煤层裂缝填充物特征及其对渗透率的影响

Characteristics of fillings in cracks of seam and influences to seam permeability

针对澳大利亚博文盆地中北部Rangal煤系地层渗透率普遍较低的特点,深入分析了区内不同煤层裂缝填充物及煤层宏观非均质性对渗透率的影响,剖析了煤层低渗成因。研究表明,煤层裂缝填充是影响煤层渗透率的主要因素,Rangal地层上部煤层裂缝以黏土矿物填充为主,下部以碳酸盐岩矿物填充为主,煤心试验分析及DST测试结果显示下部煤层渗透率远低于上部,两者相差2个数量级以上;另外,煤层矿物质含量及纵向非均质性是影响煤层渗透率的宏观因素,矿物含量越高则煤层水平渗透率越低,暗煤与亮煤的交互分布导致煤层垂向非均质性强进而严重影响纵向渗透率。研究认为,Rangal地层上部煤层渗透率相对较高,可作为重点挖潜层段。

According to the generally low permeability characteristics of the coal reservoir in the Rangal strata of Bowen Basin,Australia,the paper had an in-depth analysis on the fillings in cracks of different seam and the seam macro heterogeneity affected to the permeability and analyzed the low permeability cause of the seam. The study showed that the crack filling of the seam would be the major factor affected to the permeability of the seam. Above the Rangal strata,the filling would mainly be the clay fillings of the seam cracks and bellow the Rangal strata,the fillings would mainly be the carbonate fillings of the seam cracks. The coal core test analysis and the DST test results showed that the bellow seam permeability was far lower than the permeability of the above seam and there would be over two orders of magnitude between the two seam permeabilities. In addition,the mineral contents and the longitudinal heterogeneity of the seam would be the macro factors affected to the seam permeability. The higher mineral content was,the lower horizontal permeability of the seam would be.An interaction distribution of the durain and clarain caused the high vertical heterogeneity and would seriously influence the longitudinal permeability. The study held that above the Rangal strata,the seam permeability would be relatively high and could be the key potential mining seam.