Investigation of the production performance of horizontal wells in fractured bottom water drive reservoirs

Abstract

The performance of unfractured and fractured horizontal and vertical wells in a three-dimensional rectangular reservoir model with bottom water drive has been studied. The oil employed was a low viscosity kerosene and the rate was chosen so that the oil-water interface would be stable until it approaches the well. It was found that, in general, wells with greater contact area with the reservoir gave much more production before water breakthrough, anad experienced lower pressure drop. Thus, for example, fractured horizontal wells were better than horizontal wells which, in turn were better than the vertical wells. Interestingly, very deep fractures extending towards the water zone improved the performance. The reasons for this are explained through an analysis of the production mechanisms. Extrapolation of the results to reservoir scales indicates that long horizontal wells in quit reasonable and economic spacings can give performances equivalent to and even better than those expected of arrays of vertical wells so closely spaced that they could not be economic.