摘要
与一般煤岩相比,裂隙发育是煤岩储气层的主要物理特征,其结构较为软弱,在复杂地应力条件下易产生蠕变破坏,往往造成煤层气开采中钻井的破坏失稳。为探讨储气层煤岩钻井壁的蠕变失稳规律,采用美国RTR–1000型三轴岩石力学测试系统对储气层煤岩进行系统的单轴压缩试验。利用饱依丁–汤姆逊体与宾汉姆体,建立储气层煤岩蠕变模型,并通过拟合得到蠕变方程中的各个参数。根据储气层煤岩在不同载荷条件下的单轴压缩试验结果对蠕变模型进行验证。结果表明,所提出的储气层煤岩蠕变模型能很好地描述各蠕变阶段的变形特性,尤其是衰减阶段与稳定蠕变阶段,并能很好地反映蠕变的长期强度。同时,将煤岩蠕变特性与钻井方式相结合,提出煤层钻井液的优选思路,对保持煤岩钻井壁稳定、有效保护储集层以及高效安全建井等具有重要的实际意义。
Compared with normal coal,fracture development is the main physical characteristics of coal in coal bed gas reservoir,its structure is very complicated,and its easy to be damaged under geostress,always leads to the failure and instability of drilling during the exploitation process of coal bed gas. In order to explore the law of creep instability of borehole wall in coal bed gas reservoir,the writer adopted the American RTR-1000 triaxial rock mechanical test system to test the uniaxial creep law of coal in coal bed gas reservoir. Combined the Poyting-Thomson model with Bingham model,a creep model of coal is builted in coal bed gas reservoir and each parameter of creep equation through fitting is achieved. The creep model has been verified according to the uniaxial creep test results of coal in coal bed gas reservoir under different load conditions. The results show that the creep model of coal in coal bed gas reservoir can describe the deformation properties of each creep stage well, especially the decline stage and steady creep stage,and it can reflect the long-term strength of creep well. At the same time,combining the coal creep characteristics with the selection of drilling modes,an optimal selection idea of drilling liquid for coal bed gas reservoir has been put forward,which is significant and realistic meaning to maintain the stability of coal drilling,protect reservoir effectively and build drilling with high efficiency and safety.
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2013年第S2期3732-3739,共8页
Chinese Journal of Rock Mechanics and Engineering
基金
科技部国家重大专项项目(2008ZX05000–049)
西南石油大学"青年骨干教师培养计划"基金项目(SWPU2007JSZD07)
关键词
岩石力学
储气层
蠕变物性
本构模型
rock mechanics
coal bed gas reservoir
creep property
constitutive model
