Sand body geometry, constrained and predicted during a horizontal drilling campaign in a Lower Cretaceous turbidite sand system, Captain Field, UKCS Block 13/22a

Abstract

The Captain Field is a large viscous oil accumulation located in the Western Moray Firth, UK Block 13/22a which is being developed by long horizontal wells. The reservoir sand body geometry was defined in the appraisal phase by 20 vertical wells. Seismic attributes were not used because of the poor seismic signal to noise ratio in the reservoir interval. As the development drilling campaign has unfolded, the appraisal sand body geometry model has been significantly refined using a wealth of data from the horizontal wells. During development drilling it has proved cheap to sidetrack horizontal well sections without a requirement to isolate the abandoned hole. This has resulted in significant extra geological data (e.g. top reservoir penetrations, sand thickness data). Integrating this dataset with top reservoir topography derived from seismic and weak internal reservoir seismic reflectors, the sand body geometry model is significantly improved in undeveloped parts of the field.