State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University
National & Local Joint Engineering Laboratory of Gas Drainage in Complex Coal Seam, Chongqing University
School of Resources and Safety Engineering, Chongqing University

为了进一步认识制约煤系气合采的因素，提高煤系合层排采各产层的产气贡献，分别从动力、通道和气源条件出发，分析了煤系气合采的必备因素。基于改变地应力状态提高储层导流能力以及分层改变储层流体压力，满足多层合采动力条件的原理，提出了地面井分层卸压的煤系气合采方式。该方式通过在地面进行定向钻井，在目标储层中进行高压水射流作业，人工创造卸压空间(缝、槽、穴等)，改变地应力状态，降低有效应力伤害，增加储层导流通道的数量和开度，提高目标储层压降传递速率。待储层压力降至符合煤系气合采动力条件时进行合层排采，从而提高煤系合采各产气层的产气贡献。相较于常规增产改造措施，此方式能够减少煤系气储层在有效应力作用下的储层伤害，且有助于提高储层压降传递效率，增强煤系气的解吸和扩散，降低多层煤系气合采过程中的层间干扰。在以上研究基础上，认为地面井分层卸压的合采方式主要适用于储层地应力大、产层间距小的煤系气储层，且有望在薄互层煤系气储层增产改造及层间干扰严重的叠合共生煤系储层开发领域进行应用推广。

This study aims to gain an in-depth understanding of factors restricting the commingled production of coal-measure gas and boost the contributions of various pay zones to gas production. To this end, it analyzed the essential factors of the dynamic, channel, and gas source conditions in the commingled production. The dynamic conditions for the commingled exploitation of multiple reservoirs can be met by (1) enhancing the flow conductivity of reservoirs by altering the crustal stress state and (2) changing reservoir fluid pressure by layers. Following this principle, this study proposed a method for the commingled production of coal-measure gas through layered pressure relief in surface wells. This method involves directional drilling on the surface and then high-pressure water jet in target reservoirs to artificially create pressure-relief spaces (e.g., fractures, slots, and cavities) and alter the crustal stress state. This can reduce the damage caused by effective stress, increase the number and aperture of diversion channels in reservoirs, and accelerate pressure drop transfer in target reservoirs. Afterward, commingled production can be conducted after the reservoir pressure decreases to the dynamic conditions for the commingled production of coal-measure gas, thus enhancing the contributions of pay zones to gas production. Compared to conventional reservoir stimulation, this method can reduce the damage of effective stress to coal-measure gas reservoirs, improve the transfer efficiency of pressure drop, enhance the desorption and diffusion of coal-measure gas, and decrease the interlayer interference during the commingled production of multiple coal-measure gas reservoirs. Based on these findings, this study proposed that the commingled production of coal-measure gas through layered pressure relief in surface wells is primarily applicable to coal-measure gas reservoirs with high crustal stress and small spacings between pay zones. Furthermore, this method is expected to be widely applied to the stimulation of coal-measure gas reservoirs with thin interbeds for production growth and to the exploitation of superimposed paragenetic coal-measure reservoirs with severe interlayer interference.

国家自然科学基金青年项目(52204125)；国家自然科学基金联合基金重点项目(U19B2009)

李瑞，金丽红，夏彬伟，等. 地面井分层卸压的煤系气合采原理及方式探讨[J]. 煤田地质与勘探，2024，52(2)：171−179.

LI Rui，JIN Lihong，XIA Binwei，et al. Exploring the principle and method for commingled production of coal-measure gas through layered pressure relief in surface wells[J]. Coal Geology & Exploration，2024，52(2)：171−179.