Greenhill Petroleum Corp., Houston, last week stepped up efforts to control a workover blowout in Timbalier Bay field off Lafourche Parish, La.
Greenhill Pres. Ralph Cox said the company simultaneously was replacing wellhead equipment on the No. 250 development well and drilling a relief well in case surface kill efforts failed.
The blowout occurred as Blake Drilling & Workover Co., Belle Chasse, La., was deepening the Gulf of Mexico well. Plans called for abandoning Miocene D-4 sand perforations at 8,683-86 ft and 8,696-8,706 ft and recompleting in Miocene D-6 sand at 8,802-28 ft.
WHAT HAPPENED
The well began flowing an estimated 1 bbl/min of oil Sept. 29 when a workover contractor lost control of the hole while attempting to recomplete it in a lower zone. Well control efforts were complicated Oct. 1 when a fire broke out while Boots & Coots Inc., Houston, was positioning equipment at the wellhead.
Greenhill on Oct. 3-4 moved a rig onto a site 700-800 ft from well No. 250 to begin drilling the relief well. By the morning of Oct. 6, the relief wellbore had penetrated to a measured depth of 2,500 ft. Greenhill set 10-3/4 in. surface casing and was drilling ahead.
Also by Oct. 6, crews had severed and removed wellhead equipment, and Greenhill was beginning to drain some workover rig ballast tanks to pull the unit away from the wellsite. The company planned to install new surface equipment while No. 250 still was burning.
Greenhill was allowing the well to continue burning to minimize pollution.
"We could have doused the well, but we decided the possible pollution might be greater than we're willing to tolerate," Cox said.
Cox estimated well No. 250 could be killed by last weekend if surface equipment was replaced without further incident. If the relief well was needed to cut the uncontrolled oil flow, an additional week could be needed to cap the well.
SPILL CLEANUP EFFORT
Within 1 hr after the Sept. 29 workover mishap, Greenhill, a member of Clean Gulf Associates, had a crew from Riedel-Peterson Environmental Services, New Orleans, at the wellsite. Industrial Cleanup Inc., Garyville, La., also was called in to bring the spill under control.
Greenhill and the Coast Guard estimated about 700 bbl of oil spilled into Timbalier Bay before fire ignited Oct. 1. Despite the fire, some oil still was spilling into the water before Greenhill removed the surface equipment because the flow was not vertical. Removing the surface equipment allowed the flow to become vertical.
United Press International quoted the Coast Guard as saying an oil slick 10-60 ft wide extended about 3 miles into the gulf.
Greenhill plans to continue both well control operations until one is successful. If the company kills the well and installs new wellhead equipment before the relief well intersects well No. 250's wellbore, it either will stop drilling or redirect the relief wellbore toward another target.
"Stopping the flow doesn't mean the well is under control, just that the flow has ceased," Cox said. "We will still have to snub in equipment and circulate the well."
Copyright 1992 Oil & Gas Journal. All Rights Reserved.
