Geological controls on Upper Permian Plattendolomit Formation reservoir prospectivity, Wissey Field, UK Southern North Sea

Craig Duguid, John R. Underhill

Research output: Contribution to journalArticlepeer-review

Abstract

Interpretation of a large, well-calibrated 3D seismic volume, electrical welt-log data and core samples from the Quadrant 53 area of the Southern North Sea provides a new-found basis for understanding the controls on gas production in the Wissey Field, a successful test of the Upper Permian (Zechstein Group; Z3 Cycle) Plattendolomit Formation carbonate play in the Southern Permian Basin (SPB). The petrophysical assessment of wells combined with facies analysis demonstrates that the Plattendolomit Formation represents the northward progradation of an important upward-shoaling carbonate platform. The results show that the highest primary porosity values, lie within the uppermost reservoir sub-units of the Plattendolomit Formation, which consist of brecciated packstones and overlying oolitic grainstones developed at the shelf edge of the Z3 carbonate ramp and sealed by back-barrier lagoonal anhydride mudstones (ascribed to the Scolt Read Formation). It can now be shown that the play fairway is enhanced where two (WSW-ESE and NNW-SSE-striking) fault trends intersect and cause fracturing of the reservoir interval, providing the additional permeability critical for reservoir production. Seismic stratigraphic studies demonstrate that early (pre-Cretaceous) normal fault sets were formed on both trends and were locally affected by contractional deformation (structural inversion) during the Late Cretaceous. As well as explaining the key geological factors that contribute to production success in the Wissey Field itself, the results provide a foundation for evaluating the prospective potential that the Plattendolomit Formation has elsewhere in the SPB.

Original languageEnglish
Pages (from-to)331-348
Number of pages20
JournalPetroleum Geoscience
Volume16
Issue number4
DOIs
Publication statusPublished - Nov 2010

Keywords

  • Southern North Sea
  • Wissey Gasfield
  • Zechstein Group
  • Plattendolomit Formation
  • Southern Permian Basin
  • offshore Netherlands
  • reservoir modelling
  • inversion tectonics
  • fractured carbonate
  • PETROLEUM GEOLOGY
  • SILVERPIT CRATER
  • NETHERLANDS
  • ZECHSTEIN
  • INVERSION
  • EVOLUTION
  • MODELS

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