WANG Y,SONG X x,HU Z z,et al. Measures and effect analysis of stimulation and rehabilitation of low-production coalbed methane wells in Tunlan Block, Xishan Coalfield [J]. Journal of Henan Polytechnic University(Natural Science),doi:10.16186/j.cnki.1673-9787.2024030021. 

Received：2024-03-07

Revised：2024-05-15

Online：2024-08-21

Measures and effect analysis of stimulation and rehabilitation of low-production coalbed methane wells in Tunlan Block, Xishan Coalfield (Online)

WANG Yu¹, SONG Xiaoxia^1,2, HU Zhazha³, LIU Yanfei¹, DU Liqiang⁴, QI Wei⁵, YAN Jiwei¹,GUO Hao⁴, CHEN Weidong¹

（1.School of Mining Engineering,Taiyuan University of Technology, Taiyuan 030024, Shanxi, China; 2.Shanxi Key Laboratory of Fine Exploration of Coalbased Critical Mineral Resources, Taiyuan 030001, Shanxi, China; 3.School of Energy Science and Engineering, Henan Polytechnic University, Jiaozuo 454000, Henan, China; 4.Shanxi Xishan Lanyan coal bed Methane Co. Ltd., Taiyuan 030200, Shanxi, China; 5.Linfen Branch of Petrochina Coalbed Methane Co., Ltd., Linfen 041000, Shanxi, China)

Abstract: Coalbed methane（CBM）development in the Tunlan Block of Xishan Coalfield has reached a certain scale, but the gas production of some CBM wells has not met expectations. Therefore, there is an urgent need to carry out targeted stimulation and rehabilitation measures to increase the production of CBM wells. Objectives The objective of this study is to investigate the characteristics of primary fracturing and evaluate the effect of stimulation and rehabilitation on low-production wells in Tunlan Block. Methods Based on the geological data, engineering data and production data from 102 vertical wells and 7 horizontal wells in Tunlan Block, this study analyzes the characteristics of primary fracturing in CBM wells by considering fracturing curve types, rupture pressure, and production capacity characteristics in the study area. Additionally, a production dynamic analysis method is used to evaluate the stimulation effect of implementing dense well network on low producing CBM wells. Results The study reveals that the fracturing curves of CBM wells in Tunlan Block can be classified into four types: stable, descending, ascending and fluctuating types. Stable and descending fracturing curves are more favorable for efficient CBM extraction. The high proportion of fluctuating and ascending curves in the study area reflects the greater difficulty in fracturing the coal seam and the strong heterogeneity. By implementing a dense CBM well network in the pilot test area, seven horizontal wells were densely deployed between vertical wells, and the average daily gas production of nine nearby low-producing vertical wells was significantly increased from 150-800 m³/d to 330-6000 m³/d, demonstrating the effectiveness of the technology. Conclusions The main reasons for the low gas production of CBM wells in the study area are low original permeability of coal reservoirs and insufficient initial fracturing and rehabilitation. The technology of implementing dense CBM well network is a well-established and effective measure to increase gas production of low-production wells. This study can provide guidance and reference forthe stimulation and rehabilitation of low-production CBM wells in the study area or similar areas.

Key words：coalbed methane; Tunlan Block; fracturing curve types; production capacity characteristics; stimulation and rehabilitation measures

CLC: TE377