Recap: Week Two of Phase II of BP Oil Spill Trial

By Whit Remer, Policy Analyst, Environmental Defense Fund

BP and the U.S. Department of Justice sparred in federal court this week over how much oil gushed into the Gulf of Mexico during the 87-day Gulf oil disaster during a part of the trial named the Quantification Segment. Last week, BP defended its multiple engineering attempts to stop the oil leak during the Source Control Segment. Both of these segments make up the second phase of trial, which was originally expected to last four weeks but may wrap up sooner. The first phase, which focused on the cause of the Deepwater Horizon rig explosion, concluded in April 2013 after nearly two months in the courtroom. A yet to be scheduled third phase will focus on penalties in the case, which could reach the tens of billions of dollars.

Macondo well blowout

This week during the Quantification Segment, presiding Judge Carl Barbier has been hearing expert testimony from each side on the amount of oil spilled. BP is contending that 3.1 million barrels were released, while the U.S. government believes the number is closer to 4.9 million barrels. Both sides have agreed not to fine BP for 810,000 barrels that the company collected during the spill. BP was able to sell around 65,000 barrels of that collected oil, fetching approximately $4.5 million, which was placed in a trust fund for wildlife rehabilitation.

Experts testifying in the case specialize in fields such as hydrology, petroleum engineering and thermodynamic modeling. Judge Barbier will weigh evidence offered by these experts on possible daily flow rates and the total amount of oil spilled. On Monday and Tuesday, experts for the U.S. testified about pressure levels in the geologic formation that contained the oil where the Macondo well was being drilled. Pressure in the rock formation gives scientists an idea about how much oil could be released each day. BP argued that calculating the flow of oil from the Macondo well was possibly slowed by obstructions resulting from the rig collapse like sheared metal components. The U.S. called Stewart Griffiths, a fluid dynamics expert, to rebut the argument by testifying that the metal would have likely eroded within hours or days of the blowout.

Another complicating factor in determining the amount of oil spilled is distinguishing between solid oil and gas. Video images of oil gushing from the wellhead and broken riser pipe were played around the world during the disaster (check out the video below for clips of the spill and a timeline of events). The gushing brown stream consisted of both solid oil and gas, known collectively as hydrocarbons. Under the Clean Water Act – the primary law controlling the Quantification Segment of trail – BP can only be fined for the release of solid oil, not gas.


To help determine how much of the release consisted of solid oil, the U.S. called Aaron Zick, an independent contractor who specializes in thermodynamic modeling of oil and gas formations, to the stand. Zick offered a complex formula to help distinguish solid oil from gas when analyzing potential flow rates at the well head. The formula had to be adapted for deep sea pressure readings because the extreme differences in temperature at the ocean floor. The hydrocarbon mixture is nearing boiling when it enters the freezing ocean. The extreme reactions make the analyses more difficult than those tested in shallow water.

Chemistry class aside, the Quantification Segment is important because BP will be fined under the Clean Water Act based on how much solid oil entered the Gulf of Mexico. Through the federal RESTORE Act, that fine money will be used for environmental and economic restoration activities along the Gulf Coast.