GAUSS-JACOBI’S ITERATION METHOD FOR NATURAL GAS WELLS PRODUCTION FORECAST USING DECLINE CURVE ANALYSIS

Abstract

This study seeks to perform production forecasts of gas wells using the concept of decline curve analysis (DCA) and regression analysis. The regression analysis was performed by fitting a polynomial curve fitting model to a set of production history data, so as to determine the initial gas flowrate. In addition, Gauss Jacobi method was used to provide a solution to the solved five-by-five matrix in order to compute values for the regression coefficients. Subsequently, a computer program “ROTEX” was developed to predict the efficacy of the proposed DCA and regression analysis method. Three wells (WELL Y1, Y2 and Y3) from a field in the Niger Delta region were evaluated with respect to forecasting future gas rates till abandonment. Consequently, Well Y1 was observed to have the potential to continue producing for the next 30 years, while Well Y2 and Y3 have the potential to produce for roughly five years before they reach abandonment. R-squared values were computed for each case, as a means to validate the integrity of the fitted regression curves to the production history data. All R-squared values were observed to be very close to unity and are thus considered reliable.