临汾区块煤层气井提产阶段排采控制研究
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摘要
为查找出影响临汾区块煤层气高产稳产井和峰后下降井稳产效果差异的原因,分别对高产稳产井和峰后下降井提产阶段的井底压力下降速度、日产气增速等排采控制指标进行了对比分析,首次揭示出了产气速度对煤储层压降扩展的影响机理及在排采控制中的重要性,制定出了临汾区块煤层气井提产阶段的排采参数控制指标与方法。研究表明:峰后下降井稳产效果差的原因在于提产阶段未对井底压力降速和日产气增速进行缓慢控制;产气速度过快,易引起大颗粒煤粉运移造成堵塞,且近井地带煤层中的气相相对渗透率快速增加,水相相对渗透率急剧下降,水的流动阻力增大,影响水的有效排出,造成压降扩展变慢;临汾区块煤层气井提产阶段的压降速度合理值应控制不超过0.01MPa/d,日产气增速应控制不超过15 m~3/d为宜,可采用阶梯式稳产、提产交替进行的方式进行提产。
In order to find out the reasons that affect the CBM production difference between the stable and high-yield production wells and the post-peak production-descending wells in the Linfen Area,the speed of pressure drop in well bore and the growth rate of daily gas production in the production stage of both types of wells were contrasted and analyzed. The influence mechanism of fast gas production on pressure drop expansion of coal reservoir and its importance in drainage control was revealed and the control indexes and method for CBM well drainage parameters in the increasing production stage in Linfen were are formulated. The study results show that the reason for the poor stable production effect of the post-peak production-descending wells lies in the fact that the down hole pressure deceleration and the daily gas production increase rate are not slowly controlled during the production stage. If gas production rate is too fast,the migration of large pulverized coal particle and clogging will be induced by gas-water bubble flow. At the same time,gas saturation and its relative permeability in near borehole zones increase,and water relative permeability decreases as the flowing resistance is growing,which influence the effective discharge of water and cause pressure drop transmission becoming slower and hindered. The reasonable value of pressure drop speed in the increasing production stage of CBM wells in Linfen Area should not exceed 0.01 MPa/d,and the growth rate of daily gas production should be less than 15 m~3/d. It is advisable to use stepwise stable production and alternate production.
In order to find out the reasons that affect the CBM production difference between the stable and high-yield production wells and the post-peak production-descending wells in the Linfen Area,the speed of pressure drop in well bore and the growth rate of daily gas production in the production stage of both types of wells were contrasted and analyzed. The influence mechanism of fast gas production on pressure drop expansion of coal reservoir and its importance in drainage control was revealed and the control indexes and method for CBM well drainage parameters in the increasing production stage in Linfen were are formulated. The study results show that the reason for the poor stable production effect of the post-peak production-descending wells lies in the fact that the down hole pressure deceleration and the daily gas production increase rate are not slowly controlled during the production stage. If gas production rate is too fast,the migration of large pulverized coal particle and clogging will be induced by gas-water bubble flow. At the same time,gas saturation and its relative permeability in near borehole zones increase,and water relative permeability decreases as the flowing resistance is growing,which influence the effective discharge of water and cause pressure drop transmission becoming slower and hindered. The reasonable value of pressure drop speed in the increasing production stage of CBM wells in Linfen Area should not exceed 0.01 MPa/d,and the growth rate of daily gas production should be less than 15 m~3/d. It is advisable to use stepwise stable production and alternate production.
引文
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[12]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.
[13]王丹凤.煤层气井负压排采工艺技术研究[D].荆州:长江大学,2014:14-15.
[14]刘保民.煤层气开采的水文地质控制和产能潜力评价方法研究[D].北京:中国矿业大学(北京),2012:50-58.
[15]林文姬,王烽,汤达祯,等.韩城矿区煤储层非稳态渗流压降传播规律[J].煤炭科学技术,2016,44(S1):131-136.LIN Wenji,WANG Feng,TANG Dazhen,et al.Unsteady seepage and pressure drop transmission law in coal reservoirs of Hancheng Mining area[J].Coal Science and Technology,2016,44(S1):131-136.
[16]赵群,王红岩,李景明,等.快速排采队低渗透率煤层气井产能伤害的机理研究[J].山东科技大学学报,2008,27(3):27-31.ZHAO Qun,WANG Hongyan,LI Jingming,et al.Study on mechanism of harm to CBM well capability in low permeability seam with quick drainage method[J].Journal of Shandong University of Science and Technology,2008,27(3):27-31.
