Present address: ExxonMobil Upstream Research Company, 3319 Mercer St., Houston, TX 77027, USA.
Distribution and mechanisms of overpressure generation and deflation in the late Neoproterozoic to early Cambrian South Oman Salt Basin
Article first published online: 8 JUL 2011
© 2011 Blackwell Publishing Ltd
Special Issue: Geologically driven pore fluid pressure models and their implications for petroleum exploration
Volume 11, Issue 4, pages 349–361, November 2011
How to Cite
KUKLA, P. A., REUNING, L., BECKER, S., URAI, J. L. and SCHOENHERR, J. (2011), Distribution and mechanisms of overpressure generation and deflation in the late Neoproterozoic to early Cambrian South Oman Salt Basin. Geofluids, 11: 349–361. doi: 10.1111/j.1468-8123.2011.00340.x
- Issue published online: 11 NOV 2011
- Article first published online: 8 JUL 2011
- Received 13 January 2011; accepted 20 May 2011
- intrasalt reservoirs;
- Neoproterozoic to Cambrian South Oman Salt Basin;
- overpressure generation and deflation
Late Neoproterozoic to early Cambrian intra-salt Ara reservoirs of the South Oman Salt Basin represents a unique self-charging petroleum play with respect to hydrocarbon and overpressure generation and dissipation. Reservoir bodies (termed ‘stringers’) are isolated in salt and frequently contain low-permeable dolomites that are characterized by high initial production rates because of hard overpressures. A database of more than 30 wells has been utilized to understand the distribution and generation of overpressures in intra-salt reservoirs that can be separated by up to 350 m of salt. A temporal relationship of increasingly overpressured reservoirs within stratigraphically younger units is observed, and two distinctly independent trends emerge from the Oman dataset; one hydrostatic to slightly above hydrostatic and one overpressured from 17 to 22 kPa m−1, almost at lithostatic pressures. Structural, petrophysical and seismic data analysis suggests that overpressure generation is driven by fast burial of the stringers in salt, with a significant contribution by thermal fluid effects and kerogen conversion. Structural and geometric information indicates that present-day hydrostatic stringers have been overpressured in their earlier geologic evolution. Evidence for these initial overpressures in currently hydrostatic reservoirs is provided by hydrocarbon-veined cores from halite overlying the reservoirs. A proposed pressure deflation mechanism can be related to the complex interplay of salt tectonics and fast deposition of early Cambrian to Ordovician age clastics.