The Oil Disaster Is About Human, Not System, Failure
In response to Tony Hayward's June 4 op-ed "What BP Is Doing about the Gulf Gusher": It is time that the publicity spin that BP is putting on this disaster is put into perspective. What is alarming about the content of the article is not so much what it says, but what it does not say.
Mr. Haywood, chief executive officer of British Petroleum, asks, "How could this happen?" The answer has largely to do with BP's inability to follow its existing well-construction policies and those of the industry generally.
The BP testimony to the House Committee on Energy and Commerce on May 25 says it all, but perhaps that material needs to be explained. From looking at that evidence, this is what we know:
1) When cementing the production casing the cementing crew, which was being supervised by BP, had difficulty landing the top plug into the casing shoe. This was the first "red flag" because a satisfactory cement job to the production string is fundamental to the safe operation on a go forward basis. The fact that the cement job did not go as planned should have caused the testing operation that followed to be carefully scrutinized, it clearly was not.
2) As is normal practice, the integrity of the pressure tight seal was tested by pressuring up on the casing and observing the pressure response. If pressure bleeds off there is clearly a problem with the pressure integrity of the shoe, However, industry practice dictates that a positive test, that is no pressure drop, is not diagnostic, simply because the reservoir pressure is sufficient to retain the pressure being applied. A negative test is useful because it is diagnostic of a failed cement job. In this case the test was positive.
3) Again, as is normal industry practice a negative pressure test was run, with pressure released from inside the casing and the pressure response was measured. In this case evidence has been bought before the committee that there was a 1,400 psi pressure response. This response is highly diagnostic and is therefore the second "red flag" and at this point the BP supervisors should have concluded that they had what the industry calls a "wet shoe." That is that the cement job had failed to form a seal at the casing around the reservoir which we know contains high pressure oil and gas.
4) At this point a decision should have been made to do a remedial cement job; this is an expensive operation, but having seen a 1,400 psi response, there was no choice.
5) The BP engineers then proceeded with the balance of the operation to temporarily abandon the well. This meant replacing the 14-pound-per-gallon mud that was in the wellbore with 8.5-pound-per-gallon sea water. The denser mud had been, up until this time, the primary pressure control and was keeping the hydrocarbons in place despite the lack of an adequate cement job at the casing shoe.
Given the two red flags that had been thrown up previously, one would have expected that as a precaution a cement plug would have been placed somewhere in the wellbore as a secondary pressure seal before this primary pressure control system (heavy mud) was evacuated from the wellbore. But at the very least the mud replacement operation should have been heavily scrutinized. Clearly it was not.
6) Evidence provided at the hearing, including the pressure data transmitted from the rig for the last two hours before the explosion, is diagnostic. At 8:20 p.m. on the day of the explosion the pressure data suggest there was a constant flow of sea water being pumped into the drill pipe that was displacing the heavier mud system which was the primary pressure control for the well. The rate going in was 900 gallons per minute, but the flow data of mud coming out was steadily increasing from 900 gallons a minute at 8:20 p.m. to a rate of 1,200 gallons per minute at 8:34 p.m. During this 14-minute period one can conclude that hydrocarbons were flowing and pushing more fluid from the wellbore than was being pumped in.
This is what this data is supposed to monitor, but the well flow evidence would appear to have been ignored, because at this point the BP rig supervisors should have gone to a well kill operation and started to pump heavy mud back into the well bore to restore the primary control mechanism. Instead the mud continued to be evacuated.
7) At 9:08 there was another piece of evidence that is very clear cut. The sea water pump was shut down presumably to check the well stability. However, with the pump shut down a pressure increase was seen in the standpipe (SPP). This pressure response has to be associated with the reservoir flowing hydrocarbons and again at this point kill operations should have been initiated by the BP engineers.
8) From 9:08 p.m. to around 9:30, despite the sea-water pump either running at a constant volume or shut-in, the SPP continued to increase; again this is evidence that the well is producing hydrocarbons and should have caused a kill operation to be initiated.
9) At 9:30 p.m. the seawater pump was again shut-in to presumably observe what the well was doing, and again there is a notable increase in the standpipe pressure.
10) At 9:49 the SPP showed a very large increase and the explosion followed—this is obviously the point at which the gas and oil reached the drill floor and found an ignition source.
Mr. Hayward and BP have taken the position that this tragedy is all about a fail-safe blow-out preventer (BOP) failing, but in reality the BOP is really the backup system, and yes we expect that it will work. However, all of the industry practice and construction systems are aimed at ensuring that one never has to use that device. Thus the industry has for decades relied on a dense mud system to keep the hydrocarbons in the reservoir and everything that is done to maintain wellbore integrity is tested, and where a wellbore integrity test fails, remedial action is taken.
This well failed its casing integrity test and nothing was done. The data collected during a critical operation to monitor hydrocarbon inflow was ignored and nothing was done. This spill is about human failure and it is time BP put its hand up and admitted that.
Terry Barr, President, Samson Oil and Gas
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