PERFORMANCE OF HORIZONTAL WELLS WITH LONGITUDINAL FRACTURES IN RESERVOIRS WITH BOTTOM-WATER DRIVE

Abstract

The production performance of un-fractured horizontal wells and horizontal wells with longitudinal fractures of various vertical penetrations in reservoirs with bottom water drive has been studied using a scaled three-dimensional rectangular model. The model represented the drainage volume for a single horizontal well in one of the Middle East reservoirs. The model was packed with glass beads yielding a porosity of 0.36 and a permeability of 400 Darcies, and kerosene and distilled water were used to represent the reservoir fluids. The production rate was chosen so that the oil–water interface would remain stable until it approaches the producing well. In general, wells with greater contact area with the reservoir gave higher oil recovery before water breakthrough, and experienced lower pressure drop. Increasing the fracture penetration improved the production performance up to a limit beyond which no further improvement was obtained. Interestingly, it was found that extending the fracture penetration towards the original oil–water contact did not, as might have been expected, result in earlier water breakthrough. The fracture acted as an in situ oil–water separator and an equilibrium water level was maintained within the fracture as long as the oil–water interface was flat as it moved upward towards the well. *Currently with Qatar Gas Company.