Geothermal Well Plugging and Abandonment

In the late 1980s, two geothermal wells were drilled in Puna on the Big Island of Hawaii. One of the wells (SOH-4) is located on private property and the other well (KA1-1) is located in the Wao Kele o Puna Forest, a habitat for over 200 native Hawaiian plant and animal species.

This nearly pristine forest property was purchased from the Campbell Estate by the Office of Hawaiian Affairs (OHA) in 2006. The Department of Land and Natural Resources (DLNR) and OHA want the KA1-1 site to be partially restored to its natural condition.

The two wells were unused and after time, as the well heads corroded, these unused wells had potential to being leaking poisonous gases into the atmosphere.

A challenge presented itself via the depth of these wells. As the two geothermal wells are up to 7,850 feet deep, careful and proactive thought was critical in achieving effective well plugs. It was essential to prevent the emission of dangerous gasses from the well and no polluted stormwater runoff or well fluids could be allowed to leave the site. As one of the wells was located in a relatively pristine forest property, construction activity needed to avoid further damage to the environment. Both well sites were also heavily graded and altered. Partial restoration was a project requirement.

A possible resolution to the challenge and an alternative plan for the plugging design of KA1-1 was formed by Oceanit in the field when it was discovered that the well was blocked at 5,090 feet. The design of the well plugging included blowout preventers and carefully specified many types of safety and backup equipment. Best management practices were developed by Oceanit to minimize damage to the forest, eliminate drilling fluid runoff, and minimize the runoff from stormwater. The drilling contractor was meticulous in following these practices for the most desirable and safest results.