Operations under way in the Gulf of Mexico (GOM) to drill a relief well to stop the flow of oil from a well ruptured more than three weeks ago might actually make matters worse, according to a report by Houston-based Wild Well Control Inc. prepared for Canada’s National Energy Board (NEB).
Other methods should be tried before a relief well to stop the leak, Wild Well, a veteran of 35 years in its dramatic specialty, said in the warning to a Canadian review of Arctic deep water drilling safety, shortly before the April 20 blowout of the well in the GOM. The NEB this week replaced the review — which had begun as an exchange of papers among specialists — with a wider inquiry to take into account lessons learned from the GOM tragedy and open the discussion to the public.
BP plc is the majority owner and the operator of the well in Mississippi Canyon Block 252 (see Daily GPI, May 11). The well was being drilled by Transocean Ltd. using its Deepwater Horizon rig, which burned and sank following the blowout.
“Drilling the relief well could be more risky than drilling the original well,” Wild Well said in a 22-page contribution to the technical discussion before the NEB. A second hole is bound to take more time because it has to be “directional” or pierce the geology at an angle from a starting point some distance away from the first one, Wild Well said. BP officials have said they are confident the relief well will reach its target.
A relief well also involves more than the technical difficulties of achieving the hairline accuracy required to intersect with the first hole, Wild Well said. The second well can also run afoul of spreading leaks from the blowout that “charge” surrounding geological zones with high-pressure gas or oil, and potentially encounter entirely new and unexpected deposits.
“The relief well might become an additional or independent exploration well [into a different gas- or oil-saturated rock fault] with the same, differing or more problematic issues than the designated exploration well — therefore, essentially doubling the risks for well control issues,” Wild Well said.
The runaway well tamers describe an array of potential actions, ranging from cutting off flows with special hole-plugging substances or equipment to installing a second blowout preventer (BOP) device on top of the original one if it fails. BP is working on both of these measures.
Wild Well said the primary means of controlling wells — including relief wells — remains management of drilling fluids, known in the industry as “mud.” The materials, used in a wide range of types and mixtures, simultaneously lubricate the rotating equipment and counter underground pressures with their weight as a tall, continuous column of liquid in the drill pipe and hole.
In the United States Congress is investigating the cause of the tragedy. House Energy and Commerce Committee Chairman Henry Waxman (D-CA) Wednesday said the committee has uncovered major discrepancies in the accounts of some of the companies involved (see Daily GPI, May 13).
Transocean, which is a potential contractor for new exploration planned in Canadian waters of the Beaufort Sea, also emphasized blowout prevention with the use of suitably dense drilling fluids and BOP equipment made strong enough for the well and its natural environment.
In a 12-page paper filed with the NEB, Transocean highlighted the role of specialists like Wild Well. “In the extremely rare case where the normal well control procedures and existing blowout prevention equipment and backup blowout prevention equipment fail to contain the well, the specific conditions of the resultant blowout will determine which method of intervention will be attempted. These activities are normally through the direction of third parties who specialize in this type of operations.”
Det Norske Veritas, a Norwegian risk-management foundation with global operations, underlined the rarity of offshore drilling mishaps in a lengthy review of Beaufort Sea conditions that was commissioned by the partners in proposed Arctic deep water exploration, Imperial Oil Ltd. and ExxonMobil.
Using statistical techniques akin to the actuarial calculations of insurance firms, the risk specialists calculated the odds of losing control over offshore wells for even a moment as one incident for every 500 drilled. The estimate includes all types of mishaps, ranging from brief well hiccups known in the industry as “kicks” to serious environmental events caused by failures of equipment and control procedures.
A global review of performance by BOPs since 1980, including their record in the GOM and the North Sea, found that the probability of a failure is a modest 0.68-1.0% depending on the design of the equipment.
The chances of an outright blowout and leak due to catastrophic failure of all safety, prevention and control procedures and hardware are much slimmer. “No evidence was found of any relief wells ever being required for deepwater drilling operations using a drillship,” Det Norske said. “The study concluded with an estimated likelihood of uncontrolled flow after using all available options on the drillship to be once for every 100,000 wells drilled, or once in every 10,000 years based on 10 wells drilled per year in the Beaufort Sea.”
A previously approved deepwater Atlantic Canadian exploration well in the Orphan Basin offshore of Newfoundland was allowed to go ahead after the GOM accident by the Canada-Newfoundland Offshore Petroleum Board, a joint agency of the federal and provincial governments. But before granting any permits for deep drilling to spread to the Beaufort, NEB Chairman Gaetan Caron said, “We need to learn from what happened in the Gulf. The information taken from this unfortunate situation will enhance our safety and environmental oversight.”
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