1. n. [Well Testing, Enhanced Oil Recovery]
The variations in rock properties in a reservoir. The variations can result in directional variations in permeability. Geological processes, such as sedimentation, diagenesis and erosion, act to produce nonuniformities in rock formations. Because there are so many types of reservoir heterogeneities, a unique interpretation of test results from pressure data alone is often impossible. Expert test interpreters rely heavily on experience, core analysis, well logs and knowledge of the geology specific to the region.