有效应力对高煤级煤储层渗透率的控制作用

发布时间：2018-03-15 12:39

本文选题：有效应力　切入点：渗透率　出处：《煤田地质与勘探》2017年04期 　论文类型：期刊论文

【摘要】：为了探究有效应力对高煤级煤储层渗透率的控制作用及其应力敏感性的各向异性,对5块高煤级煤样进行了覆压孔渗实验,揭示了有效应力对煤储层渗透率的控制机理。以3.5 MPa模拟原始地层压力发现,煤岩在平行主裂隙和层理面方向具有最高的初始渗透率,垂直层理面方向初始渗透率最低;有效应力从3.5 MPa增加到15.5 MPa的过程中,渗透率呈现出良好的幂函数降低趋势;渗透率伤害/损失的各向异性表明平行主裂隙方向渗透率伤害率和损失率最大,且不同方向应力敏感性受裂隙的宽度及其展布方向的控制;裂隙压缩系数随应力的增加呈现降低趋势,但由于高煤级煤岩压缩难度大,裂隙压缩系数的各向异性不明显。有效应力对渗透率控制的实质为通过减小煤储层孔裂隙体积降低渗透率,从而对各个方向上的渗透率均造成较大的不可逆伤害。
[Abstract]:In order to investigate the effect of effective stress on permeability control and anisotropy of stress sensitivity of high coal rank coal reservoir, overpressure pore permeability experiments were carried out on 5 high coal grade coal samples. The control mechanism of effective stress on the permeability of coal reservoir is revealed. By simulating the original formation pressure with 3.5 MPa, it is found that coal and rock have the highest initial permeability in the direction of parallel main fracture and bedding plane, and the lowest initial permeability in the direction of vertical bedding plane. When the effective stress increased from 3.5 MPa to 15.5 MPa, the permeability showed a good power function decreasing trend, and the anisotropy of permeability damage / loss indicated that the permeability damage rate and loss rate were the largest in parallel to the main fracture. The stress sensitivity in different directions is controlled by the width and distribution direction of fractures, and the fracture compression coefficient decreases with the increase of stress, but it is difficult to compress coal and rock in high coal rank. The anisotropy of fracture compression coefficient is not obvious. The essence of effective stress on permeability control is to reduce permeability by reducing pore and fracture volume of coal reservoir, thus causing large irreversible damage to permeability in all directions.
【作者单位】：中国地质大学(北京)能源学院;煤层气开发利用国家工程中心煤储层实验室;中海油能源发展股份有限公司工程技术分公司;
【基金】：国家科技重大专项课题(2016ZX05044-001) 国家自然科学基金项目(41530314)~~
【分类号】：P618.13

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