页岩储层压裂水平井分段多簇裂缝干扰与延伸模拟

发布时间：2018-04-10 21:38

本文选题：水平井 + 多裂缝　；参考：《西南石油大学》2017年硕士论文

【摘要】：水平井分段多簇压裂是实现页岩气商业开发的核心技术,目前对水平井多裂缝间干扰延伸规律没有清晰认识,导致有些现场压裂效果不理想。本文针对无限大均质、各向同性页岩储层,运用位移不连续方法建立了任意位置分布、任意长度和任意间距的水力裂缝相互干扰下的诱导应力场计算模型。并以裂缝之间应力干扰为基础,运用位移不连续方法计算裂缝宽度,利用有限差分方法来处理缝内流体压力分布,利用物质平衡方程控制延伸时间,利用最大周向应力准则计算裂缝转向角,通过迭代耦合方法实现多裂缝干扰延伸模拟。利用多裂缝干扰延伸模型对不同压裂方式裂缝进行延伸模拟并进行相应的影响因素分析,得到了以下主要成果:(1)利用改进位移不连续方法计算单裂缝和多裂缝干扰下的诱导应力分布。水力裂缝在原始最小水平主应力方向诱导应力的数值大于最大水平主应力方向。水力裂缝诱导应力会降低裂缝附近原始水平应力差异系数。通过位移不连续方法计算的多裂缝诱导应力远小于解析解线性叠加计算出来的诱导应力。(2)利用裂缝转向延伸模型模拟双向受压单裂缝延伸。结果显示初始裂缝起裂方位与原始最大水平主应力方向不一致时,双向受压单裂缝在近井带转向原始最大水平主应力方向转向延伸。同时分析了水平应力差和初始裂缝起裂方位对双向受压单裂缝转向延伸裂缝形态的影响。(3)利用多裂缝干扰延伸模型对分段同时压裂、分段顺序压裂、交替压裂和拉链式同步压裂分别进行延伸模拟。研究了裂缝干扰延伸轨迹、裂缝宽度和缝内压力分布情况。对影响裂缝延伸形态的水平应力差和裂缝间距等因素进行了定量分析,掌握了不同条件下裂缝延伸形态。本文较为系统的研究了多裂缝干扰延伸规律,研究结果对于水平井分段多簇压裂设计具有较好的现实指导意义。
[Abstract]:Segmented multi-cluster fracturing in horizontal wells is the core technology to realize the commercial development of shale gas. At present, there is no clear understanding of the rules of interference and extension between multiple fractures in horizontal wells, which leads to the unsatisfactory fracturing effect in some fields.In this paper, the induced stress field model of hydraulic fractures with arbitrary location distribution, arbitrary length and arbitrary spacing is established by using displacement discontinuity method for infinite homogeneous and isotropic shale reservoirs.Based on the stress interference between fractures, the crack width is calculated by discontinuous displacement method, the fluid pressure distribution in the fracture is treated by the finite difference method, and the extension time is controlled by the material balance equation.The maximum circumferential stress criterion is used to calculate the steering angle of the fracture and the iterative coupling method is used to simulate the multi-crack interference extension.The multi-fracture interference extension model is used to simulate the fracture extension of different fracturing modes and the corresponding influencing factors are analyzed.The following main results are obtained: 1) the induced stress distribution under the interference of single crack and multiple cracks is calculated by using the improved displacement discontinuity method.The induced stress in the direction of the initial minimum principal stress is larger than that in the direction of the maximum horizontal principal stress.Hydraulic crack induced stress will reduce the original horizontal stress difference coefficient near the fracture.The induced stress of multiple fractures calculated by displacement discontinuity method is much smaller than that calculated by linear superposition of analytical solution.The results show that when the initial fracture initiation direction is not consistent with the original maximum horizontal principal stress direction, the bidirectional compression single fracture turns to the original maximum horizontal principal stress direction in the near well zone.At the same time, the influence of horizontal stress difference and initial fracture initiation orientation on the fracture morphology of bidirectional compression single fracture turning to extended fracture is analyzed.Alternate fracturing and zipper synchronous fracturing were simulated separately.The trajectory, width and pressure distribution of the fracture are studied.Quantitative analysis was made on the factors affecting fracture extension morphology, such as horizontal stress difference and fracture spacing, and the fracture extension morphology was mastered under different conditions.In this paper, the rules of multi-fracture interference extension are systematically studied, and the results are of practical significance for the design of multi-cluster fracturing in horizontal wells.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE377

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