Application of a New Mechanistic Decline Curve Method to Kern County Oil Fields

Field production data from Kern County acquired from the California state database was analyzed for production decline. A decline curve methodology based on fluid flow mechanisms was used. The model reveals a linear relationship between the oil production rate and the reciprocal of the oil recovery. Existing decline curve methods often either overestimate or underestimate reserves, and are mostly empirical in origin. The current approach not only provides a method to estimate reserves, but because of its basis on fluid flow mechanisms, can also be used to infer regional reservoir properties that may be useful in production decisions. Oil wells from six producing oil fields in Kern County were analyzed using this decline curve method and two parameters, a0, the production rate index, which measures the recovery rate, and b0, the gravity index, were mapped regionally. Since the two parameters are associated with capillary pressure and relative permeability, conclusions can be made about the geological properties of the reservoirs from the derivation of the a0 and b0 parameters. This will aid in determining which regions are more prolific, and provide a correlation based on physics to infer reserves, and reservoir rock and fluid properties. It was found that fields with higher a0 and b0 values have higher oil recovery. This study demonstrates the applicability of this decline curve analysis and provides an alternative to empirical methods.