页岩储层水力压裂裂缝相互作用机理研究

发布时间：2018-04-12 07:16

本文选题：水力压裂 + 有限元　；参考：《西安石油大学》2017年硕士论文

【摘要】：页岩气等非常规能源的有效开发已经成为了能源领域的热点研究问题,北美页岩气开发经验表明,通过缝网压裂形成复杂裂缝网络是进行页岩储层改造的重要手段,研究水力压裂裂缝间的相互作用对于体积压裂设计具有重要的理论意义。本文基于岩石断裂力学理论与有限元方法,建立了水力压裂裂缝有限元扩展模型,以数值模拟为主要研究方法,研究了水力裂缝之间的相互作用,并分析缝间距、水平应力差及多簇裂缝不等间距等因素对水力裂缝间互作用的影响,此外本文还研究了水力裂缝与天然裂缝相互作用判据,并结合实例对准则进行了全面的分析。结果表明:对于均质、各向同性储层,水平井单井两簇裂缝同步扩展时,裂缝间的区域应力场相互叠加,裂缝扩展时相互排斥远离,最终为“哑铃型”形态,缝间距以及水平应力差的增大对裂缝间相互作用起到了抑制排斥的效果;三簇裂缝等间距同步扩展时,中间裂缝的扩展受到两侧裂缝抑制,延伸长度比两侧裂缝短,而不等间距时中间裂缝向较远处的裂缝偏转,间距不对称性越大,中间裂缝偏转强度越大;而两口及以上水平井同步压裂时,裂缝相互吸引靠近,随着裂缝间横向距离逐渐减小,裂缝间形成较大的应力变化区,利于其中的天然裂缝起裂延伸并转向;水力裂缝逼近天然裂缝时,会受到一定程度的扰动,当水力裂缝与天然裂缝相交后,呈现多种模式,论文分析了各种模式中倾斜角与临界净压力值的关系,讨论了岩石抗张强度以及天然裂缝壁面摩擦系数的影响。
[Abstract]:The effective development of unconventional energy such as shale gas has become a hot research issue in the field of energy. The experience of shale gas development in North America shows that the formation of complex fracture network through fracture mesh fracturing is an important means of shale reservoir reconstruction.It is of great theoretical significance to study the interaction between fracturing fractures for volume fracturing design.Based on the theory of rock fracture mechanics and finite element method, the finite element expansion model of hydraulic fracturing fracture is established in this paper. Taking numerical simulation as the main research method, the interaction between hydraulic fractures is studied, and the fracture spacing is analyzed.The influence of horizontal stress difference and the unequal distance between clusters of cracks on the interaction between hydraulic fractures is also studied in this paper. In addition, the criterion of interaction between hydraulic fractures and natural fractures is studied in this paper, and the criterion is analyzed comprehensively with examples.The results show that for homogeneous and isotropic reservoirs, when the two clusters of fractures in horizontal wells synchronously extend, the regional stress fields between fractures superimpose on each other, and the fractures are repelled away from each other during the fracture propagation, and the final form is "dumbbell-shaped".The increase of crack spacing and horizontal stress difference has the effect of restraining and repelling the interaction between the fractures, and when the three clusters of cracks propagate synchronously with equal spacing, the expansion of the middle crack is restrained by the two sides of the crack, and the extension length is shorter than that of the two sides.When the interval is unequal, the intermediate fracture deflects to the far fracture, and the greater the asymmetry of the distance, the greater the deflection strength of the middle fracture, and when two or more horizontal wells are fractured simultaneously, the fractures attract each other close to each other.As the transverse distance between fractures decreases gradually, a larger stress variation zone is formed between the fractures, which is conducive to the initiation and extension of the natural cracks, and the hydraulic fractures will be disturbed to a certain extent when they approach the natural fractures.When the hydraulic fracture intersects with the natural fracture, there are many modes. The relationship between the angle of inclination and the critical net pressure is analyzed, and the influence of the rock tensile strength and the friction coefficient on the wall of the natural crack is discussed.
【学位授予单位】：西安石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE357.1

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