Physical processes of subsidence in geothermal reservoirs

Technical Report · Tue Jun 01 04:00:00 EDT 1982

DOI:https://doi.org/10.2172/6463623· OSTI ID:6463623

Schatz, J F

The objectives of this project were to acquire core and fluid from producing geothermal reservoirs (East Mesa, United States, and Cerro Prieto, Mexico); to test specimens of this core for their short-term and long-term (creep) compaction response; and to develop a compaction constitutive model that would allow future analysis of reservoir compaction and a surface subsidence. A total of approximately two hundred feet of core was obtained from eleven wells in the two geothermal fields. Depths and porosities ranged from 3500 to 11,000 feet and 15 to 40 percent, respectively. Several samples of geothermal fluids were also obtained. After geologically and geochemically describing the materials obtained, selected specimens were tested for their response to the pressures and temperatures of the geothermal environment and to simulated changes in those conditions that would be caused by production. Short-term tests (for example, tests for compressibility extending over a time interval of an hour or less in the laboratory) indicated that these sedimentary materials behaved normally with respect to the expected behavior of reservoir sandstones of these depths and porosities. Compressibilities were of the order 1 x 10/sup 6/ psi. Long-term tests, extending up to several weeks in duration, indicated that pore pressure reduction, simulating reservoir production, tended to cause creep compaction at an initial rate of about 1 x 10/sup -7/ percent porosity reduction per second.

• Research Organization: Terra Tek, Inc., Salt Lake City, UT (USA)
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 6463623
• Report Number(s): LBL-14605; GSRMP-12; ON: DE83011017
• Country of Publication: United States
• Language: English

Related Subjects

15 GEOTHERMAL ENERGY
150600* -- Geothermal Energy-- Environmental Aspects
152002 -- Geothermal Data & Theory-- Properties of Minerals & Rocks
CERRO PRIETO GEOTHERMAL FIELD
COMPACTING
COMPRESSIBILITY
DRILL CORES
EAST MESA GEOTHERMAL FIELD
FLUIDS
GEOTHERMAL FIELDS
GEOTHERMAL FLUIDS
GEOTHERMAL SYSTEMS
GROUND SUBSIDENCE
Geothermal Legacy
MECHANICAL PROPERTIES