高阶煤渗透率温度应力敏感性试验研究

煤储层渗透率对温度和应力的敏感性响应,是深部煤储层物性评价的基础参数之一。以山西晋城无烟煤样为研究对象,利用高温覆压孔渗测定仪测定了煤样的孔隙率和渗透率,分析了其对温度和压力的敏感性。结果表明:高阶煤的孔隙率、渗透率与压力呈幂函数式负相关关系,在低压阶段随着压力升高迅速降低,在高压阶段趋于稳定。高阶煤渗透率对温度不敏感,当压力低于2MPa时随着温度的升高而降低,压力高于2 MPa则与温度之间关系不显著。压力是影响高阶煤孔隙率和渗透率的主要因素,而温度对孔隙率和渗透率影响较小。基于曲率分析方法对成庄高阶煤渗透率应力敏感性进行了分析,并与郑庄高阶煤和韩城高阶煤对比显示,成庄矿高阶煤的应力敏感性在低应力位置较强。因此,成庄矿进行煤层气开发时,需制定合理的排采制度,避免渗透率应力敏感性导致的负产能效应。

Temperature-stress sensitivity of high-rank coal permeability

Sensitivity of the coal reservoir permeability to temperature and stress is one of the basic parameters for evaluating the physical properties of deep coal reservoir.Using the heating and overburden pressure permeability-porosity tester，the permeability and porosity of the anthracite samples from the Chengzhuang，Jincheng，Shanxi，were measured.Combining with the pore structure and other data，the sensitivity of high rank coal to temperature and pressure was discussed.It is show that the porosity and permeability of high-rank coal is negatively correlated to the pressure in a power function，reduce rapidly as the pressure rises when pressure is lower，and tend to be stable in higher pressure phase.High-rank coal permeability is not sensitive to temperature，decreases with the increase of temperature when the pressure is less than 2 MPa，and has not significant correlation with temperature once the pressure is higher than 2 MPa.Therefore，the pressure is a major effect factor to the porosity and permeability of high-rank coal，and the temperature has less influence on the porosity and permeability.Based on curvature analysis method，stress sentivity of permeability of high rank coal of Chengzhuang Mine pressure sensitivity was analyzed.Compared with Zhengzhuang and Hancheng high rank coal，Chengzhuang coal has stronger stress sensitivity in low pressure stage.Therefore，resonable pumping systen of coalbed methane development in Chengzhuang Mine should be made to avoid negative effect due to stress sensitivity of permeability.