ANCHORAGE, Alaska - Divers have placed a clamp over a hole in an underwater Alaska pipeline, stopping the flow of millions of cubic feet of natural gas into Cook Inlet, home to endangered beluga whales.
Hilcorp Alaska, a subsidiary of Houston-based Hilcorp, announced Friday that divers Thursday night covered a gash at the bottom of the 8-inch diameter line in 80 feet of water. They measured the hole at less than 0.5 square inches.
"A total of 12 dives were completed on the fuel gas line in order to locate the leak, then properly position, stabilize and prepare the pipeline for repair," Hilcorp spokeswoman Lori Nelson said by email.
Cook Inlet covers 180 miles from the Gulf of Alaska to Anchorage. A Hilcorp helicopter crew spotted gas bubbling from the line Feb. 7 about 4 miles offshore.
The pipeline carries processed natural gas to four production platforms, where it's burned to generate electricity. Analysis of gas flow indicated the pipeline probably started leaking in mid-December and initially spewed up to 310,000 cubic feet of natural gas per day.
Hilcorp lowered pressure in the line to reduce the daily flow to 85,000 to 115,000 cubic feet.
The inlet is notorious for extreme tides that produce strong currents. Hilcorp held off on repairs until the additional threat to divers of floating ice had diminished.
Divers for Hilcorp halt monthslong Cook Inlet gas leak
Author: Alex DeMarban
Updated: 6 hours ago
Hilcorp Alaska has stopped a natural gas leak in Cook Inlet that released methane for months and generated concerns about impacts to wildlife and calls for increased scrutiny of the Inlet's dated oil and gas facilities.
Dive crews on Thursday night "safely and successfully" installed a clamp on the marine pipeline, Hilcorp said in a prepared statement.
The repair required multiple dives to the seafloor over the past week. State officials have said the damaged line is 80 feet deep.
Hilcorp will continue inspecting the 52-year-old pipeline and take additional steps to stabilize and protect it, the company said.
The subsea leak was discovered Feb. 7 but Hilcorp data showed it had been occurring since late December, according to federal pipeline regulators. The leak was northwest of Nikiski, about 3 1/2 miles off the coast.
Thick sea ice presented dangers to dive crews, delaying repairs for two months.
Bob Shavelson, with watchdog group Cook Inletkeeper, said Hilcorp's inability to repair the pipeline in winter is worrisome.
"If it takes Hilcorp months and months to shut in a leaky line, we need to re-evaluate whether they can operate in the Alaska winter," he said.
Hilcorp’s Platform A on April 2. A pipeline that delivers natural gas used as fuel for this platform and three others began leaking in December. (Bill Roth / Alaska Dispatch News)
With warming weather melting the sea ice enough by Saturday, divers began efforts in the murky water to find the damaged spot.
"A total of 12 dives were completed on the fuel gas line in order to locate the leak, then properly position, stabilize and prepare the pipeline for repair," Hilcorp said in the statement issued by spokeswoman Lori Nelson.
Divers installed a steel and rubber clamp over the leak, creating a seal that won't release liquids or gas, the company said. The gash, found on the bottom of the pipeline atop a boulder embedded in the seafloor, was initially estimated to be about 2 inches wide.
But closer inspection, after the pipe was lifted more than 1 foot off the seafloor, and after divers removed mineral buildup on the outside of the pipe, showed a smaller gash, less than a half-inch long and across.
The pipeline was the first installed in Cook Inlet in 1965 as the oil and gas industry was launching a rapid construction program in the basin. By the end of the decade, 14 production platforms were built.
Originally, the pipeline delivered oil to a shore-based processing facility, tapping the Middle Ground Shoal field, the first offshore discovery in Alaska, with Shell the operator at the time.
As facilities changed hands over the decades, the line in 2005 was converted to natural gas. It delivered fuel gas 7 miles to operations at Platform A, and also to other nearby production platforms at the field. Hilcorp Alaska acquired it in 2015 from XTO Energy.
Unable to immediately make dive repairs, Hilcorp, with approval from regulators, decided against completely shutting down the line. The company said it was concerned that residual oil left in the line could leak into the environment.
But after discussions with Gov. Bill Walker, Hilcorp in late March shut down the small oil production from the field. That allowed Hilcorp to significantly reduce the amount of fuel gas flowing through the line, and reduce the leak.
The 8-inch pipeline was originally installed next to an oil pipeline that still delivers crude oil today and has generated concerns among regulators and watchdogs that it too will leak, subject to the same threats that led to the gas line leak.
Hilcorp Alaska said it is taking steps to further inspect and protect the oil line from damage.
"Neither pipeline will be returned to regular service until Hilcorp, along with state and federal regulators, agree it is safe to do so," the company said.
The leak point was located on the very bottom of the pipeline, resting on a boulder embedded in the seafloor. Initial visual inspections noted the breach to be approximately 2” in size. The affected section of the line was lifted approximately 1.5’ from the seafloor, then stabilized, allowing for closer, more careful inspection of the leak site.
