10.11440060217_si_001.pdf (20.74 MB)
Download fileCores from the Atlantic Field, Kopervik Fairway, Outer Moray Firth, UK
journal contribution
posted on 2020-04-30, 14:14 authored by J. ARGENT, R. BLIGHT, P. COX, R. HARDY, A. LAW, J. R. SMALLWOOD, D. WALTERAt first sight the 'tank of sand' provided by the Kopervik/Captain Sandstone
Member reservoir of the Atlantic Field is a development geologist's and
reservoir engineer's dream. However, the challenges posed are several:
(1) The top of the reservoir is not generally visible on seismic data, hence
geologically derived isopachs are important in creating top structure maps. The
isopachs are best controlled by mapping individual sand units; however
distinguishing between these units is difficult even in core, let alone on log data.
Petrography, textural characteristics, palaeomagnetically derived flow
directions, heavy minerals, biostratigraphy, and geological models developed
from other discoveries along the Kopervik fairway indicate that the sands may
be deposited by a mixture of the 'sausage' and 'sock' mechanisms of Law et al
(2000).
(2) The 'tank' may be subdivided by permeability barriers or baffles in the form
of thin shale units or cemented zones. Atlantic Field will be developed with only
two wells so these barriers may prove significant and it is important, although
difficult, to predict their locations and lateral extents.
(3) The high-permeability (multi-darcy) reservoir, together with the thin
hydrocarbon column and active aquifer, mean that development wells must be
designed to prevent early catastrophic water breakthrough. Accurately drilling
such wells will not be easy when the reservoir cannot easily be resolved on
seismic data, mapped or depth converted.