Advanced reservoir characterization and evaluation of CO{sub 2} gravity drainage in the naturally fractured Spraberry reservoir. [Quarterly report], September 1, 1995--December 31, 1995

The objective of this research and the pilot project planned is to test the feasibility of CO{sub 2} for recovering oil from the naturally fractured Spraberry Trend Area in the Midland Basin. This notoriously marginal reservoir has confounded operators for 40 years with rapid depletion, low recovery during primary, disappointing waterflood results and low ultimate recovery. Yet, the tremendous areal coverage and large amount of remaining oil (up to 10 Bbbl) warrants further investigation to expend all possible process options before large numbers of Spraberry wellbores need to be plugged and abandoned. CO{sub 2} injection on a continuous, pattern wide basis has not been attempted in the Spraberry Trend. This is due to the obvious existence of a network of naturally occurring fractures. However, it has become clear in recent years that neglecting CO{sub 2} injection as an option in fractured reservoirs may overlook potential projects which may be viable. The 15 well pilot filed demonstration and supporting research will provide the necessary information to quantify the conditions where by CO{sub 2} flooding would be economic in the Spraberry Trend. Technical progress for this quarter is described for field and laboratory experiments.