The depletion performance of heterogeneous reservoirs

This research aims to quantify the effects of permeability heterogeneity on reservoir performance. The geostatistical approach using simulated annealing was used to generate stochastic permeability fields of different correlation lengths and levels of heterogeneity. These stochastic permeability fields were inputted in a flow simulator and the depletion performance of both oil and gas reservoirs was simulated. The flow simulator used an 81 x 81 square grid with a well in the center of the square reservoir. The well was produced at a constant flowing bottomhole pressure. The effects of permeability heterogeneity on reservoir performance were quantified and determinations were made in cases where the rate-time data of a heterogeneous reservoir can be predicted with an equivalent homogeneous reservoir. It was found that the depletion performance of all reservoirs with randomly distributed permeability, and approximately 88 percent of reservoirs with correlated heterogeneous permeability fields, can be predicted by an equivalent homogeneous reservoir. Lastly, a heterogeneous reservoir with two producing wells was simulated to determine the effects of well interference on reservoir depletion.