CORNEA CASE STUDY: LESSONS FORTHE FUTURE

Abstract

The Cornea Field was discovered in January 1997. The Cornea structure represents a relatively simple trap configuration comprising a large, elongated, four-way dip closure, formed by the drape of Albian age sediments over a northeast to southwest trending positive basement feature. It is located on an active hydrocarbon migration fairway with proven charge and is capped by a regionally extensive Albian seal. An associated Direct Hydrocarbon Indicator extends over an area of 50 km2 and this feature coincides with gas-fluid contacts throughout the field.

Subsequent to the initial Cornea discovery wells in permit WA–241-P, further exploration drilling took place within WA–241-P, and also within two, newly-acquired, adjacent permits, WA–265-P and WA–266-P, during 1998 and 1999. Detailed field assessment during and subsequent to these wells, involving geological, geophysical and reservoir engineering disciplines, indicated that the field consisted of an extensive gas cap over a thin, laterally discontinuous oil rim. The poor quality of the Lower Cretaceous marine reservoir succession and the extremely low expected oil recovery indicated that recoverable volumes would be low.

This paper contains a review of the data and studies that led to a full understanding of the field. Key learning points from the case study are introduced here and may help future exploration campaigns in other areas.