Petrophysics of the Lance Sandstone Reservoirs in Jonah Field, Sublette County, Wyoming

摘要: Jonah field is a giant gas producing from extremely low-porosity and low-permeability sandstones. Wire-line–log data 62 wells near the center of were studied to characterize porosity, permeability, water saturation Lance reservoirs. The logs environmentally corrected normalized, shale volume porosities calculated, saturations determined by dual model, net pay was calculated using field-specific criteria. Ultimate recovery per well estimated decline curve analysis monthly production data. Within upper 2500 ft (760 m) Formation, which includes entire productive interval in nearly all wells, average has 1000 (30 sandstone, having an porosity 6.4%. permeability sandstones, core data-derived equations, astonishingly low 6 d. sandstones 45%. Net criteria cumulative storage-capacity flow-capacity plots. Although sandstone may have only 6% contribute insignificant fraction reservoir flow capacity. We estimate that more than 95% capacity with greater porosity. A small percentage high-porosity (10%) high-permeability rocks dominate behavior are probably critical economic production. Using as absolute cutoff, thickness at 440 (130 m), 9.3% 33% saturation. 25 Estimated ultimate approximately 4 bcf on current 40-ac (0.16-km2) spacing.