【作者】 曾泉树； 汪志明；

【Author】 Zeng Quanshu;Wang Zhiming;College of Petroleum Engineering,China University of Petroleum-Beijing;

【机构】 中国石油大学(北京)石油工程学院油气资源与探测国家重点实验室；

【摘要】 了解煤岩渗透率在空间中的分布及其随生产的动态变化有助于准确预测煤层气产量,并及时调整开发策略。基于自主研制的煤岩渗透率检测装置,开展了鄂东盆地典型煤样的渗透率测试,并分析了应力和温度对煤岩渗透率的影响,利用量纲分析法将渗透率的多种影响因素简化为三个无量纲关系,结合实验研究结果,建立了鄂东盆地主力产气煤层的原始渗透率表达式。模型预测结果与测井结果吻合良好,平均相对误差为28.53%。研究结果表明煤岩的裂隙变形和渗透率变化是由储层压实、基质收缩和热膨胀三种效应共同造成的,本质上取决于煤岩所受应力和温度载荷变化。煤岩渗透率随水平有效应力的降低近似呈指数增长。煤岩渗透率随温度的变化还取决于其所受应力载荷,存在反转现象,高应力下随温度的升高而降低,低应力下随温度的升高而增大。对于所研究的两个煤样,4~#煤层煤样在1.2～1.9MPa水平有效应力范围内发生反转,8~#煤层煤样在1.8～2.5MPa水平有效应力范围内发生反转。更多还原

【Abstract】 Understanding the permeability distribution in space and its change with production plays an important role in coalbed methane(CBM) recovery.On the basis of self-developed coal permeability experimental apparatus,permeability tests were conducted on two typical coals samples from Ordos Basin,and the influences of stress and temperature on permeability were further analyzed.Coal deformation and permeability evolution are considered as the result of reservoir compaction,matrix shrinkage,and thermal expansion.In essence,it depends on the stress and temperature loads acting on coal.The results show that coal permeability will increase exponentially with the decrease of effective horizontal stress.Coal permeability changes with the temperature may be the opposite of those experienced with different stresses.With significant stresses,the opposite effects on permeability are shown in thermal expansion and matrix shrinkage,contributing to the non-obvious permeability changes.As the stresses weaken,any two of the curves at different temperatures will meet where the permeability decrease due to thermal expansion is offset by matrix shrinkage.The curves for the 4~# specimen inverse in a range from 1.2 to 1.9 MPa,while those of the 8~# specimen have a range from 1.8 to 2.5 MPa.Once the reservoir compaction is too weak to suppress the thermal expansion,the cleat will swell more rapidly than the matrix instead,and together with the dominant matrix shrinkage,further improve the permeability.更多还原