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Introduction
Geothermal wells
are drilled at expenses of high costs and tremendous human and
technological efforts. Geothermal wells not only are the conduit
for geothermal fluids to reach the surface, but they are the only
means to get a picture of the real conditions in the underground.
Like
a letter from the underground, cores and cuttings (Figs.1 and
2) recovered during the drilling of a geothermal well (Figs.3
and 4) bring to surface direct information from which these underground
conditions can be deducted.
The
careful examination and analysis of cores and cuttings provides
the data necessary to describe the geological stratigraphy around
the vicinities of the drilled zones. The integration of the stratigraphy
of several wells and information derived from other geoscientific
studies allows to define the geological structure, location of
heat source, cap rock and even to map the distribution of temperatures
within the geothermal reservoir and the characteristics of underground
geothermal water. All of these are indispensable aspects to construct
a conceptualized model of a geothermal area.
Knowledge
on the geothermal system is gradually accrued as development proceeds.
Comparison of information recovered from successful wells and
that from wells failing to fulfill expectations is of extreme
importance to disclose the bound of areas for exploitation and
to assess the dimensions of the geothermal resource.
In order
to comprehensively and most efficiently utilize the information
engraved in the cores and cuttings, West JEC, through many years
of endeavor has developed techniques to measure and to analyze
this information. This technology has been successfully applied
to many geothermal fields in Japan and in other countries of the
world.
The
technology developed by West JEC to analyze cores and cuttings
information is based upon the application of the 8 different techniques.
The objective of these studies is to construct a geothermal model
which best explains the results of surface exploration and that
derived from wells (Fig.5). The technology developed by West JEC
to extract information from cores and cuttings is base upon the
following eight procedures.
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