Abstract: Geothermal Energy in Hawaii--Present and Future

John W. Shupe, Paul C. Yuen

Drilling at geothermal well HGP-A on the Island of Hawaii was completed on April 27, 1976, to a depth of 6,450 ft (1,966 m). Completion of this well culminated a 4-year program of planning, exploratory surveys, related research, and experimental drilling requiring over $2.5 million of federal, state, county, and private funding. Maximum downhole temperature recorded was 358°C (676°F), and initial sampling indicated that the quality of the fluid was excellent--low in chloride, mercury, and hydrogen sulfide content.

Subsequent ERDA and state funding supported a comprehensive well-testing program, with the following preliminary results.

The Kapoho reservoir: (1) is liquid-dominated; (2) has a nonporous formation with permeability thickness of approximately 1,000 md-ft; (3) has high temperatures and formation pressures--350°C and 2,000 psi; (4) is a potentially large reservoir, possibly 1,000 Mw(e) for 50 years; and (5) contains slightly brackish, relatively benign fluid, although high in dissolved silica.

The HGP-A geothermal well, drilled in the Kapoho reservoir, probably has severe skin damage, since the flow rate increases with each test. Other characteristics of this well are (1) a well-head pressure of 160 psi (1,101.2 kPa) at a steam-flow rate of 60,000 lb/hour; (2) a potential power output of 3.5 Mw(e) for at least 30 years; (3) indicates that flashing occurs in the formation; (4) during flashing the borehole contains steam and water at saturation; and (5) the probable producing zones are at bottom hole and 4,300 ft (1,300 m).

Approval has been obtained from the U.S. Department of Energy (DOE) for major funding for a wellhead generator of around 2 Mw(e) capacity--the limit of the existing power line in the area. State and county matching funds will be provided and negotiations are under way. The utility company of the Island of Hawaii has agreed to purchase the power and assist with construction.

Deterrents to rapid expansion of geothermal energy on the Island of Hawaii are: (1) limited guaranteed power demand; (2) the only confirmed geothermal resource is in an active volcano rift zone; and (3) state geothermal regulations have not yet (February 1, 1978) been adopted. Driving forces for geothermal development include: (1) high vulnerability of seaborne imported petroleum and high energy costs; (2) major potential markets in mineral refining and other energy intensive industry; (3) potential nonelectrical geothermal uses; and (4) a very positive attitude toward geothermal energy at all levels of government in Hawaii, as well as by the general public.

AAPG Search and Discovery Article #90962©1978 AAPG 2nd Circum-Pacific Energy and Minerals Resource Conference, Honolulu, Hawaii