Zhang Zhou, Ren Junshan, Zhao Yang, Wang Meizhu, Yang Jiaosheng, Zhang Cong
School of Resources and Environment, Henan Polytechnic University, Jiaozuo 454000, China.
Collaborative Innovation Center of Coalbed Methane and Shale Gas for Central Plains Economic Region, Jiaozuo 454000, Henan Province China.
ACS Omega. 2023 Dec 7;8(50):47530-47539. doi: 10.1021/acsomega.3c05358. eCollection 2023 Dec 19.
Many low-production and low-efficiency wells in the Zhengzhuang, Fanzhuang, Lu'an, and Yangquan blocks of the Qinshui Basin seriously hinder the development of coalbed methane in China. Through in-depth research on the geological conditions and development technology of coalbed methane, it was found that the main reasons for the existence of a large number of low-production and low-efficiency wells are the fragmentation of coal structure, poor adaptability of vertical well types, sizable well spacing, and mismatched stimulation measures. On this basis, it is proposed to adopt an L-shaped horizontal well and staged Fracking technology in the block with a complete coal structure but low permeability. For stress-concentration areas, the first fracturing of a vertical well has a single crack and a small coverage area; After a period of drainage and production, the use of repeated fracturing technology can increase the complexity of fractures and increase gas production; For the fractured area of coal structure, the use of roof fracturing technology effectively solves the problem of coal fragmentation. In natural fracture development areas, new fractures are formed using fracture turning technology to achieve the effect of increasing production. The above technologies have achieved good results in the Qinshui Basin engineering experiment. Therefore, in-depth research on the geological conditions of coalbed methane and matching related development technologies are the main ways to solve low-efficiency and low-production wells in coalbed methane development blocks.
沁水盆地郑庄、樊庄、潞安及阳泉区块存在众多低产低效井，严重制约了我国煤层气的开发。通过对煤层气地质条件及开发技术的深入研究发现，大量低产低效井存在的主要原因是煤体结构破碎、直井井型适应性差、井距偏大以及压裂措施不匹配。在此基础上，提出在煤体结构完整但渗透率低的区块采用L型水平井及分段压裂技术。对于应力集中区，直井首次压裂裂缝单一、波及范围小；排水采气一段时间后，采用重复压裂技术可增加裂缝复杂性、提高产气量；对于煤体结构破碎区，采用顶板压裂技术有效解决了煤体破碎问题。在天然裂缝发育区，利用转向压裂技术形成新裂缝，实现增产效果。上述技术在沁水盆地工程试验中取得了良好效果。因此，深入研究煤层气地质条件并配套相关开发技术是解决煤层气开发区块低产低效井的主要途径。
