Earth Tidal Analysis

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Exploration Technique: Earth Tidal Analysis

Exploration Technique Information
Exploration Group: Downhole Techniques
Exploration Sub Group: Well Testing Techniques
Parent Exploration Technique: Well Testing Techniques
Information Provided by Technique
Lithology: Enables estimation of in-situ reservoir elastic parameters.
Hydrological: Enables estimation of in-situ reservoir hydraulic parameters.
Earth Tidal Analysis:
Earth tidal analysis is the measurement of the impact of tidal and barometric fluctuations on effective pore volume in a porous reservoir.
Other definitions:Wikipedia Reegle

Use in Geothermal Exploration
Earth tidal analysis can be applied to a geothermal reservoir in order to estimate its elastic and hydraulic parameters. In order to collect these measurements in-situ, it is necessary to perturb the reservoir system out of equilibrium within the well in the vicinity of the pressure gauge.

Fluid pressure is traditionally perturbed using well pumping tests (fluid injection or production). However, earth tidal analysis enables the measurement of these reservoir parameters by taking advantage of minute pressure fluctuations due to tidal strain and barometric pressure.[1]

Earth tidal analysis allows for the estimation of the in-situ porosity-total compressibility product and the permeability-thickness product of a geothermal reservoir.[1]

Field Procedures
Tidal strain-induced pressure response can be measured through the application of a multi-day recording of downhole pressure data at a specified sampling interval. In the Salton Sea Geothermal Field, downhole pressure was recorded for 660 hours at a sampling interval of 10 minutes. The downhole instrument used was a Paroscientific quartz pressure gauge which was suspended in a shut-in well at 100 feet below the water level.[1]

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