沁水盆地赵庄井田煤层气产出特征及其影响因素
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摘要
沁水盆地赵庄井田3~#煤的煤层气虽然资源丰度高,但由于储集物性差等因素,导致煤层气解吸、扩散、运移产出速度缓慢,不但煤层气井单井产量低,而且产量衰减快,稳产期短,煤层气开发难度大。因此,针对煤层气产出不理想的情况,采用室内实验模拟结果和现场测试分析数据相结合方法对影响煤层气产出的原因进行了分析,指出了煤层气产出困难的3个主要影响因素:(1)3~#煤层裂缝极为发育,裂隙连通性差、充填堵塞严重;3~#煤大孔占比少,细孔、微孔占比大,煤层的渗流条件差,煤层的可动流体饱和度低,排水降压可产出的孔隙流体少,气体可解吸、扩散、渗流产出量少,致使煤层气的产出程度低;(2)3~#煤的临储比和含气饱和度低,煤层气井排水降压的可降幅程度小,压降漏斗的扩展面积小,致使产气效果较差;(3)煤层的塑性强、应力差异系数小,煤层与围岩的应力差小,煤层压裂裂缝延伸难度大,裂缝容易突破顶底板纵向延伸,压裂容易形成多裂缝,限制了裂缝长度的扩展延伸,致使压裂增产效果差。并提出优选煤层气开发有利区域、强化煤层压裂改造措施和分段压裂水平井抽采技术是实现赵庄井田3~#煤层下一步煤层气高效开发的3个有利措施。
The 3~#coal in Zhaozhuang well field in Qinshui Basin has high abundance of CBM resources.The output speed of coalbed methane desorption,diffusion and migration is slow,the exploitation of coalbed methane in this coal seam faces issues such as unstable and low production and fast decline of gas production etc.,and the exploitation of coalbed methane in this coal seam is more difficult.Therefore,according to the characteristics of the coalbed methane production,the factors influencing coalbed methane production were studied by combining experiment and field test analysis.Three affecting factors of coalbed methane production difficulties are discussed:(1)3~#coal is characterized by very good development of fractures,poor fracture connectivity and filling jams.The macropore proportion of 3~#coal is small and the micropore proportion is large.The seepage condition of coal seam is poor,and it has low movable fluid saturation.The drainage decompression can produce less pore fluid,and the coalbed methane output level is low.(2)The ratio between the critical desorption pressure and reservoir pressure and the gas saturation of coal seam islow,the drainage pressure drop of coalbed gas wells is small,and the expansion area of pressure drop funnel is small,resulting in poor gas production effect.(3)Coal seam has the features of strong plasticity,low stress difference between coal seam and surrounding rock,greater extension difficulty of the fracturing fracture,easy breaking through the roof and floor for longitudinal extension,easy formation of more cracks under fracturing,limited expansion of the crack length,and poor fracturing production.It is also suggested that optimizing favorable areas for CBM development,strengthening measures for coal seam fracturing and extraction technology for sublevel fracturing horizontal wells are three favorable measures for realizing efficient CBM development in 3~# coal seam in Zhaozhuang field.
The 3~#coal in Zhaozhuang well field in Qinshui Basin has high abundance of CBM resources.The output speed of coalbed methane desorption,diffusion and migration is slow,the exploitation of coalbed methane in this coal seam faces issues such as unstable and low production and fast decline of gas production etc.,and the exploitation of coalbed methane in this coal seam is more difficult.Therefore,according to the characteristics of the coalbed methane production,the factors influencing coalbed methane production were studied by combining experiment and field test analysis.Three affecting factors of coalbed methane production difficulties are discussed:(1)3~#coal is characterized by very good development of fractures,poor fracture connectivity and filling jams.The macropore proportion of 3~#coal is small and the micropore proportion is large.The seepage condition of coal seam is poor,and it has low movable fluid saturation.The drainage decompression can produce less pore fluid,and the coalbed methane output level is low.(2)The ratio between the critical desorption pressure and reservoir pressure and the gas saturation of coal seam islow,the drainage pressure drop of coalbed gas wells is small,and the expansion area of pressure drop funnel is small,resulting in poor gas production effect.(3)Coal seam has the features of strong plasticity,low stress difference between coal seam and surrounding rock,greater extension difficulty of the fracturing fracture,easy breaking through the roof and floor for longitudinal extension,easy formation of more cracks under fracturing,limited expansion of the crack length,and poor fracturing production.It is also suggested that optimizing favorable areas for CBM development,strengthening measures for coal seam fracturing and extraction technology for sublevel fracturing horizontal wells are three favorable measures for realizing efficient CBM development in 3~# coal seam in Zhaozhuang field.
