Drilling and testing geothermal wells in an active volcanic domain, Puna geothermal field, Hawaii, USA

Abstract

Thermal Power Company, Operator for the Puna Geothermal Venture which includes AMFAC and Dillingham, has drilled and tested two geothermal wells in the Puna Geothermal Field, Hawaii, USA. The field is located in the East Rift Zone of Kilauea which is one of the world’s most active volcanoes. The wells were drilled to a depth of 7,290 and 8,005 feet and completed with 9 5/8" production casing to 4,200 feet and 7" perforated liner extending to bottom. A high temperature, 660°F plus, two-phase geothermal reservoir was encountered. Noncondensible gas concentration is only 0.2% by weight but contains 1,100 ppm H2S which must be abated to meet environmental concerns. Flow testing proved to be a complex affair. However, 100% steam production has been identified in both wells with the assistance of a separator. These two wells, along with the U.S. Department of Energy/University of Hawaii HGP-A well which now generates 3 MW of electric power, have defined a 25 MW reserve capacity on the Puna Geothermal Venture leasehold. A third well with substantially improved casing design will be drilled by Thermal later in 1984 to refine plans for the wellfield and generating plant.