WEST OF SHETLANDS
THERMAL, TECTONIC AND HYDROCARBON GENERATION HISTORY BASED ON NEW AFTA AND VITRINITE REFLECTANCE DATA

The West of Shetlands region, offshore UK, is an area that has seen significant exploration success in the last few years and several new oil and gas finds have been announced recently. Evaluation of the full potential of this region requires detailed knowledge of the thermal history - critical to the understanding of oil and gas generation history and hence to the proper assessment of hydrocarbon prospectivity.

In 1990, Geotrack carried out a regional reconnaissance study and produced thermal history data from 13 wells. This study showed the thermal history to be complex, including several paleothermal episodes interpreted as being due to deeper burial before uplift and erosion and lateral heat transfer due to fluid movement and igneous activity. Since that time Geotrack have made significant refinements to the acquisition and interpretation of thermal history data and the new project aims to provide the most detailed and comprehensive investigation of thermal history that can be achieved by modern methods. A larger number of open file wells have been sampled and some new samples from the previous study wells are included in the study.

The study is divided into two areas. One report covers the northern part including wells in Quads 205, 206 and 214. The other covers the southern part including wells and shallow boreholes in Quads 202, 203, 204 and 205 and some boreholes in 155, 166 and 201 to link with N Scotland outcrop data. This allows interested companies three options - purchase of one or the other, or both together, the latter attracting a significant discount.

The study is based on approx. 70 new AFTA and 275 Vitrinite Reflectance samples from 25 exploration wells and 10 offshore shallow boreholes:

Study wells: 202/2-1 202/3-1 202/3a-3 202/8-1 202/9-1 202/19-1 204/19-1 204/23-1 204/29-1 204/30-1 205/10-2b 205/21-1a 205/23-1 205/26a-2 206/3-1 206/7-1 206/8-5 206/9-1 206/9-2 206/10a-1 208/26-1 214/27-1 214/28-1 214/29-1

Published AFTA data from approx. 12 samples from N.Scotland, Lewis and the Orkney Islands will also be included in the study.

Objectives

  • Full evaluation of thermal history from new AFTA and VR data including identification of the main paleothermal episodes, estimation of maximum and subsequent peak paleotemperatures and their geological timing and calculation of paleogeothermal gradients.
  • Investigation of causes of elevated paleotemperatures; burial prior to uplift and erosion, fluid movement, igneous activity.
  • Estimation of the amount of section missing due to uplift and erosion
  • Evaluation of implications for source rock maturity and oil/gas generation history
  • Provide a sound basis for basin modelling studies

For further details please contact us


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