Igneous intrusions in the Faroe Shetland basin and their implications for hydrocarbon exploration: new insights from well and seismic data

N.J. Mark, N. Schofield, S. Pugliese, D. Watson, S. Holford, D. Muirhead, R. Brown, D. Healy

Research output: Contribution to journalArticlepeer-review

53 Citations (Scopus)
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Abstract

Igneous sills and dykes that intrude pervasively into prospective sedimentary basins are a common occurrence in volcanic margins, impacting the petroleum system and causing geological and technical drilling challenges during hydrocarbon exploration. The Faroe-Shetland Basin (FSB), NE Atlantic Margin, has been the focus of exploration for over 45 years, with many wells penetrating igneous intrusions. Utilising 29 FSB wells (with 251 intrusions) and 3D seismic data, this study presents new insights into the impacts that igneous intrusions have on hydrocarbon exploration. Examination of cores reveals additional igneous material in individual wells, compared to estimates using seismic or petrophysical data alone, leading to potential underestimation of the volume of the igneous component in a basin. Furthermore, analysis of petrophysical data shows that within the FSB there are silicic intrusions such as diorite and rhyolite, in addition to the commonly encountered mafic intrusions. These silicic intrusions are difficult to recognise in seismic and petrophysical data due to their low density and compressional velocity and have historically been misidentified on seismic reflection data as exploration targets. Drilling data acquired through intrusions provide valuable insight into the problems exploration wells can encounter, often unexpectedly, many of which can be detrimental to safe drilling practice and result in prolonged non-productive time.
Original languageEnglish
Pages (from-to)733-753
Number of pages21
JournalMarine and Petroleum Geology
Volume92
Early online date7 Dec 2017
DOIs
Publication statusPublished - Apr 2018

Bibliographical note

The lead author's PhD is funded by JX Nippon Exploration and Production (U.K.) Limited as part of the Volcanic Margin Research Consortium Phase 2. PGS are thanked for allowing the author access to the MegaSurveyPlus data and for allowing permission to publish this work. Seismic interpretation was carried out using IHS Kingdom software. Well log analysis was carried out using Schlumberger Techlog software and Ikon RokDoc software. Mick Caulfield is thanked for useful comments. Alistair Maguire and Christian Eide are thanked for useful discussions and assistance. Stuart Archer is thanked for his comments which greatly improved the revisions of this paper. Well data was obtained from the UK Oil and Gas Authority (OGA) Common Data Access (CDA). Core photographs were obtained from the BGS Offshore well database.

Keywords

  • igneous intrusions
  • seismic imaging
  • drilling
  • Atlantic Margin

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