Exploring the Resource Potential of a Dormant Deepwater Tight Gas Condensate Accumulation Using Modern Seismic Technology—The Spanish Point Discovery, Main Porcupine Basin, Offshore Ireland

摘要

The Spanish Point gas condensate discovery is located in the Main Porcupine Basin, approximately 150 km off the west coast of Ireland in water depths of 300-400 m. The discovery well, which was drilled in 1981 by Phillips Petroleum, is situated near the crest of a number of NE—SW trending rotated fault blocks and encountered a gross c. 400 m hydrocarbon—bearing interval in a series of stacked over—pressured Upper Jurassic deep—water gravity flow sands. Drill stem testing yielded rates of 4.85 MMscf/D and 925 BOPD from the shallowest of four logged hydrocarbon—bearing intervals at a depth of c. 4,000 m. Individual sandstone units are medium to thick bedded with average sandstone units of 50 m which are separated by shales of the Kimmeridge Clay Formation. The well test data imply relatively low permeabilities (generally <1 mD), which may be due to the presence of clay minerals within the sands, or to secondary hydrothermal alteration as a result of local igneous intrusions. The latest geological model, which is based on modern rock—physics and seismic inversion has significantly increased the potential resource base and suggests a median un—risked recoverable contingent resource of 1.4 Tcf and 160 MMBO. Whilst the Spanish Point discovery is primarily a structural trap, mapping of its northern extent indicates that the spill point may be shallower than the gas—down—to seen in the 35/8-2 discovery well. This observation, together with the over-pressured reservoir regime, which is not seen in wells further to the north, raises the possibility of a stratigraphic component to the trapping mechanism. A 3D seismic survey acquisition programme is planned for 2009, which aims to further enhance our understanding of this accumulation as well as being of use for positioning of any potential future appraisal well locations.