Uncertainty of Estimated Petrophysical Parameters of Ahvaz Oil Reservoir

Abstract

In oil exploration projects, the risks due to uncertainties associated with natural variations in petrophysical parameters can only be reduced when spatial distribution of the reservoir parameters is specified in detail. The reservoir under study is an oil field in South-Western Iran. The information available on this reservoir includes laboratory measurements of porosity and permeability along with data on its formation lithology. In order to determine the presence of any spatial trends in petrophysical parameters, experimental directional variograms and a 3-D geometrical anisotropy were determined. The values of porosity and permeability which were estimated and the information on formation lithology were then used to compute the mean hydrocarbon saturation percentage of the studied reservoir which was found to be about 32% with an estimated oil reserve of 888.6106 cubic meters. The porosity values were performed to estimate the uncertainty and the estimated values were then inputted into the proposed PEP function, which is a simple multiplication of porosity, estimated uncertainty, and permeability to locate the high risk areas. Finally the associated sectional and planar maps were prepared and the optimum locations for complementary drilling were proposed. Also suggestions for reducing estimation errors and further detailed exploration were presented.