The analysis of oil production data using decline curves is a modeling and forecasting technique. Actual production rate and time data are history matched to a theoretical model using specialized graphs known as type curves.
This study begins with a review of the previously developed decline curve construction and analysis methods. It consists of reproducing Arps-Fetkovich type curves and the derivative type curves for advanced decline curve analysis. A Program was developed to generate the dimensionless rate-pressure and time data necessary to construct Fetkovich type curves.
Combining the analytical solution derivative for transient flow based on numerical analysis, and the empirical solution derivative for boundary dominated flow develops the derivative type curves.
The type curves is used to identify the transient versus depletion stages and to estimate reservoir parameters and future decline paths.
Field production data are generally difficult to match with the type curve for this reason a Universal Fitting Equation is proposed as an alternative to manual type curve matching. This equation combines both Arp’s empirical equation and Fetkovich analytical solutions. It equation offer the following advantages:
Fitting with the equation is more precise than type curve matching to obtain reservoir dimensionless radius reD, Arp’s exponent b, matching points q/qDd, and tDd/t.
The real production data can be fitted directly by the equation without using smoothing techniques.
The radial and pseudosteady state regions are determined automatically and easily from fitting.
Some production data that were insufficient to be analyzed with manual type-curve matching can be interpreted with the Fitting Equation.
This procedure has been applied to some Real field data from Hassi Messaoud field cases and it has given significant results.