Eighty percent of reserve pits closed out

All of Alaska’s 600 oil, gas drill sites have been inspected

Kristen Nelson

Petroleum News Editor-in-Chief

There are some 600 oil and gas drill sites in Alaska, the state knows where they are, and is requiring reports on, and proper closure of, all reserve pits at those sites. Eighty percent of those reserve pits, where ground-up rock and drilling mud were deposited as wells were drilled, have been closed to the satisfaction of the Alaska Department of Environmental Conservation, Judd Peterson, the department's reserve pit closure coordinator, told Petroleum News in July. Required cleanup at the remaining 20 percent is being done, at a rate of about 10 sites a year.

Peterson said part of the reason Alaska's drill sites are known is because the state had its major discoveries, Swanson River on the Kenai Peninsula in 1957 and Prudhoe Bay on the North Slope in 1967, so relatively late. There were some scattered wildcats drilled in the state, but Alaska's isolation made it expensive to drill here, so most drilling in the state — even very early wells — was done by major companies, or partnered by major companies or major companies later acquired the leases, and those companies are responsible for the reserve pits.

Peterson said that while there are some "orphan" sites, sites where the responsible party is not known, all known orphan sites have been visited and there are no problems that need correcting.

The other reason Alaska knows where reserve pits are located is because only some 5,000 oil and gas wells have been drilled in the state, Peterson said, compared to 220,000 in Louisiana. Then there is Texas, with some half a million active wells, never mind those no longer producing.

"Alaska is truly unique in regard to this program because, even though we have 20 percent of the domestic oil production and the two largest oil fields in North America, we have a tiny fraction of the number of drill sites of a typical state. So Alaska only has approximately 600 drilling sites, oil and gas drilling sites, in the entire state."

Reserve pits are allowed

Congress made the states responsible for regulating drilling waste, as solid waste, in the mid-1980s.

"Up until that time," Peterson said, "the management of drilling waste was actually sort of in semi-limbo — certainly in Alaska and I assume in the rest of America."

The Department of Environmental Conservation wrote regulations for drilling waste and issued its first permits in the late 1980s. This was about the same time the Natural Resources Defense Council sued ARCO over reserve pits on the North Slope, Peterson said. "And so reserve pits — drilling waste issues — were a high-profile subject."

The court ruled in the Natural Resource Defense Council suit that production site reserve pits which were above grade on the North Slope, where there was some leaching from reserve pits, were impacting water quality adjacent to the sites and ARCO was faced with a major cleanup.

"As a result of that, all drilling waste on the North Slope now is ground and injected," he said.

Reserve pits became "almost old technology" after that, and "the companies started switching to disposal technology which did not have a surface impact," Peterson said.

What is drilling waste

The state still allows reserve pits, but land managers don't like them and regulations require companies to monitor the water quality around reserve pit sites for a number of years, "and they are responsible for that site basically into perpetuity."

So, even though reserve pits are allowed, "the technology now is to grind and inject drilling waste." Because grind and inject is the technology used on the North Slope, new drilling pads are smaller and the area of surface disturbance is minimized, he said.

Old reserve pits regulated

In Alaska the companies were required to visit each drilling site, collect water samples and report on the status of the reserve pit.

"All reports had to be submitted by Jan. 28 of 2002. So all those reports, all that field work was done. And all the reports have been submitted."

Reserve pits typically don't have to be removed, Peterson said. They are a regulated and managed waste.

What the department looks at, he said, is whether the reserve pit has been capped. Or was the pit just left open?

"Regardless if it's an open impoundment or if it's been backfilled, we collect water samples at the site … if it's open, from the open impoundment. If it's been capped we collect water samples around the site."

The department checks for various contaminants.

"What we found was that metals are essentially not an issue," rarely exceeding state water standards.

Sites with contaminant release or the risk of contaminant release require corrective action, or demonstration that the risk isn't significant enough to require corrective action.

At sites where pits remain open the contaminant that is likely to be found is diesel, Peterson said, because it was common in the 1960s and 1970s to mix diesel into drilling mud as an additive.

"And that diesel to this day, even after 30-40 years, will produce a sheen in the drilling waste when … you stick a shovel into the drilling waste in the pit and scoot it around. And if there's diesel in there you will find out instantly. It will sheen to the top.

"Sheen is a violation of state water quality standards, by definition," he said.

The companies are required to go back and properly cap the waste in place with five or six feet of material, and let if freeze back into permafrost. This is the typical solution, Peterson said, because most of the state's drill sites are on the North Slope.

Removal in face of erosion

Five sites on the North Slope were identified as at risk of eroding into the Beaufort Sea and the drilling waste was removed from the reserve pits, "so that as the sites do in fact erode into the Beaufort Sea, there's no waste left to be released," Peterson said. Exxon did two waste removal projects at Flaxman Island, BP did two projects on Sag Delta and Occidental — which hasn't been active in the state for years — did one project.

Peterson said the state didn't know what to expect at old drill sites, especially remote exploration sites, but found that at "probably 80 percent of them … the pits had been backfilled and buried at site closure, even though it was back in the '60s and '70s and there was pretty minimal regulatory oversight."

On the Kenai Peninsula, early drilling from the 1950s is "so overgrown they're really difficult to even find." We can find most of the Kenai drilling pads, Peterson said, and "they are just completely re-vegetated or soiled over, naturally over time." And then, he said, much of the early Kenai drilling was done on the refuge, and "that's always had a lot of oversight, federal oversight."

Six hundred sites covers all drilling

The North Slope production pads now use grind and inject disposal, Peterson said, and Marathon has a grind and inject facility in the Kenai gas field, and has been disposing of its drilling wastes there.

There is also a reuse program for drilling waste. "It's ground up rock," he said, and the companies "are required to wash the drilling muds off of it and once they wash the drilling muds off of it, it's ground up rock, and they reuse that … for a materials source."

And as for orphan wells, Peterson said he has visited some drilling sites in Southcentral with no known responsible party — but sites where all the pits are backfilled.

"If we know there's not a problem there, we're not going to beat a dead horse" to try to find a company "to tell us there's not a problem.

"We can go out there and see there's not a problem. We have a common sense approach to the whole thing.

"But if we found a site that was a problem, it would be dealt with."