层理对侏罗系油藏水力裂缝扩展形态影响研究  

Study on influence of bedding on hydraulic fracture propagation morphologies in Jurassic reservoirs

作　　者：袁丽娜 王广涛[2] 王成旺[2] 侯瑞 孙峰[1] YUAN Lina;WANG Guangtao;WANG Chengwang;HOU Rui;SUN Feng(College of Pipeline and Civil Engineering,China University of Petroleum(East China),Qingdao,Shandong 266580,China;Research Institute of Oil and Gas Technology,Changqing Oilfield,Xi'an,Shaanxi 710021,China;Natural Gas Evaluation Project Department,Changqing Oilfield,Qingyang,Gansu 745000,China)

机构地区：[1]中国石油大学(华东)储运与建筑工程学院,山东青岛266580 [2]长庆油田油气工艺研究院,陕西西安710021 [3]长庆油田天然气评价项目部,甘肃庆阳745000

出　　处：《油气藏评价与开发》2024年第6期908-917,共10页Petroleum Reservoir Evaluation and Development

基　　金：国家自然科学基金项目“深层页岩热流固耦合致裂机制的实验及数值模拟研究”(42274155);中央高校基本科研业务费专项资金项目“高温高压高应力环境下水力裂缝扩展力学机制研究”(23CX03008A)。

摘　　要：鄂尔多斯盆地侏罗系层段埋深介于300~2200 m,油藏中分布着大量的水平层理,导致压裂过程中裂缝形态和扩展方向变化复杂。通过室内巴西劈裂试验测试考虑层理影响的侏罗系层段岩心的抗拉性能,比较垂直层理面和平行层理面下试样的抗拉强度差异。基于测试数据,采用cohesive单元法建立可以表征多层理侏罗系油藏水力压裂的三维有限元模型,研究层理面强度和地应力差对水力裂缝形态及扩展路径的影响。结果表明:层理面强度和地应力差是影响水力裂缝发生转向的主要因素;高层理强度和高地应力差会降低层理面对水力裂缝的限制,增强水力裂缝纵向穿层能力;低层理强度和低应力差会导致层理面的开启,使裂缝由垂直方向转而向层理面扩展。研究结果可为侏罗系油藏压裂施工的优化设计提供指导。The Jurassic formations of the Ordos Basin,with burial depths ranging from 300 to 2,200 m,exhibit numerous horizontal bedding planes within the reservoirs,leading to complex variations in fracture morphology and propagation direction during hydraulic fracturing.Laboratory Brazilian splitting tests were conducted to evaluate the tensile strength of core samples from Jurassic formations,considering the impact of bedding.The tensile strength differences between specimens perpendicular to and parallel to bedding planes were compared.Based on the experimental data,a three-dimensional finite element model using the cohesive element method was developed to characterize hydraulic fracturing in multilayered Jurassic reservoirs,focusing on the effects of bedding strength and in-situ stress differences on fracture morphology and propagation paths.The results indicated that bedding strength and stress differences were the primary factors influencing fracture deflection.High bedding strength and large stress differences reduced the restraining effect of bedding on fractures,enhancing their vertical penetration across layers.Conversely,low bedding strength and small stress differences led to the opening of bedding planes,causing fractures to deviate and propagate along bedding surfaces.These findings provide guidance for optimizing hydraulic fracturing operations in Jurassic reservoirs.

关 键 词：侏罗系油藏 层理结构 水力压裂 裂缝形态 有限元模拟 

分 类 号：TE319[石油与天然气工程—油气田开发工程]