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Gulf of Mexico Region

Losses of Well Control - 1998

January 6, 1998 – Hall-Houston Oil Company

Remarks: The crew ran the 10-¾ inch casing in Well No. 3, and began cementing operations. During cementing operations, the crew lost returns at the surface for approximately 5 minutes, and then they regained returns. After they completed cementing operations, the crew washed out cement down to the mud line hanger with a 1-¼ inch line. They made a rough cut on the 10-¾ inch casing, and laid down one joint of casing. They landed the diverter, and began to nipple down the diverters, chains, and cables. The well suddenly vented fluid from the 10-¾ inch by 16-inch annulus. The crew began to nipple up the diverter by installing several bolts. They then noticed flow from the bell nipple, and closed the diverter. While the well was flowing on diverter, the crew began rigging up the Haliburton unit to kill the well. Gas began leaking around the seals of the 16-inch wellhead. They decided to evacuate the rig. All personnel were accounted for. They monitored the well from a workboat for the next three days. On January 9, a crew boarded the rig, started the standby generator, rigged up fire hoses for a water curtain, removed the bell nipple, re-hung the Texas deck, and hung the 13-3/8 inch BOP stack. The flow had slowed considerably, and eventually stopped. On January 11, the well was dead. The crew began securing the well and restarting the rig’s systems.

January 16, 1998 – Chevron U.S.A., Inc.

Remarks: On 1/16/98 gas was found bubbling around Platform B (unmanned). All but one well (B-7) had been plugged. B-7 was a low volume gas well. Attempts to control the flow through surface intervention from the platform proved to be too hazardous and were abandoned. Fire boats and oil clean-up boats were on location. The decision was made to drill a relief well. The Diamond Ocean Crusader was onsite 1000 feet away within 96 hours. On 2/14/98 the relief well intercepted well B-7, and heavy kill fluid followed by cement was pumped into B-7, which stopped the flow. Well B-7 was plugged and abandoned on 2/18/98. The operator determined that the SCSSV was cut out by gas/liquid/ sand flow. This eroded holes in the 7-inch and 10-3/4 inch casings.

April 30, 1998 – Vastar Resources Inc.

Remarks: While attempting to come out of the hole on a wiper trip, the pipe began to stick. When the operator pulled 100,000 pounds over the drill weight, "gumbo" mud started to come over the kelly bushing. The pumps were turned off, and the hole began unloading, blowing the rotary bushing out of the rotary table. All personnel except the drillers evacuated the rig floor. The diverter system was engaged at the master control panel. The well started to blow gas and was diverted. The pumps were engaged, pumping 11.1 ppg mud in the hole. After 15 minutes, the well bridged over. They began mixing and pumping 12.0 ppg mud down the hole. When they were unable to get returns, the driller began pumping 12.0 ppg mud down the annulus to fill the hole. They were still unable to establish returns, so they backed the annulus pressure off and worked the drill pipe. The crew opened the diverter and found the diverter plugged above the diverter lines. The riser was then filled with mud and cleared of the "gumbo" which was plugging the diverter lines. They then filled the hole with 12.0 ppg mud through the casing valve at the wellhead, and regained control of the well.

July 8, 1998 – Newfield Exploration Company

Remarks: The operator was plugging and abandoning well B-7. At the time of the loss of well control the crew was performing sand-washing operations. They washed through a sand bridge and encountered high-pressure gas. When the high-pressure gas hit the surface equipment, it cut a hole in the gas buster allowing gas to escape to the atmosphere. The operator closed the upper and lower stripper rams and the 1-¼ inch safety ram. The pressure on the pump manifold was 7200 psi, and the operator closed the manual choke located on the inlet to the gas buster. The choke line piping failed and parted in four places. The failed choke line began whipping back and forth, and damaged the hydraulic control lines to the BOP stack. An attempt to close the shear rams failed, and the operator decided to evacuate the facility. Eleven people evacuated the platform and were rescued (all personnel accounted for). A crew boarded the facility on July 9, and attempted unsuccessfully to close the well in by reattaching the hydraulic lines. On July 10 the well was brought under control by bullheading a lost circulation pill ahead of 16.5 ppg mud. On July 11, well control operations continued by circulating kill mud to assure the well was free of migrating gas. An estimated 1.5 barrels of condensate was spilled into the water during the incident.

November 22, 1998 – Ocean Energy Inc.

Remarks: A coil tubing unit was being used to wash sand inside a 2-3/8 inch production tubing. The coil tubing operator encountered difficulty snubbing the tubing into the hole. The crew removed the stripper rubber in the pack-off. The drag on the tubing eventually freed and washing operations resumed. The coil tubing operator then observed water spewing from between the pack-off and the injection head. Flow continued, eventually turning into a dry gas and water mixture. The operator initiated shut-in procedures by setting the slips on the coil tubing, then closing the cutter rams. An attempt to pull the coil tubing from the blind ram cavity failed (it was later learned that this step failed because the coil tubing pipe had parted above the pack off assembly). The blind rams were closed on the tubing to reduce the flow. Both pipe rams were closed and successfully sealed the outside of the coil tubing. Flow continued out of the coil tubing. The crew attempted to shut off flow by closing a manual valve on top of the tree. Flow still continued. Personnel were evacuated from the facility. On November 23 they removed the injector head and pack off from the Bowen connection above the BOP’s to allow a valve and riser pipe to be stabbed over the broken stub. The valve was stabbed and a chicksan line was installed to vent gas into the choke manifold. The valve was closed and SITP measured at 200 psi. The well was killed by pumping 11.6 ppg calcium chloride down the coil tubing annulus and up the coil tubing. There were no injuries or pollution.

December 9, 1998 – Petrobras America Inc.

Remarks: A coil tubing unit was being rigged up to jet-in Well A-1 with nitrogen at 1930 hours on December 8. While attempting to stab the coil tubing injector head, the crew determined that the ram block retainer and piston on the No. 4 ram had stripped out threads that could not be repaired on location. A new BOP stack for the coil tubing unit was ordered. While waiting on the replacement BOP’s, the crew removed the old BOP, and pickled the coil tubing with 15% hydrochloric acid. The crew installed the replacement stack and tested at 0800 on December 9. Several attempts to shift a sliding sleeve with a wireline were unsuccessful. At approximately 1900 hours, the crew determined that the flowline segment was not equipped with a proper sampling valve. The crew decided to install a weld-o-let and 1-inch ball valve. Seventy feet of 3-1/16 inch riser extended from the crown valve on the well to the drill floor. The BOP stack was in place at the top of the riser with no coil tubing in the hole. The well was shut in by the vertical run automatic surface safety valve, and the flowline was isolated with a closed manual block valve on the departing pipeline. The crown valve was open, and the riser and flowline were filled with 15% hydrochloric acid and water. During the process of opening the wing automatic valve to remove a fusible locking cap, one of the crew mistakenly/inadvertently opened the vertical run automatic surface safety valve subjecting the riser and BOP stack to a sudden surge of well pressure of 3550 psi. The hammer effect of the sudden of high pressure and the riser fluid column sheared the retainer ring inside the Bowen connection located just under the BOP stack. The uncontrolled well pressure blew the BOP stack off the riser and into the derrick approximately 40 to 50 feet. The BOP stack landed on the southwest corner of the heliport and fell into the water. The uncontrolled flow was immediately brought under control by the same crew member closing the vertical run surface safety valve.

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Last Updated: 06/24/08, 03:07 PM