多裂缝应力干扰研究

发布时间：2018-01-08 00:27

本文关键词：多裂缝应力干扰研究　出处：《西南石油大学》2015年硕士论文　论文类型：学位论文

【摘要】：近年来,在水平井分段压裂、同步压裂等新技术的推动下,中国非常规页岩气开采不断地取得新突破。页岩储层的开发都采用了水平井分段压裂技术,水平井各段裂缝之间的应力干扰作用使原场应力改变是裂缝网络形成的基础。研究裂缝宽度方向、裂缝长度方向的应力干扰以及停泵时间、排量等参数对应力干扰的影响对确定合理的水平井裂缝参数、解释缝网成因有一定理论指导意义。本文对多裂缝应力干扰进行了一定的研究,主要内容包括： (1)以均质、各向同性的二维平面应变模型为基础,依据变形后的人工裂缝诱导应力计算模型,结合复变函数理论和弹塑性力学知识计算了裂缝周围诱导应力差值的分布特征,并把诱导应力场中水平最大、最小主应力方向发生反转作为判断依据,得到了应力干扰条件下水平井分段压裂最优段间距优化方法。 (2)将复变函数理论与位错理论相结合,以双水平井多裂缝为研究对象,建立了无限大介质中裂缝尖端应力强度因子计算的数学模型。分析了不同裂缝长度比值、裂缝间距、裂缝交叠长度对缝尖应力强度因子的影响。 (3)推导建立了带时间、无因次距离的应力干扰量数学模型,分析了停泵时间、排量、滤失系数等参数对无因次应力干扰量的影响,并且分析了这些参数与不同压裂方式的关系。 (4)推导建立了内外裂缝刚度系数计算模型,计算了不同裂缝条数条件下刚度系数、裂缝宽度比值随无因次距离的变化,并分析了这些变化与弹性模量和缝宽的关系。本文主要从上述四个方面对应力干扰进行了机理研究,取得了一些更深的认识。
[Abstract]:In recent years, in the horizontal well fracturing, new technology driven synchronous fracturing under Chinese unconventional shale gas continue to achieve new breakthroughs. The development of shale reservoir with horizontal well fracturing technology, horizontal well sections between the crack stress disturbance makes the original stress field change is the basis of fracture network study on crack formation. The width direction, interference stress crack length and the pump stop time, horizontal well fracture parameters to determine the reasonable influence of displacement parameters such as stress interference, explain the causes of fracture network has a certain theoretical significance. In this paper many cracks stress interference was studied, the main contents include:
(1) in a homogeneous, isotropic two-dimensional plane strain model based on artificial fracture after deformation induced by stress calculation model, combined with complex knowledge to calculate the distribution of stress difference induced by cracks around the mechanics of plastic function theory and elastic, and the induced stress field in the level of maximum and minimum principal stress the direction of the force is reversed as the basis of judgment, the stress interference conditions of horizontal well fracturing optimal segment spacing optimization method.
(2) the complex function theory and the theory of dislocation combined with multiple cracks in double horizontal wells as the research object, the establishment of the crack tip in an infinite medium should be a mathematical model to calculate the stress intensity factor. Analysis of different crack length ratio, crack spacing, crack overlap length on tip stress intensity factor.
(3) a mathematical model of stress interference with time and dimensionless distance is derived. The influence of pump stopping time, displacement and filtration coefficient on dimensionless stress interference is analyzed, and the relationship between these parameters and different fracturing modes is analyzed.
(4) the stiffness coefficient calculation model of internal and external cracks is derived and calculated. The stiffness coefficient and the ratio of crack width ratio with dimensionless distance are calculated under different crack numbers, and the relationship between these changes and elastic modulus and slit width is also analyzed.
This paper mainly studies the mechanism of force interference from the above four aspects, and has obtained some deeper understanding.

【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE357.1

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