PRELIMINARY RESULTS OF DRilLLlNG AND TESTING IN THE PUNA GEOTHERMAL SYSTEM, HAWAII Page: 2 of 10
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PROCEEDINGS, Tenth Workshop on Geothermal Reservoir Engineering
Stanford University, stanford, California, January 22-24, 1985
PRELIMINARY RESULTS OF DRILLING AND TESTING
IN THE PUNA GEOTHERMAL SYSTEM, HAWAII
J. L. lovenitti and W. L. D'Olier
Diamond Shamrock Thermal Power Company
3333 Mendocino Avenue, Suite 120
Santa Rosa, California 95401
Diamond Shamrock Thermal Power Company, oper-
ator for the Puna Geothermal Venture has drilled
and tested two geothermal wells in the Puna geo-
thermal system, Hawaii. The wells were drilled to
depths of 7290 and 8005 feet and completed with
9-5/8 inch production casing to about 4200 feet
and 7 inch perforated liner to bottom. Preliminary
short term testing has demonstrated 100% satu-
rated 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 an average H2S concentration
of 1100 ppm by weight. The well flowing charac-
teristics appear to stem from a high temperature
(greater than 6500F) 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 ef-
fectively 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 sur-
passed 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 characteris-
tics for electrical power plant consideration which
includes wellfield development costs.
The Puna geothermal system is located within the
lower East Rift Zone of Kilauea Volcano on the
island of Hawaii (Figure 1). Kilauea is one of the
world's most active volcanos. The Puna Geother-
mal Venture (PGV) wells are stepouts to the suc-
cessful HGP-A well drilled jointly by the US De-
partment of Energy, State of Hawaii and Univer-
sity of Hawaii.
HGP-A was completed in 1976 to a total depth of
6450 feet with a bottomhole temperature of 6760F.
The well has been producing 110,000 lbs/hr at 166
psig wellhead pressure with approximately 43%
steam quality (Thomas, 1983) to a 3 MW turbine
generator in nearly continuous operation since
May, 1982. The well results have been summarized
by Kihara et al (1977), Chen et al (1978), Stone and
Fan (1978), Thomas (1982), and Waibel (1983).
HGP-A demonstrated the feasibility of generating
electrical. power from a Hawaii volcanic resource.
It is the objective of PGV to develop geothermal
energy in Hawaii for reliable electric power pro-
duction at a marketable price. PGV consists of
Diamond Shamrock Thermal Power Company,
Dillingham Geothermal, Inc. and Amfac Energy,
Inc. Competitor drilling in the region has report-
edly found high bottomhole temperatures but pro-
duction has not been demonstrated.
Reported herein are some highlights of the PGV
wellfield activity. These data are integrated to
formulate a conceptual model of the Puna Geo-
thermal System. We hope that this overview will
assist the work being done in the development of
high temperature, two-phase geothermal systems
for electrical production.
East Rift Zone of Kilauea is one of the conduits for
the lateral migration of basaltic magma from the
holding chamber beneath the volcano's summit cal-
dera. It is manifested at the surface as a linear
belt, 1 - 2 km wide, consisting of linear and open
fissures; faults, small grabens, pit craters, cones
.and vents for numerous eruptions. In the lower
portion of the rift zone eruptions have occurred as
recently as 1740, 1840, 1955, 1960 and 1961. The
rift zone is a constructional ridge some 150 - 1500
feet above the adjoining terrain throughout its
length except in its lowermost portion where the
ridge disappears into a series of grabens and spat-
ter deposits (Moore, 1983). The successful drilling
actitivy to date lies in the transition area from the
constructional ridge to the more subdued topo-
graphy. Underlying the surface expression of the
East Rift Zone is a much broader (5-15 mile) dike
complex inferred on the basis of gravity and mag-
netic data (Furumoto, 1978). This complex is
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Iovenitti, J.L. & D'Olier, W.L. PRELIMINARY RESULTS OF DRilLLlNG AND TESTING IN THE PUNA GEOTHERMAL SYSTEM, HAWAII, article, January 22, 1985; United States. (digital.library.unt.edu/ark:/67531/metadc876523/m1/2/: accessed October 20, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.