In their stiffest, most explicity criticisms to date, House Energy and Commerce members Markey, Stupak and Waxman released this week a bill drafting memo which spells out how BP failed to control the Deepwater Horizon well with industry standard practices, tests and equipment.
In particular their memo points out BP’s failure to maintain hydrocarbon control. Once pressurized, hydrocarbons become volatile. Once they reach the surface, as was the case with the Deepwater Horizon rig, they cause explosions and fires.
The relevant portion of the committee’s Blowout Preventer Act of 2010 briefing memo follows.
“Perhaps the most critical safety issue with regard to oil and gas drilling is the maintenance of well control – i.e. control over conditions in the well bore where high pressures threaten to drive oil and gas toward the surface from subsurface formations. If these pressurized hydrocarbons cannot be controlled, they may reach the surface and cause a fire or explosion.
“On the Deepwater Horizon, an uncontrolled influx of gas into the well is believed to have caused the uncontrolled blowout and ensuing explosion. Current drilling technology uses a number of lines of defense to prevent the loss of well control:
“(1) the circulation of heavy drilling mud through the well, which helps to equalize pressure and prevent uncontrolled upward flow of hydrocarbons;
“(2) the use of cement and mechanical barriers in and around the steel casing (which lines the well and forms the conduit between the hydrocarbon reservoir and the surface) preventing the upward flow of oil and gas.
“In the event of complete loss of well control, exploration wells are equipped with blowout preventers which include a series of devices intended to seal the wellhead as a last resort during a well control event threatening a blowout.
B.Blowout Preventers and Secondary Control Systems
“A blowout preventer (BOP) is a piece of equipment installed at the wellhead and designed to prevent an uncontrolled release of hydrocarbons from a well. It consists of several independent systems that may be used to ensure well control, which may include:
“-Annular Preventers which seal the wellbore with a variable-width rubber aperture that can close on itself or around any pipe that may be strung through the wellbore;
“-Variable Bore Rams which seal around drill pipe with rubber-tipped steel blocks;
“-Blind Shear Rams, the well-control mechanism of last resort, designed to cut through drill pipe and seal the well during an emergency; and
“-Casing or Super Shear Rams,which are designed to cut through casing or other obstructions that may be present in the wellbore, allowing blind shear rams to close and seal the well during an emergency.
“Because the blowout preventer is intended to be a failsafe last resort that must function in an emergency, blowout preventers are often designed with redundant equipment and control systems, to ensure that at least one set of emergency systems is always functional. However, in numerous cases, blowout preventers have failed to operate, often with catastrophic consequences. The blowout preventer installed on the Macondo well failed to control the blowout.
“The Committee identified several potential problems that might have resulted in this failure. According to a 2004 report commissioned by the Minerals Management Service, blind shear rams are not designed to cut through drill pipe tool joints, the thick-walled connections between sections of pipe.
“Casing shear rams also may not cut through tool joints. These tool joints may take up as much 10 percent of a pipe’s length. The use of redundant shear rams could eliminate this risk, ensuring that there is always one shear ram that is not opposite a tool joint. But Minerals Management Service (MMS) regulations currently do not require redundant blind shear rams and casing shear rams. The Deepwater Horizon included only one of each.
“Blowout preventers usually include one or more emergency backup (or secondary control) systems, including a system commonly called a deadman switch, to close the blind shear rams and seal the well in case of a loss of communication with the drilling rig.
“In order for the deadman switch on the Deepwater Horizon to be activated, three separate lines from the rig to the BOP had to be severed: power, communication, and hydraulics. If any one of those lines remained active, the deadman switch would not have been triggered even though the blind shear rams could not be activated from the surface. The Deepwater Horizon also did not have an acoustic backup switch, which might have been able to activate the BOP remotely from the surface.13
“Offshore drilling operators rely on remote-operated vehicles (ROVs) to activate blowout preventers as a last resort. These unmanned, submersible vehicles travel to the bottom of the ocean and can directly trigger blowout preventers via an interface on the BOP itself. The Deepwater Horizon’s BOP, however, has not sealed the well even after many days of ROV intervention.”
Source: House Committee on Energy and Commerce