Appalachian Reservoir Heterogeneity

Non-uniform composition and permeability of a reservoir, commonly referred to as reservoir heterogeneity, is recognized as a major factor in the efficient recovery of oil during primary production and enhanced recovery operations. Heterogeneities are present at various scales and are caused by various factors, including folding and faulting, fractures, diagenesis and depositional environments. Thus, a reservoir consists of a complex flow system, or series of flow systems, dependent on lithology, sandstone genesis, and structural and thermal history. Ultimately, however, fundamental flow units are controlled by the distribution and type of depositional environments. Reservoir heterogeneity is difficult to measure and predict, especially in more complex reservoirs such as fluvial-deltaic sandstones. The Appalachian Oil and Natural Gas Research Consortium (AONGRC), a partnership of Appalachian basin state geological surveys in Kentucky, Ohio, Pennsylvania, and West Virginia, and West Virginia University, studied the Lower Mississippian Big Injun sandstone in West Virginia. The Big Injun research was multidisciplinary and designed to measure and map heterogeneity in existing fields and undrilled areas. The main goal was to develop an understanding of the reservoir sufficient to predict, in a given reservoir, optimum drilling locations versus high-risk locations for infill, outpost, or deeper-pool tests.