Abstract

Although numerous sandstone acidizing simulators have been developed during the past decade, none have been field validated. This paper addresses the field validation of a numerical simulator.

The simulator calculates the pressure at the formation face and within the matrix of multiple layers along with the corresponding flow rates. Diversion and mineral dissolution with the corresponding permeability changes are also calculated. The key to simulator validation is good well data including pre and post-treatment pressure buildup analyses, PLT data, log and/or core data, formation mineralogy and a knowledge of the damage mechanism. Skin evolution plots versus volume of acid injected allow the design engineer to easily optimize the treating fluid volume, injection rate and diversion schedule. Post-validation simulations indicate the "rule of thumb" guidelines for mud acid volume may not yield the best results. Simulations support the concept that diversion is essential and can easily be "observed" via the flow per layer output. This study indicates a matrix treatment design is not "engineered" until it is simulated using valid models. Application of the validated simulator results in increased production. A detailed description of the validation process and the supporting well data are presented.