Reservoir characterization and sequence stratigraphy of the Pennsylvanian Bartlesville Sandstone, Oklahoma

This work investigates the Pennsylvanian Bartlesville Sandstone in terms of reservoir sedimentology, reservoir characterization, and sequence stratigraphy. Regional scale to reservoir scale studies are performed in both outcrop and subsurface over a 10,000 square mile area in northeastern Oklahoma.; A new interpretation regarding the depositional origin of the Bartlesville Sandstone is demonstrated, and characterizes the Bartlesville Sandstone as mainly fluvial incised-valley fill deposited in a transgressive manner from a lower braided fluvial to an upper tidal-influenced meandering fluvial depositional systems. Outcrop survey, well log correlation, and core study all illustrate that a type-1 sequence boundary exists at the base of the Bartlesville Sandstone, indicated by subaerial erosion of underlying Savanna Shale, basinward facies shift across the boundary, and thickening of the Bartlesville Sandstone at the expense of underlying Savanna Shale. The incised valley extends over 140 miles (225 km.) north-south within Oklahoma, and is 6 to 8 mile (9.7 to 12.8 km.) wide in Washington County to about 60 mile (96.5 km.) wide in the Eufaula area. Thickness of Bartlesville Sandstone varies from 140-280 ft. (42.7-85.3 m.) within the valley to less than 20 ft. (6.1 m.) outside the valley. With upward-increase of marine influence, the incised-valley fill consists of two sequence stratigraphic architectural elements: (1) the lowstand system tract (LST), 80-150 ft. (24.4-45.7 m.), dominated by braided fluvial deposits overlain by; (2) the transgressive system tract (TST), 80-100 ft. (24.4-30.5 m.), dominated by meandering fluvial deposits. The regional Inola Lime marker, capping the Bartlesville Sandstone interval, is equivalent to a condensed section representing maximum flooding.; Detailed reservoir characterization was conducted for a portion of Glenn Pool field through integration of core, well log, outcrop, and borehole image information. A hierarchy of reservoir architectures, ranging from subfacies, to facies, discrete genetic intervals (DGI), then to multi-storey DGIs were reconstructed in terms of lithologic heterogeneities. The Bartlesville Sandstone is subdivided into seven DGIs. A high resolution facies map was constructed for each DGI. Petrophysical property variations among different DGIs and facies are evaluated by using core measurements.; Original oil in place (OOIP) and remaining resources potential are incorporated into sequence stratigraphic architecture and facies architecture. The LST, holding about two-thirds of OOIP for many fields/reservoirs, played a key role in the ninety-year development history and is almost depleted. The TST, more heterogeneous and less developed by comparison, offers the main potential for future development. Results of this study are significant to many other field/reservoir systems in the world as well.