引文
[1] Liu Yijun,Lou Jianqing.Study on reservoir characteristics and development technology of coal-bed gas in China[J].Natural Gas Industry,2004,24(1):68-71.刘贻军,娄建青.中国煤层气储层特征及开发技术探讨[J].天然气工业,2004,24(1):68-71.
[2] Zhao Xianzheng,Yang Yanhui,Sun Fenjin,et al.Enrichment mechanism and exploration and development technologies of high rank coalbed methane in south Qinshui Basin,Shanxi Province[J].Petroleum Exploration and Development,2016,43(2):303-309.赵贤正,杨延辉,孙粉锦,等.沁水盆地南部高阶煤层气成藏规律与勘探开发技术[J].石油勘探与开发,2016,43(2):303-309.
[3] Lau H C,Li H Y,Huang S.Challenges and opportunities of coalbed methane development in China[J].Energy&Fuels,2017,31(5):4588-4602.
[4] Tang D Z,Deng C Y,Meng Y J,et al.Characteristics and control mechanisms of coalbed permeability change in various gas production stages[J].Petroleum Science,2015,12(4):684-691.
[5] Qin Yi,Li Yangmin,Bai Jianmei,et al.Technologies in the CBM production of wells in the southern Qinshui Basin with high-rank coal beds[J].Natural Gas Industry,2011,31(11):22-25.秦义,李仰民,白建梅,等.沁水盆地南部高煤阶煤层气井排采工艺研究与实践[J].天然气工业,2011,31(11):22-25.
[6] Li Sheng,Luo Mingkun,Fan Chaojun,et al.Quantitative characterization of the effect of acidification in coals by NMR and low-temperature nitrogen adsorption[J].Journal of China Coal Society,2017,42(7):1748-1756.李胜,罗明坤,范超军,等.基于核磁共振和低温氮吸附的煤层酸化增透效果定量表征[J].煤炭学报,2017,42(7):1748-1756.
[7] Li Aifen,Ren Xiaoxia,Wang Guijuan,et al.Characterization of pore structure of low permeability reservoirs using a nuclear magnetic resonance method[J].Journal of China University of Petroleum:Edition of Natural Science,2015,39(6):92-98.李爱芬,任晓霞,王桂娟,等.核磁共振研究致密砂岩孔隙结构的方法及应用[J].中国石油大学学报:自然科学版,2015,39(6):92-98.
[8] Jiang Wenping,Zhang Qun,Jiang Zaibing,et al.Effect on CBM drainage characteristics of pore structure of tectonic coal[J].Natural Gas Geoscience,2016,27(1):173-179.降文萍,张群,姜在炳,等.构造煤孔隙结构对煤层气产气特征的影响[J].天然气地球科学,2016,27(1):173-179.
[9] Bai Jianping,Zhang Diankun,Yang Jianqiang,et al.Thermodynamic characteristics of adsorption-desorption of methane in coal seam 3at Sihe Coal Mine[J].Journal of China Coal Society,2014,39(9):1812-1819.白建平,张典坤,杨建强,等.寺河3#煤甲烷吸附解吸热力学特征[J].煤炭学报,2014,39(9):1812-1819.
