酸压井压后压力递减分析模型  

A Model with pressure decline curve for acid fracturing wells

作　　者：郭建春[1] 赵金洲[1] 任勇[1] 

机构地区：[1]西南石油大学油气藏地质及开发工程国家重点实验室,四川成都610500

出　　处：《石油钻采工艺》2007年第2期42-45,共4页Oil Drilling & Production Technology

基　　金：四川省杰出青年学科带头人基金(项目编号:05ZQ026-027"酸化压裂中酸蚀蚓孔和酸液滤失模型研究");教育部博士学科点专项科研基金(基金编号:20040615003"酸蚀蚓孔扩展及酸液滤失机理研究")资助

摘　　要：油气酸压井压后的压力递减分析和评估技术,发展相对比较缓慢。酸压井施工停泵后,裂缝壁面的酸岩反应还在继续进行,酸岩反应产生的CO2对酸液和残酸的压缩性,以及停泵后的压力动态都会有很明显的影响;裂缝壁面的酸液滤失机理与压裂液的滤失机理有很大的不同。提出了一种酸压井施工压力递减分析的方法,在考虑流体压缩性和地层温度的影响下,推导了停泵后流体的连续性方程,建立了利用酸压压力递减资料计算裂缝参数的数学模型,给出了压降数据拟合求解数学模型的方法,编制了酸压井停泵后压力递减分析解释软件。实例分析表明,酸压井的压降解释中必须考虑温度和流体压缩性的影响;采用计算机自动拟合压降曲线的方法可有效提高解释工作质量。由于该方法模拟了停泵后缝内的物理、化学变化过程,解释的酸压井的滤失系数和裂缝几何参数更接近地层真实情况,可以为酸压施工评价和优化酸压设计提供直接可靠的技术手段。The pressure decline analysis and evaluating techniques for acid fracturing wells develop quite slowly. When operation of the acid fracturing well is completed, the acid-rock reaction on the fracture face is still going on and generates CO2, which exerts obvious effect on the compressibility of acidizing fluid and residual acid and the pressure response of the acid fracturing well after shut-in. The leakoff mechanism of the acidizing fluid is quite different from that of the fracturing fluid. This paper therefore puts forward a new method to analyze the pressure decline for acid fracturing wells. Based on taking fluid compressibility and strata temperature into account, it deduces the continuity equation of fluid after shut-in, establishes a mathematic model to calculate the fracture parameters in terms of the pressure decline data, shows the solution technique for the mathematic model by matching pressures decline data, and builds the interpretation software to analyze the pressure decline after shut-in. Case analysis shows that strata temperature and fluid compressibility must be taken into consideration to analyze the pressure decline for acid fracturing wells, which will be improved by employing the method that uses computers to fit the pressure decline curve, because it simulates the physical and chemical change in fractures after pumping and the leakoff coefficient and fracture geometry parameters interpreted in this paper are more close to the reality of strata. Therefore, the model and method presented in this paper can provide reliable techniques for evaluating acid fracturing operation and optimizing the acid fracturing design.

关 键 词：酸压井 压力递减 滤失系数 裂缝几何参数 

分 类 号：TE357.2[石油与天然气工程—油气田开发工程]