Deepwater Horizon BOP concluded."Det NorskeVeritas. Det Norske Veritas, 23 Mar 2011. Web. 8 May 2013.

.Restrepo, Carlos, F. Charles Lamphear, and et al. "IXTOC I OIL SPILL ECONOMIC IMPACT

STUDY."Bureau of Ocean Energy Management. Restrepo & Associates, 27 Aug 1979.

Web. 8 May 2013. .

Urbina, Ian. "Documents Show Early Worries About Safety of Rig."New York Times. 29 May2010: n. page. Web. 8 May. 2013.

.

Megan Gilmore: Research Question 3, Events Leading to the BP Oil Spill Failure, and the

following articles

An internal BP incident investigation teamsDeepwater Horizon Accident Investigation Report.(September 8, 2010).

Mayer, Emmett and Shea, Dan.What Happened on the Deepwater Horizon. The Times-

Picayune. Web. 6 May 2013.Hebert, H., and Frederic Frommer. "What Went Wrong at Oil Rig? A Lot, Probers Find - ABC

News."ABCNews.com - Breaking News, Politics, Online News, World News, Feature


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Stories, Celebrity Interviews and More - ABC News. The Associated Press-Washington.

Web. 6 May 2013. .

Leifer, Ira, William J. Lehr, et al. "State of the Art Satellite and Airborne Marine Oil SpillRemote Sensing: Application to the BP Deepwater Horizon Oil Spill."Remote Sensing ofEnvironment124 (2012): 185-209.DigitalCommons. Elsevier. Web. 6 May 2013.

.Romm, Joe. "The Spilling Fields: How BP Made The Gulf Oil Disaster More Toxic While

Covering It Up." ThinkProgress RSS. N.p., 23 Apr. 2013. Web. 09 May 2013.

.

"Gulf Oil Spill 2010: Deep Water Horizon Oil Spill Human Health Interim Clinical

Guidance."CDC. N.p., n.d. Web. 09 May 2013..

Jimoh, Abdulfatai, and Mohammed Alhassan. "Modelling and Simulation of Crude OilDispersion from Leonardo Electronic Journal of Practices and Technologies."

Department of Chemical Engineering, Federal University of Technology, Minna,

Nigeria,, n.d. Web. 09 May 2013. .

Cherise Chang: Research Question 4, Purpose, Conclusion, and the following articles

Griffiths, S.K. (2012). Oil Release from Macondo Well MC252 Following the Deepwater

Horizon Accident.Environ. Science and Technology, 2012, 46 (10), pp 56165622. doi:

10.1021/es204569t

McNutt, M. K., Camilli, R., Crone, T. J., Guthrie, G. D., Hsieh, P. A., Ryerson, T. B., . . .

Shaffer, F. (2012). Review of flow rate estimates of the deepwater horizon oil spill.

Proceedings of the National Academy of Sciences of the United States of America,

109(50), 20260-20267. doi:10.1073/pnas.1112139108