The House Committee on Energy and Commerce released today its comprehensive memo detailing the technical faults, oversight failures and cost-cutting measures that lead to the Deepwater Horizon rig explosion, fire and spill.
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The memo describes specific faults with BP’s blowout preventer, the BP cementing shortcuts and pressure testing failures the lead to excessive pressure in the well. Each contributed to the catasrophic explosions which lead to the fire and, ultimately, the rig’s failure. The memo, reproduced below, includes a clearn, non-technical explanation of how blowout preventers work.
On April 20, 2010, at about 10:00 pm, an explosion occurred on the Deepwater Horizon oil drilling which was drilling a well in BP’s Macondo Prospect, approximately 40 miles south of the Louisiana coast in the Gulf of Mexico. There were 126 people on the rig at the time of the explosion. Fifteen of those were injured and eleven died. The Coast Guard responded to the explosion and fire which caused the rig to sink and resulted in the ongoing blowout.
Serious questions have been raised about the causes of the explosion and the adequacy of industry practices and regulatory standards relating to oil and gas drilling. Ongoing investigations are being conducted by a Marine Board of Investigation (a joint effort under the Coast Guard and the Minerals Management Service), a Presidential Commission, the U.S. Chemical Safety and Hazard Investigation Board, and several Congressional Committees, including the Committee on Energy and Commerce.
The President also ordered the Secretary of the Interior to review the accident and propose additional precautions and technologies to improve the safety of offshore oil and gas drilling; the findings of this review were published on May 27, 2010 in a document usually referred to as the DOI 30-day Report.
The Energy and Commerce Committee’s Subcommittee on Oversight and Investigation has held three hearings on the explosion and blowout.
The subcommittee’s investigation revealed that numerous key safety precautions were neglected by BP prior to the Deepwater Horizon disaster. BP chose a well design that used only a single barrier to prevent flow of dangerous gases rather than a design that used multiple barriers. BP ignored the advice of its contractor, Halliburton, and chose a cement sealing approach for the well that was predicted to fail. BP failed to conduct a key cement test. BP failed to fully circulate well fluids, and BP did not install a key piece of equipment at the wellhead prior to the explosion.
Several of these steps, though considered industry best practices, are not mandated under current law. All of these decisions saved time and money for BP, but increased risks.
On Friday, June 25, 2010, the Committee on Energy and Commerce released a discussion draft of Blowout Preventer Act of 2010″, which is the subject of this legislative hearing. The discussion draft, a section-by-section summary of which is attached, establishes a number of standards and procedures to help ensure the use of appropriate safety equipment and practices during high-risk oil and gas drilling activities. Several of the key issues addressed by the discussion draft are summarized below.
A. Well Control Issues
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.
The Committee has also learned that there were several issues with the Deepwater Horizon’s maintenance of its BOP system. There are no MMS regulations requiring testing of emergency systems, and BP did not conduct these tests. ROVs discovered several leaks in the hydraulic lines that provide pressure for BOP functions, and found unexpected modifications to the original design of the BOP. These problems resulted in wasted time in the critical days following the accident and might have contributed to the initial failure of the blowout preventer.
Well Design, Fluid Circulation and Displacement, and Cementing Practices
The Committee’s investigation has also uncovered several questions about decisions BP made in regard to the design and execution of the Macondo well plan.
The Macondo well was designed with a long string production casing which extended from the sea floor down to the reservoir from which oil was to be produced. This well design leaves only two barriers along one flow path, through which hydrocarbons could flow between the reservoir and the blowout preventer: a layer of cement at the bottom of the well, and a mechanical seal at the wellhead itself.
Another design, a liner-tieback approach, would have made a blowout less likely by requiring four barriers between the reservoir and the BOP: two mechanical seals and two layers of cement.
The mechanical seal at the wellhead required a lockdown sleeve to seal the well against pressure from below as well as pressure from above. This lockdown sleeve was never installed on the Macondo well, even though drillers on the Deepwater Horizon began procedures that would have put upward pressure on the wellhead seal.
Because the Macondo well was designed with a long string casing, it was critically important that the cement job at the bottom of the well successfully seal off the reservoir. But BP cut several corners on its final cement job: it ran casing with an insufficient number of centralizers required to ensure an even seal around the entire casing; it failed to circulate drilling mud before cementing, in accordance with industry best practices; and it failed to run a cement bond log test, which could have uncovered failures or imperfections in the bonded cement.
The legislation addresses these issues by directing the appropriate Federal official to promulgate regulations to require: three independent barriers across potential flow paths; appropriate fluid circulation and displacement practices; and appropriate cementing practices, including mandatory cement bond logs.
D. Regulatory Development and Implementation
In addition to critical equipment and well design issues, the discussion draft also addresses a number of issues related to periodic review and updating of regulatory standards, implementation and enforcement of standards through independent third-party certification, inspections, and other mechanisms, as well as stop-work authority and whistleblower protections.
Source: House Energy and Commerce Committee