[17]陈振宏,王一兵,郭凯,等.高煤阶煤层气藏储层应力敏感性研究[J].地质学报,2008,82(10):1390-1395.CHEN Zhenhong,WANG Yibing,GUO Kai,et al.Stress sensitivity of high-rank coalbed methane reservoir[J].Acta Geologica Sinica,2008,82(10):1390-1395.
[18]张亚蒲,何应付,杨正明,等.煤层气勘探开发理论与实践:煤层气藏渗透率应力敏感性研究[M].北京:石油工业出版社,2007:281-284.
[19]傅雪海,秦勇,姜波,等.高煤级煤储层煤层气产能“瓶颈”问题研究[J].地质评论,2004,50(5):507-513.FU Xuehai,QIN Yong,JIANG Bo,et al.Study on the“bottleneck”problem of coalbed methane productivity of high-rank coal reservoirs[J].Geological Review,2004,50(5):507-513.
[20]HARPALANI S,SHRAUFNAGEL R A.Shrinkage of coal matrix with release of gas and its impact on permeability of coal[J].Fuel,1990,69:551-556.
[21]李俊乾,刘大锰,姚艳斌,等.气体滑脱及有效应力对煤岩气相渗透率的控制作用[J].天然气地球科学,2013,24(5):1074-1078.LI Junqian,LIU Dameng,YAO Yanbin,et al.Control of gas slippage and effective stress on the gas permeability of coal[J].Natural Gas Geoscience,2013,24(5):1074-1078.
[22]张永平,杨艳磊,唐新毅,等.沁南地区高煤阶煤储层流速敏感性及影响因素[J].煤田地质与勘探,2015,43(4):36-40.ZHANG Yongping,YANG Yanlei,TANG Xinyi,et al.Velocity sensitivity and its influencing factors of high-rank coal reservoirs in southern Qinshui Basin[J].Coal Geology&Exploration,2015,43(4):36-40.
[23]陈金刚,徐平,赖永星,等.煤储层渗透率动态变化效应研究[J].岩土力学,2011,32(8):2512-2516.CHEN Jingang,XU Ping,LAI Yongxing,et al.Research on dynamic variation effect of coal reservoirs permeability[J].Rock and Soil Mechanics,2011,32(8):2512-2516.
[2]樊彬,秦义,崔金榜,等.压降速度对煤层气井产量的影响分析[J].中国煤层气,2010,7(6):20-23.FAN Bin,QIN Yi,CUI Jinbang,et al.Analysis of the influence of pressure drop velocity on CBM well production[J].China Coalbed Methane,2010,7(6):20-23.
[3]张遂安,曹立虎,杜彩霞.煤层气井产气机理及排采控压控粉研究[J].煤炭学报,2014,39(9):1927-1931.ZHANG Suian,CAO Lihu,DU Caixia.Study on CBM produciton mechanism and control theory of bottom-hole pressure and coal fines during CBM well production[J].Journal of China Coal Society,2014,39(9):1927-1931.
[4]柳迎红,房茂军,廖夏.煤层气排采阶段划分及排采制度制定[J].洁净煤技术,2015,21(3):121-123.LIU Ying hong,FANG Maojun,LIAO Xia.Production stages division and drainage production system development of coalbed methane[J].Clean Coal Technology,2015,21(3):121-123.
[5]谢学恒,樊明珠,王前阔,等.煤层气井排采强度对产气量敏感性的数值模拟[J].油气藏评价与开发,2013,3(5):74-76.XIE Xueheng,FAN Mingzhu,WANG Qiankuo,et al.Sensitivity numerical simulation of production intensity on the gas production rate of CBM wells[J].Reservoir Evaluation and Development,2013,3(5):74-76.
[6]倪小明,胡海洋,曹运兴,等.煤层气直井提产阶段合理压降速率的确定[J].河南理工大学学报:自然科学版,2015,34(6):759-763.NI Xiaoming,HU Haiyang,CAO Yunxing,et al.Determination the reasonnable pressure dropping rate of CBM vertical wells in increasing production stage[J].Journal of Henan Polytechnic University Natural Science,2015,34(6):759-763.
[7]倪小明,胡海洋,曹运兴,等.煤层气井合理放气套压的确定及其应用[J].石油钻探技术,2015,43(4):113-117.NI Xiaoming,HU Haiyang,CAO Yunxing,et al.The determination of casing releasing pressure of CBM wells and its application[J].Petroleum Drilling Techniques,2015,43(4):113-117.
