Influencing factors of the dynamic permeability of CBM reservoir and CBM well drainage control measures

Authors

WANG Qing, College of Geosciences, Yangtze University, Wuhan 430100, China
YANG Fei, College of Geosciences, Yangtze University, Wuhan 430100, China
GONG Weicheng, College of Geosciences, Yangtze University, Wuhan 430100, China
XU Tianxin, College of Geosciences, Yangtze University, Wuhan 430100, China
LI Yichao, College of Geosciences, Yangtze University, Wuhan 430100, China

Abstract

The drainage and production control method has significant impact on the permeability of coalbed methane reservoir. Based on the main control factors of the permeability at different stages of drainage and production of coalbed methane wells, this paper puts forward targeted drainage and production countermeasures with the goal of improving the permeability. When the bottom-hole flow pressure was greater than the original reservoir pressure, the step-down velocity was between 0.08 and 0.1 MPa/d to reduce fracturing fluid and velocity-sensitive damage. When the bottom hole flow pressure was between reservoir pressure and desorption pressure, the pressure could be reduced at a rate less than 0.03 MPa/d to avoid aggravating the “permeability funnel” of the reservoir. When the desorption pressure was 0.2-0.3 MPa, the pressure decreased at the rate of 0.01 MPa/d. When the pressure was stabilized for 30 days near the desorption pressure, the casing pressure was controlled at about 0.2- 0.3 MPa after desorption, so as to avoid the decrease of water-phase permeability caused by two-phase flow. The permeability of reservoir was improved by increasing matrix shrinkage with variable speed. In the stable production period, the reasonable stable production could be determined by increasing production per unit pressure drop to achieve long-term high and stable production of CBM wells. The field test shows that the method is effective.

Keywords

CBM well, dynamic permeability, drainage and mining method, depressurization rate, stage of drainage

DOI

10.3969/j.issn.1001-1986.2020.02.018

Recommended Citation

WANG Qing, YANG Fei, GONG Weicheng, et al. (2020) "Influencing factors of the dynamic permeability of CBM reservoir and CBM well drainage control measures," Coal Geology & Exploration: Vol. 48: Iss. 2, Article 19.
DOI: 10.3969/j.issn.1001-1986.2020.02.018
Available at: https://cge.researchcommons.org/journal/vol48/iss2/19

Reference

[1] 胡秋嘉,贾慧敏,祁空军,等. 高煤阶煤层气井单相流段流压精细控制方法:以沁水盆地樊庄-郑庄区块为例[J]. 天然气工业,2018,38(9):76-81. HU Qiujia,JIA Huimin,QI Kongjun,et al. A fine control method of flowing pressure in single-phase flow section of high-rank CBM gas development wells:A case study from the Fanzhuang-Zhengzhuang block in the Qinshui basin[J]. Natural Gas Industry,2018,38(9):76-81.

[2] 宋岩,柳少波,琚宜文,等. 含气量和渗透率耦合作用对高丰度煤层气富集区的控制[J]. 石油学报,2013,34(3):417-426. SONG Yan,LIU Shaobo,JU Yiwen,et al. Coupling between gas content and permeability controlling enrichment zones of high abundance coalbed methane[J]. Acta Petrolei Sinica,2013,34(3):417-426.

[3] 付玉通,马建强,李永臣,等. 延川南区块深层煤层气井产能主控因素[J]. 煤田地质与勘探,2017,45(5):48-53. FU Yutong,MA Jianqiang,LI Yongchen,et al. Research on key factors of CBM well productivity in deep strata in block of south Yanchuan[J]. Coal Geology & Exploration,2017,45(5):48-53.

[4] 魏迎春,李超,曹代勇,等. 煤层气开发中煤粉产出机理及管控措施[J]. 煤田地质与勘探,2018,46(2):68-73. WEI Yingchun,LI Chao,CAO Daiyong,et al. The output mechanism and control measures of the pulverized coal in coalbed methane development[J]. Coal Geology & Exploration,2018,46(2):68-73.

