平顶山矿区煤层气赋存特征及开发潜力

平顶山矿区二１支富含煤层甲烷气体，其资源量估算达３０２亿ｍ＾３以上。本文通过对控制煤层气赋存的二１煤层的储层几何形态，地质特征，煤质变化，特别是物性特征的研究，指出本区二１煤层渗透性较好，渗透率随着围限压力增加而降低，且与割理发育程度，构造应力变化有密切关系。     

华北盆山演化对深部煤与煤层气赋存的制约

深部煤和煤层气的聚集及赋存与盆山演化有着密切的关系.在对华北陆块中新生代盆山演化过程与特征研究的基础上,以其主要含煤区为研究区域,探讨了华北陆块盆山演化对其含煤区深部煤和煤层气的制约作用.结果表明:华北不同地区盆山演化特征不仅导致了含煤盆地结构的复杂多变,也使煤层埋深及煤的储层物性发生了不同程度的变化.渤海湾盆地,受挤压和伸展控制作用,其煤层埋藏深;煤层气沿断裂运移至上覆岩层中,形成常规天然气藏,但仍有部分煤层气赋存于深部煤层中,形成煤层气富集层.鲁西含煤区以伸展滑脱作用为主,煤层埋深增加;由于张性断裂作用,煤层含气量降低.两准含煤区以逆冲推覆作用为主,使煤层埋深增加;淮北煤田岩浆-热作用相对淮南煤田强烈,煤层含气性局部变好,渗透率也有所增高.豫西含煤区重力滑动产生的牵引褶皱区,煤层埋深增加,煤层气保存较好.沁水盆地以挤压复向斜构造为主,使煤层埋深增加,且岩浆-热作用明显,煤层含气性较好,而叠加后期形成的构造裂隙,渗透率较好.鄂尔多斯盆地受沉积厚度的影响而煤层埋深增加;由于煤中内生裂隙较多,渗透性也较好.     

河南胡襄煤田煤层赋存特征及控气因素

以河南胡襄煤田为研究区,通过定性分析和定量研究,探讨了煤层厚度、煤层埋深、上覆基岩厚度、地质构造、顶底板岩性以及变质程度等因素对煤层气富集的控制作用.通过数理统计方法,得出了煤层厚度、埋深、上覆基岩厚度与煤层含气量的回归方程,并进行了显著性检验.研究结果表明,随着煤层厚度的增加,含气量有着增大的趋势,两者之间具有线性正相关关系;随着埋深和上覆基岩厚度的增加,含气量都有着先快速增大而后缓慢增大的趋势,且具有对数正相关关系;煤变质程度是二1煤层和二2煤层含气量变化的影响因素之一,且含气量随Ro,max的增加而增大;次级褶曲向斜翼部和背斜轴部富气,且向抬升区域运移;断层或煤层露头线附近,含气量较小;断层的上升盘含气量明显小于下降盘;断层尖灭端附近,含气量大;煤层顶底板岩性对含气量有一定的影响.     

高煤级煤储层渗透率在煤层气排采中的动态变化数值模拟

针对高煤级煤储层渗透率尤其是其动态变化规律极少开展研究的现状，基于现代测试技术和沁水盆地排采效果较好的煤层气井实测排采数据，利用目前国际上较为先进的煤层气数值模拟软件CINET2，采用分段拟合的方法对煤层气井的产气、产水过程进行历史拟合和修正，进而对高煤级煤储层渗透率在开采中的动态变化规律进行了探讨．研究结果表明，煤层气并工作制度的变化会引起煤层气井采动状况发生变化，导致煤储层渗透率产生波动．煤储层渗透率随着煤层气井排采时间呈指数规律缓慢衰减，与物理模拟实验结果显示的渗透率与有效应力的关系具有相似的结论．     

两软一硬煤层突出控制因素与发生规律

针对两软一硬煤层特殊的瓦斯地质条件,以云盖山井田一矿二1煤层为例,探寻了两软一硬煤层煤与瓦斯突出的控制因素,分析了掘进工作面掘进期间突出预测指标的分布特征,总结归纳了"两软一硬"煤层煤与瓦斯突出发生规律.研究结果表明,由于地质构造变动,云盖山一矿二1煤层产状变化较大,煤层倾角发生急剧变化的地带,地应力集中;受层间滑动构造的影响,煤层厚度变化较大,具有突然增厚、变薄以至尖灭、挤灭现象;二1煤层构造软煤呈连续层状发育.因此,在煤层薄、厚交接处(煤层急剧变化带),小断层附近,应力集中,瓦斯积聚,煤体破坏严重,易发生突出.此项研究,可为地质条件类似矿井开展瓦斯地质研究和瓦斯灾害防治工作提供方法借鉴和理论指导.     

