Analysis of over-pressure mechanisms in the Uinta Basin, Utah
- Geological Survey, Menlo Park, CA (United States)
Extremely high pore fluid pressures exist in the area of the Altamount/Bluebell oil field in the Uinta basin, Utah. We discuss two possible mechanisms for the cause of these over-pressures in this paper: (1) compaction disequilibrium, and (2) conversion of kerogen to liquid hydrocarbon (oil). Compaction disequilibrium occurs during periods of rapid sedimentation. If the permeability of deeply buried strata is low, then connate water within the rock matrix does not escape rapidly enough as compaction occurs; as sedimentary deposition continues, high pore fluid pressures develop. Conversion of solid kerogen to a liquid generates both a liquid and additional pore space for the liquid to occupy. If the volume of the liquid generated is just sufficient to fill the pore space generated, then there will be no accompanying effect on the pore pressure. If the liquid is less dense than the solid it replaces, then there is more liquid than pore space created; pore pressure will increase, causing flow away from the area of the reaction. Pore pressure is a sensitive measure of the balance between hydrocarbon generation and expulsion from the source into adjacent strata. If high pore pressures exist only where source rocks are thought to be generating oil, then kerogen conversion is a likely over-pressure mechanism. However, if over-pressures are found in low-permeability strata regardless of source rock proximity, then sedimentary compaction is probably a more dominant mechanism.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 107178
- Report Number(s):
- LBL-37200; CONF-9503110-; ON: DE95014788; TRN: 95:006737-0018
- Resource Relation:
- Conference: TOUGH 95: transport of unsaturated ground water and heat workshop, Berkeley, CA (United States), 20-22 Mar 1995; Other Information: PBD: Mar 1995; Related Information: Is Part Of Proceedings of the TOUGH Workshop `95 Lawrence Berkeley Laboratory, Berkeley, California, March 20--22, 1995; Pruess, K. [ed.]; PB: 380 p.
- Country of Publication:
- United States
- Language:
- English
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