ON GOLD-BEARING CHARACTERISTICS OF GEOSYNCLINAL TECTONIC LAYER IN XUEFENG MOUNTAIN TECTONIC BELT,HUNAN,CHINA

1. Material composition of the geosynclinal tectonic LayerThe geosynclinal tectonic layer is mainly composed of the following two parts: sandyslate rocks of Precambrin and volcanic rocks inbeded within the sand-slate rocks.The sandy-slate rocks embrace the chemical compositional characteristics of light metamorphic rocks: SiO2=54.5681.63（Wt%）, with average of 63.96（wt%）（n=58, the same as following）; Al2O3=9.4717.75（wt%）, with average of 15.36（wt%）, and Al2O3】K2O+Na2O+CaO; the content of （FeO+Fe2O3） varies greatly with FeO】Fe2O3; （CaO+MgO）=0.789.22 （wt%）with average of 23 （wt%）, and MgO】CaO; the ratios of K2O/Na2O rang from 2 to 4（】1）. By comparing all this chemical data with that of the other kind rocks, We can know that the sand y-slate rocks were the eunic and /or bathyal sediments which formed under the strongly active eugeosynclinal tectonic setting.

Tectonic Evolution and Geological Characteristics of Hydrocarbon Reservoirs in Marine Mesozoic-Paleozoic Strata in the South Yellow Sea Basin

The South Yellow Sea Basin is the main body of the lower Yangtze area in which marine Mesozoic–Paleozoic strata are widely distributed.The latest geophysical data were used to overcome the limitation of previous poor-quality deep data.Meanwhile,the geological characteristics of hydrocarbon reservoirs in the marine Mesozoic–Paleozoic strata in the South Yellow Sea Basin were analyzed by comparing the source rocks and the reservoir and utilizing drilling and outcrop data.It is believed that the South Yellow Sea Basin roughly underwent six evolutionary stages:plate spreading,plate convergence,stable platform development,foreland basin development,faulted basin development,and depression basin development.The South Yellow Sea Basin has characteristics of a composite platform-fault depression geological structure,with a half-graben geological structure and with a ‘sandwich structure' in the vertical direction.Four sets of hydrocarbon source rocks developed – the upper Permian Longtan–Dalong formation,the lower Permian Qixia formation,the lower Silurian Gaojiabian formation,and the lower Cambrian Hetang formation/Mufushan formation,giving the South Yellow Sea Basin relatively good hydrocarbon potential.The carbonate is the main reservoir rock type in the South Yellow Sea area,and there are four carbonate reservoir types:porous dolomitic,reef-bank,weathered crust,and fractured.There are reservoir-forming horizons similar to the typical hydrocarbon reservoirs in the Yangtze land area developed in the South Yellow Sea,and there are three sets of complete source-reservoir-cap rock assemblages developed in the marine strata,with very good hydrocarbon potential.

Time-domain characteristics of overlying strata failure under condition of longwall ascending mining

Ascending mining is one of the most effective ways to solve problems of water inrush, gas outburst and rock burst in coal seams mining. In order to reveal the law of motion and spatiotemporal relationship of overlaying strata, field measurement has been done in a mine. Long distance drillings were constructed from 4# coal seam to 6# coal seam at several certain typical positions, and movement and failure law of overlying strata after mining was analyzed by drilling video and observing the fluid leakage. Besides, we also analyzed the spatiotemporal development law of overlying strata failure with different mining heights and time intervals in the lower coal seam. The results show that: ascending mining is significantly affected by time-domain characteristics of overlaying strata failure after the lower coal seam's mining, height equations of caving zone and fractured zone are given in this paper, and the feasibility of ascending mining was compartmentalized concretely according to the spatiotemporal relationship. Research methods and conclusions of this paper have certain referential significance for the study of ascending mining, mining under water, mining under building, mining under railway and stress-relief mining.

Geological conditions and reservoir characteristics of various shales in major shalehosted regions of China

