四川盆地志留系龙马溪组页岩裂缝应力敏感实验

发布时间：2018-05-28 11:22

本文选题：人工裂缝 + 渗透率　；参考：《天然气地球科学》2017年09期

【摘要】：裂缝网络是页岩气有效开发的基础,为研究页岩裂缝渗透率在有效应力作用下的变化规律,选取具有代表性的四川盆地龙马溪组页岩样品,通过实验考察了基质、微裂缝和人工裂缝渗透率对应力的敏感程度,总结了孔渗幂指数模型、Gangi模型和Walsh模型对裂缝渗透率的拟合和修正结果,并探讨了支撑裂缝和裂缝滑移降低应力敏感性的作用机理。研究结果表明,微裂缝和人工无填充裂缝的渗透率的应力敏感最强,随着有效应力的增加呈指数式递减,Gangi模型和Walsh模型的拟合精度都在97%以上,参数分析结果表明可通过增加裂缝面的粗糙度和向裂缝加入支撑剂来降低其应力敏感系数。有支撑和滑移裂缝的应力敏感性最低,仅仅在一定应力范围内满足Walsh模型。高应力状态下,优选强度较高、耐压性好的陶粒支撑剂有利于提高裂缝的导流能力,而裂缝滑移在一定程度上比裂缝支撑剂更能增加裂缝渗透率,因此在水力压裂模型中应该考虑设计裂缝滑移来降低裂缝的应力敏感性。
[Abstract]:The fracture network is the foundation of shale gas development. In order to study the change law of shale fracture permeability under effective stress, the representative Sichuan basin Long Maxi group shale sample is selected. Through the experiment, the sensitivity of matrix, micro crack and artificial fracture permeability is investigated, and the pore permeability exponent model, Gangi is summarized. The model and the Walsh model are used to fit and modify the fracture permeability, and the mechanism of the stress sensitivity of the support cracks and crack slips is discussed. The results show that the stress sensitivity of the permeability of the micro cracks and the artificial unfilled cracks is the strongest, and the effective stress increases exponentially with the Gangi model and the Walsh model. The fitting accuracy is above 97%. The results of parameter analysis show that the stress sensitivity coefficient can be reduced by increasing the roughness of the fracture surface and adding the proppant to the crack. The stress sensitivity of the supporting and sliding cracks is the lowest, and the Walsh model is satisfied only within a certain stress range. Under the high stress state, the best strength and the pressure resistant pottery is preferred. The grain proppant is beneficial to improve the conductivity of the fracture, and the fracture slip can increase the fracture permeability more than the fracture proppant. Therefore, in the hydraulic fracturing model, the design of crack slip should be considered to reduce the stress sensitivity of the fracture.
【作者单位】：中国石油勘探开发研究院;
【基金】：国家“十三五”科技重大专项“页岩气气藏工程及采气工艺技术”(编号:2017ZX05037-001) 国家重点基础研究发展计划“973”项目“中国南方海相页岩气高效开发的基础研究”(编号:2013CB228000)联合资助
【分类号】：TE311

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