An experimental investigation of geomechanical properties of deep tight gas reservoirs
An experimental investigation of geomechanical properties of deep tight gas reservoirs
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深层致密气藏地质力学特性实验研究
DOI：
10.1016/j.jngse.2017.09.004
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发表时间：
2017-11-01
影响因子：
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通讯作者：
Li, Dandan
中科院分区：
文献类型：
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作者：
Hou, Bing;Diao, Ce;Li, Dandan
超深井（-3700 m ~ 7,000 m）地层温度高（100-180 ℃），纵向岩性交错分布，对井壁稳定和水力裂缝扩展影响较大。目前，对不同岩性在高温下的变形特征和溶洞结构的系统认识还很少。本文通过一系列岩石力学试验，研究了不同岩性在不同温度下的岩石力学特性。结果表明，温度对不同岩性岩石强度和破坏模式的影响是不同的。在高温作用下，细砂岩和泥质细砂岩的强度略有增加，而中砂岩和泥岩的强度下降严重。在本试验条件下，泥岩的破坏模式为拉伸破坏，砂岩的破坏模式为剪切破坏。对于无裂纹的碳酸盐岩，当温度高于80 ℃时，强度随温度升高而降低;对于宏观裂纹发育的碳酸盐岩，如果岩石破坏带与裂纹走向平行，则断裂强度随温度升高而迅速下降。但如果岩石破坏区垂直于裂纹走向，温度的影响就会很小。高温低围压条件下，泥页岩的强度和弹性模量较低，泊松比较高。在破坏模式上，25 ℃时泥页岩为拉伸破坏，110 ℃时泥页岩为剪切破坏或拉剪复合破坏。根据实验结果，建立了考虑温度影响的泥质岩邓肯模型，可用于井壁稳定性和水力压裂研究。(C)2017由Elsevier B. V.出版
An ultra-deep well (-3700 m-7,000 m) has high formation temperature (100-180 degrees C) and interlaced distributed lithology in longitude which has significant influence on wellbore stability and hydraulic fracture propagation. At present, few findings are available for a systematic understanding of different lithologies' deformation properties and fracture-cave structures under high-temperature. In this paper, a series of rock mechanical tests are conducted to study the rock mechanical properties of different lithologies under different temperatures. The results show that the influences of temperature on strength and failure mode for different lithologies are not the same. Under high temperature, the strength of fine sandstone and argillaceous fine sandstone increases slightly while the strength of medium sandstone and mudstone decreases seriously. As to failure mode, mudstone suffers from tensile failure and sand stones suffer from shear failure under the experiment condition in this study. For carbonate without crack, strength decreases as temperature increases when the temperature is higher than 80 degrees C; for carbonate with macrocrack developed, if the rock failure zone is parallel to the crack trend, the fracture strength will rapidly decline as the temperature increases. However, if the rock failure zone is vertical to the crack trend, the influence of temperature will be small. For shale, the strength and elasticity modulus are lower and the Poisson's ratio is higher under the condition of high temperature and low confining pressure. As to failure mode, shale suffers from tensile failure at 25 degrees C, and suffers from shear failure or tensile-shear combined mode at 110 degrees C. Based on the experiment results, a modified Duncan model for mudstone considering temperature influence is established, which could be used in the study of wellbore stability and hydraulic fracturing. (C) 2017 Published by Elsevier B.V.