China is home to shales of three facies:Marine shale,continental shale,and marine-continental transitional shale.Different types of shale gas are associated with significantly different formation conditions and major controlling factors.This study compared the geological characteristics of various shales and analyzed the influences of different parameters on the formation and accumulation of shale gas.In general,shales in China’s several regions exhibit high total organic carbon(TOC)contents,which lays a sound material basis for shale gas generation.Marine strata generally show high degrees of thermal evolution.In contrast,continental shales manifest low degrees of thermal evolution,necessitating focusing on areas with relatively high degrees of thermal evolution in the process of shale gas surveys for these shales.The shales of the Wufeng and Silurian formations constitute the most favorable shale gas reservoirs since they exhibit the highest porosity among the three types of shales.These shales are followed by those in the Niutitang and Longtan formations.In contrast,the shales of the Doushantuo,Yanchang,and Qingshankou formations manifest low porosities.Furthermore,the shales of the Wufeng and Longmaxi formations exhibit high brittle mineral contents.Despite a low siliceous mineral content,the shales of the Doushantuo Formation feature a high carbonate mineral content,which can increase the shales’brittleness to some extent.For marine-continental transitional shales,where thin interbeds of tight sandstone with unequal thicknesses are generally found,it is recommended that fracturing combined with drainage of multiple sets of lithologic strata should be employed to enhance their shale gas production.

Characteristics of Gas Emission at Super-Length Fully-Mechanized Top Coal Caving Face

Characteristics of gas emission at the K8206 working face in the Third mine of the Yangquan Coal Group were investigated. The effects of strata movement,advancing velocity of working face,production capacity of working face and gas extraction capability of strike high-level entry on gas emission at K8206 working face were analyzed. A regression equation,reflecting the relationship between relative gas emission rate and the production capacity of work-ing faces,was established. Another regression equation showing the relationship between the gas emission rate from adjacent layers when the working face was advancing for one metre and advancing velocity was derived. It can be con-cluded that,1) the amount of gas emitted at the K8206 working face is far greater than that of ordinary top coal caving faces with a dip length of 180-190 m; 2) the dynamic process of gas emission from adjacent layers during the initial mining stage is controlled by the movement of key strata; 3) the amount of gas emitted that needs to be forced out by air is greatly affected by the capability of gas extraction; 4) when the advancing velocity is between 3.5-5.5 m/d or when the output is up to 8-12 kt/d,the gas emission from adjacent layers is almost constant.

Time-dependent safety of lining structures of circular tunnels in weak rock strata

Following tunnel excavation and lining completion,fractured surrounding rock deforms gradually over time;this results in a time-dependent evolution of the pressure applied to the lining structure by the surrounding rock.Thus,the safety of the tunnel lining in weak strata is strongly correlated with time.In this study,we developed an analytical method for determining the time-dependent pressure in the surrounding rock and lining structure of a circular tunnel under a hydrostatic stress field.Under the proposed method,the stress–strain relationship of the fractured surrounding rock is assumed to conform to that of the Burgers viscoelastic component,and the lining structure is assumed to be an elastomer.Based on these assumptions,the viscoelastic deformation of the surrounding rock,the elastic deformation of the lining structure,and the coordinated deformation between the surrounding rock and lining structure were derived.The proposed analytical method,which employs a time-dependent safety coefficient,was subsequently used to estimate the durability of the lining structure of the Foling Tunnel in China.The derived attenuation curve of the safety coefficient with respect to time can assist engineers in predicting the remaining viable life of the lining structure.Unlike existing analytical methods,the method derived in this study considers the time dependency of the interaction between the surrounding rock and tunnel lining;hence,it is more suitable for the evaluation of lining lifetime.

Strata behavior in extra-thick coal seam mining with upward slicing backfilling technology

Based on the character of upward slicing backfilling mining and the condition of Gonggeyingzi coal mine in Inner Mongolia,this paper describes the studies of the strata behavior and the stress distribution in the process of backfilling mining in extra-thick coal seams.This was achieved by setting up and analyzing the elastic foundation beam model using the ABAQUS software.The results show that:(1) With the gradual mining of different slices,the roof appears to bend continuously but does not break.The vertical stress in the roof decreases and the decreasing amplitude reduces,while the tensile stress in the roof grows with the mining slices and the maximum tensile stress will not exceed the allowable tensile stress.(2) The front vertical stress at the working face exceeds the rear vertical stress and both show a trend of decrease with decreasing amplitude of decrease.(3) The slices mined early have more influence on the surrounding rock than the later ones.Similarly,the strata behavior experiences the same trend.The field measured data show that the roof does not break during the mining process,which is consistent with the conclusion.