[5] 乔康. 低煤阶煤储层敏感性分析及对煤层气排采的影响[J]. 煤矿安全,2018,49(5):14-16. QIAO Kang. Sensitivity analysis of low rank coal reservoir and its influence on coalbed methane drainage[J]. Safety in Coal Mines,2018,49(5):14-16.

[6] 王钧剑. 煤岩应力敏感性实验及单相排水阶段非稳态渗流模型研究[D]. 北京:中国地质大学(北京),2013. WANG Junjian. Stress sensitivity experiments of coal samples and unsteady percolation model of water[D]. Beijing:China University of Geosciences(Beijing),2013.

[7] 郭春华,周文,孙晗森,等. 考虑应力敏感性的煤层气井排采特征[J]. 煤田地质与勘探,2011,39(5):27-30. GUO Chunhua,ZHOU Wen,SUN Hansen,et al. The relationship between stress sensitivity and production of coalbed methane wells[J] Coal Geology & Exploration,2011,39(5):27-30.

[8] 张双斌. 基于"三场"耦合的煤层气井排采控制理论与应用[D]. 焦作:河南理工大学,2014. ZHANG Shuangbin. Drainage controlling theory and application in coalbed methane well based on "Three Fields" coupling[D]. Jiaozuo:Henan Polytechnic University,2014.

[9] 许科,崔彬. 等温吸附曲线在煤层气排采中的应用:以织金区块为例[J]. 油气藏评价与开发,2015,5(6):73-75. XU Ke,CUI bin. Application of isothermal adsorption curves in coalbed methane production:A case study in Zhijin block[J]. Reservoir Evaluation and Development,2015,5(6):73-75.

[10] 杨秀春. 煤层气排采过程中产能与物性变化动态耦合研究[D]. 北京:中国矿业大学(北京),2011. YANG Xiuchun. The research of capacity and gas-bearing permeability change dynamic with coupling in the process of coal-bed methane's discharging and mining[D]. Beijing:China University of Mining & Technology(Beijing),2011.

[11] 陈刚,秦勇,杨青,等. 不同煤阶煤储层应力敏感性差异及其对煤层气产出的影响[J]. 煤炭学报,2014,39(3):504-509. CHEN Gang,QIN Yong,YANG Qing,et al. Different stress sensitivity of different coal rank reservoir permeability and its effect on the coalbed methane output[J]. Journal of China Coal Society,2014,39(3):504-509.

[12] 孟召平,张纪星,刘贺,等. 考虑应力敏感性的煤层气井产能模型及应用分析[J]. 煤炭学报,2014,39(4):593-599. MENG Zhaoping,ZHANG Jixing,LIU He,et al. Productivity model of CBM wells considering the stress sensitivity and its application analysis[J]. Journal of China Coal Society,2014,39(4):593-599.

[13] 刘世奇,桑树勋,李梦溪,等. 沁水盆地南部煤层气井网排采压降漏斗的控制因素[J]. 中国矿业大学学报,2012,41(6):943-950. LIU Shiqi,SANG Shuxun,LI Mengxi,et al. Control factors of coalbed methane well depressurization cone under drainage well network in southern Qinshui basin[J]. Journal of China University of Mining & Technology,2012,41(6):943-950.

[14] 赵金,张遂安. 煤层气排采储层压降传播规律研究[J]. 煤炭科学技术,2012,40(10):65-68. ZHAO Jin,ZHANG Sui'an. Study on pressure drop transmission law of coal bed Methane drainage reservoir stratum[J]. Coal Science and Technology,2012,40(10):65-68.

[15] 倪小明,张崇崇,王延斌,等. 气水两相流阶段煤基质收缩量预测方法[J]. 煤炭学报,2014,39(增刊1):174-178. NI Xiaoming,ZHANG Chongchong,WANG Yanbin,et al. Prediction of coal matrix shrinkage in gas-water two-phase flow stage[J]. Journal of China Coal Society,2014,39(S1):174-178.