Preliminary results of drilling and testing in the Puna geothermal system, Hawaii

Iovenitti, Joe L.
D'Olier, William L.
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Stanford University
Diamond Shamrock Thermal Power Company, operator for the Puna Geothermal Venture has drilled and tested two geothermal wells in the Puna geothermal system, Hawaii. The wells were drilled to depths of 7290 and 8005 feet and completed with 9-5/8 inch production casing to about 4,200 feet and 7 inch perforated liner to bottom. Preliminary short term testing has demonstrated 100% saturated steam production (1185 Btu/lb) at certain wellhead pressures. Cyclic flow with a minimum 55% steam quality has also been observed. Initial estimate of non-condensible gas concentration is 0.2% by weight with on average H2S concentrationof 1100 ppm by weight. The well flowing characteristics appear to stem from a high temperature (greater than 650 F) two-phase liquid-dominated geothermal reservoir which contains a variable steam fraction. Produced steam quality variation at the surface in this field is attributed to both mechanical and reservoir factors.The geothermal system appears to lie within the East Rift Zone of Kilauea Volcano. It is a blind system masked by overlying groundwaters and effectively sealed by impermeable rocks. Basaltic magma stored in the rift zone is postulated as the heat source. The high temperature portion of the geothermal reservoir begins at about 4000 feet and extends to an unknown depth. The wells are interpreted to have encountered multiple producing horizons and interzonal flow is evident. Saturation conditions prevail below the 9-5/8 inch production casing. The critical point of water may be surpassed at depth in this system. Initial test results are sufficiently encouraging to warrant an additional well by the Puna Geothermal Venture to identify reservoir and well characteristics for electrical power plant consideration which includes well field development costs.
On cover: "Preprints, tenth workshop on Geothermal Reservoir Engineering, January 22-24, 1985. Stanford Geothermal Program, Interdisciplinary Research in Engineering and Earth Science, Stanford University."
Kapoho State, Thermal Power, exploration, production testing, Puna, Hawaii, drilling
Iovenitti JL, D'Olier WL. 1985. Preliminary results of drilling and testing in the Puna geothermal system, Hawaii. Stanford (CA): Stanford University.
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