A New Acid Washing Evaluation Approach for Horizontal Well in Porous Carbonate Reservoir

The acid washing is a common stimulation method for horizontal injectors in porous carbonate reservoirs with the simple procession and affordable cost. Currently, the evaluation method of acid washing is primarily based on the comparison of well test interpretation results before and after acid washing. This method does not consider the uncertainty of well test interpretation so that the method is subjective to some degree. Moreover, the pressure derivative curve before and after flow acid washing and the injection performance are not considered, which is a constraint of this method. Therefore, based on the pressure derivate curves before and after acid washing and the injection and production performance in patterns, this paper proposes a new integrated evaluation method of acid washing. This method can successfully evaluate the effect of acid washing and reflect the mechanism of effective acid washing. This new approach also can guide the selection of candidate wells for acid washing which can make assistance in the optimization of reservoir injection development and repression of watercut. Favorable results have been obtained in the reservoir application and this new method can be applied in other porous carbonate reservoirs successfully.