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Lithofacies Description and Fracture Evaluation of
an Unconventional Reservoir in 
Geothermal
Reservoir Characterization
Chitale, D. V. (Vivek)1, Ramon Sanchez2 (1) Halliburton
Energy Services, Energy Services,
Role of an electrical borehole image becomes especially critical
in reservoir characterization when the only other well data available are
gamma- and temperature logs! The challenge becomes even bigger when the
reservoir to be characterized is non-conventional and it contains geothermal
energy! This paper reports such a case history documenting a successful
application of borehole imaging in characterizing geothermal reservoirs of
An Operator in geothermal energy. Operational
considerations allowed neither mud logs nor wireline
logs except gamma ray and temperature. Borehole images were interpreted to
accurately describe the litho-facies and diagnose
fractures holding the geothermal energy. Image interpretation software called
“sculpturing” (Chitale et. al. 2004) was used to
quantify the fractured porosity.
This paper shows
how XRMI and the software “sculpturing” achieved characterization of the andesite reservoirs containing geothermal energy
, which was
done without any help from other logs except gamma- and temperature. Further,
the borehole images differentiated reservoirs from shales
or impermeable rocks, which proved crucial for the Operator since the common
shale indicator- gamma log was affected by radioactive minerals in the volcanics. Borehole images also enabled core-like
description of the litho-facies thereby saving costs
of conventional coring in a tough borehole environment. Thus, borehole imaging
proved critical in the reservoir development efforts and significantly reduced
the E&P risks for the Operator in these geologically complex areas of