酸处理降低地层破裂压力的计算分析

针对超深储层的破裂压力很高，对压裂施工设备的功率和承载能力要求更高，在施工安全上存在一定隐患的实际，研究了超深储层的破裂压力模型以及利用岩石力学性质的酸敏性，采取酸化预处理降低地层破裂压力，建立了射孔井筒破裂压力预测模型，分析了酸化预处理降低地层破裂压力机理。利用西部某深层气藏岩样室内酸处理前后岩石弹性模量、泊松比和岩石抗压强度变化结果，计算了该气藏酸处理前后的破裂压力，结果表明酸预处理后破裂压力大幅下降，对降低压裂施工压力有重要作用。为在现有工程条件和技术条件下，准确预测破裂压力和施工压力、合理选用施工设备、降低储层改造的工程风险提供了方法。

The Calculation Analysis of Decreasing Formation Fracturing Pressure by Acidizing Pretreatment

The fracturing pressure of ultra-deep reservoir is high, and the requirement on power and carrying capacity of treatment equipment is even more strict, so that there are some hidden troubles in safe work practice. Fracturing pressure model of ultra-deep reservoir is studied, fracturing pressure prediction model of perforated well established by utilizing acid sensitivity of rock mechanical properties and acid pretreatment to decrease formation fracturing pressure, and mechanisms of acidizing pretreatment decreasing fracturing pressure analyzed. According to lab study for a certain western deep gas reservoir about the variation of rock elastic modulus, Poisson ratio and rock compressive strength, fracturing pressure of the reservoir before and after acidizing pretreatment is calculated. The results show that fracturing pressure declines dramatically after acidizing pretreatment, and acidizing pretreatment has significant effect on decreasing pressure of fracturing operation. Under available engineering and technical condition, the job supplies good means for accurately forecasting fracturing pressure and operation pressure, reasonably selecting operation equipment and decreasing risk of reservoir reformation.