Deep-Water Facies of the Spraberry Formation (Permian), Reagan County, Texas

Abstract

The Spraberry Formation forms the heart of a multibillion-barrel oil field in the Midland Basin, west Texas. Production is from very fine sandstones and siltstones that form low-permeability and low-pressure reservoirs across eight counties in west Texas. The Sun Oil Co., Lottie Jalonick #1 core is continuous through the upper 222 feet (68 m) of the Spraberry Formation and is ideal for facies analysis. Four lithofacies comprise the terrigenous clastics of the Spraberry and Dean Formations: (1) cross-laminated, massive, and parallel-laminated sandstone, (2) laminated siltstone, (3) bioturbated siltstone, and (4) black, organic-rich shale. Silty dolomite mudstone is a very minor carbonate component. Though not common in other cores, numerous fining-upward sequences of sandstone overlain by shale and laminated siltstone are common in the Jalonick core. These are interpreted to be deposits from saline density currents, generated in shelf lagoons and salt pans, as they were dispersed beyond channel mouths in the distal fringe of an upper Spraberry submarine fan. Laminated siltstones were deposited out of suspension from saline density interflows.

Evaluation of Shale Source Rocks and Clay Mineral Diagenesis in the Permian Basin, USA: Inferences on Basin Thermal Maturity and Source Rock Potential

“…Upper Pennsylvanian Wolfcamp D/Cline formation is commonly gray to black organic-rich marine shales with increased carbonated detritus near the margins of the basin (Figure 2) [57]. In the Early Permian, continued subsidence accompanied by deltaic progradation from the north and east supplied clastic sediment from the Ouachita fold-thrust belt [58] though incised valleys and troughs along the Eastern Shelf, giving rise to the Wolfcamp formation (Figure 2) [61][62][63]. Sediment conduits captured carbonate detritus and debris from exposed platform shelves, creating a series of mass flows, turbidite, and basin-floor submarine facies fanning throughout the basin [61,[64][65][66].…”

Advanced Reservoir Characterization and Evaluation of CO{sub 2} Gravity Drainage in the Naturally Fractured Spraberry Trend Area

“…However, for the most part, they lack evidence of deposition from tractional currents. Handford (1981) proposed that such deposits result from density stratification of the water column when shelf derived density currents periodically move out over the basin as an interflow suspended above the basin floor.…”

“…The angularity of about half of the detrital grains and the presence of numerous strain shadows is described by as a physical wear that can only occur due to impact during long reworking and transportation by water. Suspension settling, saline density currents, and turbidites are the main mechanisms of sediment transport (Handford, 1981;N.Tyler and Gholston, 1988;. Very fine sandstones and siltstones commonly form the coarser bottom part of fining upward sequences having sharp erosional contacts with underlying shales and muddy burrowed tops.…”

Late Pennsylvanian (Virgilian) to Early Permian (Leonardian) Conodont Biostratigraphy of the "Wolfcamp Shale", Northern Midland Basin, Texas

“…3). Following a reciprocal sedimentation model, these siliciclastic deposits would prograde across the shelves and into the basin through turbidity flows during lowstand cycles, while calcareous muds and carbonate debris flows would deposit during highstand cycles (Silver and Todd, 1969;Meissner, 1972;Jeary, 1978;Handford, 1981;Sarg, 1988;Schlager et al, 1994).…”

“…the available accommodation space, causing shedding of carbonate material into the basin (Sarg, 1988). Terrigenous-siliciclastic sediment wedges deposit during lowstand systems when realtive sea level lowers enough to expose the shelf, resulting in a shut-off of carbonate supply and allowing bypass of clastic sediment into the basin (Meissner, 1972;Silver and Todd, 1969;Jeary, 1978;Handford, 1981;Sarg, 1988;Schlager et al, 1994). Throughout the Late Pennsylvanian, much of the southern Midland Basin experienced starved conditions as siliciclastic sediment was trapped by reef barriers at the shelf margins (Adams et al, 1951;Wright, 2011), resulting in a condensed Wolfcamp D.…”