【作者】 卫明明；

【导师】 薛传东； 琚宜文；

【作者基本信息】 昆明理工大学 ， 构造地质学， 2011， 硕士

【摘要】 近年来,沁水盆地南部成为煤层气开发的热点地区。但受中新生代区域构造.热演化的影响,沁水盆地南部煤储层在深成变质作用基础上,不同程度地叠加了构造动力变质作用和岩浆热变质作用,产生特征各异的变质作用；经历了挤压—伸展—挤压多期构造应力场作用,产生多期不同方向、不同性质和不同强度的构造变形,导致其在煤厚、埋深、变质程度、含气性及渗透性等方面各具不同的分布特征,这些均影响制约着煤层气的富集和高渗。因而,加强对沁水盆地南部高丰度煤层气富集区高煤级煤的变形特征及其对煤层气富集高渗的制约研究,既有明确的现实价值,更具有重要的理论意义。鉴于沁水盆地煤层气勘探开发进展及当前研究不足之处,本论文选取沁水盆地南部为研究区域,通过对区内高庙山断层和寺头断层两侧3个区域的7个代表性矿区进行系统的煤岩野外调查和样品采集,采用煤储层裂隙的宏观观察、荧光显微镜和扫描电镜微观观测、镜质组反射率测试、压汞孔隙测试、低温氮吸附测试、Micro-CT及煤岩渗透率测试等技术和手段进行综合分析测试,详细研究了沁水盆地南部煤储层各向异性特征、煤储层孔.以及裂隙系统特征与分形维数特征及研究区煤层气富集高渗构造分异等方面进行研究。研究获得以下主要成果与认识：1.沁水盆地南部煤层气富集区储层参数通过煤储层镜质体各向异性研究及孔.裂隙分形研究,采用自然形变系数(εs)及孔.裂隙分形维数(D)两个参数来定量表征煤储层构造变形强度,查明沁水盆地南部构造变形特征对煤层气富集高渗的制约,将研究区煤储层划分为3种类型,即：Ⅰ类储层：当0.2<εs<0.4、1.4<D<1.7时,煤储层含气量及渗透性较好,储层产能高,采收率高。Ⅱ类储层：当εs>0.4、D>1.7时,煤储层含气量及渗透性中等,储层产能中等,采收率中等。Ⅲ类储层：当Es<0.2、D<1.4时,煤储层含气量及渗透性较差,储层产能低,采收率低。2.沁水盆地南部煤层气富集区富集参数(1)根据煤孔隙分形计算结果,结合煤孔隙孔容增量突变孔径的自然显现规律、煤层气扩散、渗流特征及煤层气中各分子的平均自由程的关系,以0.06gmm(即60nm)为界,将煤孔径划分为>60nm的渗流孔隙和<60nm的吸附.扩散孔隙。(2)同煤级的糜棱煤(SH-12)的液氮吸附量远大于其它脆性系列煤样品；揭示变质作用对构造煤纳米级孔隙的特征参数影响不明显,但是变形作用对孔隙特征参数的演化起决定性作用。3.沁水盆地南部煤层气富集区渗流参数(1)提出最小有效孔径(r0,min)及有效似孔喉比(λ0)的概念,并用其来表征煤储层孔隙结构的渗流性特征。最小有效孔径(r0,min)的大小对流体流动特征有重要影响；有效似孔喉比(λ0)可以表征有效连通空间内的最小有效孔径(r0,min)的相对均一程度,影响目标储层的渗透率大小及经济可采性；退汞效率(Wc)反映了非润湿相毛细管效应采收率,退汞效率越高,则目标储层中的流体采收率就越高。这三个参数之间具有一定的相关性,即,最小有效孔径与有效似孔喉比呈指数负相关,有效似孔喉比与退汞效率呈负相关。(2)孔.裂隙系统分形维数与煤岩样品的变形特征关系更密切。孔隙分形维数随着变形强度(即自然形变系数εs)的增强,出现明显波动式变化。随着分形维数的增大,煤岩样品裂隙变形强度(即自然形变系数)显著增大；同时,变形强度(即自然形变系数)与裂隙面密度呈明显正相关关系,即,变形强度越强,其煤岩裂隙面密度相应也越大。这说明,构造应力是使裂隙面密度增大的主要原因。(3)基于研究区主要矿区6块不同变质变形煤岩柱样的Micro-CT扫描实验,发现Micro-CT扫描技术在全方位表征煤的孔.裂隙系统信息方面具有优势。三维可视化结果显示,相同煤岩类型样品,孔.裂隙系统空间配置不同,渗透率差异较大。4.沁水盆地南部煤层气富集区存在明显构造分异特征受中生代以来的构造运动及燕山期岩浆侵入活动的影响,沁水盆地南部煤储层物性特征出现明显的构造分异,具有“东西展布、南北分带”的分布特征；并且,沿盆地复向斜主轴方向及燕山期岩浆侵入方向,形成三个煤层气富集高渗构造区块,即：枣园.潘庄区块(TREND1)、寺底.成庄区块(TREND2)和郑庄区块(TREND3),其富集高渗条件依次降低。在TREND1区块内部,又可以细分为潘庄区块(1A)、枣园区块和胡底.蒲池区块(1B)和樊庄区块(1C)。其中,潘庄区块由于位于两期褶皱轴部叠加的部位,其富集高渗性最好；1B区块的富集高渗性次之,1C区块最低。更多还原

