Well under control
Responders stop spray of gas and oil from leaking Prudhoe Bay wellhead
In the early hours of April 17 the team responding to the venting of gas from a well on Drill Site 2 of the Prudhoe Bay oil field succeeded in killing the well and thus achieving control of hydrocarbons escaping from the wellhead. The team killed the well by pumping salt water containing potassium chloride and mixed with methanol into the well, thus offsetting the upward pressure that had been driving gas from the well, according to a situation report issued on April 17 by the Alaska Department of Environmental Conservation.
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However, since this dynamic kill of the well means that pressure has to be continuously applied to the wellhead, a mechanical plug will need to be installed before the well can be officially designated as secured, ADEC said. BP is preparing a plan for placing a plug in the well, the agency said.
The venting of gas from the wellhead was discovered at 7:30 a.m. on April 14. Initially the gas leak also generated a spray of oil that impacted the well pad. BP set up a command post on the North Slope for the incident and ramped up an incident management team involving BP, the Alaska Department of Environmental Conservation, the Environmental Protection Agency and the North Slope Borough.
The response team determined that there were two leaks on the wellhead: an oil leak near the top and a gas leak farther down. The sprayed oil had been coming from the top leak, which was stopped by activating the wellís surface safety valve, according to an April 15 situation report. BP has said that, following the kill action on April 17, all leakage from the well has now been stopped.
The cause of the leaks has yet to be determined.
Rose three to four feetAccording to ADEC, an initial attempt to bring the well under control on April 14 failed because of damage to a well pressure gauge. Apparently, the wellhead had risen three to four feet, causing the pressure gauge to break off, thus preventing the responders from pumping fluid into the well to kill it. The wellhead has since settled by 11 inches and has not moved further, ADEC said. Personnel from well control contractor Boots and Coots safely entered the well house on April 16 and placed a plug in the damaged piping coming from the well head. That then enabled the responders to pump the necessary fluid into the well to kill it.
The initial spray of oil associated with the gas venting landed on the Drill Site 2 gravel pad. According to ADEC, a forward looking infrared overflight on April 14 showed that the crude spray plume did not leave the pad, and that the impact of the oil leak is limited to the padís reserve pit. However, there have not yet been any reports from cleanup responders on the extent of the oil contamination.
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