沁水盆地中高煤阶煤储层覆压孔渗试验研究
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摘要
为了研究中、高煤阶煤储层在覆压条件下孔隙度、渗透率及应力敏感性的差异变化特征,从山西沁水盆地采集4块中煤阶样品和4块高煤阶样品,开展了覆压孔渗试验对比研究,探讨了中煤阶煤和高煤阶煤的应力敏感性的差异,研究了应力敏感性随煤阶改变的变化规律。研究结果表明:煤的孔隙度随镜质组最大反射率R_(o,max)的增大呈现先增大后减小的趋势,而渗透率则与镜质组最大反射率之间无明显关系;中、高煤阶煤覆压下的孔隙度和渗透率均随有效应力增加呈现指数式减小;高煤阶煤平均孔隙压缩系数、应力敏感性系数分别是中煤阶煤的1.61倍和1.26倍,高煤阶煤的孔隙度和渗透率损害率分别是中煤阶煤的1.42倍和1.1倍,中、高煤阶煤的无因次渗透率曲率随有效应力的增加而降低,当有效应力为12 MPa时,高煤阶煤的平均渗透率曲率是中煤阶煤的1.33倍。随R_(o,max)的增大,煤的应力敏感性呈现增强的趋势,即高煤阶煤的应力敏感性高于中煤阶煤。因此,在不同煤阶煤储层排采过程中,针对不同煤阶煤储层所采用的生产压差应当有所差异。与中煤阶煤储层相比,高煤阶煤储层随有效应力增加孔隙度、渗透率损害率高,渗透率曲率降低幅度大,因此针对高煤阶煤储层排采过程中所采用的生产压差应低于中煤阶煤储层,才能获得较高的煤层气产出量。
In order to study the variation characteristics of porosity,permeability and stress sensitivity of medium and high rank coal reservoirs in net confining stress,four medium and high rank coal samples were collected from Qinshui Basin in Shanxi Province.Comparative study of the porosity and permeability of coal in net confining stress experiments.This study discussed the difference of stress sensitivity between medium-rank coal and high-rank coal.And it studied the change rule of stress sensitivity with the change of coal rank.The results show that the porosity of coal increases first and then decreases with the increase of R_(o,max).There is no obvious relationship between permeability and R_(o,max).The porosity and permeability of medium and high coal rank coal in net confining stress decrease exponentially with the increase of effective stress.The average pore compressibility coefficient and stress sensitivity coefficient of high-rank coal are 1.61 times and 1.26 times of medium-rank coal respectively.The damage rate of porosity and permeability of high-rank coal is 1.42 times and 1.1 times of that of medium-rank coal,respectively.The permeability curvature of medium and high coal grade coal decreases with the increase of effective stress.When the effective stress is 12 MPa,the average permeability curvature of high rank coal is 1.33 times of that medium coal rank coal.With the increase of Ro,max,the stress sensitivity of coal tends to increase,that is,the stress sensitivity of high-rank coal is higher than that of medium-rank coal.Therefore,in the process of drainage and mining of different coal-rank coal reservoirs,the production pressure differential adopted for different coal-rank coal reservoirs should be different.Compared with medium-rank coal reservoirs,highrank coal reservoirs show that as porosity increases with effective stress and permeability damage rate is high,permeability curvature decreases by a large margin.Therefore,in order to obtain a higher CBM output,the production pressure differential used in the drainage and mining process of high-rank coal reservoirs should be lower than that of medium-rank coal reservoirs.
In order to study the variation characteristics of porosity,permeability and stress sensitivity of medium and high rank coal reservoirs in net confining stress,four medium and high rank coal samples were collected from Qinshui Basin in Shanxi Province.Comparative study of the porosity and permeability of coal in net confining stress experiments.This study discussed the difference of stress sensitivity between medium-rank coal and high-rank coal.And it studied the change rule of stress sensitivity with the change of coal rank.The results show that the porosity of coal increases first and then decreases with the increase of R_(o,max).There is no obvious relationship between permeability and R_(o,max).The porosity and permeability of medium and high coal rank coal in net confining stress decrease exponentially with the increase of effective stress.The average pore compressibility coefficient and stress sensitivity coefficient of high-rank coal are 1.61 times and 1.26 times of medium-rank coal respectively.The damage rate of porosity and permeability of high-rank coal is 1.42 times and 1.1 times of that of medium-rank coal,respectively.The permeability curvature of medium and high coal grade coal decreases with the increase of effective stress.When the effective stress is 12 MPa,the average permeability curvature of high rank coal is 1.33 times of that medium coal rank coal.With the increase of Ro,max,the stress sensitivity of coal tends to increase,that is,the stress sensitivity of high-rank coal is higher than that of medium-rank coal.Therefore,in the process of drainage and mining of different coal-rank coal reservoirs,the production pressure differential adopted for different coal-rank coal reservoirs should be different.Compared with medium-rank coal reservoirs,highrank coal reservoirs show that as porosity increases with effective stress and permeability damage rate is high,permeability curvature decreases by a large margin.Therefore,in order to obtain a higher CBM output,the production pressure differential used in the drainage and mining process of high-rank coal reservoirs should be lower than that of medium-rank coal reservoirs.
