EFFECT OF HETEROGENEITY ON THE PERFORMANCE OF IMMISCIBLE DISPLACEMENTWITH HORIZONTAL WELLS

A three-dimensional, finite difference, chemical flood simulator (UTCH EM) was used to study the performance of immiscible displacement with horizontal and vertical wells in several heterogeneous reservoirs. Thr ee-dimensional heterogeneous permeability fields were generated geosta tistically with Dykstra-Parsons coefficient and spatial correlation as characterizing parameters. A total of 21 permeability fields were gen erated to cover a wide range of Dykstra-Parsons coefficients and spati al correlations. Initially, simulations of immiscible displacement wit h two horizontal wells (one injector and one producer) were performed in all these permeable media. The effect of the amount of cross flow b etween producing layers on the flood performance was investigated. The se results were then compared to those obtained with two vertical well s (one injector and one producer) for all the permeable media. Finally , investigations were carried out on a heterogeneous reservoir to stud y in detail the sensitivity of the displacement performance to the hor izontal well length and to the ratio of horizontal to vertical permeab ility using various well combinations. These well combinations consist ed of vertical injector-vertical producer, horizontal injector-horizon tal producer, vertical injector-horizontal producer, and vertical prod ucer-horizontal injector. Results show that the degree and the structu re of the reservoir heterogeneity have a significant effect on the eff iciency of immiscible displacements with horizontal wells. Long horizo ntal wells in highly heterogeneous reservoirs do not necessarily guara ntee improved oil recovery.