Permeability, electrical impedance, and acoustic velocities on reservoir rocks from the Geysers geothermal field

Conference · Wed Jan 24 04:00:00 EST 1996

OSTI ID:889843

Boitnott, G N; Boyd, P J

Previous measurements of acoustic velocities on NEGU- 17 cores indicate that saturation effects are significant enough to cause V_p/V_s anomalies observed in the field. In this study we report on the results of new measurements on core recently recovered from SB-15-D along with some additional measurements on the NEGU-17 cores. The measurements indicate correlations between mechanical, transport, and water storage properties of the matrix which may prove useful for reservoir assessment and management. The SB-15-D material is found to be similar to the NEGU-17 material in terms of acoustic velocities, being characterized by a notably weak pressure dependence on the velocities and a modest V_p/V_s signature of saturation. The effect of saturation on V_p/V_s appears to result in part from a chemo-mechanical weakening of the shear modulus due to the presence of water. Electrical properties of SB-15-D material are qualitatively similar to those of the NEGU-17 cores, although resistivities of SB-15-D cores are notably lower and dielectric permittivities higher than in their NEGU- 17 counterparts. While some limited correlations of measured properties with depth are noted, no clear change in character is observed within SB-15-D cores which can be associated with the proposed cap-rock/reservoir boundary.

• Research Organization: New England Research, Inc., White River Junction, VT
• Sponsoring Organization: USDOE
• OSTI ID: 889843
• Report Number(s): SGP-TR-151-48
• Country of Publication: United States
• Language: English

Related Subjects

Geothermal Legacy