Prediction Of Acidic Pressure Production In Horizontal Wells Of Carbonate

Acid fracturing is a technology which applied in carbonate reservoir stimulation, and it plays an important role. Due to the high-cost and high-risk of acid fracturing, it is necessary to simulate productivity of several designs and determine the optimal fracture parameters before construction. In terms of acid fracturing horizontal well productivity prediction model, it has made a large number of achievements. But they are not considered the changes of acid etched fracture conductivity changes over time, which may resulted in distinction between predicted productivity and real productivity.For the above situation, this paper uses the reservoir engineering and numerical simulation methods, studied acid etched fracture closure model, derived acid etched fracture long-term conductivity model. In the base of carbonate reservoir horizontal well acid fracturing productivity model, considering the effect of acid etched fracture conductivity changes over time, several main understandings and conclusions achieved:(1) Based etched fracture closure mechanism, combined with rock’s dissolution, diffusion in etched fracture contacting surface, and dissolution/precipitation in free surface, this paper established acid etched fracture long-term conductivity model which considered pressure dissolution. This model could calculate acid etched fracture conductivity changes over time;(2) This paper established a three-dimensional two-phase flow acid fracturing productivity prediction model of horizontal well. The model considered the effects of acid etched fracture conductivity changes over time. In this model, fractures and reservoir were seen as two separate systems, and solved by numerical methods;(3) According to the established model, established acid fracturing productivity prediction numerical simulation program of horizontal well, which considered acid etched fracture conductivity changes over time. This program analyzed main factors affecting the productivity of horizontal well qualitatively and quantitatively,obtained the optimal fracture parameter combination;(4) The main factors affecting the acid fracturing horizontal well productivity were simulated orthogonal. The affective degree of factors:the number of fractures>porosity> water saturation>fracture conductivity> formation permeability> fracture interval> fracture length.This paper enriched and improved acid fracturing productivity model of horizontal wells. And has a certain theoretical and practical significance to horizontal wells acid fracturing technology of carbonate reservoir.