| Title | Compaction and Permeability of Cerro Prieto Cores: a Laboratory Evaluation |
|---|---|
| Authors | A. S. Abou-Sayed, J. F. Schatz, K. M. Wolgemuth |
| Year | 1979 |
| Conference | DOE-CFE Symposium on Cerro Prieto |
| Keywords | |
| Abstract | As part of the Lawrence Berkeley Laboratory Geothermal Subsidence Research Program, an experimental program has been carried out to determine the mechanical and physical response of cores from selected wells at the Cerro Prieto Geothermal Field. In particular, the effects of pore pressure reduction (due to reservoir drawdown) on rock compaction and vertical permeability are investigated. Initially, a specimen is subjected to reservoir conditions of temperature, confining pressure, and pore pressure. Then pore pressure is reduced to simulate well production and axial and transverse strain as well as ejected fluid volume are measured as a function of time. In some tests permeabilities are also measured. Both short duration (~1 hour) and long duration (~8 hours) tests have been performed. The short duration tests indicate instantaneous response, while the long duration. tests are intended to monitor creep compaction. The results of the study are related. to reservoir engineering, well integrity and subsidence potential at the Cerro Prieto field. Como parte del LBL Geothermal Subsidence Research Program, ha side lIevado a cabo un programa experimental para determinar la respuesta mecimica y fisica de nucleos de pozos seleccionados en el campo geotermico de Cerro Prieto. En particular, se investigan los efectos de la reduccion de la presion de poro (debido al abatimiento de la presion del vacimiento) sobre la compactacion de la roca y la permeabilidad vertical. Inicialmente, los especfmenes se someten a las condiciones de temperatura, presion de confinamiento y presion de poro del vacimiento. Luego, Se reduce la presion de poro para simular la produccion del pozo. La deformacion axil y transversal, asi como el volumen de fluido extrafdo, se miden en funcion del tiempo. En algunas pruebas tambien se miden permeabilidades. Se lIevaron a cabo pruebas de corta duracion (~1 hora) y de larga duracion (~8 horas). Las de corta duracion indican respuesta instantanea, mientras que las de larga duracion intentan monitorear la compactacion permanente (creep compaction). Los resultados de este estudio se relacionan con la ingenieria de vacimientos, la integridad del pozo y el potencial de hundimiento del campo de Cerro Prieto. |