动态裂缝对地层压力分布规律影响规律研究

发布时间：2018-05-27 23:21

本文选题：天然裂缝 + 地层压力　；参考：《东北石油大学》2017年硕士论文

【摘要】：低渗裂缝储层在长期注水过程中,原始状态下闭合、充填的天然裂缝被激动、复活所产生有效裂缝通道。天然裂缝存在影响了地层压力分布,不利于调整井钻井安全。针对这一问题,本文将从单一天然裂缝的不同力学条件的渗流能力出发,考虑天然裂缝分布影响,对注水井注水、关井泄压和溢流泄压注水井周围地层压力分布规律进行研究。本文研究了不含裂缝基质岩石和含闭合裂缝岩石储层条件下的渗透率随地层压力变化关系。对储层天然裂缝开启后,考虑天然裂缝的缝高和裂缝开启长度的影响,基于缝宽计算模型,建立缝内压力与缝宽的关系模型。结合缝内流动立方定律模型,得出了考虑天然裂缝的缝高和裂缝开启长度的裂缝等效渗透率与地层压力关系模型。随后,借助分形几何方法描述储层天然裂缝的分布,基于多组天然裂缝等效渗透率等效叠加方法,得出了考虑天然裂缝分布,低渗裂缝储层地层渗透率随地层压力动态变化关系。应用到考虑流固耦合效应的注采条件下地层压力分布模型中,计算并分析低渗裂缝储层注水井注水,关井泄压和溢流泄压水井周围地层压力分布。研究结果表明,低渗裂缝储层渗透率受储层地层压力、地应力、天然裂缝的产状、开启闭合状态、裂缝形状共同影响;注水井附近天然裂缝张开压力传导率高,远端天然裂缝处于闭合状态压力传导率差,是注水井近井带平均地层压力高,形成近井带憋压的原因;注水井溢流泄压,近井带天然裂缝闭合阻碍了地层流体流向井口,降低了注水井远端地层压力通过反排泄压的效率;注水井溢流泄压不考虑天然裂缝开启闭合的影响,会导致预测调整井待钻处地层压力偏低。对于注水井溢流泄压待钻调整井地层压力预测,需以考虑天然裂缝开启闭合的地层压力分布为调整井钻井液设计指导。研究有利于明确低渗裂缝储层开发后,受油田开发调整影响地层压力分布规律。为低渗裂缝储层调整井钻井,固井的地层压力预测提供理论依据。
[Abstract]:In the process of long-term water injection, the low permeability fractured reservoir is closed in the original state, the filled natural fracture is excited, and the effective fracture path is produced by the resurrection of the reservoir. The existence of natural fractures affects the distribution of formation pressure and is not conducive to the drilling safety of adjustment wells. In order to solve this problem, considering the influence of natural fracture distribution, the distribution of formation pressure around water injection wells, shut-in wells and overflow pressure relief wells is studied based on the percolation ability of single natural fracture under different mechanical conditions. In this paper, the relationship between permeability and pressure variation in reservoirs with no fracture matrix and closed fracture is studied. Considering the influence of fracture height and fracture opening length, the relationship model between fracture pressure and fracture width is established based on the calculation model of fracture width. Based on the cubic law model of flow in a fracture, the relationship model of fracture equivalent permeability and formation pressure considering the fracture height and fracture opening length is obtained. Then, the distribution of natural fractures in reservoirs is described by means of fractal geometry. Based on the equivalent permeability superposition method of multiple groups of natural fractures, the distribution of natural fractures is considered. Dynamic change of formation permeability and formation pressure in low permeability fractured reservoir. In the model of formation pressure distribution considering the fluid-solid coupling effect, the distribution of formation pressure around injection wells, shut-in wells and overflow pressure wells in low permeability fractured reservoirs is calculated and analyzed. The results show that the permeability of low permeability fractured reservoir is affected by formation pressure, in-situ stress, occurrence of natural fractures, opening and closing state, and fracture shape. The low pressure conductivity of the distal natural fractures in closed state is the reason for the high average formation pressure in the near well zone of water injection wells, and the overflow and release pressure in the injection wells, and the closure of natural fractures in the near well zone hinders the flow of formation fluids to the wellhead. The efficiency of formation pressure passing through reverse discharge pressure at the far end of water injection well is reduced, and the effect of opening and closing of natural fracture is not considered, which will lead to low formation pressure in the well to be drilled. In order to predict the formation pressure of the overflowing pressure relief and adjustment well, the drilling fluid design should be guided by considering the distribution of formation pressure with natural fracture opening and closing. The study is helpful to clarify the distribution law of formation pressure after the development of low permeability fractured reservoir and the adjustment of oilfield development. It provides theoretical basis for drilling and cementing formation pressure prediction of low permeability fractured reservoir adjustment well.
【学位授予单位】：东北石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE311

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