PetroStrat's stratigraphic database that covers more than 200 wells in the West of Shetlands area has recently been upgraded and unified in order to provide sequence interpretation from first returns all the way to TD.

West of Shetlands Multiclient Database

PetroStrat inherited a rich 25-year history of biostratigraphic, chemostratigraphic and sedimentology projects across the West of Shetlands, from Ichron Limited, through the acquisition of the Specialist Geology division of RPS.

Ichron Sequence Establishment Across the WoS

Ichron supported the majority of exploration, appraisal, and development drilling campaigns, after first becoming involved in 1995 at the BP Foinaven and Schiehallion fields. Prior to Ichron involvement, seismic sequences were being applied and combined with biostratigraphy at wellsite to confirm stratigraphic position. Comparing Foinaven (main reservoir unit T32) and Schiehallion (main reservoir unit T31), Ichron stratigraphers noted inconsistencies in how sequences were being assigned and proposed instilling a unified stratigraphic terminology. This would involve rationalisation of conflicting stratigraphic nomenclature (i.e., biozones, biomarkers and taxonomy) that various consultants had historically applied. Data was reviewed, reinterpreted & stratigraphic zones were linked to BP seismic sequences. This regional biostratigraphic review helped demonstrate T31 and T32 at Foinaven and Schiehallion to actually be time contemporaneous.

Development of Multiclient Database

Operators that Ichron had been supporting with routine proprietary analyses, then gave permission for studies to be incorporated within a series of regionally correlatable multiclient datasets, between 2003-2014. Supplementary new palynological & micropalaeontological analysis of slides at the BGS were made to increase confidence in age assignments throughout each entire wellbore. The stratigraphy of each well was now presented within the Ichron sequence scheme, with the Ichron ‘T’ sequence notation broadly calibrating with the BP/Shell ‘T’ sequence terminology. The multiclient stratigraphic database was continuously expanded to include over 200 wells from the North Rockall Trough to the Møre Basin UKCS and include the Faroese licence area wells.

Unified and Updated Version

The entire collective stratigraphic database of 206 wells, originally made available in 11 geographically-defined subsets has been unified to provide stratigraphic interpretation throughout each entire wellbore where previously, many subsets included just a Tertiary or Mesozoic/Palaeozoic interpretation. All Ichron Sequence assignments have also been revised to capture our latest understanding on the evolution and extent of these depositional system, against structural evolution in the area.

West of Shetlands Multiclient Database Example Chart

Deliverables

• Tabulated stratigraphic sequence depths for each individual well
• Stratigraphic summary chart per well, including. Age, lithostratigraphy, sample data points & biostratigraphic marker events, set against wireline/ MWD 
• Correlation panels highlighting regional thickness trends, stratigraphic breaks and hiatal surfaces within the context of the regional structural elements
• Stratigraphic framework & zonation scheme
• Digital data export of stratigraphic sequences and lithostratigraphic boundaries
• Database

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