Pressure Core Measurements in Tight Sandstone Lenses During the Multi-Well Experiment

摘要

A pressure coring operation was performed in two tight sandstone lenses of the Mesaverde group during the drilling of one well of DOE's Multi-Well Experiment. The goals were: (1) to obtain accurate water saturation data; (2) to measure the amount and composition of gas on a foot-by-foot basis; and (3) to recover fluids for water chemistry analysis. This application of pressure coring had not been tried before; it was felt to be the best approach for accurate water saturation measurements in tight sandstone core. Several changes to usual pressure coring procedures were adopted. These included the development of an organic noninvasive coring fluid, compatible with the oil-based drilling fluid used that would help preserve water saturation. Three 15-ft pressure core barrels were taken in two sandstone lenses 20 and 30 ft thick; all three barrels were filled with sandstone. Goals 1 and 2 were met. Water saturation values are reported and discussed. The type and duration of the water extraction processes are shown to be very important in determining water saturations in tight sands. Gas species and amount are available on a foot-by-foot basis. 4 references, 1 figure, 5 tables. (ERA citation 09:019686)