针对裂缝性储层应力敏感性的常规研究方法难以做到与实际相符且不能定量分析的问题,采用储层裂缝数值模拟方法,对克深气田裂缝性储层的应力敏感性进行了研究,并分析了应力敏感性的影响因素。研究结果显示:随着有效应力的增加,裂缝的孔隙度和渗透率均随之下降,表现出较强的应力敏感,且裂缝渗透率的应力敏感程度强于裂缝孔隙度,并可采用指数函数对应力敏感曲线进行拟合;储层裂缝孔渗参数的初始值越高,其应力敏感性越强,即相对高渗储层的应力敏感性要强于相对低渗储层;对于低渗透的裂缝性储层,储层岩石塑性越强其应力敏感程度越高;不同充填程度裂缝的应力敏感性由强到弱依次为未充填缝、半充填缝和全充填缝。

There are certain difficulties in practical research and quantitative analysis of stress sensitivity in fractured reservoirs usingconventional methods.The stress sensitivity and its influencing factors in fractured reservoirs are investigated by numerical simula-tion of the fractures in Kuqa depression Keshen gas field.Results show that both the porosity and permeability of fractures declinewith increasing effective stress,showing strong stress sensitivity.Fracture permeability has higher stress sensitivity than fractureporosity,and their stress sensitivity curves can be fitted using an exponential function.The reservoir with higher initial fracture per-meability has stronger stress sensitivity.That is,high-permeability reservoir has higher stress sensitivity than low-permeability res-ervoir;in the latter case,the reservoir with greater rock plasticity has higher stress sensitivity.In fractures with different extents offilling,stress sensitivity declines in the order of unfilled fractu

采用变流压定围压试验方式,在高温、高压条件下模拟了气藏开发过程,研究了复杂火山岩气藏储层渗透率应力敏感性,对比了变流压定围压与常规的定流压变围压方式评价储层应力敏感性的异同。试验结果表明,火山岩储层渗透率随着孔隙压力的减小而减小,渗透率减小主要发生在孔隙压力从40 MPa下降至25 MPa的变化区间,渗透率损失率与其初始渗透率之间的相关性较差,这与常规沉积砂岩储层具有一定的差别。变流压定围压试验评价的应力敏感性强于定流压变围压评价结果,气藏储层有效应力变化范围内两种试验评价的应力敏感性结果差异更大。基于渗流力学理论,推导得到考虑应力敏感性的气井产能方程。计算结果表明,考虑应力敏感性时气井无阻流量约为不考虑应力敏感性时的63.28%,应力敏感性对气井产能的影响随着生产压差的增大而增大。

Permeability-stress sensitivity of complex volcanic reservoir has been studied using the variable pore pressure-constant confining pressure method. Meanwhile, permeability stress-sensitivity obtained from two different experimental methods also has been compared. The experimental results indicate that the volcanic reservoir permeability declines with the decrease of reservoir pore pressure. Decrease of reservoir permeability mainly occurs in the pore pressure from 40 MPa to 25 MPa. There is no good relationship between rock initial permeability and its loss rate, which is different from that of the sedimentary sandstone reservoir. Permeability-stress sensitivity of tight volcanic gas reservoir obtained from variable pore pressure-constant confining pressure is much stronger than that obtained from constant pore pressure-variable confining pressure. And this difference becomes larger during the actual gas reservoir effective stress range. The gas well productivity equation has been math

为了研究断裂力学问题中裂纹尖端区域的局部变形场和断裂特性,采用数字梯度敏感法对带有中心贯穿裂纹的有机玻璃有限宽板条进行了静态实验研究。实验过程中通过CCD记录裂纹尖端区域不同应力状态下的散斑图,对记录的散斑图进行相关运算,得到了不同应力状态下裂纹尖端周围区域内的光线偏转角,并通过偏转角对Ⅰ型裂纹的应力强度因子进行了提取。结果表明,通过数字梯度敏感方法计算得到的应力强度因子与理论值吻合相对较好。

In order to study the local deformation field of crack tip and fracture characteristics in fracture mechanics , static fracture tests of the limited-width polymethyl methacrylate specimen with center-crack were carried out with digital gradient sensing method .Speckle patterns under different states of stress near the crack tip were recorded by CCD in the experiment .Angular deflection was obtained by digital image correlation method and stress intensity factor in mode Ⅰcrack was extracted by angular deflection . It shows that the stress intensity factor calculated by digital gradient sensing measurement method is consistent with theoretical results .

煤层气开发过程中煤岩应力敏感性对渗透率产生影响,而渗透率的变化直接决定着煤层气资源商业开采的成败。试验测定了鄂尔多斯盆地老坑口矿井煤岩在平行面割理、垂直面割理及垂直层理面3个不同方向的渗透率随有效应力变化情况,对比分析了增压过程和降压过程中不同割理方向煤岩应力敏感性差异。结果表明：不同割理方向煤岩应力敏感强烈阶段有所不同,平行面割理方向应力敏感强烈阶段集中在有效应力小于8 MPa,垂直面割理及垂直层理面则分别在6和4 MPa附近；鉴于煤层气井排采中储层应力敏感效应的影响,提出动液面在接近煤层中深200 m后,谨慎降液排采,同时建议实施减小渗透率降低幅度和时间的排采；基于平行面割理方向煤岩渗透率更有优势,因此,井网长轴平行面割理方向是井网部署合理方向。

Coal stress-sensitivity has serious impacts on the value of permeability during coalbed methane development, meanwhile, the permeability change would directly determine the success or failure of commercial exploitation of coalbed methane resources. The experi-mental studies have done for permeability change with different effective stress in different directions of coal in the Laokengkou mine of southeastern margin of Ordos Basin,such as parallel face cleats,vertical face cleats and vertical bedding.The comparative analysis of coal permeability loss value accompanying direction changes during the pressurization and step-down process was done.The results showed that the phases of stress sensitivity were varied in different coal cleat orientation,where the strong stress sensitivity phase for parallel to the face cleats focuses on the effective stress was less than 8 MPa range,vertical cleats and vertical bedding planes concentrated in less than 6 MPa,4 MPa respectively.Consider

焊接接头疲劳应力分析方法多种多样,热点应力法能很好通过有限元技术进行求解,但其受到很多因素的影响。本文通过有限元法在验证了热点应力法对网格非常敏感和外推法对其影响不大的情况下,重点分析了焊趾上峰值路径和中心路径取外推点进行热点求解所得热点应力的偏差,结果表明不同取值路径下的热点应力相差不大,对热点应力的影响有限。

there were many methods on fatigue stress analysisof welded joint , hot spot stress method is fit for finite element technology , but it is effected by many factors .In this paper , grid sensitivity and extrapolation insensitivity were verified by FEA .And hot spot stress of peak path and center path were solved .The result show that the bias of hot spot stress is a little under different paths ,no affect for hot spot stress .