页岩气井可压裂性综合评价方法研究及应用  

Research and application of comprehensive evaluation on fracability of shale gas wells

作　　者：王松[1,2] 杨洪志[1] 赵金洲[3] 李农[1,2] 李勇明[3] 

机构地区：[1]中国石油西南油气田分公司勘探开发研究院,四川成都610051 [2]页岩气评价与开采四川省重点实验室,四川成都610051 [3]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：《油气地质与采收率》2016年第2期121-126,共6页Petroleum Geology and Recovery Efficiency

基　　金：国家"973"计划"中国南方海相页岩气高效开发的基础研究"(2013CB228004);国家科技重大专项"地应力分布特征及控缝高技术研究"(2011ZX05014-006)

摘　　要：页岩气井可压裂性评价是保证压裂改造效果的重要基础。目前对可压裂性研究主要是在常规物性基础上将岩石脆性矿物含量或岩石力学参数作为水平井压裂施工段优选的重要依据。但压裂过程中沟通并延伸天然裂缝是形成缝网的关键,因此须将分支裂缝的形成条件作为页岩气井可压裂性评价的重要组成,以提高有利层段选评的准确性。通过分析人工裂缝与天然裂缝相交后起裂力学条件,提出相交后形成的分支裂缝起裂压力计算方法,再根据人工裂缝内的压力变化情况和储层地应力状态,建立人工裂缝与天然裂缝相交后的起裂模式并将其无因次化后作为评价的组成要素,形成页岩气井可压裂性综合评价方法。基于四川盆地南部页岩气Wx2直井的地质、测井数据对龙马溪组有利层段的分析,按照综合评价结果进行射孔和压裂,其测试产量明显高于该区块其他常规可压裂性评价的直井。表明该方法具有较高的准确性和适用性,既能保证压裂改造效果,又能降低施工风险和成本。Fracabilty evaluation of shale gas reservoir is a key technique to improve fracturing results. Resent research of fracability assessment focuses on the effect of brittle minerals content and rock mechanical parameters as important basis for treatment section optimization of horizontal wells in shale gas formation. However,complex fracture network can only be created by connection and propagation of natural fractures. Therefore,forming condition of multi-stranded fractures constitutes the important part of the fracability assessment of shale gas reservoir,bringing more accuracy to favorable interval selection. After analyzing the mechanical condition of intersection between hydraulic and natural fractures,calculation method of initiation pressure of the multi-stranded fractures was put forward. Dilation mode of multi-stranded fractures can be established and applied as critical ingredients by dimensionless process to realize fracability synthetic assessment for shale gas reservoir based on pressure in the hydraulic fractures and in situ stress state of oil reservoir. Based on favorable interval analysis of the Longmaxi Formation on geophysics and logging data of the shale gas well,Wx2,in the southern Sichuan basin,evaluation results can determine the perforation and fracturing location. Compared with other vertical shale gas wells evaluated by conventional appraisement in this block,the test production of Well Wx2 is higher after the treatment. This case study demonstrates the reliability and practicability of the method for optimal selection of fracturing section,which canincrease stimulation effectiveness and reduce treatment risk and cost.

关 键 词：页岩气井 可压裂性 地应力 起裂模式 综合评价方法 

分 类 号：TE375[石油与天然气工程—油气田开发工程]