焦作煤田煤层气资源特征及开发利用研究

煤层气是国家高度重视和亟待勘查开发的重要能源矿种，也是我国紧缺与需要的战略能源．通过对焦作煤田煤层气地质条件、资源特征及开发利用方法现状的研究，认为焦作煤田具备煤层气开采条件及煤层气赋存地质条件；焦作煤田有大面积的石炭二叠系含煤地层分布，并且含煤层数多，煤层较为稳定，储量大；因此，焦作煤田拥有丰富的煤层气资源，含气饱和度和煤层渗透率较高，资源密度高，有利于煤层气开发利用．焦作煤田煤层气的开发对改善焦作市能源供给结构，提高资源利用率、保护生态环境具有重要意义．     

乡宁矿区煤储层地质特征研究

煤层气富集成藏受煤储层地质特征的制约。通过对大量实验测试数据的分析与对比,研究了乡宁矿区煤层气成藏基础地质特征,主要包括煤储层发育特征、煤岩学特征、煤化学与工艺特征及煤级与煤相特征等。结果表明,本区主要煤层煤空间展布稳定、累计厚度大、煤质好、热演化程度高,具备煤层气成藏的基础条件。     

煤基块弹性能及其与地质控制因素之间的关系

煤储层弹性能是联系成藏动力学条件与煤层气藏之间的桥梁和纽带，煤基块弹性能是储层能量的主要组成部分，是煤层气成藏的关键．本文通过煤基块弹性能物理模拟实验，对影响煤基块弹性能的参数进行了研究，分析了其与地质控制因素之间的关系．研究表明：煤基块弹性能受控于煤体自身的岩石力学性质，与地质历史时期的煤储层埋藏深度、煤级演化程度密切相关．煤基块弹性能随着煤储层埋深的增加而降低，随着煤级的升高而增大．     

河南省下二叠统山西组二_1煤煤层气储层描述

从煤厚、煤岩组成、煤级、煤体结构、裂隙系统、渗透性、吸附／解吸特性等方面对河南省的主可采煤层二１煤的煤层气的储层特征进行了详细论述．指出镜质组含量较高、割理比较发育、外生裂隙发育适中的原生结构煤和碎裂煤渗透性最好,是最有利的储层;外生裂隙发育适中的无烟煤是有利储层;碎粒煤为不利储层;糜棱煤为不可开发储层．临界解吸压力较高、含气量较高的中煤级煤分布区是煤层气勘探开发的首选地区．     

考虑有效应力和煤基质收缩效应的渗透率模型

针对煤层气的生产过程中所存在的两个相反的效应:(1) 储层压力下降,有效应力增加,煤层裂隙压缩闭合,渗透率降低;(2) 煤层气解吸,煤基质收缩,煤层气流动路径张开,渗透率升高;建立了包含煤基质收缩效应的煤层孔隙度和渗透率理论模型,模型与已有的一些研究结果反映的规律一致.根据模型得出在体积应力恒定条件下,渗透率随孔隙压力变化存在一临界压力,孔隙压力小于临界压力时,渗透系数随孔隙压力的增加而减少,孔隙压力大于临界压力时,渗透系数随孔隙压力的增加而增大,给出了该临界压力的计算式.对不同情形下渗透率对孔隙压力的变化响应进行了讨论,结果表明,临界压力的存在与否与影响渗透率的多种因素有关,应对影响煤层渗透性的众多因素进行动态耦合研究.     

