沁水盆地南部高煤阶煤层气井“变速排采-低恒套压”管控方法
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摘要
为了提高煤层气井排采管控的科学性,以沁水盆地南部3号煤为研究对象,基于储层气-水运移产出过程和相对渗透率特征,探讨了煤储层气水产出控制机理及其影响因素,通过开展不同尺度裂隙系统内气水运移实验,分析了各类气水产出影响因素的影响模式及主要作用阶段。以降低气水运移影响因素造成的储层伤害、减小各排采阶段渗透率损失为主要目的,建立了适应于沁水盆地南部高煤阶煤层气井的"变速排采-低恒套压"排采控制方法。研究表明,气水产出依次通过基质孔隙、微观裂隙、宏观裂隙和人工裂缝,期间受到毛细管力、有效应力、启动压力和气水相渗等4要素耦合控制,压裂增压后地层毛细阻力明显增大、排水降压后有效应力会导致裂缝闭合、启动压力使气体产出滞后、气水相渗影响流态的稳定。当气井处在不同的排采阶段时,影响排采效率的主控影响因素各不相同。可将煤层气井降压产气过程依据储层压力(Pc)、临界解吸压力(Pde)、见气压力(Pjq)与井底流压(Pjd)的关系划分为4个阶段,认为Pc In order to improve the scientificity of CBM drainage and production,take Fanzhuang block of south Qinshui basin as a study case,based on the gas-water transport process and relative permeability characteristics of No.3 coal reservoir,the controlling mechanism and influencing factors of gas-water productive process in coal reservoir are discussed,and the influencing models and main stages of various factors affecting gas-water production are analyzed by carrying out experiments on gas-water migration in different scale fracture systems. For reducing reservoir damage caused by factors affecting gas-water migration and permeability loss in each drainage stage,the "Variable speed drainage-low casing pressure"control method is used for Qinnan block. The research shows that the gas and water products are successively passed through matrix pores,microscopic pores,macroscopic fractures and artificial fractures,during the passing period,the capillary force,effective stress,trigger pressure and the relative permeability of the four elements coupling control the process. In particular,the resistance of the capillary force increases significantly after fracturing,the increase of effective stress leads to crack closure,starting pressure makes gas output lag,and relative permeability affects the stability of flow regime.The main influencing factors of drainage and production efficiency are different in each production stages.Based on the differences above,the process of CBM well pressure reduction and gas production can be divided into four stages according to the relationship between reservoir pressure( Pc),critical desorption pressure( Pde),gas sight pressure( Pjq) and flow pressure( Pjd). When Pc< Pjd,it needs to be drained at0. 1 MPa/d to overcome capillary force quickly.When Pjx
引文
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[11]李辛子,王运海,姜昭琛,等,深部煤层气勘探开发进展与研究[J].煤炭学报,2016,41(1):24-31.LI Xinzi,WANG Yunhai,JIANG Zhaochen,et al. Progress and study on exploration and production for deep coalbed methane[J].Journal of China Coal Society,2016,41(1):24-31.
[12]秦勇,申建,沈玉林.叠置含气系统共采兼容性———煤系“三气”及深部煤层气开采中的共性地质问题[J].煤炭学报,2016,41(1):14-23.QIN Yong,SHEN Jian,SHEN Yulin. Joint mining compatibility of superposed gas-bearing systems:A general geological problem for extraction of three natural gases and deep CBM in coal series[J].Journal of China Coal Society,2016,41(1):14-23.
[13]倪小明,陈鹏,朱明阳.煤层气垂直井产能主控地质因素分析[J].煤炭科学技术,2010,38(7):109-113.NI Xiaoming,CHEN Peng,ZHU Mingyang. Analysis on main controlled geological factors of production capacity of coal bed methane vertical drilling Well[J]. Coal Science and Technology,2010,38(7):109-113.
[14] LIU S,SANG S,WANG G,et al.FIB-SEM and X-ray CT characterization of interconnected pores in high-rank coal formed from regional metamorphism[J]. Journal of Petroleum Science and Engineering,2017,148:21-31.
[15] LIU S,SANG S,PAN Z,et al.Study of characteristics and formation stages of macroscopic natural fractures in coal seam No. 3 for CBM development in the east Qinnan block,Southern QUISHUI Basin,China[J].Journal of Natural Gas Science and Engineering,2016,34:1321-1332.
[16]杨延辉,刘世奇,桑树勋,等.基于三维空间表征的高阶煤连通孔隙发育特征[J].煤炭科学技术,2016,44(10):70-76.YANG Yanhui,LIU Shiqi,SANG Shuxun,et al. Interconnected pore development features of high rank coal based on 3D space characteristics[J]. Coal Science and Technology,2016,44(10):70-76.
