| Abstract: | Reservoir depletion at the Geysers from 1974 to 1977 is evident in measured changes in gravity, surface strain, and pore pressure drainage. The drainage area increased about 20%, the maximum gravity decrease was about -120 mu Gal, and the maximum elevation change was about 6 cm during this period. Since the net mass withdrawal is known, it may be combined with the gravity change to estimate a drainage volume. The maximum drainage volume is 25 km3. Because the depth of the caprock and extent of the pore pressure drainage is known, this volume limit implies that no significant mass withdrawal occurs below a depth of 4 km. The ratios of surface elevation changes to horizontal contraction coinciding with the drainage area imply an equant drainage geometry, assuming that fluid production produces negative dilatation. Using the same cylindrical geometry used to model the gravity, negative dilatational strain rates of 4 to 5 X 10-5/yr were found to produce the observed surface displacements. The likelihood of boiling in the system to produce steam combined with apparent large bulk moduli (from seismic velocities) and small pore pressure declines suggest that most of the reservoir contraction is due to cooling. -Authors |
| Genre: | Article |
| ProdID: | 70012071 |
| Citation Author: | Denlinger, R. P.; Isherwood, W. F.; Kovach, R. L. |
| Citation Contributing Office: | |
| Citation Datum: | |
| Citation Day: | |
| Citation Edition: | |
| Citation Editor: | |
| Citation End Page: | 6096 |
| Citation Issue: | B7 |
| Citation Keywords: | |
| Citation Language: | English |
| Citation Larger Work Title: | Journal of Geophysical Research |
| Citation LatN: | |
| Citation LatS: | |
| Citation LonE: | |
| Citation LonW: | |
| Citation Month: | |
| Citation No Pagination: | |
| Citation Number Of Pages: | 6 |
| Citation Online Only Flag: | |
| Citation Phsyical Description: | |
| Citation Projection: | |
| Citation Public Comments: | |
| Citation Publisher: | |
| Citation Series: | |
| Citation Series Code: | |
| Citation Series Number: | |
| Citation Search Results Text: | Geodetic analysis of reservoir depletion at the Geyser steam field in northern California.; 1981; Article; Journal; Journal of Geophysical Research; Denlinger, R. P.; Isherwood, W. F.; Kovach, R. L. |
| Citation Start Page: | 6091 |
| Citation Volume: | 86 |
| Citation Year: | 1981 |
| Type: | citation/reference |
| Text: | Geodetic analysis of reservoir depletion at the Geyser steam field in northern California.; 1981; Article; Journal; Journal of Geophysical Research; Denlinger, R. P.; Isherwood, W. F.; Kovach, R. L. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Thu, 1 Jan 1981 00:00 -0600 |
| Publisher: | |