沁水盆地山西组煤储层含气性及控制因素分析

依据实测资料,在统计分析研究区３号煤层含气性特征的基础之上,对控气地质机理进行了探讨,总体上来看,研究区甲烷含量较高高及甲烷浓度较大,而含气饱和度偏低。在埋深１０００ｍ以浅,向盆地内部方向以及随煤层埋深加大,甲烷含量,甲烷浓度和含气孢和度具有增大趋势,显示出埋探控气以及次级向斜相对富气的特点,这种特征可以起源于地质历史时期中煤层抬升卸压过程所导致的煤层气解吸扩散作用。因此,进一步查明次级构造的发育     

焦作矿区山西组二1煤层含气量的控制因素探讨

分析了焦作矿区煤层气含量的分布规律 ;探讨了断块构造、煤层埋深、上覆岩层厚度等对煤层气的控制作用 .结果表明 :焦作矿区山西组二1煤煤层气含量较高 ,最高达 3 2 .7m3 /t(daf) ,平均为 1 6 .7m3 /t(daf) ;由于煤变质及其演化、煤层的有效埋藏深度、抬升剥蚀作用和地质构造等因素对煤储层特性产生显著的影响 ,使本区煤层气含量分布具有明显的规律性 ,从西部断块至东部断块煤层气含量由高到低变化 ,且各断块内由浅部向深部逐渐增高 .     

Application of structural curvature of coalbed floor on CBM development in the Zaoyuan block of the southern Qinshui Basin

Based on controls of structural style and the position in coalbed methane(CBM)development,we used a method of curvatures to study its relations with CBM development parameters.We calculated structural curvatures of contours of the No.3coal seam floor of the Shanxi Formation in the Zaoyuan block of the Qinshui Basin and analyzed its relations with development parameters of coalbed methane wells.The results show that structural curvature is negatively related to coal reservoir pressure,while positively related to permeability.With an increase in structural curvature,the average production of coalbed methane wells increases at first and then decreases,reaching the highest production at 0.02 m-1 of structural curvature.Therefore,structural curvature can be an important index for potential evaluation of coalbed methane development and provide a basis for siting coalbed methane wells.     

淮北地区煤储层物性及煤层气勘探前景

研究了淮北地区地物构造演化及控气特征,结果认为：淮北地区印支期以来的构造演化对煤储层物性控制作用十分显著,以EW向的宿北断裂为界,北部地区煤层气勘探前景不佳,南部地区的东部,煤层的展布受褶皱形态的控制。在宿面向斜和南坪向斜中,煤层埋深、煤体结构、含气性、含气量和渗透率等储层物性均有利于煤层气的运移、聚集和保存,具有较好的煤层气勘探前景;临涣矿区强变形构造煤发育,煤体结构复杂,基本无勘探前景;涡阳矿区正断层发育,煤层气含量相对较小,但渗透性较好,值得进一步深入研究。     

古汉山井田煤层气赋存特征

以焦作煤田古汉山井田为研究区,通过定性分析与定量研究,探讨了煤层埋深、顶底板岩性、煤层埋深以及地质构造等因素对煤层含气性的控制;通过数理统计的方法,得出了埋深、有效埋藏深度以及煤厚与煤层含气量的回归方程,并对回归方程进行了显著性检验.研究结果表明,煤厚、断裂构造以及埋深是影响古汉山井田煤层气赋存特征的主要因素,并表现为:①随着煤厚的增加,含气量线形增大.②随着埋深和有效埋藏深度的增加,含气量先是急剧增大,到了一定阶段后,增大趋势变慢,之间具有对数正相关关系.③在断层尖灭端,含气量大,断裂带内含气量小;正断层的下降盘的含气量大于上升盘,同一正断层的上升盘附近,距离断层面越远,含气量越大.煤层的顶板岩性对含气量有一定的影响,但不是引起井田内煤层含气量变化的主控因素.     

新兴煤矿22号煤层瓦斯赋存影响因素分析

为了研究新兴煤矿地质构造对瓦斯赋存的控制作用,以瓦斯地质原理为基础,采用瓦斯赋存构造逐级控制理论方法,以煤层厚度、煤层埋藏深度、断层性质和凝灰岩厚度等影响因素为依托,建立了煤层瓦斯与地质影响因素相互关系的多元回归数学模型,并得出与实际值比较接近的预测值.研究结果表明:煤层埋藏深度是影响新兴煤矿22号煤层瓦斯含量的主控因素;上覆凝灰岩对煤层瓦斯保存起到了积极作用;NW-NWW向断层附近容易发生煤与瓦斯动力现象.     

