Eefficient fracturing technology and fine drainage system of ultra-deep coalbed methane in southeast Chongqing：A case study of NY1 well

Authors

FANG Dazhi, SINOPEC Chongqing Shale Gas Co., Ltd., Chongqing 408400, ChinaFollow
CHENG Zehu, SINOPEC Chongqing Shale Gas Co., Ltd., Chongqing 408400, China
LI Jiaxin, SINOPEC Chongqing Shale Gas Co., Ltd., Chongqing 408400, China

Abstract

According to the results of China’s new round of coalbed methane (CBM) resource evaluation, the CBM development mainly focuses on medium and shallow coal seams, and the geological conditions of deep-ultra deep coal reservoirs are more complicated. Thus, the reservoir fracturing technology and drainage management technology are two major factors in the development of CBM wells for deep coal reservoirs. In the area of southeast Chongqing, the coal seam of Longtan Formation is as deep as nearly 2 000 m, and there is no experience in ultra-deep CBM well development in this area. The NYI well is taken as an example, and its fracturing operation is completed according to the technical idea of large displacement, low sand ratio, pulsed and composite sand addition of different particle sizes by optimizing the fracturing process based on fracturing fluid system of drag reducing water. In the drainage, the method of segmented control, gradual speed reduction, timely adjustment, and low-pressure production is adopted to increase the flowback rate of CBM wells before gas breakthrough, extend the air supply radius as much as possible, and avoid the formation of velocity sensitive effect caused by large fluctuation of the liquid level and affecting the seepage channels of coal reservoirs. The results show that during the fracturing process of the NY1 well, the construction pressure is stable without sand plug occurring, and the daily gas production maintains at 2 800-3 000 m³ in the drainage. In the practice, the NY1 well has achieved high and stable production. The successful application of the fracturing technology and drainage system provide certain guidance for the theoretical research and development of ultra-deep CBM wells.

Keywords

coalbed methane, ultra-deep coal seam, fracturing technique, drainage system, southeast Chongqing

DOI

10.12363/issn.1001-1986.21.08.0437

Recommended Citation

FANG Dazhi, CHENG Zehu, LI Jiaxin, et al. (2022) "Eefficient fracturing technology and fine drainage system of ultra-deep coalbed methane in southeast Chongqing：A case study of NY1 well," Coal Geology & Exploration: Vol. 50: Iss. 5, Article 7.
DOI: 10.12363/issn.1001-1986.21.08.0437
Available at: https://cge.researchcommons.org/journal/vol50/iss5/7

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