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Coal Geology & Exploration

Abstract

The fracturing construction curve is considered to be an important basis for reflecting the fracturing effect, while the dynamic change of reservoir permeability in the fracturing stage can more intuitively reflect the effect of fracture formation. In this paper, a quantitative evaluation method for reservoir dynamic permeability in fracturing stage was established based on the principle of well testing. Then, the method was applied to evaluate the fracturing effect of two coalbed methane (CBM) wells in a block in southern Junggar Basin, and the dynamic permeability curve of reservoir during fracturing stage is obtained. Meanwhile, the G-function method was used to further evaluate the fracturing effect. The results show that the fracturing effect reflected by the dynamic permeability curve is consistent with the G-function analysis and the evaluation results based on the relationship between displacement and bottom hole pressure, which can reflect the opening and extension effects of fractures in the reservoir. Large-scale fracture network transformation of coal reservoirs and surrounding rocks was implemented in Well CMG-01, and the reservoir permeability in the fracturing stage was up to 2.5 μm2, showing a good fracturing effect. While the reservoir permeability of CBM-02 Well was kept below 1.8 μm2 after conventional hydraulic fracturing was performed in the coal reservoir. There are significant differences between conventional hydraulic fracturing of coal reservoirs and large-scale fracture network reconstruction of coal reservoirs and surrounding rocks. The formation of the quantitative evaluation method for reservoir dynamic permeability in fracturing stage can make up for the lack of quantitative evaluation of the fracturing effect, which provides a basis for optimizing hydraulic fracturing technologies of CBM or coal measure gas wells.

Keywords

coalbed methane, hydraulic fracturing, dynamic permeability, fracturing effect evaluation

DOI

10.12363/issn.1001-1986.21.09.0536

Reference

[1] 路艳军,杨兆中,SHELEPOV V V,等. 煤层气储层压裂现状及展望[J]. 煤炭科学技术,2017,45(6):73−84. LU Yanjun,YANG Zhaozhong,SHELEPOV V V,et al. Status and prospects of coalbed methane reservoir fracturing[J]. Coal Science and Technology,2017,45(6):73−84.

[2] 王绪性,仲冠宇,郭布民,等. 沁水盆地南部3号煤压裂曲线特征及施工建议[J]. 煤田地质与勘探,2016,44(3):36−39. WANG Xuxing,ZHONG Guanyu,GUO Bumin,et al. Characteristics of fracturing curve of seam No. 3 in south of Qinshui Basin and suggestion about operation[J]. Coal Geology & Exploration,2016,44(3):36−39.

[3] 张聪,李梦溪,王立龙,等. 沁水盆地南部樊庄区块煤层气井增产措施与实践[J]. 天然气工业,2011,31(11):26−29. ZHANG Cong,LI Mengxi,WANG Lilong,et al. EOR measures for CBM gas wells and their practices in the Fanzhuang block,southern Qinshui Basin[J]. Natural Gas Industry,2011,31(11):26−29.

[4] 徐刚,彭苏萍,邓绪彪. 煤层气井水力压裂压力曲线分析模型及应用[J]. 中国矿业大学学报,2011,40(2):173−178. XU Gang,PENG Suping,DENG Xubiao. Hydraulic fracturing pressure curve analysis and its application to coalbed methane wells[J]. Journal of China University of Mining & Technology,2011,40(2):173−178.

[5] 雷毅. 松软煤层井下水力压裂致裂机理及应用研究[D]. 北京:煤炭科学研究总院,2014.

LEI Yi. Study on mechanism and application of hydraulic fracturing in soft seam underground mine[D]. Beijing:China Coal Research Institute,2014.

[6] 吴奇,胥云,王腾飞,等. 增产改造理念的重大变革:体积改造技术概论[J]. 天然气工业,2011,31(4):7−12. WU Qi,XU Yun,WANG Tengfei,et al. The revolution of reservoir stimulation:An introduction of volume fracturing[J]. Natural Gas Industry,2011,31(4):7−12.

[7] 苏现波,马耕,宋金星,等. 煤系气储层缝网改造技术及应用[M]. 北京:科学出版社,2017.

[8] 吴奇,胥云,张守良,等. 非常规油气藏体积改造技术核心理论与优化设计关键[J]. 石油学报,2014,35(4):706−714. WU Qi,XU Yun,ZHANG Shouliang,et al. The core theories and key optimization designs of volume stimulation technology for unconventional reservoirs[J]. Acta Petrolei Sinica,2014,35(4):706−714.

[9] 陈作,薛承瑾,蒋廷学,等. 页岩气井体积压裂技术在我国的应用建议[J]. 天然气工业,2010,30(10):30−32. CHEN Zuo,XUE Chengjin,JIANG Tingxue,et al. Proposals for the application of fracturing by stimulated reservoir volume (SRV) in shale gas wells in China[J]. Natural Gas Industry,2010,30(10):30−32.

