覆岩不同采动损伤煤样应力敏感性研究
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摘要
为了研究覆岩不同采动损伤程度煤样渗透率的应力敏感性,基于覆岩各分带内煤岩损伤裂隙发育情况,将煤体分为弹性煤样(弯曲下沉带)、贯穿裂隙煤样(裂隙带)以及破碎煤样(垮落带).结合不同损伤程度煤样循环加卸载实验拟合参数,提出绝对应力敏感性系数及相对应力敏感性系数评价各类煤样重复加卸载过程中的应力敏感性大小及变化趋势.研究结果表明:第1次加载阶段的绝对应力敏感性远大于之后的加载阶段.在应力加载初期,贯穿裂隙煤样的绝对应力敏感性系数大于破碎煤样且远大于弹性煤样,而弹性煤样的相对应力敏感性系数大于破碎煤样与贯穿裂隙煤样;在应力加载后期,破碎煤样的绝对与相对应力敏感性系数均大于贯穿裂隙煤样及弹性煤样.
In order to study the permeability stress sensitivity of coal samples in each fracture zones,the coal samples were divided into the elastic coal samples(bending zone),the persistent fracture coal samples(fractured zone)and the broken coal samples(caving zone).The permeability experiments of coal samples with different damage degree under cyclic loading and unloading were carried out in this paper.Based on the fitting permeability model,the absolute stress sensitivity coefficient and the relative stress sensitivity coefficient were proposed to analyze the stress sensitivity and the changing trend of the coal samples' permeability.The results indicate that the absolute stress sensitivity of coal samples with different damage degree is the largest at the first loading stage.At the beginning of the loading stage,the absolute stress sensitivity of broken coal samples is much larger than that of persistent fracture coal samples and elastic coal samples,while the relative stress sensitivity of elastic coal samples is greater thanthat of broken coal samples and persistent fracture coal samples.At the later of loading stage,the absolute and relative stress sensitivity coefficients of broken coal samples are greater than that of the persistent fracture coal samples and the elastic coal samples.
In order to study the permeability stress sensitivity of coal samples in each fracture zones,the coal samples were divided into the elastic coal samples(bending zone),the persistent fracture coal samples(fractured zone)and the broken coal samples(caving zone).The permeability experiments of coal samples with different damage degree under cyclic loading and unloading were carried out in this paper.Based on the fitting permeability model,the absolute stress sensitivity coefficient and the relative stress sensitivity coefficient were proposed to analyze the stress sensitivity and the changing trend of the coal samples' permeability.The results indicate that the absolute stress sensitivity of coal samples with different damage degree is the largest at the first loading stage.At the beginning of the loading stage,the absolute stress sensitivity of broken coal samples is much larger than that of persistent fracture coal samples and elastic coal samples,while the relative stress sensitivity of elastic coal samples is greater thanthat of broken coal samples and persistent fracture coal samples.At the later of loading stage,the absolute and relative stress sensitivity coefficients of broken coal samples are greater than that of the persistent fracture coal samples and the elastic coal samples.
引文
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[20]周勇,徐黎明,纪友亮,等.致密砂岩相对高渗储层特征及分布控制因素研究-以鄂尔多斯盆地陇东地区延长组长82为例[J].中国矿业大学学报,2017,46(1):106-120.ZHOU Yong,XU Liming,JI Youliang,et al.Characteristics and distributing controlling factors of relatively high permeability reservoir:A case study from Chang 82 sandstones of Yanchang formation in Longdong area,Ordos basin[J].Journal of China University of Mining&Technology,2017,46(1):106-120.
[2]张村,屠世浩,袁永,等.卸压开采地面钻井抽采的数值模拟研究[J].煤炭学报,2015,40(增2),392-400.ZHANG Cun,TU Shihao,YUAN Yong,et al.Numerical simulation of surface gas venthole extraction in pressure relief mining[J].Journal of the China Coal Society,2015,40(Sup2):392-400.
[3]CUI X,BUSTIN R M.Volumetric strain associated with methane desorption and its impact on coalbed gas production from deep coal seams[J].Aapg Bulletin,2005,89(9):1181-1202.
[4]PALMER I.Permeability changes in coal:Analytical modeling[J].International Journal of Coal Geology,2009,77(1):119-126.
[5]SHI J Q,DURUCAN S,SHI J Q,et al.Exponential growth in san juan basin fruitland coalbed permeability with reservoir drawdown:model match and new insights[J].Spe Reservoir Evaluation&Engineering,2010,13(6):915-925.