Divers removed scaling and cleaned the exterior of the line. Exact measurements of the breach were taken, recording the actual size at 3/16”W x 3/8”L. After proper cleaning and preparation, a steel and rubber clamp was installed over the leak. The clamp assures a gas tight, liquid tight seal that will reinforce the pipeline.
The repair operation was provided to the Alaska Department of Environmental Conservation and the Pipeline and Hazardous Materials Safety Administration.
Now that the leak has been stopped, over the next several days, as weather permits, further inspection and stabilization of both the oil and gas pipelines in Middle Ground Shoal will be completed. Neither pipeline will be returned to regular service until Hilcorp, along with state and federal regulators, agree it is safe to do so.
Dive crews mobilized from Homer on Friday April 7th and have been able to safely work through the weekend. Divers have identified the leak location, and are working to prepare the site to
allow for the installation of a temporary clamp.
The leak point, approximately two inches in length, was noted to be on the very bottom of the pipeline resting on a boulder embedded in the seafloor.
Following completion of the initial repair, further inspection and work will be done to permanently repair the affected segment of pipe. The line will not be returned to service until permanent repairs have been completed, the line has been pressure tested, and regulators have approved a re-start.
We will provide further updates as new information becomes available.
After recent discussions with Governor Walker and meetings with the Alaska Department of Environmental Conservation, the parties have agreed to reduce the pressure in the gas pipeline to approximately 65 psi. This will necessitate shutting in oil production from Middle Ground Shoal platforms A & C. Hilcorp appreciates the proactive and transparent way Governor Walker has expressed his concerns regarding this matter.
Previous weather conditions have prevented Hilcorp from shutting in oil production at an earlier date. Shutting in wells and idling lines and equipment in very cold temperatures create a known risk of freeze-up and potential rupture. Warmer ambient temperatures now permit a safer shut in process of the wells along with the associated lines and equipment.
Shutting in oil production allows the gas pipeline to operate with 65 psi, the minimum positive pressure. Minimum positive pressure is necessary to prevent water from entering the line and a potential washout of the residual crude oil that remains in the pipeline. Further, maintaining minimum pressure on the line will allow for the platforms to run essential equipment and safety systems.
As Hilcorp works with state and federal agencies to finalize the plan to reduce gas line pressure, shut-in production and repair the pipeline, the safety of personnel, wildlife and the environment remain the top priority.
Planning and preparations have already begun, and once approved by the regulators, shut-in procedures will begin this weekend.
Hilcorp’s response team and the necessary equipment are ready to immediately commence repair operations as soon as it can be done safely. Based on current weather forecasts Hilcorp anticipates repair operations to occur in the next two weeks.
Weather and ice conditions allowed the sampling and monitoring programs approved by the Alaska Department of Environmental Conservation (ADEC) to begin on March 18th.
Water quality data was collected by floating a sampling buoy directly downstream from the identified leak location. Initial laboratory results from numerous samples taken in the area of the leak showed no meaningful adverse impacts to water quality. The full sampling report was provided to ADEC on March 22nd. Samples were consistent with previous modeling and, to date, all water samples have measured notably better than ADEC’s minimum Water Quality Standards for Coastal Marine Waters. Hilcorp believes the samples also demonstrate that current water quality does not pose a threat to wildlife. As an added precaution, certified marine mammal and wildlife observers will continue to monitor the leak site and surrounding areas.
Hilcorp will continue our monitoring program and we will be working with ADEC to review the data we collect. Air and Water Interface Sampling equipment is being calibrated and is expected to deploy today.
Ice conditions continue to delay our repair operations. However, the weather forecasts have improved and based on these current forecasts Hilcorp anticipates repair operations to occur in the next two weeks.
The “B” pipeline currently transports produced fluid to shore and is operating normally. The steel pipeline is 8” in diameter and 8.6 miles in length. Hilcorp acquired the pipeline in September 2015 at which time the company completed a successful pressure test on the line.
Ice conditions continue to delay repair operations at this time. Hilcorp is conducting frequent ice observations utilizing National Oceanic and Atmospheric Administration guidelines. Cook Inlet Regional Citizens Advisory Council has also provided access to its ice camera network to assist with that effort.
Hilcorp’s response team is ready and the necessary equipment has been staged to commence repair operations as soon as conditions permit a safe working environment for response personnel. Once conditions allow for safe operations, Hilcorp will undertake repairs which will take several days.
Hilcorp conducted baseline air and water sampling, and continues to conduct direct observation of the affected area, and impact modeling of the natural gas release. To date, no significant impacts to wildlife or the environment have been observed and the release does not pose a threat to the general public.
Today the Alaska Department of Environmental Conservation gave preliminary approval to Hilcorp’s broader sampling and monitoring program that was submitted last week. We will begin implementing the monitoring program in several stages as conditions allow using marine vessels, buoys and other equipment. Additional updates will be provided as significant new information is available.