[10] 薛海飞,朱光辉,王伟,等. 沁水盆地柿庄区块煤层气井压裂增产效果关键影响因素分析与实践[J]. 煤田地质与勘探,2019,47(4):76−81. XUE Haifei,ZHU Guanghui,WANG Wei,et al. Analysis and application of key influencing factors of CBM well fracturing effects in Shizhuang area,Qinshui Basin[J]. Coal Geology & Exploration,2019,47(4):76−81.

[11] SU Xianbo,WANG Qian,LIN Haixiao,et al. A combined stimulation technology for coalbed methane wells:Part 1. Theory and technology[J]. Fuel,2018,233:592−603.

[12] SU Xianbo,WANG Qian,LIN Haixiao,et al. A combined stimulation technology for coalbed methane wells:Part 2. application[J]. Fuel,2018,233:539−551.

[13] 王乾. 淮北某区块煤层气井二次改造关键技术[D]. 焦作:河南理工大学,2017.

WANG Qian. The key technologies of secondary stimulation for coalbed methane well in a block of Huaibei[D]. Jiaozuo:Henan Polytechnic University,2017.

[14] SUN Bin,JU Yiwen,LU Shuangfang,et al. Reconstruction evaluation method and application of coal measure three gases co–mining reservoirs in Linxing block,East Ordos Basin[J]. Advances in Geosciences,2020,10(2):85−99.

[15] CHONG K K,GRIESER B. A completions roadmap to shale–play development:A review of successful approaches toward shale–play stimulation in the last two decades[R]. Society of Petroleum Engineers,Beijing,SPE–130369,2010.

[16] 沈永星,冯增朝,周动,等. 天然裂缝对页岩储层水力裂缝扩展影响数值模拟研究[J]. 煤炭科学技术,2021,49(8):195−202. SHEN Yongxing,FENG Zengchao,ZHOU Dong,et al. Study on numerical simulation of effect on natural fractures to hydraulic fracture propagation in shale reservoirs[J]. Coal Science and Technology,2021,49(8):195−202.

[17] 张晓娜,康永尚,姜杉钰,等. 沁水盆地柿庄区块3号煤层压裂曲线类型及其成因机制[J]. 煤炭学报,2017,42(增刊2):441−451. ZHANG Xiaona,KANG Yongshang,JIANG Shanyu,et al. Fracturing curve types and their formation mechanism of coal seam 3 in Shizhuang block,Qinshui Basin[J]. Journal of China Coal Society,2017,42(Sup.2):441−451.

[18] 张永成,郝海金,李兵,等. 煤层气水平井微地震成像裂缝监测应用研究[J]. 煤田地质与勘探,2018,46(4):67−71. ZHANG Yongcheng,HAO Haijin,LI Bing,et al. Application of microseismic monitoring and imaging of fractures in horizontal CBM well[J]. Coal Geology & Exploration,2018,46(4):67−71.

[19] 毛国扬,胡永全,赵金洲,等. 裂缝性油藏压后压降分析[J]. 断块油气田,2009,16(1):69−71. MAO Guoyang,HU Yongquan,ZHAO Jinzhou,et al. Pressure decline curve analysis of naturally fractured reservoir after being fractured[J]. Fault Block Oil & Gas Field,2009,16(1):69−71.

[20] BARREE R D,MISKIMINS J L,GILBERT J V. Diagnostic fracture injection tests:Common mistakes,misfires,and misdiagnoses[J]. SPE 169539,2014.

[21] 李传亮. 油藏工程原理(第二版)[M]. 北京:石油工业出版社,2011.

[22] 王聚团,刘银山,黄志明,等. G函数压降分析方法优化及应用[J]. 非常规油气,2020,7(4):81−84. WANG Jutuan,LIU Yinshan,HUANG Zhiming,et al. Pressure drop analysis methods for small–scale fracturing[J]. Unconventional Oil & Gas,2020,7(4):81−84.

[23] 王兴文. 裂缝性油藏压裂压力递减分析研究与应用[D]. 成都:西南石油学院,2004.

WANG Xingwen. Research and application of fracturing pressure decline analysis in fractured reservoirs[D]. Chengdu:Southwest Petroleum Institute,2004.

[24] NOLTE K G. Determination of fracture parameters from fracturing pressure decline[R]. SPE 8341,1979.

[25] NOLTE K G,MANIERE J L,OWENS K A. After–closure analysis of fracture calibration tests[R]. SPE 38676,1997.

[26] 赵文,张遂安,孙志宇,等. 基于G函数曲线分析的压后裂缝复杂性评估研究[J]. 科学技术与工程,2016,16(33):1671−1815. ZHAO Wen,ZHANG Suian,SUN Zhiyu,et al. Evaluative research for the fracture complexity after fracturing based on the G–function curves analysis[J]. Science Technology and Engineering,2016,16(33):1671−1815.

[27] 毛国扬,杨怀成,张文正. 裂缝性储层压降分析方法及其应用[J]. 石油天然气学报,2011,33(7):116−118. MAO Guoyang,YANG Huaicheng,ZHANG Wenzheng. Pressure drow down analysis method and its application in fractured reservoir[J]. Journal of Oil and Gas Technology,2011,33(7):116−118.

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