重庆地区二叠系龙潭组煤系地层非常规气地质特征分析

为探索重庆地区二叠系龙潭组煤系地层非常规气地质特征,基于区内煤田勘查、煤层(系)气勘查取得的地质资料及测试数据,对二叠系龙潭组煤系地层煤储层、暗色泥页岩储层、致密砂岩储层基本特征进行分析总结。研究表明,区内煤储层具有煤体结构以碎裂—块状为主、埋深中等、孔隙不发育、低孔低渗、含气量高的特点;暗色泥页岩储层具有低脆性、单层厚度薄、孔隙不发育、低孔低渗、含气量一般的特点;致密砂岩储层具有单层厚度薄、孔隙不发育、低孔低渗、含气性一般的特点。若考虑组合开发,具备一定的开发前景。

宁武盆地南部深部煤层气临界深度与成藏特征

近年来,随着深部煤层气勘探开发技术的不断突破,深部煤层气已逐渐成为中国油气资源重要的勘探开发新领域。但是,关于煤层气深度界线的科学内涵、深部煤层气藏的地质特征、煤层气富集模式等基础科学问题仍处于初期探索阶段。为此,以宁武盆地宁武南区块上石炭统太原组9号煤层为研究对象,基于区块20余口煤层气井的钻井、测井及试井资料等,联合等温吸附、气体同位素等实验测试手段,探讨了宁武南区块深部煤层气临界深度与成藏特征。研究结果表明:①研究区深部煤层气临界深度为1200 m,临界深度以深,深部煤层气藏具有煤层厚度大、热演化程度高、含气量及含气饱和度高、煤体结构好和孔隙度低的地质特征。②地温梯度和热演化程度是影响研究区深部煤层气临界深度及煤层气成藏条件的重要因素。结论认为,该盆地的宁武南区块深部煤层气地质特征与鄂尔多斯盆地大宁—吉县、临兴、延川南等深部煤层气区块具有可比性,展现出宁武盆地深部煤层气良好的勘探开发前景。

淤泥-岩石地层爆破临近给水管道振动特征

盾构机通过淤泥-岩石地层时,可以在地面钻孔预先爆破破碎岩石,但是淤泥-岩石地层爆破产生的振动威胁爆区周围供水管道的安全。通过对爆破振动进行现场测试和数值模拟,首先验证爆破现场材料的物理和力学参数,然后研究了爆区附近供水管道的动态响应。得出如下结论:在管道轴向上,节点峰值速度(PPV)随着距爆炸源水平距离的增加而减小;在管道正上方地表沿管道轴向,节点峰值速度也随着距爆炸源水平距离的增加而减小;管道上节点峰值速度与管道上方地面的节点峰值速度之间存在函数关系。管道内壁最大PPV是最小PPV的3.97倍,管道内壁90°处的节点峰值速度最高,管道外壁最大PPV是最小PPV的1.03倍,管道外壁150°处的节点峰值速度最高,每个节点的PPV彼此不同,给水管道内壁PPV大于外壁,内壁PPV变化较大,但外壁PPV相对接近。单元的最大峰值有效应力是单元的最小峰值有效应力的4.06倍,在管道外壁240°~270°处单元的峰值有效应力最高。本研究的结论可以为确定爆区周围供水管道的安全性提供参考。

Characteristics and Hydrocarbon Potential of Mesozoic Strata in Eastern Pearl River Mouth Basin, Northern South China Sea

The well LF35-1-1 in the eastern Pearl River Mouth basin （PRMB） of the northern South China Sea revealed unmetamorphosed Middle-Late Jurassic neritic-bathyal sediments and Cretaceous fluvial-lacustrine sediments. Three tectonic movements were identified in Late Jurassic to Early Cretaceous, late Early Cretaceous, and Late Cretaceous to Paleocene, respectively. The Late Jurassic marine facies mainly contain the hydrocarbon source and reservoir-seal assemblages, providing a main exploration target.

沁水盆地榆社—武乡区块二叠系煤系页岩储层地质建模及“甜点”预测

沁水盆地煤系页岩气资源丰富,但勘探开发处于初期阶段。基于钻井、测井和地震解释资料,结合有机地球化学与储层物性实验测试数据,通过三维地质建模技术,建立了沁水盆地榆社—武乡区块二叠系山西组底部—太原组上部煤系页岩地质模型,并预测了煤系页岩气“甜点”区。研究结果表明:(1)沁水盆地榆社—武乡区块石炭系—二叠系煤系地层模型反映了煤系页岩储层的发育主要受控于构造活动,呈“东浅西深、整体连续”的分布格局。(2)基于序贯指示法建立沉积相模型,指示研究区在太原期—山西期由海陆过渡相转变为近海陆相沉积环境,为稳定优质页岩储层的形成提供了有利的沉积环境。(3)通过相控属性建模实现了储层参数空间分布模拟和精细表征,泥地比、孔隙度、含气量、总有机碳含量和镜质体反射率的平均值分别为0.57,10.02%,1.21 m^(3)/t,2.18%,2.45%,揭示了研究区煤系页岩较好的储集能力、含气性、有机质丰度和资源潜力,脆性指数模型指示出页岩压裂后的有利区带。(4)在精细三维地质建模的基础上,将三维网格单元赋值积分,计算研究区二叠系煤系页岩气地质资源量为1 344.98×10^(8)m^(3),运用层次分析法和模糊评价法预测页岩气“甜点”区,Ⅰ类“甜点”区为地质与工程双重甜点,分布于研究区东北部、中部和西北部局部区域。

