Mathematical simulation of horizontal well performance in naturally fractured rock formations



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Texas Tech University


The purpose of horizontal drilling is to increase the well contact area with the formation, thereby enhancing production and injection. Application of horizontal wells in naturally fractured reservoirs has proven to be highly successful. In this study a dual-porosity, oil-water black oil simulator is developed and used to predict the performance of a horizontal well in fractured reservoirs.

To avoid problems associated with discontinuous properties within the matrix and fracture system a fully implicit formulation is used to develop the flow equations. Point Successive Over Relaxation iterative method is successfully applied to solve the fully implicit system of equations for a dual porosity fractured reservoir. The model results were verified with volumetric calculations, analytic solution, and a dual porosity example.

The matrix fracture transfer term is derived and found to be different from conventional expressions. It is seen that when a horizontal producer intersects high permeability vertical fractures more oil can be recovered which cannot be achieved by vertical wells. Hence application of horizontal wells can be very successful in formations having higher density of vertical fractures. Recovery has been found to be significantly sensitive to matrix water-oil relative permeability and capillary pressure but similar properties of the fracture system has much less effect.