Shearwater (UK Block 22/30b): managing changing uncertainties through field life

Development of the Shearwater Field, a deep gas-condensate accumulation in the HPHT region of the UKCS, began in 1997 with the initiation of development drilling and construction of topside facilities. It formed part of the major development of the Central North Sea HPHT gas play throughout the late 1990s, together with other gas developments across Elgin/Franklin and Erskine. As such, Shearwater should be viewed, together with these other structures, as part of an expansion of the gas sector in the North Sea in an area of challenging subsurface conditions and limited development experience to constrain production uncertainty. Field sanction was based on the understanding and modelling of key subsurface uncertainties. Development experience since then has tested that initial subsurface view and lessons learnt will provide a key analogue to help constrain the development of any future HPHT gas accumulations. This paper describes the subsurface model for the Shearwater structure and how recent development experience and production performance has constrained the reservoir characterization uncertainty of the Fulmar Formation.