酸化压裂井停泵压力三维分析模型和解释方法

A 3-D analytical model and interpretation method of pressure decline for acid fracturing well

为了对酸化压裂井压后裂缝参数进行准确的分析和解释,以模拟停泵前后裂缝内的物理、化学变化过程为思路,以停泵后缝内的物质平衡方程为主线,建立酸化压裂井停泵后的缝内压力递减模型,并提出了针对酸化压裂井裂缝参数解释、评估的“曲线拟合”法。该模型考虑了地层温度和流体(残酸和CO2)压缩性的影响,能有效模拟停泵后的压力降落,进而解释出酸蚀裂缝几何尺寸、闭合压力、酸液滤失系数及液体效率等参数,从而为酸化压裂施工评价和优化酸化压裂设计提供直接可靠的技术手段。

With the rapid development of hydraulic fracturing, more and more attention has been paid to the techniques of fracture diagnosing and evaluating after fracturing. There are stilt few studies about fracture diagnosing and evaluating for acid fracturing well. The pressure decline analysis method for acid fracturing well is a kind of ＂curve fitting＂ method whose main idea is simulating the physical and chemical changes before and after pump off, and whose main line is the material balance equation. The models consider the influence of temperature and the compressibility of fluids （ residual acid and CO2）. They can effectively simulate the pressure decline after pump off, in turn, interpret the acid fracture geometry, closure pressure, acid loss coefficient, etc, and provide dependable techniques for evaluating acid fracturing as well as optimizing the reservoir stimulation.