[17]刘世奇,桑树勋,李仰民,等.沁水盆地南部煤层气井压裂失败原因分析[J].煤炭科学技术,2012,40(6):108-112.LIU Shiqi,SANG Shuxun,LI Yangmin,et al.Analysis on fracturing failure cause of coal bed methane well in south part of Qinshui Basin[J].Coal Science and Technology,2012,40(6):108-112.
[18]倪小明,苏现波,李玉魁.多煤层合层水力压裂关键技术研究[J].中国矿业大学学报,2010,39(5):728-732.NI Xiaoming,SU Xianbo,LI Yukui. Study of the key technologies of the hydraulic fracturing used in multi-layer coal seam[J].Journal of China University of Mining&Technology,2010,39(5):728-732.
[19]杨胜来,杨思松,高旺来.应力敏感及液锁对煤层气储层伤害程度实验研究[J].天然气工业,2006,26(3):90-92.YANG Shenglai,YANG Sisong,GAO Wanglai. Experimental study of damage of stress and liquid sensitivities to coal-bed gas reservoir[J].Natural Gas Industry,2006,26(3):90-92.
[20]张国华,梁冰,毕业武.水锁对含瓦斯煤体的瓦斯解吸的影响[J].煤炭学报,2012,37(2):253-258.ZHANG Guohua,LIANG Bing,BI Yewu. Impact of water lock on gas desorption of coal with gas[J].Journal of China Coal Society,2012,37(2):253-258.
[21]张先敏,同登科.低渗透煤层气非线性流动分析[J].工程力学,2010,27(10):219-223.ZHANG Xianmin,TONG Dengke. Nonlinear flow analysis of methane in low permeability coal seams[J]. Engineering Mechanics,2010,27(10):219-223.
[22]李相臣,康毅力.煤层气储层破坏机理及其影响研究[J].中国煤层气,2008,5(1):35-37.LI Xiangchen,KANG Yili. Study of failure mechanism and impact on CBM reservoir[J]. China Coalbed Methane,2008,5(1):35-37.
[2]刘世奇,赵贤正,桑树勋,等.煤层气井排采液面-套压协同管控———以沁水盆地樊庄区块为例[J].石油学报,2015,36(S1):97-108.LIU Shiqi,ZHAO Xianzheng,SANG Shuxun,et al. Cooperative control of working fluid level and casing pressure for coalbed methane production:A case study of Fanzhuang block in Qinshui Basin[J].Acta Petrolei Sinica,2015,36(S1):97-108.
[3]李允,陈军,张烈辉.一个新的低渗气藏开发数值模拟模型[J].天然气工业,2004,24(8):65-68,132.LI Yun,CHEN Jun,ZHANG Liehui. New model of numeral simulation for development of gas reservoirs with low permeability[J].Natural Gas Industry,2004,24(8):65-68,132.
[4]宋革,傅雪海,葛燕燕,等.压力控制下高煤阶储层煤层气井排采的流体效应[J].煤炭科学技术,2014,42(8):60-64.SONG Ge,FU Xuehai,GE Yanyan,et al. Fluid effect during coalbed methane well drainage of high rank coal reservoir under pressure control[J].Coal Science and Technology,2014,42(8):60-64.
[5]杨延辉,陈彦君,郭希波,等.沁水盆地南部高煤阶煤岩渗透率压敏效应分析[J].煤炭科学技术,2015,43(12):152-156.YANG Yanhui,CHEN Yanjun,GUO Xibo,et al.Analasis on effect of stress sensitivity on permeability of high rank coal in southern Qinshui Basin[J]. Coal Science and Technology,2015,43(12):152-156.
[6]杨延辉,汤达祯,杨艳磊,等.煤储层速敏效应对煤粉产出规律及产能的影响[J].煤炭科学技术,2015,43(2):96-99,103.YANG Yanhui,TANG Dazhen,YANG Yanlei,et al.Influence on velocity sensitivity effect of coal reservoir to production law of pulverized coal and gas productivity[J]. Coal Science and Technology,2015,43(2):96-99,103.
[7]程乔,胡宝林,徐宏杰,等.沁水盆地南部煤层气井排采伤害判别模式[J].煤炭学报,2014,39(9):1879-1885.CHENG Qiao,HU Baolin,XU Hongjie,et al. Discrimination model on damage mechanism in the extraction porcess of CBM wells in Southern Qinshui Basin[J].Journal of China Coal Society,2014,39(9):1879-1885.
[8]刘世奇,桑树勋,李梦溪,等.樊庄区块煤层气井产能差异的关键地质影响因素及其控制机理[J].煤炭学报,2013,38(2):277-283.LIU Shiqi,SANG Shuxun,LI Mengxi,et al. Key geologic factors and control mechanisms of water production and gas production divergences between CBM wells in Fanzhuang block[J]. Journal of China Coal Society,2013,38(2):277-283.
