利用邻层反演水平层理页岩地应力方法

Horizontal Bedding Shale in-Situ Stress Calculation Inverted from Adjacent Beds

张立刚 陶鑫 闫铁 金明 王涛

Zhang Ligang Tao Xin Yan Tie Jin Ming Wang Tao

东北石油大学石油工程学院, 黑龙江大庆 163318; 中国石油大庆石化建设公司, 黑龙江大庆 163318

School of Petroleum Engineering, Northeast Petroleum University, Daqing, Heilongjiang, 163318, China; CNPC Daqing Petrochemical Construction Company, Daqing, Heilongjiang, 163318, China

水平层理页岩垂直和平行层理方向岩石力学特性的强差异及岩石的破碎性,造成现有地应力计算方法精度不够及地应力室内岩心试验困难。为了有效地指导钻井和压裂设计,开展了页岩地应力评价方法研究。利用单轴压缩试验,获得了不同层理面方向的页岩弹性参数,岩石呈现明显的横观各向同性特征。基于横观各向同性材料的本构关系、并假设在沉积和后期地质构造运动过程中地层和地层之间不发生相对位移,建立了利用邻层砂泥岩地应力反演水平层理页岩地应力的模型,并分析了地应力的敏感性因素及其影响规律。结果表明,页岩地应力受控于邻层砂泥岩的弹性模量、泊松比、地应力值和页岩自身的弹性参数,利用该方法计算的最大和最小水平主应力值比Terzaghi和Newberry模式高,处于黄荣樽模式的上、下限范围内。研究结果为评价水平层理页岩地应力提供了新的方法。

Due to rock friability and the strong difference of rock mechanical characteristics between parallel and vertical bedding directions of the horizontal bedding shale, existing in-situ stress calculation methods could not meet the accuracy requirements and it is difficult to perform laboratory in-situ tests on the cores. Therefore, shale in-situ stress evaluation methods were studied in this paper so as to provide the effective guidance for well drilling and fracturing design. The shale elasticity parameters in different bedding directions were obtained by means of uniaxial compression tests, and the transversely isotropic characteristics were presented obviously. Based on the constitutive relation of transversely isotropic materials, the model for horizontal bedding shale in-situ stress inverted from its adjacent sand-shale in-situ stress was established, after it was assumed that there was no relative displacement between the formations in the process of the deposition and later tectonic movement. An analysis was conducted on sensitivity factors and influence laws. It is shown that the shale in-situ stress was controlled by its own elastic parameters and the elastic modulus, Poisson’s ratio and in-situ stress value of its adjacent sand-shale beds. The two horizontal in-situ stresses calculated with this method were higher than those obtained with the Terzaghi and Newberry models, and they were between the upper and lower limits of Huang Rongzun model.The research results in this paper provided a new method for evaluating the in-situ stress of horizontal bedding shale.

国家自然科学基金重大项目"页岩油气高效开发基础理论研究"(编号:51490650)、国家自然科学"致密储层井工厂压裂应力场演化机理及调控方法"(编号:51504067)和"基于应力-渗流-损伤多场耦合的清水压裂机理及储层筛选研究"(编号:51274069)、东北石油大学青年"致密砂岩储层体积压裂应力场改造控制机理研究"(编号:NEPUQN2014-26)联合资助。

https://doi.org/10.11911/syztjs.201505005