致密砂岩气藏缝网系统渗流力学和岩石断裂动力学  

Fluid mechanics and rock fracture kinetics of fracture mesh system in tight sand gas reservoirs

作　　者：赵海峰[1] 蒋迪 石俊[1] 

机构地区：[1]中国石油大学(北京),北京102249 [2]中核集团中国核电工程有限公司,北京100840

出　　处：《天然气地球科学》2016年第2期346-351,共6页Natural Gas Geoscience

基　　金：国家科技重大专项课题(编号:2016ZX05009-004);中国石油大学(北京)基金(编号:ZX20150191)联合资助

摘　　要：基于渗流力学方程和伽辽金法建立水平井体积压裂缝网渗流场的有限元模型,研究了不同缝网形式与规模下产能随缝网导流能力的变化关系,研究发现致密砂岩与页岩不同,压裂的缝网规模并非越大越好,而应该维持在中小规模(0.1≤FCI≤0.25),且需要高导流能力的支撑主缝。在确定了裂缝形态的基础上,计算得到产能与SRV曲线,研究发现存在SRV临界值(优化值),若SRV超出临界值,产能增幅明显变小。在压裂实践中可由SRV临界值和FCI值,确定水平井分段压裂簇间距和簇数之间的关系。研究了形成中小规模缝网对应的施工条件,首先由岩石断裂动力学给出压裂液排量、黏度、岩石动态断裂韧性、弹性模量、地应力、天然裂缝参数与缝内净压力之间的解析关系,再由缝网前沿动态扩展条件给出形成中小缝网所需排量(优化排量)。Based on fluid mechanics equations and the Galerkin method,a finite element model has been established to simulate fracture mesh seepage field of horizontal wells volume fracturing,and the relationship between fracture mesh conductivity and production has been studied under different fracture mesh scale.Unlike shale gas,fracture mesh scale is not the bigger the better for tight sand stone gas.It should be maintained in a small-to-medium scale（0.1≤FCI≤0.25）and a high conductivity main fracture is also required.From production-SRVcurve,it is found that there exists a critical SRVvalue（optimal value）,and the production increase is significantly smaller when SRVis beyond the critical value.In practice,together with FCI,the critical SRVvalue can be used to determine cluster spacing and number of clusters in horizontal well fracturing.This paper has studied the process conditions to form small-to-medium scale fracture mesh.An analytic relationship among fracturing fluid pump rate,viscosity,rock dynamic fracture toughness,elastic modulus,Poisson＇s ratio,stress,natural fracture parameters and fracture net pressure is given by rock fracture kinetics,and then the optimized pump rate to form small-to-medium scale fracture mesh is determined by dynamic extension conditions on the fracture mesh edge.

关 键 词：致密砂岩气 体积压裂 缝网规模 断裂动力学 优化排量 

分 类 号：TE311[石油与天然气工程—油气田开发工程]