鄂尔多斯盆地东缘煤阶制约下煤储层物性发育特征研究

发布时间：2018-01-19 14:16

本文关键词： 鄂尔多斯盆地东缘孔裂隙吸附特征变质作用控制因素　出处：《中国地质大学(北京)》2017年硕士论文　论文类型：学位论文

【摘要】：在分析整理鄂尔多斯盆地东缘地层发育和构造特征,主力煤层分布的基础上,对孔裂隙系统及吸附性等储层物性特征进行研究,分析探讨了煤化作用导致的孔裂隙系统阶段性变化以及吸附能力的控制因素,并剖析了深成变质作用与岩浆变质作用对储层物性的影响。此次研究目标煤层是区内山西组4+5#煤层和太原组8+9#煤层,埋深介于260-2600 m,厚度为1-21m。镜质体反射率为0.44%-3.2%,从长焰煤到无烟煤,各煤级均有发育。煤岩方面,宏观类型主要为光亮煤和半亮煤,半暗煤和暗淡煤次之;有机显微组分镜质组占优,惰质组较少,壳质组含量最低,其中镜质组含量呈现北低南高特征,惰质组含量则相反。煤岩工业分析表明,随着煤变质程度的升高,水分与挥发分逐渐下降,固定碳逐渐变高,灰分变化不大。物性研究表明,研究区微裂隙主要以C型与D型为主,孔隙度为2.7-9.4%,孔隙以小于100 nm的微小孔为主,大孔和中孔都不甚发育,BET比表面积为1.782 m2/g,BJH总孔容为0.005mL·g-1,平均孔直径为12.43nm,兰氏体积在9.11-30.24 m3/t之间,兰氏压力在1.84-6.81 MPa之间。随煤化作用进行直到第二次跃变,孔隙度呈下降趋势,孔隙结构中微孔占比上升,中小孔下降,大孔变化不大,微孔体积、BET比表面积与BJH总孔容均逐渐下降,兰氏体积迅速上升,第二次跃变之后,除BET比表面积与BJH总孔容略有上升之外,其余参数变化不大,第三次跃变之后,孔隙度逐渐升高,微孔体积与BET比表面积呈上升趋势,BJH总孔容持续下降,兰氏体积略有下降。岩浆热变质作用导致煤变质程度上升,微孔占比明显上升,中小孔所占比例下降,微孔体积、BET比表面积与BJH总孔容均明显下降,兰氏体积上升。煤阶控制下吸附能力影响因素研究表明,孔隙结构对吸附能力做出了一定的贡献,影响着煤储层的吸附空间,但并不能主导煤储层吸附能力的变化;孔隙形态特别是墨水瓶孔对储层吸附能力控制较强;镜质组在中低煤变质阶段对储层吸附能力起一定控制作用,在高变质阶段,惰质组中丝质体与兰氏体积相关性更强;煤质方面,固定碳含量与吸附能力的相关性较强,煤中的水和挥发性物质由于占据了气体吸附空间,对煤储层吸附能力也有着一定的影响。
[Abstract]:Based on the analysis of stratigraphic development and structural characteristics in the eastern margin of Ordos Basin and the distribution of main coal seams, the physical characteristics of pore fracture system and absorbability are studied. The phase change of pore and fissure system caused by coalification and the controlling factors of adsorption ability are analyzed and discussed. The effects of deep metamorphism and magmatic metamorphism on reservoir physical properties are analyzed. The target coal beds in this study are Shanxi formation 4 coal seam and Taiyuan 8 9# coal seam. The depth of burying is between 260-2600 m and the thickness is 1-21m.The vitrinite reflectance is 0.44- 3.2m. from long flame coal to anthracite, each coal rank has developed. The macroscopic types are mainly bright coal and semi-bright coal, followed by semi-dark coal and dim coal. The vitrinite of organic macerals is dominant, the inertinite is less, and the crustal group is the lowest. The vitrinite is characterized by north, low and south high, while the inertinite is opposite. The analysis of coal and rock industry shows that the content of vitrinite is higher than that of vitrinite. With the increase of metamorphic degree of coal, moisture and volatile matter gradually decreased, fixed carbon gradually increased, and ash content changed little. The study of physical properties shows that the microfractures in the study area are mainly C-type and D-type. The porosity is 2.7-9.4, the porosity is smaller than 100 nm, the specific surface area of BET is 1.782 m2 / g. The total pore volume of BJH was 0.005 mL 路g ~ (-1), the average pore diameter was 12.43 nm, and the Lansch volume was between 9.11-30.24 m ~ (3 / t). The Lansch pressure is between 1.84-6.81 MPa. With the coalification process and the second jump, the porosity shows a downward trend, the proportion of micropore in pore structure increases, the ratio of mesopore decreases, and the change of macropore is not obvious. The specific surface area of BET and the total pore volume of BJH decreased gradually, but the volume of Ranch increased rapidly. After the second jump, the specific surface area of BET and the total pore volume of BJH increased slightly. The other parameters changed little, after the third jump, the porosity gradually increased, and the micropore volume and BET specific surface area showed an upward trend. The thermal metamorphism of magma leads to the increase of metamorphic degree of coal, the increase of the ratio of micropore to micropore, the decrease of the proportion of mesopore, the specific surface area of micropore and the total pore volume of BJH. The study of influencing factors of adsorption capacity under the control of coal rank shows that the pore structure contributes to the adsorption capacity and affects the adsorption space of coal reservoir. But it can not lead to the change of adsorption ability of coal reservoir. The pore morphology, especially the ink bottle pore, has a strong control over the reservoir adsorption capacity; Vitrinite plays a certain role in controlling the adsorption capacity of reservoir in the middle and low coal metamorphism stage, and in the high metamorphic stage, the correlation between the silk body and Lansch volume is stronger in the inertinite formation. In terms of coal quality, the fixed carbon content has a strong correlation with the adsorption capacity, and the water and volatile substances in coal have a certain influence on the adsorption capacity of coal reservoir because they occupy the gas adsorption space.
【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】：P618.13

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