引文
[1]傅雪海,秦勇,姜波,等.煤割理压缩试验及渗透率数值模拟[J].煤炭学报,2001,26(6):573-577.FU Xuehai,QIN Yong,JIANG Bo,et al.Compress experiment of coal cleat and mathematical simulation of coal reservoir permeability[J].Journal of China Coal Society,2001,26(6):573-577.
[2]汪岗,秦勇,申建,等.基于变孔隙压缩系数的深部低阶煤层渗透率试验[J].石油学报,2014,35(3):462-468.WANG Gang,QIN Yong,SHEN Jian,et al.Experimental studies of deep low-rank coal reservoirs'permeability based on variable pore compressibility[J].Acta Petrolei Sinica,2014,35(3):462-468.
[3]孟雅,李治平.覆压下煤的孔渗性试验及其应力敏感性研究[J].煤炭学报,2015,40(1):154-159.MENG Ya,LI Zhiping.Experimental study on the porosity and permeability of coal in net confining stress and its stress sensitivity[J].Journal of China Coal Society,2015,40(1):154-159.
[4]Min K B,Rutqvist J,Tsang C F,et al.Stress-dependent permeability of fractured rock masses:a numerical study[J].International Journal of Rock Mechanics&Mining Sciences,2004,41(7):1191-1210.
[5]ZHANG J,Standifird W B,Roegiers J C,et al.Stress-dependent fluid flow and permeability in fractured media:from lab experiments to engineering applications[J].Rock Mechanics&Rock Engineering,2007,40(1):3-21.
[6]TENG T,GAO F,YANG J,et al.How moisture loss affects coal porosity and permeability during gas recovery in wet reservoirs?[J].International Journal of Mining Science and Technology,2017,27(6):899-906.
[7]Enever J R,Henning A.The relationship between permeability and effective stress for Australian coal and its implications with respect to coalbed methane exploration and reservoir modeling[C]//Proceedings of the 1997 International Coalbed Methane Symposium.1997:13-22.
[8]贾慧敏,孙世轩,毛崇昊,等.基于煤岩应力敏感性的煤层气井单相流产水规律研究[J].煤炭科学技术,2017,45(12):189-193.JIA Huimin,SUN Shixuan,MAO Chonghao,et al.Study on water production law of single-phase flow in CBM wells based on stress sensitivity of coal and rock[J].Coal Science and Technology,2017,45(12):189-193.
[9]陈浩,秦勇,李贵中,等.基于脉冲衰减法的煤岩渗透率应力敏感性研究[J].煤炭科学技术,2018,46(6):167-172.CHEN Hao,QIN Yong,LI Guizhong,et al.Study on stress sensitivity of coal rock permeability based on pulse-decay method[J].Coal Science and Technology,2018,46(6):167-172.
[10]王运海.延川南深部煤层气井排采制度研究[J].煤炭科学技术,2018,46(6):132-137.WANG Yunhai.Study on drainage and production system of deep coalbed methane well in South Yanchuan Block[J].Coal Science and Technology,2018,46(6):132-137.
[11]侯旭伟,周效志,陶智辉,等.重复荷载下不同饱水压力中阶煤应力敏感性研究[J].煤炭科学技术,2018,46(8):120-124.HOU Xuwei,ZHOU Xiaozhi,TAO Zhihui,et al.Stress sensitivity of medium-rank coal under different saturated pressures under repeated loading[J].Coal Science and Technology,2018,46(8):120-124.
[12]JASINGE D,RANJITH P G,CHOI S K.Effects of effective stress changes on permeability of latrobe valley brown coal[J].Fuel,2011,90(3):1292-1300.
