‘Vertically transferred’ overpressures in Brunei: Evidence for a new mechanism for the formation of high-magnitude overpressure

Abstract

Research Article| November 01, 2007 ‘Vertically transferred’ overpressures in Brunei: Evidence for a new mechanism for the formation of high-magnitude overpressure Mark R.P. Tingay; Mark R.P. Tingay 1Australian School of Petroleum and School of Earth and Environmental Sciences, University of Adelaide, Adelaide 5005, Australia Search for other works by this author on: GSW Google Scholar Richard R. Hillis; Richard R. Hillis 2Australian School of Petroleum, University of Adelaide, Adelaide 5005, Australia Search for other works by this author on: GSW Google Scholar Richard E. Swarbrick; Richard E. Swarbrick 3GeoPressure Technology Mountjoy Research Centre, Stockton Road, Durham DH1 3UZ, UK Search for other works by this author on: GSW Google Scholar Chris K. Morley; Chris K. Morley 4PIT Exploration and Production Public Company Limited, 555 Vibhavadi-Rangsit Road, Bangkok 10900, Thailand Search for other works by this author on: GSW Google Scholar Abdul Razak Damit Abdul Razak Damit 5Brunei Shell Petroleum, Jalan Utara, Seria KB3534, Brunei Search for other works by this author on: GSW Google Scholar Geology (2007) 35 (11): 1023–1026. https://doi.org/10.1130/G23906A.1 Article history received: 05 Apr 2007 rev-recd: 09 Jul 2007 accepted: 15 Jul 2007 first online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Mark R.P. Tingay, Richard R. Hillis, Richard E. Swarbrick, Chris K. Morley, Abdul Razak Damit; ‘Vertically transferred’ overpressures in Brunei: Evidence for a new mechanism for the formation of high-magnitude overpressure. Geology 2007;; 35 (11): 1023–1026. doi: https://doi.org/10.1130/G23906A.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Overpressures in sedimentary basins are commonly assumed to be the result of two distinct and separate mechanisms: disequilibrium compaction and fluid expansion. However, the potential for overpressures to be redistributed or transferred to other pressure compartments over time has been seldom considered and rarely demonstrated. Pore-pressure data and velocity-effective stress plots from 61 fields across the Baram Delta province of Brunei (northwest Borneo) reveal that two different types of overpressure occur in stratigraphically defined sections: the basal pro-delta shales contain overpressures generated by disequilibrium compaction, whereas the overlying sand/shale deltaic sequence contains overpressures that appear to be generated by fluid expansion. However, the geology of the deltaic sequences and high magnitude of the pore pressures precludes the overpressures in the deltaic sequences being generated by any conventional fluid expansion mechanism, such as kerogen-to-gas maturation or clay diagenesis. The fluid expansion overpressures are located in fields that were inverted during the Pliocene, an event that resulted in large-scale fluid migration from the pro-delta shales into the deltaic sequences, including charging of the numerous oil fields in the inner shelf. Hence, we propose that the overpressures in Brunei provide the first evidence for a new overpressuring mechanism whereby overpressured fluids have been “vertically transferred” from the pro-delta shales into the deltaic sequences during basin inversion. Furthermore, vertical transfer may be a mechanism for explaining overpressures observed in basins that have been recently uplifted or inverted. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.