山西中高煤阶煤储层孔裂隙特征及对渗透性的影响

发布时间：2018-05-19 16:04

本文选题：分形理论 + 核磁共振　；参考：《中国地质大学(北京)》2017年硕士论文

【摘要】：对23块煤岩样品进行核磁、压汞、低温氮及渗透率测试,研究煤储层孔裂隙特征及对渗透性的影响。由于煤储层的复杂性,孔裂隙特征很难被定义。因此本文通过核磁、压汞、低温氮技术和分形理论结合孔裂隙流体特性,从微观角度用一种清晰简明的方法探究煤储层孔裂隙特性及对渗透性的影响。1.研究区域位于山西中部,属于山西组和太原组含煤地层,微裂隙密度高度发育593~4540条不等;微裂隙主要呈树枝状和网状两种类型,连通性普遍较好,指示研究区域是构造煤发育区域。2.山西中高煤阶煤储层孔裂隙系统非均质性表现为分形非均质性:核磁分形维数(D)低温氮分形维数(DN)压汞分形维数(DMIP);受体弛豫时间(T2B)和自扩散时间(T2D)的影响,核磁方法表征小孔存在一定局限性;煤化作用在Ro,m=1.8~2.0%发生第三次跃变,使煤储层孔裂隙类型发生突变。3.孔裂隙流体非均质性体现在自由流体分形维数(DM)束缚水分形维数(Dir)饱和水分形维数(Dw);流体空间有四种类型:“C”、“Z”、“S”和“T”,对应四种孔裂隙结构“A”、“B”、“C”和“D”;煤化作用对孔裂隙流体孔隙度和百分数影响不一致。4.渗透率反映孔裂隙系统的影响。当孔裂隙空间的连通性变好,非均质性减弱,煤岩各孔隙类型分形维数趋于稳定时,渗透率K0.025mD;不同孔裂隙流体受空间表面影响形成“摆动环”阻碍孔裂隙渗流能力;渗透率受自由流体与束缚流体的影响,与渗流孔BVM/BVI成正比,与吸附孔和过渡孔BVM/BVI成反比。通过核磁、压汞、低温氮技术和分形理论结合,使我们能够定量表征煤储层孔裂隙特征及煤化作用对煤储层孔裂隙的影响;渗透率与孔裂隙非均质性和BVM/BVI的关系,有利于预测煤层气有利开发区域。
[Abstract]:Nuclear magnetic field (NMR), mercury injection (Hg), low temperature nitrogen (N) and permeability tests were carried out on 23 coal samples to study the pore fracture characteristics of coal reservoir and its influence on permeability. Because of the complexity of coal reservoir, it is difficult to define the characteristics of pore and fissure. Therefore, by means of nuclear magnetic field, mercury injection, low-temperature nitrogen technology and fractal theory combined with pore and fissure fluid characteristics, a clear and concise method is used to study the pore fracture characteristics of coal reservoir and its influence on permeability from a microscopic point of view. The study area is located in the middle of Shanxi Province, which belongs to the coal-bearing strata of Shanxi formation and Taiyuan formation. The density of microfractures varies from 593to 4540. The microfractures are mainly of dendritic and reticular types, and the connectivity is generally good. The study area is tectonic coal development area. The heterogeneity of pore and fissure system in middle and high rank coal reservoirs in Shanxi Province is characterized by fractal heterogeneity: fractal dimension of nuclear magnetic field (D), fractal dimension of low temperature nitrogen (D), fractal dimension of mercury (DMIP), receptor relaxation time (T 2B) and self diffusion time (T 2D). There are some limitations in characterizing the pore by nuclear magnetic field method, and the third jump occurs in the coalification of the coal reservoir at 1.8% 2.0%, which causes the fracture type of coal reservoir to change. 3. The heterogeneity of pore and fissure fluid is embodied in the fractal dimension of free fluid and the dimension of bound water form and saturated water form, and there are four types of fluid space: "C", "Z", "S" and "T", corresponding to four types of pore and fissure structure "A". "B", "C" and "D"; the effect of coalification on porosity and percentage of pore and fissure fluid is not consistent. Permeability reflects the influence of pore fracture system. When the connectivity of the pore and fissure space becomes better, the heterogeneity weakens, and the fractal dimension of each pore type of coal and rock tends to be stable, the permeability K 0.025mD, the fluid of different holes and fissures form a "swing ring" which hinders the percolation ability of the pore and fissure by the influence of the space surface. The permeability is directly proportional to the percolation pore BVM/BVI and inversely proportional to the adsorption pore and transition pore BVM/BVI under the influence of free fluid and bound fluid. Through the combination of nuclear magnetic field, mercury injection, low-temperature nitrogen technology and fractal theory, we can quantitatively characterize the pore fracture characteristics of coal reservoir and the influence of coalification on coal reservoir pore fracture, and the relationship between permeability and pore fracture heterogeneity and BVM/BVI. It is propitious to predict the favorable development area of coalbed methane.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD84

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