Abstract An integrated reservoir description of the Smackover Formation in Walker Creek Field in southern Arkansas was conducted in order to evaluate the field's hydrocarbon potential and to determine the best method of increasing recovery. Geologic, petrophysical and engineering studies comprise the multi-disciplinary reservoir description of Walker Creek Field. Evaluating the field's potential included optimizing current operations, proposing options that accounted for reservoir complexities, and planning future operations that would maximize the unit's economic value. The specific aspects of the reservoir description consist of: Determining the depositional and diagenetic controls on reservoir lithologies and the resulting reservoir geometry; Establishing the internal geometry of the reservoir for the purpose of 1) zonation of reservoir flow units, 2) discrimination of pay from non-pay intervals and 3) evaluation of the continuity of different pay zones and of barriers to flow; Relating facies to reservoir properties, including 1) petrographic evaluation of pore types, 2) relating depositional and diagenetic textures to capillary pressure (Pc) trends and 3) recognizing log responses associated with reservoir layers; Providing a depositional and diagenetic model of the occurrence and distribution of reservoir and non-reservoir units in Walker Creek Field, which may have applications to exploration efforts elsewhere in the Smackover Formation.

Abstract A carbonate buildup was cored in the Lower Cretaceous Shuaiba Formation of the eastern Arabian Peninsula. The sequence is 58 m (190 ft) thick and consists of a basal algal bank overlain by a bioherm composed of caprinid rudists with point-to-point contact in a muddy matrix. Upward growth of the bioherm into the surf zone led to development of extensive sheets of skeletal sand and gravel. Subsequent subaerial exposure and fresh water leaching led to creation of secondary moldic and microvugular porosity. Proximity to open basins, a pre-existing topographic high, and either rapid subsidence or eustatic rise to channel the accumulation of successive rudist generations vertically are necessary to construct buildups of sufficient size and thickness to be hydrocarbon exploration targets. Early and Middle Cretaceous rudists lacked framework constructing potential, as a result their communities are typically developed in sheltered habitats or below wavebase and the resultant buildup is mud-dominated. Creation of reservoir-quality porosity and permeability in such buildups usually requires fresh-water leaching, dolomitization or fracturing.