BP has released their internal investigation report of the oil rig disaster in the Gulf of Mexico. The report is obviously an initial investigation on the causes and does not go into why the failures occurred. This is stated by BP as follows:
It may also be appropriate for BP to consider further work to examine potential systemic issues beyond the immediate cause and system cause scope of this investigation. The summary of the report findings are given below:
1. The investigation team concluded that there were weaknesses in cement design and testing, quality assurance and risk assessment.
2. The investigation team concluded that hydrocarbon ingress was through the shoe track, rather than through a failure in the production casing itself or up the wellbore annulus and through the casing hanger seal assembly.
3.The investigation team has identified potential failure modes that could explain how the shoe track cement and the float collar allowed hydrocarbon ingress into the production casing.
4.The Transocean rig crew and BP well site leaders reached the incorrect view that the test was successful and that well integrity had been established.
5.The rig crew did not recognize the influx and did not act to control the well until hydrocarbons had passed through the BOP and into the riser.
6.If fluids had been diverted overboard, rather than to the Mud gas separator (MGS), there may have been more time to respond,and the consequences of the accident may have been reduced.
7.The design of the MGS system allowed diversion of the riser contents to the MGS vessel although the well was in a high flow condition. This overwhelmed the MGS system.
8.The heating, ventilation and air conditioning system probably transferred
a gas-rich mixture into the engine rooms, causing at least one engine to overspeed, creating a potential source of ignition.
9.Through a review of rig audit findings and maintenance records, the investigation team found indications of potential weaknesses in the testing regime and maintenance management system for the Blow out presenter (BOP).
Point no. 8 is a repeat of the ignition source in the BP Texas city refinery explosion where a pick up truck took in vapours through its air intake and triggered the initial explosion.Are we learning from our incidents?
Read the executive summary of the report in this link.
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