[10] Ma Dongmin,Zhang Suian,Lin Yabing.Isothermal adsorption and desorption experiment of coal and experimental results accuracy fitting[J].Journal of China Coal Society,2011,36(3):477-480.马东民,张遂安,蔺亚兵.煤的等温吸附-解吸实验及其精确拟合[J].煤炭学报,2011,36(3):477-480.
[11] Hu Qiujia,Li Mengxi,Qiao Maopo,et al.Analysis of key geologic factors of fracturing effect of CBM wells for high-rank coal in southern Qinshui Basin[J].Journal of China Coal Society,2017,42(6):1506-1516.胡秋嘉,李梦溪,乔茂坡,等.沁水盆地南部高阶煤煤层气井压裂效果关键地质因素分析[J].煤炭学报,2017,42(6):1506-1516.
[12] Feng Qing,Wu Caifang,Lei Bo.Coal/rock mechanics features of Qinshui Basin and fracturing crack control[J].Coal Science and Technology,2011,39(3):100-103.冯晴,吴才芳,雷波.沁水盆地煤岩力学特征及其压裂裂缝的控制[J].煤炭科学技术,2011,39(3):100-103.
[13] Meng Zhaoping,Tian Yongdong,Li Guofu.Characteristics of in-situ stress field in southern Qinshui Basin and its research significance[J].Journal of China Coal Society,2010,35(6):975-981.孟召平,田永东,李国富.沁水盆地南部地应力场特征及其研究意义[J].煤炭学报,2010,35(6):975-981.
[14] Tang Shuheng,Zhu Baocun,Yan Zhifeng.Effect of crustal stress on hydraulic fracture in coalbed methane wells[J].Journal of China Coal Society,2011,36(1):65-69.唐书恒,朱宝存,严志丰.地应力对煤层气井水力压裂裂缝发育的影响[J].煤炭学报,2011,36(1):65-69.
[15] Shan Xuejun,Zhang Shicheng,Li Anqi,et al.Analyzing the fracture extend law of hydraulic fracturing in coalbed gas wells[J].Natural Gas Industry,2005,25(1):130-132.单学军,张士诚,李安启,等.煤层气井压裂裂缝扩展规律分析[J].天然气工业,2005,25(1):130-132.
[16] Yang Jiaosheng,Wang Yibing,Li Anqi,et al.Experimental study on propagation mechanism of complex hydraulic fracture in coal-bed[J].Journal of China Coal Society,2012,37(1):73-77.杨焦生,王一兵,李安启,等.煤岩水力裂缝扩展规律试验研究[J].煤炭学报,2012,37(1):73-77.
[2] Zhao Xianzheng,Yang Yanhui,Sun Fenjin,et al.Enrichment mechanism and exploration and development technologies of high rank coalbed methane in south Qinshui Basin,Shanxi Province[J].Petroleum Exploration and Development,2016,43(2):303-309.赵贤正,杨延辉,孙粉锦,等.沁水盆地南部高阶煤层气成藏规律与勘探开发技术[J].石油勘探与开发,2016,43(2):303-309.
[3] Lau H C,Li H Y,Huang S.Challenges and opportunities of coalbed methane development in China[J].Energy&Fuels,2017,31(5):4588-4602.
[4] Tang D Z,Deng C Y,Meng Y J,et al.Characteristics and control mechanisms of coalbed permeability change in various gas production stages[J].Petroleum Science,2015,12(4):684-691.
[5] Qin Yi,Li Yangmin,Bai Jianmei,et al.Technologies in the CBM production of wells in the southern Qinshui Basin with high-rank coal beds[J].Natural Gas Industry,2011,31(11):22-25.秦义,李仰民,白建梅,等.沁水盆地南部高煤阶煤层气井排采工艺研究与实践[J].天然气工业,2011,31(11):22-25.
[6] Li Sheng,Luo Mingkun,Fan Chaojun,et al.Quantitative characterization of the effect of acidification in coals by NMR and low-temperature nitrogen adsorption[J].Journal of China Coal Society,2017,42(7):1748-1756.李胜,罗明坤,范超军,等.基于核磁共振和低温氮吸附的煤层酸化增透效果定量表征[J].煤炭学报,2017,42(7):1748-1756.
