近直立煤储层裂隙系统及优势渗流通道特征研究

为系统研究近直立煤储层裂隙系统发育特征,利用新疆库拜煤田中部近直立煤储层地表出露良好和生产矿井煤储层裂隙便于观测的有利条件,采用地表高精度构造裂隙填图和矿井煤储层裂隙观测技术,结合实验室扫描电镜和偏光显微镜观测方法,研究了近直立煤储层宏观和微观裂隙系统的发育特征。研究发现该区层面裂隙和外生裂隙延伸长、宽度大,是煤层气运移的优势渗流通道。同时分析了不同埋深条件下地应力场状态,阐明了研究区3种优势渗流通道分布特征为:(1)670 m以浅,优势渗流方向为NNW、NNE向;(2)670 m左右,优势渗流方向为近EW、NNW和NNE向;(3)670 m以深,优势渗流方向为近EW向。解释了层面裂隙、外生裂隙、内生裂隙和微裂隙的形成原因,揭示了渗流通道的形成模式,为研究区煤层气的勘探开发提供了地质依据。

Distribution Characteristics and Formation Mechanism of Dominant Percolation Channel in Near-vertical Coal Reservoir

Taking advantage of the favorable conditions of good surface exposure of near vertical coal reservoir in the central Kuba coalfield in Xinjiang and the favorable condition of producing coal reservoir fissures for easy observation, the surface high precision structural fissures mapping and the observation technique of coal reservoir fissures are adopted. Based on the observation methods of scanning electron microscope and polarizing microscope in laboratory,the development characteristics of macroscopic and microscopic fracture systems in near- vertical coal reservoirs are studied.It is found that the extension and width of layer fracture and exogenetic fissure in the study area are long and wide, which is the dominant seepage channel. At the same time,the state of in-situ stress field under different buried depths is analyzed. The distribution characteristics of three dominant seepage channels in the study area are:①lessthan 670 m,dominant direction is NNW,NNE;② around 670 m,dominant direction is EW, NNW and NNE;③ deeper than 670 m,dominant seepage direction is near EW direction.