GRRM/How To/Technique

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Applying the Methodology to Geothermal Projects

Technique Indices
Temperature | Volume | Reservoir | Fluid Chemistry

The following tables provide the analytic methods and exploration techniques that differentiate technique index values. For each resource attribute components (temperature, volume, reservoir, and fluid chemistry), select the 1 - 5 index value that corresponds to the technique used to collect project data. If more than 1 technique is used, identify the index values for all techniques that provide project data.

Technique Index: Estimating Temperature
Applicable Technique(s)
5 Measured temperatures: Downhole temperature probe readings (well(s) drilled into reservoir)
4 Extrapolated temperatures: (TGH/well(s) not drilled into reservoir)
3 Geothermometry (reservoir brines)
2 Geothermometry (immature or mixed fluids, or inconsistent results between geothermometers)
1 Regional heat flow data

Technique Index: Estimated Volume
Applicable Technique(s): Area Applicable Technique(s): Thickness
5 Flow testing: multiple wells
4 Subsurface temperature probe: multiple wells
2 Core Stratigraphy, Magnetic Surveys Gravity surveys, TEM
1 Field mapping / surveys of surface manifestations and geologic structures

Technique Index: Estimating Reservoir Sustainability
Applicable Technique(s)
5 Flow tests (with pressure-temperature-spinner logs); Tracer tests
4 Lithologic cores (and laboratory measurements); FMI - BHTV
3 Resistivity logs; Acoustic Reflectivity
2 Vertical Seismic Profiling (VSP) and reflection seismic
1 Temperature logs; distribution of thermal features

Technique Index: Fluid Chemistry
Applicable Technique(s):
pH (at STP)
Applicable Technique(s):
Applicable Technique(s):
Total Dissolved Solids
5 Probe – reservoir fluid directly sampled in field Titration – reservoir fluid Chemical analyses of steam and water/brine fractions: produced wells.
Surface water samples: chloride springs
4 Probe – mixed fluid directly sampled in field Calculation from analysis of Total CO2
3 Paper test strips in field Alkalinity – immediate titration of reservoir fluid in field
2 Probe – bottled reservoir fluid in lab Alkalinity – titration of bottled fluid in lab
1 Probe – bottled mixed fluid in lab Calculated / assumed from pH alone Subsurface temperature or conductivity probe

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