[6]杨金保,冯夏庭,潘鹏志.考虑应力历史的岩石单裂隙渗流特性试验研究[J].岩土力学,2013,34(6):1629-1635.YANG Jingbao,FENG Xiating,PAN Pengzhi.Experimental study of permeability characteristics of single rock fracture considering stress history[J].Rock&Soil Mechanics,2013,34(6):1629-1635.
[7]肖维民,夏才初,邓荣贵.岩石节理应力-渗流耦合试验系统研究进展[J].岩石力学与工程学报,2014,33(2):3456-3465.XIAO Weimin,XIA Caichu,DENG Ronggui.Advances in development of coupled stress-flow test system for rock joints[J].Chinese Journal of Rock Mechanics&Engineering,2014,33(2):3456-3465.
[8]SINGH K K,SINGH D N,RANJITH P G.Laboratory simulation of flow through single fractured granite[J].Rock Mechanics and Rock Engineering,2015,48(3):987-1000.
[9]HOEK E,BRAY J W.Rock slope engineering[J].Engineering Geology,1981,9(1):92-93.
[10]ATKINSON T,DOW R,BROM R W C.A review of hydrological investigations for deep coal mines,with special reference to petrophysical methods[J].International Journal of Mine Water,1984,3(3):19-34.
[11]魏建平,秦恒洁,王登科.基于水分影响的加-卸载围压条件下含瓦斯煤渗流特性研究[J].采矿与安全工程学报,2014,31(6):987-994.WEI Jianping,QIN Hengjie,WANG Dengke.Seepage characteristics of coal mass containing gas considering moisture effect in loading-unloading confining pressure test[J].Journal of Mining&Safety Engineering,2014,31(6):987-994.
[12]许江,李波波,周婷,等.循环荷载作用下煤变形及渗透特性的试验研究[J].岩石力学与工程学报,2014,33(2):226-234.XU Jing,LI Bobo,ZHOU Ting,et al.Experimental study of deformation and seepage characteristics of coal under cyclic loading[J].Chinese Journal of Rock Mechanics&Engineering,2014,33(2):226-234.
[13]李东印,王文,李化敏,等.重复加-卸载条件下大尺寸煤样的渗透性研究[J].采矿与安全工程学报,2010,27(1):111-125.LI Dongyin,WANG Wen,LI Huamin,et al.Research on permeability of large-sized coal sample in loading and unloading test[J].Journal of Mining&Safety Engineering,2010,27(1):111-125.
[14]SEIDLE J P,JEANSONNE M W,ERICKSON D J,et al.Application of matchstick geometry to stress dependent permeability in coals[J].Spe Rocky Mountain Regional Meeting,1992:433-444.
[15]MCKEE C R,BUMB A C,KOENIG R A.Stress-dependent permeability and porosity of coal and other geologic formations[J].Spe Formation Evaluation,1988,3(1):81-91.
[16]CHEN D,PAN Z,YE Z.Dependence of gas shale fracture permeability on effective stress and reservoir pressure:Model match and insights[J].Fuel,2015(139):383-392.
[17]CHEN D,PAN Z,YE Z,et al.A unified permeability and effective stress relationship for porous and fractured reservoir rocks[J].Journal of Natural Gas Science&Engineering,2016(29):401-412.
[18]WARREN J E,ROOT P J.The behavior of naturally fractured reservoirs[J].Society of Petroleum Engineers Journal,1963,3(3):245-255.
[19]孟召平,侯泉林.煤储层应力敏感性及影响因素的试验分析[J].煤炭学报,2012,37(3):430-437.MENG Zhaoping,HOU Quanlin.Experimental research on stress sensitivity of coal reservoir and its influencing factors[J].Journal of the China Coal Society,2012,37(3):430-437.
[20]周勇,徐黎明,纪友亮,等.致密砂岩相对高渗储层特征及分布控制因素研究-以鄂尔多斯盆地陇东地区延长组长82为例[J].中国矿业大学学报,2017,46(1):106-120.ZHOU Yong,XU Liming,JI Youliang,et al.Characteristics and distributing controlling factors of relatively high permeability reservoir:A case study from Chang 82 sandstones of Yanchang formation in Longdong area,Ordos basin[J].Journal of China University of Mining&Technology,2017,46(1):106-120.