甲烷气渗流作用对煤岩强度的影响

发布时间：2018-05-05 17:40

本文选题：煤层气 + 渗流　；参考：《石油钻采工艺》2017年02期

【摘要】：煤层气井在排采生产阶段,由于甲烷的不断脱附、渗流,煤层孔隙压力和有效应力逐渐发生变化,煤岩力学强度减弱,进而对储层孔隙度、渗透率,甚至井壁稳定性均有一定影响。对煤层气在煤层间的渗流过程与煤岩的力学性质间的耦合关系进行了室内实验,为煤层气井完井、开发等方案制定提供了理论支持。声波发射实验和单轴/三轴抗压实验结果表明,随着CH4流经煤岩岩心时间的延长,煤岩弹性模量逐渐降低,表明煤岩力学强度下降。单轴/三轴抗压实验表明,煤岩的弹性模量和最大抗压强度随围压的下降而减小,且在高围压条件下下降较慢,低围压条件下下降较快。该结果表明,在煤层气生产一定时间后,井下煤层可能产生坍塌、掉块而影响生产作业。
[Abstract]:In the stage of coal bed methane production, due to the continuous desorption of methane, percolation, the pore pressure and effective stress of coal seam gradually change, the mechanical strength of coal and rock weakens, and the porosity and permeability of the reservoir are further reduced. Even the stability of the shaft wall has a certain effect. The coupling relationship between the percolation process of coalbed gas in coal seam and the mechanical properties of coal rock is tested in laboratory, which provides theoretical support for the formulation of well completion and development scheme of coalbed methane well. The results of acoustic emission experiment and uniaxial / triaxial compression test show that the elastic modulus of coal and rock decreases with the time of CH4 flowing through the core of coal and rock, indicating that the mechanical strength of coal and rock decreases. Uniaxial / triaxial compression tests show that the modulus of elasticity and maximum compressive strength of coal and rock decrease with the decrease of confining pressure, and decrease slowly under high confining pressure and faster under low confining pressure. The results show that after the coal bed methane is produced for a certain time, the underground coal seam may collapse, and the production operation will be affected by the dropping of the coal seam.
【作者单位】：中联煤层气有限责任公司;
【基金】：国家“十三五”油气重大专项(2016ZX05044003)“易漏易塌地层钻完井及储层保护技术研究”课题
【分类号】：TD712

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