【Abstract】 By the affection of regional tectonic-thermal evolution, the coal reservoirs have undergone the plutonic metamorphism, tectonic-dynamic metamorphism and magmatic thermal metamorphism, and they were caused into different degrees of metamorphic and deformation in the south of Qinshui Basin, and where also went through three periods of tectonic stress field. The reservoirs possess different characteristics in many aspects of physical properties, such as metamorphic and deformation, gas bearing capacity and permeability. Those characteristics control the enrichment and the high permeability of coalbed methane. There are great significance in reality and theory by researching aboves.In this paper, Qinshui Basin is picked as the study area, which is a poupular area for coalbed methane esploration, because of the peogress and shortcomings of the current research in coalbed methane exploration. And the samples were collected from Gaomiaoshan Fault to Sitou Fault, where contain 3 regions and 7 representative coal mines. According to the micro-macro observation of structure, fracture occurrence statistics and vitrinite reflenctance ananlyse, fluorescence microscopic and field-emission scanning electorn microscropic obvervation, mercury injection experiment and low temperature nitrogen adsorption analyse, Micro-CT scanning and permeability testing, this paper mainly discusses the characterics of the vitrinite reflenctance anisotropy, the characterics of pore-fracture in coal and its fractal characterics and the tectonic differentiation of coalbed methane enrichment areas. The following conclusions can be achieved:1. Reservoir parameters of coalbed methane enrichment areas in Qinshui BasinAccording to the characterics of the vitrinite reflenctance anisotropy, the characterics of pore-fracture in coal and its fractal characterics, the degrees of structure deformations can be setted quantitatively by using natural deformation coefficient (εs) and the fractal dimension of pore-fracture (D). By the research of this thesis,3 different types of coal reservoirs in study area are summarized.Type I:when 0.2<εs<0.4 and 1.4<D< 1.7, high gas bearing capacity and permeability, high productivity, high economical recovery factor;TypeⅡ:whenεs>0.4 and D>1.7, medium gas bearing capacity and permeability, medium productivity, medium economical recovery factor;TypeⅢ:whenεs<0.2 and D<1.4, low gas bearing capacity and permeability, low productivity, low economical recovery factor。2. Enrichment parameters of coalbed methane enrichment areas in Qinshui Basin(1) According the fractal dimension of pore, the pore natural behavior law of the mutation of incremental pore volume, the characterics of proliferation and flow and the mean free path of moleculars in coalbed methane, the coal pore can be bouned at 0.06μm (ie 60nm), dividing into seepage pores and adsorption-diffusion pores, which are up to 60nm, or blew 60nm.(2) The nitrogen adsorption in the coal mylonitic coal (SH-12) in the same coal rank is far more than other brittle deformation coals. It can be seen that the metamorphism has little effect on nano-pore of deformed coals, while the deformation grasps the handle.3. Seepaging parameters of coalbed methane enrichment areas in Qinshui Basin(1) It’s the first time to create the minmum effective aperture (ro,min) and effective seemly pore throat ratio (λ0) to characterization of the flow of coal pore structure.The ro,min has great important influence on the flow, and theλ0 shows the relative homogeneity of the r0,min in effectively connected space. Those parameters control the permebility and the economical recovery factor of the coal reveior. The mercury withdrawal efficiency (We) reflects the recovery factor of capolary effect in non-wetting phase. The higher the We, the higher the fluid recovery in the coal reservoir. These three parameters have some correlations, ie, the ro,min andλ0 are in a negative exponential correlation, and theλ0 and We are in a negative correlation.(2) The relationships between the fractal dimensin of pore- fracture and the deformation in coal resvoir are more closely.The fractal dimensin of pore will be increases with theεs, and will take place significant changes in wave-type.With the increasing of fractal dimensin, theεs increases significantly, meanwhile, theεs and the fracture density are positively correlated, that is, the stronger the deformation, the greater the fracture density. That is to say that the tectonic stress is the main reason that makes the fracture increase.(3) According to the Micro-CT scanning to 6 coal samples of different degrees of metamorphic and deformation, it found that the Micro-CT scanning technology has the adventages of characterizing the pore-frature fully.3-D visualization results show that if the space configuration among pore-fructure the same type of deformed coal is different, the permeability is quite different too.4. The coalbed methane enrichment areas show obvious regional differentiationThe coalbed methane enrichment areas show obvious regional differentiation and form three NE-NNE structural regions, which have the same spreading direction with the direction of synclinorium spindle and magma intrusion in Yanshan period. The structural regions are Zaoyuan-fanzhuang region (TREND 1), Sidi-chengzhuang region (TREND2) and Zhengzhuang region (TREND3). Their gas content and permeability possess obvious distribution in EW and SN. From east to west, the gas content and permeability in TREND 1, TREND2 and TREND3 reduce one by one. From south to north, the TREND1 can also be divided into three parts: Panzhuang block (1A), Zaoyuan block and Hudi-pichi block (1B) and Fanzhuang block (1C). The gas content and permeability is best in 1 A, medium in 1B, low in 1C.更多还原