Reservoir reconstruction technologies for coalbed methane recovery in deep and multiple seams

Multiple coal seams widely develop in the deep Chinese coal-bearing strata. Ground in situ stress and coal seam gas pressure increase continuously with the increase of the mining depth, and coal and gas outburst disasters become increasingly severe. When the coal is very deep, the gas content and pressure will elevate and thus coal seams tends to outburst-prone seams. The safety and economics of exploited firstmined coal seams are tremendously restricted. Meanwhile, the multiple seams occurrence conditions resulted in different methane pressure systems in the coal-bearing strata, which made the reservoir reconstruction of coal difficult. Given the characteristics of low saturation, low permeability, strong anisotropy and soft coal of Chinese coal seams, a single hydraulic fracturing surface well for reservoir reconstruction to pre-drain the coalbed methane(CBM) of multiple seams concurrently under the different gas pressure systems has not yet gained any breakthroughs. Based on analyses of the main features of deep CBM reservoirs in China, current gas control methods and the existing challenges in deep and multiple seams, we proposed a new technology for deep CBM reservoir reconstruction to realize simultaneous high-efficiency coal mining and gas extraction. In particular, we determined the first-mined seam according to the principles of effectiveness and economics, and used hydraulic fracturing surface well to reconstruct the first-mined seam which enlarges the selection range of the first-mined seam. During the process of mining first-mined seam, adjacent coal seams could be reconstructed under the mining effect which promoted high-efficiency pressure relief gas extraction by using spatial and comprehensive gas drainage methods(combination of underground and ground CBM extraction methods). A typical integrated reservoir reconstruction technology, ‘‘One well for triple use", was detailed introduced and successfully applied in the Luling coal mine. The application showed that the proposed technology could effectively promote coal mining safety and simultaneously high-efficiency gas extraction.     

Estimation of correction coefficients for measured coal bed methane contents

Improving the accuracy and precision of coal bed methane (CBM) estimates requires correction of older data from older coal exploration surveys to newer standards. Three methods, the depth gradient method, the contour aerial weight method, and the well-point aerial weight method, were used to estimate the correction coefficient required to predict CBM gas content from coal exploration data. The data from the Nos. 3 and 15 coal seams provided the coal exploration data while the CBM exploration stages within the X1 well block located in the southern part of the Qinshui Basin provided the data obtained using newer standards. The results show the correction coefficients obtained from the two aerial weight methods are similar in value but lower than the one obtained from the depth gradient method. The three methods provide similar results for the Nos. 3 and 15 seams in that the correction factor is lower for the former seam. The results from the depth gradient method taken together with the coal seam burial depth and the coal rank suggest that variations in the correction factor increase linearly along with coal seam burial depth and coal rank. The correlation obtained can be applied to exploration and the evaluation of coal bed gas resources located in coalfields.     

Status of research on biogenic coalbed gas generation mechanisms

Biogenic coalbed gas,how it is generated and the geochemical characteristics of the gas are gaining global attention.The ways coalbed gas is generated,the status of research on the generation mechanism and the methods of differentiating between biogenic gasses are discussed.The generation of biogenic coalbed methane is consistent with anaerobic fermentation theory.Commercial biogenic coalbed gas reservoirs are mainly generated by the process of CO2 reduction.The substrates used by the microbes living in the coal include organic compounds,CO2,H2 and acetate.The production ratio and quantity of biogenic coalbed methane depend on the exposed surface area,the solubility and permeability of the coal and the microbial concentration in the coal seam.It is generally believed that biogenic coalbed gas has a value for σ13C1＜-5.5%,C1/C1+＞0.95.The H isotope ratio is controlled by both the environment and the generation mechanism:typically σD1＜-20%.Biogenic methane formed by CO2 reduction has more σD1 than that formed by acetate fermentation.     

黄岩汇煤矿瓦斯地质规律及区域预测

在收集整理黄岩汇煤矿地质资料和瓦斯资料的基础上,运用地质构造控制理论,展开井下实测和地质编录,以分析矿区和井田地质构造分布特征,研究地质构造、顶底板岩性、煤层埋藏深度等地质因素对瓦斯赋存的影响,得出了井田内15号煤层瓦斯含量分布规律和构造煤的分布规律;同时,对黄岩汇煤矿15号煤层突出危险性也进行了区域预测．研究表明,煤层埋藏深度是影响黄岩汇煤矿15号煤层瓦斯含量分布的主控因素,其他地质因素仅仅影响煤层瓦斯的局部变化;将埋深大于321m的15号煤层划分为突出危险区,其余的则为非突出危险区．