Automatic type-curve matching for well test analysis

This paper presents a general method for automatic well test interpretation. The method matches the field data with theoretical reservoir models using a constrained, nonlinear, least-squares regression technique coupled with numerical Laplace inversion of pressure-drawndown equations. Pressure gradients are computed by forward finite-difference approximations. Hence, reservoir models whose pressure gradients are difficult to obtain analytically can be readily included. Only equations for drawndown type curves of reservoir models are needed. Simulated pressure tests and actual field data are analyzed to illustrate the application of the method. The method reduces the time required to perform well test analysis and minimizes the subjectivity of interpretation.