鸡西盆地梨树镇坳陷城子河组煤岩物理力学特性实验研究

An Experimental Study on Chengzihe Formation Coal and Rock Physical and Mechanical Characteristics in Lishuzhen Depression, Jixi Basin

鸡西盆地煤炭资源丰富，其南部的梨树镇坳陷城子河组厚度大，含煤性好，是煤层气勘探开发的重点区域。为了解该区煤岩物理力学特性，选取城子河组23#煤层岩样进行实验研究。通过测定岩样的泊松比、弹性模量、内聚力以及内摩擦角等力学参数，确定该层煤岩具有低弹性模量、高泊松比和大脆性的特性。分析煤岩物性参数得出：随着应力增加，煤岩渗透率呈指数下降，不利于煤层气的开采，而温度对煤岩渗透率影响较小；煤岩的孔隙度主要集中在3.6%～6.1%，平均约4.98%，程度偏低，中孔和小孔比较发育；低阶煤和中阶煤煤样的排驱压力相差较大，中阶煤煤样压力值较小，渗透性好；结合中值半径和退汞效率的实验数据，显示该区煤储层的渗透性整体较差。

The Jixi Basin has abundant coal resources;the Chengzihe Formation in the Lishuzhen depression in southern part of the ba-sin has large thickness, good coal-bearing property, thus a key area to exploit CBM. To find out coal and rock physical and mechanical characteristics, taking the samples from the coal No.23 carried out experimental study. Through rock sample mechanical parameters set-ting out Poisson’s ratio, elastic modulus, cohesion and internal friction angle, determined coal and rock in the seam have characteris-tics of low elastic modulus, high Poisson’s ratio and high brittleness. The coal and rock sample physical parameters setting out find out that along with stress increasing, permeability presents exponential lowering, thus unfavorable for CBM exploitation, while temperature impact less on permeability. Porosity of coal and rock is mainly concentrated between 3.6%~6.1%, average about 4.98%, on the low side, medium and small pores relatively developed. Displacement pressures of low and medium rank coal samples have large differ-ence;medium rank coal samples have smaller pressure values with good permeability. Combined with experimental data of median radi-us and efficiency of mercury withdrawal, have indicated rather poor permeability of coal reservoir in the area as a whole.