[9]胡友林,乌效鸣.煤层气储层水锁损害机理及防水锁剂的研究[J].煤炭学报,2014,39(6):1107-1111.HU Youlin,WU Xiaoming. Research on coalbed methane reservoir water blocking damage mechanism and anti-water blocking[J].Journal of China Coal Society,2014,39(6):1107-1111.
[10]李仰民,王立龙,刘国伟,等.煤层气井排采过程中的储层伤害机理研究[J].中国煤层气,2010,7(6):39-43.LI Yangmin,WANG Lilong,LIU Guowei,et al.Study on coal reservoir damage mechanism in dewatering and extraction process of CBM wells[J].China Coalbed Methane,2010,7(6):39-43.
[11]李辛子,王运海,姜昭琛,等,深部煤层气勘探开发进展与研究[J].煤炭学报,2016,41(1):24-31.LI Xinzi,WANG Yunhai,JIANG Zhaochen,et al. Progress and study on exploration and production for deep coalbed methane[J].Journal of China Coal Society,2016,41(1):24-31.
[12]秦勇,申建,沈玉林.叠置含气系统共采兼容性———煤系“三气”及深部煤层气开采中的共性地质问题[J].煤炭学报,2016,41(1):14-23.QIN Yong,SHEN Jian,SHEN Yulin. Joint mining compatibility of superposed gas-bearing systems:A general geological problem for extraction of three natural gases and deep CBM in coal series[J].Journal of China Coal Society,2016,41(1):14-23.
[13]倪小明,陈鹏,朱明阳.煤层气垂直井产能主控地质因素分析[J].煤炭科学技术,2010,38(7):109-113.NI Xiaoming,CHEN Peng,ZHU Mingyang. Analysis on main controlled geological factors of production capacity of coal bed methane vertical drilling Well[J]. Coal Science and Technology,2010,38(7):109-113.
[14] LIU S,SANG S,WANG G,et al.FIB-SEM and X-ray CT characterization of interconnected pores in high-rank coal formed from regional metamorphism[J]. Journal of Petroleum Science and Engineering,2017,148:21-31.
[15] LIU S,SANG S,PAN Z,et al.Study of characteristics and formation stages of macroscopic natural fractures in coal seam No. 3 for CBM development in the east Qinnan block,Southern QUISHUI Basin,China[J].Journal of Natural Gas Science and Engineering,2016,34:1321-1332.
[16]杨延辉,刘世奇,桑树勋,等.基于三维空间表征的高阶煤连通孔隙发育特征[J].煤炭科学技术,2016,44(10):70-76.YANG Yanhui,LIU Shiqi,SANG Shuxun,et al. Interconnected pore development features of high rank coal based on 3D space characteristics[J]. Coal Science and Technology,2016,44(10):70-76.
[17]刘世奇,桑树勋,李仰民,等.沁水盆地南部煤层气井压裂失败原因分析[J].煤炭科学技术,2012,40(6):108-112.LIU Shiqi,SANG Shuxun,LI Yangmin,et al.Analysis on fracturing failure cause of coal bed methane well in south part of Qinshui Basin[J].Coal Science and Technology,2012,40(6):108-112.
[18]倪小明,苏现波,李玉魁.多煤层合层水力压裂关键技术研究[J].中国矿业大学学报,2010,39(5):728-732.NI Xiaoming,SU Xianbo,LI Yukui. Study of the key technologies of the hydraulic fracturing used in multi-layer coal seam[J].Journal of China University of Mining&Technology,2010,39(5):728-732.
[19]杨胜来,杨思松,高旺来.应力敏感及液锁对煤层气储层伤害程度实验研究[J].天然气工业,2006,26(3):90-92.YANG Shenglai,YANG Sisong,GAO Wanglai. Experimental study of damage of stress and liquid sensitivities to coal-bed gas reservoir[J].Natural Gas Industry,2006,26(3):90-92.
[20]张国华,梁冰,毕业武.水锁对含瓦斯煤体的瓦斯解吸的影响[J].煤炭学报,2012,37(2):253-258.ZHANG Guohua,LIANG Bing,BI Yewu. Impact of water lock on gas desorption of coal with gas[J].Journal of China Coal Society,2012,37(2):253-258.
[21]张先敏,同登科.低渗透煤层气非线性流动分析[J].工程力学,2010,27(10):219-223.ZHANG Xianmin,TONG Dengke. Nonlinear flow analysis of methane in low permeability coal seams[J]. Engineering Mechanics,2010,27(10):219-223.
[22]李相臣,康毅力.煤层气储层破坏机理及其影响研究[J].中国煤层气,2008,5(1):35-37.LI Xiangchen,KANG Yili. Study of failure mechanism and impact on CBM reservoir[J]. China Coalbed Methane,2008,5(1):35-37.
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