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BLM making progress in sealing NPR-A legacy wells; just 6 remain
Alan Bailey for Petroleum News
In a recent report on its legacy well remediation program in the National Petroleum Reserve-Alaska the Bureau of Land Management has said that only six wells still need to be plugged.
The agency said that the remediation program resulted from the drilling of 136 test wells in the reserve following the establishment of the reserve in 1923. The wells were drilled to try to locate oil and gas resources while also developing new technologies and pad designs for drilling in the Arctic. However, upon abandonment the wells were not adequately plugged and consequently became environmental hazards, with the potential to contaminate groundwater and cause flooding and the formation of sinkholes.
In 1976 BLM became responsible for managing the NPR-A and in 1982 the agency also became responsible for the oversight of all onshore oil and gas actions on public lands. Consequently, since 2002 BLM has been operating a program to plug and clean up legacy wells throughout the NPR-A, using a strategic plan that is regularly reviewed and updated, BLM says.
A multi-step process Plugging a well involves a multi-step process requiring an inspection of the site, site preparation and the pumping in of plugging materials such as cement. Underground plugs seal the oil and gas production zones, and porous rock formations. Following pressure tests of the adequacy of the sealing process, and with additional sealing, if necessary, the well is capped and reclamation of the surface area around the well begins. The entire process for a single well can take a year or more to complete, BLM says.
Conducting this work in the Arctic conditions of Alaska's North Slope proves particularly challenging. While specialized equipment is needed to prevent damage to the delicate surface of the tundra, work cannot commence until tundra operations are approved for the winter season, when there is adequate snow cover and sufficient frost depth for tundra protection. In the absence of adequate protection, it can take years or even decades for some delicate Arctic plant species to recover, BLM says.
Although the materials used to plug the wells are similar to those used in the Lower 48, plugging operations on the North Slope require a special blend of cement designed to properly harden in frozen ground conditions, the agency says.
Given the various complexities it can take at least six to eight months to plan a remediation project. And, depending on the location of the project, access to the well site can require a snow trail that is more than 100 miles in length, taking several days to traverse, BLM says.
Each project is unique Each legacy well remediation project tends to be unique, with its own challenges, depending on factors including the well location, well downhole conditions, the material used for the original drilling and the specialized equipment required for the remediation, BLM says. And, for a well drilled near the coast, there can also be the threat of coastal erosion impacting the well site. This type of situation requires close monitoring, with the development of plans to address the erosion threat.
Agency coordination BLM says that its well remediation program involves coordination with various federal and state entities, including the Alaska Oil and Gas Conservation Commission, the Alaska Department of Environmental Conservation and Alaska Native corporations. BLM also collaborates with Native-owned small businesses, the agency says.
BLM says that it has collaborated with its partners in its well remediation program every winter since the program began. And now only 22 of the original 136 wells have not been remediated. However, the U.S. Geological Survey uses 16 of these remaining wells for monitoring Arctic temperatures. Consequently, BLM now only has six wells that still need to be plugged, the agency says.
--ALAN BAILEY
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