[13]杨晓东,张苗,魏巍,等.沁水盆地古县区块煤系“三气”储层孔隙特征对比[J].天然气地球科学,2017,28(3):356-365.YANG Xiaodong,ZHANG Miao,WEI Wei,et al.Comparison of pore characteristics of the“Three Gas”reservoir in the coal seams of Guxian County,Qinshui Basin[J].Natural Gas Geoscience,2017,28(3):356-365.
[14]程鸣,傅雪海,张苗,等.沁水盆地古县区块煤系“三气”储层覆压孔渗试验对比研究[J].天然气地球科学,2018,29(8):1163-1171.CHENG Ming,FU Xuehai,ZAHNG Miao,et al.Comparative study on porosity and permeability in net confining stress of three natural gases in coal series reservoirs in Guxian County,Qinshui Basin[J].Natural Gas Geoscience,2018,29(8):1163-1171.
[15]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.
[16]苏付义.围限压力下煤岩孔隙度的变化特征及应用[J].煤田地质与勘探,1994,22(3):27-31.SU Fuyi.Characteristics of coal rock porosity change under confining pressure and its application[J].Coal Geology Exploration,1994,22(3):27-31.
[17]杨满平,王刚,许胜洋,等.考虑应力敏感性的煤层气稳定流动气井产能方程[J].天然气地球科学,2011,22(2):347-351.YANG Manping,WANG Gang,XU Shengyang,et al.Steady flow productivity equation for stress sensitivity coal bed methane gas well[J].Natural Gas Geoscience,2011,22(2):347-351.
[18]孟召平,侯泉林.高煤阶煤储层渗透性与应力耦合模型及控制机理[J].地球物理学报,2013,56(2):667-675.MENG Zhaoping,HOU Quanlin.Coupling model of stress-dependent permeability in high-rank coal reservoir and its control mechanism[J].Chinese Journal of Geophysics-Chinese Edition,2013,56(2):667-675.
[19]陈术源,秦勇,申建,等.高阶煤渗透率温度应力敏感性试验研究[J].煤炭学报,2014,39(9):1845-1851.CHEN Shuyuan,QIN Yong,SHEN Jian,et al.Experimental study on temperature sensitivity of high rank coal permeability[J].Journal of China Coal Society,2014,39(9):1845-1851.
[20]朱庆忠,汤达祯,左银卿,等.樊庄区块开发过程中煤储层渗透率动态变化特征[J].煤炭科学技术,2017,45(7):85-92.ZHU Qingzhong,TANG Dazhen,ZUO Yinqing,et al.Permeability dynamic variation features of coal reservoir in exploitation process of Fanzhuang Block[J].Coal Science and Technology,2017,45(7):85-92.
[21]陈刚,秦勇.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.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.
[2]汪岗,秦勇,申建,等.基于变孔隙压缩系数的深部低阶煤层渗透率试验[J].石油学报,2014,35(3):462-468.WANG Gang,QIN Yong,SHEN Jian,et al.Experimental studies of deep low-rank coal reservoirs'permeability based on variable pore compressibility[J].Acta Petrolei Sinica,2014,35(3):462-468.
[3]孟雅,李治平.覆压下煤的孔渗性试验及其应力敏感性研究[J].煤炭学报,2015,40(1):154-159.MENG Ya,LI Zhiping.Experimental study on the porosity and permeability of coal in net confining stress and its stress sensitivity[J].Journal of China Coal Society,2015,40(1):154-159.
[4]Min K B,Rutqvist J,Tsang C F,et al.Stress-dependent permeability of fractured rock masses:a numerical study[J].International Journal of Rock Mechanics&Mining Sciences,2004,41(7):1191-1210.
[5]ZHANG J,Standifird W B,Roegiers J C,et al.Stress-dependent fluid flow and permeability in fractured media:from lab experiments to engineering applications[J].Rock Mechanics&Rock Engineering,2007,40(1):3-21.
[6]TENG T,GAO F,YANG J,et al.How moisture loss affects coal porosity and permeability during gas recovery in wet reservoirs?[J].International Journal of Mining Science and Technology,2017,27(6):899-906.
[7]Enever J R,Henning A.The relationship between permeability and effective stress for Australian coal and its implications with respect to coalbed methane exploration and reservoir modeling[C]//Proceedings of the 1997 International Coalbed Methane Symposium.1997:13-22.