重复采动影响下含瓦斯岩层瓦斯运移规律

受重复采动影响,煤层邻近岩层中赋存的瓦斯解吸涌出,成为工作面瓦斯主要来源之一。为研究重复采动影响下含瓦斯岩层中瓦斯运移规律,以沙曲一矿5#煤及其邻近煤岩层为工程背景,在测定煤岩体瓦斯基础参数的基础上,通过数值模拟研究了重复采动影响下煤岩体卸压增透范围,得到了含瓦斯岩层渗透率的空间分布情况,进而对含瓦斯岩层瓦斯运移规律进行模拟。研究结果表明:邻近岩层中,L5灰岩层瓦斯赋存量最高,含量约为5#煤层的14.3%;重复采动导致煤岩体卸压程度增大,L5灰岩层卸压区分布在永久煤柱的边缘区;L5灰岩层卸压区内渗透率最高可达4.8×10^(-15)m^(2),为初始渗透率的7.7倍,高渗区域与卸压区域分布一致;L5灰岩层内赋存的瓦斯解吸并上涌至工作面,致使上隅角瓦斯浓度由6.1%升高至7.1%;受巷道通风影响,L5灰岩层瓦斯主要聚积在岩层后方与回风巷侧,是瓦斯抽采时应关注的重点区域。

四川盆地二叠系龙潭组页岩气储层特征与勘探潜力

通过宏观野外实测、岩芯观察以及微观薄片鉴定、氩离子抛光扫描电镜观察(SEM)等技术手段,对四川盆地上二叠系龙潭组页岩气的储层特征进行了系统分析。龙潭期主要沉积环境从南向北依次发育:河流三角洲、滨岸沼泽、潮坪、混积陆棚与碳酸盐岩台地相。富有机质泥页岩主要发育在滨岸沼泽与深水陆棚相区,川北深水陆棚相页岩具有“四高一低”的特征:高含气量(>5 m^(3)/t)、高TOC(>4%)、高孔隙度(>6%)与低黏土矿物(<38%),是未来勘探的重点区。

不同地层下钻机回转系统随载调速动态特性研究

由于钻进成井地层中岩石分布具有不确定性和随机性,导致钻机回转液压系统的动态特性复杂多变,若钻具的回转速度无法根据地层情况自动调节,将导致钻具出现“卡钻”和“偏斜”现象。以钻机回转液压系统为研究对象,对地下资源的地层分布情况进行研究,并计算出不同地层下适用的扭矩及转速;基于AMESim和Simulink构建钻机回转系统的机电液联合仿真模型;最后,研究系统在4类地层破岩作业时的动态特性及其对钻具转速的调控效果。结果表明:钻机回转系统的压力能够在0.01 s内由初始0上升至工作压力2.1 MPa,在负载扭矩突增时系统表现出良好的抗干扰能力和稳定性;此外,利用马达进出口压差来控制钻具转速的方法,其滞后性为0.5 s且误差值不超过5%,响应速度较快、控制精度较高。

贵州省陆相成煤环境特征分析

为了最大限度客观反映贵州省陆相成煤环境典型矿床的基本地质特征,在收集以往地质勘查资料及现场踏勘了解现状的基础上,合理确定煤炭沟煤矿和罗州煤矿采样位置及数量,并对煤岩样进行分析。研究得出,2个煤矿的样品固结较好,均能代表陆相成煤环境特征,具有相应的煤类特征。同时,通过实地调查选定赫章县可乐乡作为实测剖面位置,采集并保存含煤岩系地层中具有代表性的不同规格的岩石、煤炭、化石标本和钻孔样品。结果表明,宣威组主要是由灰色细砂岩、粉砂岩、粉砂质泥岩、泥质粉砂岩、黏土岩及煤层组成的韵律层,较明显地反映了含煤地层宣威组(P_(3)x)的沉积环境特征,为一套陆相地层的含煤沉积建造。

