The Catcher, Varadero and Burgman fields, Block 28/9a, UK North Sea

Abstract

The Catcher area fields – Catcher, Varadero and Burgman – were discovered in the Central North Sea between 2010 and 2011. The three fields are found in Block 28/9a. Oil is produced from Eocene sandstones stratigraphically equivalent to the Cromarty and Tay Sandstone members of the Sele and Horda formations, respectively. The reservoir for the Catcher area fields was formed by the large-scale injection of sand from the Eocene Cromarty turbidite system into shallower Sele and Horda Formation mudstones to form the Greater Catcher area injectite complex. The Catcher area development is a floating production, storage and offloading (FPSO) based development, with 18 production and injection wells drilled from two drilling templates per field, tied back to the centrally located BW Offshore Catcher FPSO. A further development well will be drilled in 2020 to complete the base development. A phased approach to development drilling, with focused data acquisition, allowed the well layout and count to be optimized as the fields were being developed. Excellent well results have meant that the well count has been reduced relative to the development plans at sanction while delivering an increase in predicted reserves. Further infill wells and satellite field development drilling is planned for the future.

Effect of Hydrocarbon Presence and Properties on the Magnetic Signature of the Reservoir Sediments of the Catcher Area Development Region, UK North Sea

“…(Gibson et al, 2020). The closely spaced oilfields (distance between individual fields is 2-5 km) and associated gas attics present a complex fluid migration to trapping system that has been influenced significantly by prior Cenozoic faulting and sand injection events (Gibson et al, 2020). Although not apparent from the present-day structural interpretation of the region, geochemical analysis of the crude from these reservoirs strongly suggests a connectivity between these fields that resulted in a fill-spill chain mechanism of hydrocarbon filling (Forsythe et al, 2017a).…”

“…There is an increase in density (or decrease in API gravity) and level of degradation of the oil as the reservoir shallows. In these fields, an inverse relationship exists between biodegradation and API gravity (Forsythe et al, 2017b;Gibson et al, 2020) which is typical of the North Sea hydrocarbons (Badejo et al, 2021c), and 3) the presence of "dry" sands from the same stratigraphic level from neighbouring wells that can serve as the background signal. These sands are reported as "dry" in well reports and represent sandstone that have not been infiltrated by migrating hydrocarbon.…”

“…temperature) range under consideration is emphasized as this has been shown by thermodynamic models (Burton et al, 1993;Machel, 1995) and experimental studies (Kars et al, 2014;Abubakar et al, 2015) to affect the diagenetic processes and the generation of magnetic minerals. (Gibson et al, 2020). The closely spaced oilfields (distance between individual fields is 2-5 km) and associated gas attics present a complex fluid migration to trapping system that has been influenced significantly by prior Cenozoic faulting and sand injection events (Gibson et al, 2020).…”

“…The Tay sandstone is the main CAD reservoir sand with the Cromarty sands forming part of the reservoir of the deepest field (Figures 1B, 2). The Upper Tay sands also known as the 'Orkney' sands (Gibson et al, 2020) are the host to the isolated attic gas accumulations. The reservoirs are generally thin with a net thickness of between 10 and 30 m. The reservoir properties are very similar for the different fields, while the fluid properties exhibit a depth relationship (Gibson et al, 2020).…”

“…The Upper Tay sands also known as the 'Orkney' sands (Gibson et al, 2020) are the host to the isolated attic gas accumulations. The reservoirs are generally thin with a net thickness of between 10 and 30 m. The reservoir properties are very similar for the different fields, while the fluid properties exhibit a depth relationship (Gibson et al, 2020). The sandstones are intercalated with variable and significant amounts of shale.…”