[8]倪小明,苗杰,叶建平,等.单一煤储层煤层气井直井合理日产气量的确定[J].特种油气藏,2016,23(3):136-139.NI Xiaoming,MIAO Jie,YE Jianping,et al.Determination of reasonable daily production in CBM vertical well with mono-coal reservoir[J].Special Oil and Gas Reservoirs,2016,23(3):136-139.
[9]巢海燕,王延斌.鄂尔多斯盆地东南缘临汾区块煤层气成因及其影响[J].煤炭学报,2016,41(7):1769-1775.CHAO Haiyan,WANG Yanbin.Origin of coalbed methane and its influence in Linfen,Southeastern Ordos Basin[J].Journal of China Coal Society,2016,41(7):1769-1775.
[10]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.
[11]邵先杰,王彩凤,汤达祯,等.煤层气井产能模式及控制因素[J].煤炭学报,2013,38(2):271-276.SHAO Xianjie,WANG Caifeng,TANG Dazhen,et al.Productivity mode and control factors of coalbed methane wells:a case from Hancheng region[J].Journal of China Coal Society,2013,38(2):271-276.
[12]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.
[13]王丹凤.煤层气井负压排采工艺技术研究[D].荆州:长江大学,2014:14-15.
[14]刘保民.煤层气开采的水文地质控制和产能潜力评价方法研究[D].北京:中国矿业大学(北京),2012:50-58.
[15]林文姬,王烽,汤达祯,等.韩城矿区煤储层非稳态渗流压降传播规律[J].煤炭科学技术,2016,44(S1):131-136.LIN Wenji,WANG Feng,TANG Dazhen,et al.Unsteady seepage and pressure drop transmission law in coal reservoirs of Hancheng Mining area[J].Coal Science and Technology,2016,44(S1):131-136.
[16]赵群,王红岩,李景明,等.快速排采队低渗透率煤层气井产能伤害的机理研究[J].山东科技大学学报,2008,27(3):27-31.ZHAO Qun,WANG Hongyan,LI Jingming,et al.Study on mechanism of harm to CBM well capability in low permeability seam with quick drainage method[J].Journal of Shandong University of Science and Technology,2008,27(3):27-31.
[17]陈振宏,王一兵,郭凯,等.高煤阶煤层气藏储层应力敏感性研究[J].地质学报,2008,82(10):1390-1395.CHEN Zhenhong,WANG Yibing,GUO Kai,et al.Stress sensitivity of high-rank coalbed methane reservoir[J].Acta Geologica Sinica,2008,82(10):1390-1395.
[18]张亚蒲,何应付,杨正明,等.煤层气勘探开发理论与实践:煤层气藏渗透率应力敏感性研究[M].北京:石油工业出版社,2007:281-284.
[19]傅雪海,秦勇,姜波,等.高煤级煤储层煤层气产能“瓶颈”问题研究[J].地质评论,2004,50(5):507-513.FU Xuehai,QIN Yong,JIANG Bo,et al.Study on the“bottleneck”problem of coalbed methane productivity of high-rank coal reservoirs[J].Geological Review,2004,50(5):507-513.
[20]HARPALANI S,SHRAUFNAGEL R A.Shrinkage of coal matrix with release of gas and its impact on permeability of coal[J].Fuel,1990,69:551-556.
[21]李俊乾,刘大锰,姚艳斌,等.气体滑脱及有效应力对煤岩气相渗透率的控制作用[J].天然气地球科学,2013,24(5):1074-1078.LI Junqian,LIU Dameng,YAO Yanbin,et al.Control of gas slippage and effective stress on the gas permeability of coal[J].Natural Gas Geoscience,2013,24(5):1074-1078.
[22]张永平,杨艳磊,唐新毅,等.沁南地区高煤阶煤储层流速敏感性及影响因素[J].煤田地质与勘探,2015,43(4):36-40.ZHANG Yongping,YANG Yanlei,TANG Xinyi,et al.Velocity sensitivity and its influencing factors of high-rank coal reservoirs in southern Qinshui Basin[J].Coal Geology&Exploration,2015,43(4):36-40.
[23]陈金刚,徐平,赖永星,等.煤储层渗透率动态变化效应研究[J].岩土力学,2011,32(8):2512-2516.CHEN Jingang,XU Ping,LAI Yongxing,et al.Research on dynamic variation effect of coal reservoirs permeability[J].Rock and Soil Mechanics,2011,32(8):2512-2516.