软硬交替地层超深竖井围护结构受力和变形特性

研究区地层条件以“硬岩”(泥质粉砂岩、岩屑砂岩)与“软岩”(泥岩)互层为特征,形成了明显的软硬交替地层,使竖井的受力与变形尤为复杂。采用Flac3D数值模拟方法对竖井开挖施工全过程进行研究,详细分析了施工过程中圆形地连墙和内衬的受力及变形特性,结果表明:1)在基坑开挖过程中,当开挖深度高于或处于“硬岩”时,地连墙在该软硬分界面位置处产生反弯点,向坑外发生弯曲变形,而当坑内“硬岩”被挖除后,整体向坑内产生水平位移。2)地连墙的环向应力和水平位移变形规律为“E”型,地连墙的最大环向应力和水平位移总是集中在“软岩”深度范围内,而在“硬岩”深度范围内环向应力和水平位移最小;同时,地连墙的最大弯矩总是出现在软岩岩层交界面深度附近。3)内衬的环向应力和水平位移变形规律为“阶梯”型增长,但在“硬岩”深度处出现减小;内衬受坑内岩体隆起影响明显,最大弯矩总是出现在内衬底部,同时向坑外产生位移。

我国煤系铀矿形成条件及成矿模式研究

我国铀资源对外依存度高达78%,供应安全不容乐观,煤系铀是一种非常规铀资源,对其开发能为我国铀资源安全供给提供保障。近年来随着煤铀协同勘查的推进,在我国北方地区发现了多个大型煤系砂岩型铀矿,对今后煤系铀矿勘探提供了大量可借鉴的参考资料。煤系铀矿成矿是一个复杂的过程,目前关于煤系铀成矿的研究还比较分散,尤其是对其赋存和成矿规律还不够明确。综合国内外最新研究成果,对煤系地层中铀矿床成因类型、铀的赋存状态、成矿有利条件和成矿模式进行了较为全面的阐述。并进一步提出了我国煤系铀矿的研究仍很不充足,特别亟需加强铀的微观地质选择过程、铀矿的矿化时间和期次等方面的研究,以便深入了解和阐释煤系铀矿的成矿机理,同时在今后研究中也需更加关注煤岩铀和砂岩铀的成因联系。

西湖凹陷Z地区平湖组煤系地层沉积背景及水动力特征

西湖凹陷是中国近海最重要的含油气凹陷之一,在凹陷断陷期末期阶段发育一套巨厚煤系地层,是西湖凹陷主力烃源岩层系,由于受到多解性的影响,很难通过岩性组合、沉积构造等宏观特征详细解释研究区沉积背景及水动力特征,尝试通过煤系地层干酪根显微组分,煤系地层显微岩石学特征等对西湖凹陷Z地区平湖组煤系地层沉积环境及水动力特征展开分析。研究表明,研究区不同地区干酪根显微组分存在较大差异,岩心具有交错纹层状、条带状、水平纹层状、结核状4种形态特征的菱铁矿,均指示Z地区平面及纵向上煤系地层沉积背景及水动力特征存在较大的差异:低凸A区沉积时期以弱氧化-还原沉积环境为主,水浅且间歇性出露水面,其上可发育天然堤与洼地,有利于水道发育;凹陷B区是受外缘低凸起遮挡而形成的半封闭潟湖,整体处于还原沉积背景,在大潮期间,潮流可越过低凸起,将隆起区及隆起区外侧碎屑物搬运至凹陷区而形成冲越扇;低凸C区长期位于水面之上,处于氧化环境,平中段时期受到间歇性潮汐的影响而被水体覆盖,从而形成浅水沼泽;凹陷D区为水体相对较深的沉积背景,是三角洲前缘沉积的有利场所。总体而言,Z地区平湖组沉积环境及水动力特征自南向北受地貌影响存在较大差异:低凸A及C区因长期暴露地表,整体表现为氧化环境,河控为主,间歇性受到潮流影响;凹陷B及D区,整体处于还原沉积环境,受潮汐影响较大。通过对西湖凹陷Z地区沉积背景及水动力特征认识的深化,为该地区勘探部署提供了重要理论支撑。

贵州织纳煤田三塘向斜X区块煤层气储层特征研究

为了查明贵州织纳煤田三塘向斜内煤层气储层特征,通过露头、录井、测井、试井等资料,开展了室内实验、测井曲线分析等内容综合分析。研究表明,三塘向斜内主要含煤地层为龙潭组,煤层层数多而薄,煤体结构以碎裂煤和原生结构煤为主,主要煤层含气量在8.98~18.05 m^(3)/t,孔隙度在1.47%~7.67%,渗透率在0.027 1~0.21 m D,节理缝连通性较好,微裂缝发育,部分被充填。研究取得的成果对三塘向斜后续煤层气规模化开发时压裂地质选层提供了参考依据,具有一定的指导意义。