Present-day stress and neotectonics of Brunei: Implications for petroleum exploration and production

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dc.contributor.authorTingay, M.
dc.contributor.authorHillis, R.
dc.contributor.authorMorley, C.
dc.contributor.authorKing, R.
dc.contributor.authorSwarbrick, R.
dc.contributor.authorDamit, A.
dc.date.issued2009
dc.description.abstractThe present-day state of stress in Tertiary deltas is poorly understood but vital for a range of applications such as wellbore stability and fracture stimulation. The Tertiary Baram Delta province, Brunei, exhibits a range of contemporary stress values that reflect the competing influence of the northwest Borneo active margin (situated underneath the basin) and local stresses generated within the delta. Vertical stress (sigmav) gradients at 1500-m (4921-ft) depth range from 18.3 MPa/km (0.81 psi/ft) at the shelf edge to 24.3 MPa/km (1.07 psi/ft) in the hinterland, indicating a range in the shallow bulk density across the delta of 2.07ndash2.48 g/cm3. The maximum horizontal stress (sigmaHmax) orientation rotates from margin parallel (northeastndashsouthwest; deltaic) in the outer shelf to margin normal (northwestndashsoutheast; basement associated) in the inner shelf. Minimum horizontal stress (sigmahmin) gradients in normally pressured sequences range from 13.8 to 17.0 MPa/km (0.61ndash0.75 psi/ft) with higher gradients observed in older parts of the basin. The variation in contemporary stress across the basin reveals a delta system that is inverting and self-cannibalizing as the delta system rapidly progrades across the margin. The present-day stress in the delta system has implications for a range of exploration and production issues affecting Brunei. Underbalanced wells are more stable if deviated toward the sigmahmin direction, whereas fracture stimulation in mature fields and tight reservoirs can be more easily conducted in wells deviated toward sigmaHmax. Finally, faults near the shelf edge are optimally oriented for reactivation, and hence exploration targets in this region are at a high risk of fault seal breach.
dc.description.statementofresponsibilityMark R. P. Tingay, Richard R. Hillis, Chris K. Morley, Rosalind C. King, Richard E. Swarbrick, Abdul Razak Damit
dc.identifier.citationAmerican Association of Petroleum Geologists (AAPG) Bulletin, 2009; 93(1):75-100
dc.identifier.doi10.1306/08080808031
dc.identifier.issn0149-1423
dc.identifier.issn1558-9153
dc.identifier.orcidHillis, R. [0000-0002-5222-7413]
dc.identifier.orcidKing, R. [0000-0001-9160-996X]
dc.identifier.urihttp://hdl.handle.net/2440/53256
dc.language.isoen
dc.publisherAmer Assoc Petroleum Geologist
dc.relation.grantARC
dc.source.urihttps://doi.org/10.1306/08080808031
dc.titlePresent-day stress and neotectonics of Brunei: Implications for petroleum exploration and production
dc.typeJournal article
pubs.publication-statusPublished

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