Study of Geologically Consistent History Matching Peculiarities by Means of Gradient-Free Optimization Methods

Abstract

This paper presents some results and distinctive features of the algorithm for automated history matching of 3D reservoir flow models using gradient-free methods. Widely used Nelder-Mead method was chosen for optimization. In order to preserve geological consistency of a model within the history matching process, control parameters are comprised of “porosity-to-permeability” relation parameters, anisotropic (semi)variogram parameters, and reservoir properties at pilot points. The control parameters are used at each iteration of the history matching process to generate porosity and permeability distributions based on static well data and perform flow simulations. Test studies were conducted for a specially developed synthetic model representing a inhomogeneous five-spot well pattern element. Oil flow rates at production wells and water flow rate at the injection well, as well as bottomhole pressures of all wells were chosen as measured dynamic data in the objective function. The influence of initial guess of parameter values and relative weights in the objective function on the quality of reconstruction of the ‘true’ solution and convergence rate were evaluated. Problems of gradient-free optimization methods application and specific features of residuals normalization in the objective function, as well as influence of pilot points are discussed.