基于岩心分析的页岩气压裂工艺参数优选

页岩气藏的特异性显著。新的页岩气井压裂改造前要进行室内实验,根据实验结果了解气藏特征,提高开发策略的针对性。采用室内实验和理论分析相结合的方法,对中国和北美主要页岩气储层进行了矿物组成、力学参数、微观成像研究,推导出了适用于页岩压裂的闭合压力和缝宽计算方法,计算了埋藏条件下的页岩脆性指数、闭合压力和缝宽,提出了压裂液体系、黏度、排量和支撑剂类型的优选原则,利用黑色页岩进行了室内模拟压裂。结果表明,岩心分析技术能够为压裂工艺参数优选提供必要支撑,龙马溪组页岩的力学特性与Haynesville页岩较为相似,低黏度、大排量压裂时产生的裂缝网络更加复杂。实例计算表明,根据室内分析方法计算的压裂工艺参数具有较强的实用性,能够提高压裂的效果。 

Shale Gas Fracturing Technology Parameters Optimization Based on Core Analysis

Specificities of shale gas reservoirs are usually practically common.It’s important to conduct a systematic laboratory experiment before the fracturing treatment of a new shale gas well to enhance the pertinency of development strategy.A combination method of laboratory experiment and theoretical analysis was used.Mineral composition,mechanical parameters and micro-imaging results for shale gas reservoirs in North America and South China were presented.Calculation methods of closure pressure and fracture width for shale fracturing were derived and the brittleness index,closure pressure and ideal fracture width were calculated for a real well case.Optimization principles of fracture fluid system,viscosity,pump rate and proppant type were introduced and indoor simulating fracture was conducted on black shale samples.The result shows that core analysis technology can provide necessary support for the optimization of fracturing parameter and the mechanical properties of Longmaxi shale are much more similar to that of Haynesville shale.It tends to generate more complex fracture networks with low-viscosity fluid and high pump rate.Case calculation results show that hydraulic fracture parameters selected from core analysis results have a practical advantage and can improve the fracturing effect.