[7] Li Aifen,Ren Xiaoxia,Wang Guijuan,et al.Characterization of pore structure of low permeability reservoirs using a nuclear magnetic resonance method[J].Journal of China University of Petroleum:Edition of Natural Science,2015,39(6):92-98.李爱芬,任晓霞,王桂娟,等.核磁共振研究致密砂岩孔隙结构的方法及应用[J].中国石油大学学报:自然科学版,2015,39(6):92-98.
[8] Jiang Wenping,Zhang Qun,Jiang Zaibing,et al.Effect on CBM drainage characteristics of pore structure of tectonic coal[J].Natural Gas Geoscience,2016,27(1):173-179.降文萍,张群,姜在炳,等.构造煤孔隙结构对煤层气产气特征的影响[J].天然气地球科学,2016,27(1):173-179.
[9] Bai Jianping,Zhang Diankun,Yang Jianqiang,et al.Thermodynamic characteristics of adsorption-desorption of methane in coal seam 3at Sihe Coal Mine[J].Journal of China Coal Society,2014,39(9):1812-1819.白建平,张典坤,杨建强,等.寺河3#煤甲烷吸附解吸热力学特征[J].煤炭学报,2014,39(9):1812-1819.
[10] Ma Dongmin,Zhang Suian,Lin Yabing.Isothermal adsorption and desorption experiment of coal and experimental results accuracy fitting[J].Journal of China Coal Society,2011,36(3):477-480.马东民,张遂安,蔺亚兵.煤的等温吸附-解吸实验及其精确拟合[J].煤炭学报,2011,36(3):477-480.
[11] Hu Qiujia,Li Mengxi,Qiao Maopo,et al.Analysis of key geologic factors of fracturing effect of CBM wells for high-rank coal in southern Qinshui Basin[J].Journal of China Coal Society,2017,42(6):1506-1516.胡秋嘉,李梦溪,乔茂坡,等.沁水盆地南部高阶煤煤层气井压裂效果关键地质因素分析[J].煤炭学报,2017,42(6):1506-1516.
[12] Feng Qing,Wu Caifang,Lei Bo.Coal/rock mechanics features of Qinshui Basin and fracturing crack control[J].Coal Science and Technology,2011,39(3):100-103.冯晴,吴才芳,雷波.沁水盆地煤岩力学特征及其压裂裂缝的控制[J].煤炭科学技术,2011,39(3):100-103.
[13] Meng Zhaoping,Tian Yongdong,Li Guofu.Characteristics of in-situ stress field in southern Qinshui Basin and its research significance[J].Journal of China Coal Society,2010,35(6):975-981.孟召平,田永东,李国富.沁水盆地南部地应力场特征及其研究意义[J].煤炭学报,2010,35(6):975-981.
[14] Tang Shuheng,Zhu Baocun,Yan Zhifeng.Effect of crustal stress on hydraulic fracture in coalbed methane wells[J].Journal of China Coal Society,2011,36(1):65-69.唐书恒,朱宝存,严志丰.地应力对煤层气井水力压裂裂缝发育的影响[J].煤炭学报,2011,36(1):65-69.
[15] Shan Xuejun,Zhang Shicheng,Li Anqi,et al.Analyzing the fracture extend law of hydraulic fracturing in coalbed gas wells[J].Natural Gas Industry,2005,25(1):130-132.单学军,张士诚,李安启,等.煤层气井压裂裂缝扩展规律分析[J].天然气工业,2005,25(1):130-132.
[16] Yang Jiaosheng,Wang Yibing,Li Anqi,et al.Experimental study on propagation mechanism of complex hydraulic fracture in coal-bed[J].Journal of China Coal Society,2012,37(1):73-77.杨焦生,王一兵,李安启,等.煤岩水力裂缝扩展规律试验研究[J].煤炭学报,2012,37(1):73-77.