State to Plug 20-year-old Geothermal Research Wells

The state Legislature has earmarked $2.5 million to plug and abandon two 20-year-old research wells that were part of a program to determine the extent of geothermal resources in lower Puna.

The Hawaiian Scientific Observation Hole Program consisted of three wells drilled in in the early 1990s to obtain cores from Kilauea volcano’s east rift zone.

One of the two wells to be plugged, SOH-1, is located on land in Pohoiki leased by Puna Geothermal Venture, the state’s only active geothermal energy plant. The other, SOH-2, is located several miles to the northeast towards Kapoho.

According to the Department of Land and Natural Resources, the project involves the placing of cement plugs in the wells which would be filled with mud and sand. The top segments of the well casing as well as any above-ground structures will be removed and the site restored to its “natural condition.”

The capital improvement budget recently approved by lawmakers contains $250,000 for the upcoming fiscal year for planning of the project, and $2.3 million in the following year for the plugging phase.

A third well from the program, SOH-4, was previously plugged, as was KA1-1, which was drilled as a production well by True/Mid-Pacific Geothermal Venture in the Wai Kele O Puna forest.

True abandoned its project after state drilling permits were temporarily suspended for both it and Puna Geothermal Venture following the 1991 blowout of a well being drilled by PGV. The project was also met with considerable public protest.

The SOH program was funded by the state Legislature in 1988 through the Department of Business, Economic Development and Tourism and managed by the University of Hawaii’s Hawaii Natural Energy Institute.

According to a 1993 UH report, the program was designed “to stimulate geothermal development and confirm the geothermal resources of Hawaii.”

“Although much work remains to be done, the SOH program was successful in providing both geothermal developers on the Big Island with vital details of the subsurface geology of the KERZ [Kilauea East Rift Zone], and in initiating the geothermal assessment of Hawaii,” the report said.

It said the cost of drilling the three holes was $4.2 million.

According to the report, the SOH-2 well reached a depth of 6,802 feet where a temperature of 602 degrees was recorded. SOH-1 was drilled to 5,526 feet where the temperature was 403 degrees.

The SOH program initially was to include two additional wells to be drilled on Maui, but those plans were cancelled following “intense local opposition,” the report said.

The SOH program followed the establishment of the experimental HGP-A geothermal production well project just to the west of where PGV is now located.

HGP-A went on-line in 1982, generating approximately 3 megawatts, and was operational for eight years.