[8]贾慧敏,孙世轩,毛崇昊,等.基于煤岩应力敏感性的煤层气井单相流产水规律研究[J].煤炭科学技术,2017,45(12):189-193.JIA Huimin,SUN Shixuan,MAO Chonghao,et al.Study on water production law of single-phase flow in CBM wells based on stress sensitivity of coal and rock[J].Coal Science and Technology,2017,45(12):189-193.
[9]陈浩,秦勇,李贵中,等.基于脉冲衰减法的煤岩渗透率应力敏感性研究[J].煤炭科学技术,2018,46(6):167-172.CHEN Hao,QIN Yong,LI Guizhong,et al.Study on stress sensitivity of coal rock permeability based on pulse-decay method[J].Coal Science and Technology,2018,46(6):167-172.
[10]王运海.延川南深部煤层气井排采制度研究[J].煤炭科学技术,2018,46(6):132-137.WANG Yunhai.Study on drainage and production system of deep coalbed methane well in South Yanchuan Block[J].Coal Science and Technology,2018,46(6):132-137.
[11]侯旭伟,周效志,陶智辉,等.重复荷载下不同饱水压力中阶煤应力敏感性研究[J].煤炭科学技术,2018,46(8):120-124.HOU Xuwei,ZHOU Xiaozhi,TAO Zhihui,et al.Stress sensitivity of medium-rank coal under different saturated pressures under repeated loading[J].Coal Science and Technology,2018,46(8):120-124.
[12]JASINGE D,RANJITH P G,CHOI S K.Effects of effective stress changes on permeability of latrobe valley brown coal[J].Fuel,2011,90(3):1292-1300.
[13]杨晓东,张苗,魏巍,等.沁水盆地古县区块煤系“三气”储层孔隙特征对比[J].天然气地球科学,2017,28(3):356-365.YANG Xiaodong,ZHANG Miao,WEI Wei,et al.Comparison of pore characteristics of the“Three Gas”reservoir in the coal seams of Guxian County,Qinshui Basin[J].Natural Gas Geoscience,2017,28(3):356-365.
[14]程鸣,傅雪海,张苗,等.沁水盆地古县区块煤系“三气”储层覆压孔渗试验对比研究[J].天然气地球科学,2018,29(8):1163-1171.CHENG Ming,FU Xuehai,ZAHNG Miao,et al.Comparative study on porosity and permeability in net confining stress of three natural gases in coal series reservoirs in Guxian County,Qinshui Basin[J].Natural Gas Geoscience,2018,29(8):1163-1171.
[15]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.
[16]苏付义.围限压力下煤岩孔隙度的变化特征及应用[J].煤田地质与勘探,1994,22(3):27-31.SU Fuyi.Characteristics of coal rock porosity change under confining pressure and its application[J].Coal Geology Exploration,1994,22(3):27-31.
[17]杨满平,王刚,许胜洋,等.考虑应力敏感性的煤层气稳定流动气井产能方程[J].天然气地球科学,2011,22(2):347-351.YANG Manping,WANG Gang,XU Shengyang,et al.Steady flow productivity equation for stress sensitivity coal bed methane gas well[J].Natural Gas Geoscience,2011,22(2):347-351.
[18]孟召平,侯泉林.高煤阶煤储层渗透性与应力耦合模型及控制机理[J].地球物理学报,2013,56(2):667-675.MENG Zhaoping,HOU Quanlin.Coupling model of stress-dependent permeability in high-rank coal reservoir and its control mechanism[J].Chinese Journal of Geophysics-Chinese Edition,2013,56(2):667-675.
[19]陈术源,秦勇,申建,等.高阶煤渗透率温度应力敏感性试验研究[J].煤炭学报,2014,39(9):1845-1851.CHEN Shuyuan,QIN Yong,SHEN Jian,et al.Experimental study on temperature sensitivity of high rank coal permeability[J].Journal of China Coal Society,2014,39(9):1845-1851.
[20]朱庆忠,汤达祯,左银卿,等.樊庄区块开发过程中煤储层渗透率动态变化特征[J].煤炭科学技术,2017,45(7):85-92.ZHU Qingzhong,TANG Dazhen,ZUO Yinqing,et al.Permeability dynamic variation features of coal reservoir in exploitation process of Fanzhuang Block[J].Coal Science and Technology,2017,45(7):85-92.
[21]陈刚,秦勇.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.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.