柴达木盆地西北区新近系细粒沉积岩油气储集特征与成岩演化研究

发布时间：2018-04-19 04:04

本文选题：细粒沉积岩 + 储集特征　；参考：《中国地质科学院》2017年博士论文

【摘要】：柴达木盆地西部北区新近系为典型的咸化湖盆沉积,细粒沉积物沉积特征特殊,非均质性强,成烃与成储机制复杂,研究程度相对薄弱。本文利用大量岩芯样品,通过开展有机地球化学、X-衍射、孔渗、高压压汞、低温液氮吸附、薄片观察和扫描电镜等系列实验分析测试,对细粒沉积岩的沉积展布、岩性、矿物组成和储集性能进行了研究。结合自然演化剖面和热模拟实验分析了孔隙演化特征和控制因素,并利用分形理论和方法,研究了细粒沉积岩储层成岩特征及演化规律,优选了油气勘探的有利区。研究表明,柴西北区新近系盐度在纵横向上有较好的变化规律,早期沉积盐度较低而晚期沉积盐度较高,平面上沉积中心盐度较高。气候和沉积中心的迁移控制了沉积水体的盐度和沉积物的岩性特征。随着地层时代变新,研究区新近系细粒沉积岩中碳酸盐岩类和混合岩类增加,在湖盆沉积中心厚度增大,但孔隙度和渗透率降低。细粒沉积岩孔隙结构复杂,非均质性强,压汞曲线表现为前峰型(大于100nm孔隙发育)、后峰型(小于100nm孔隙优势明显)和多峰型三种类型。上干柴沟组细粒沉积岩介孔优势明显,孔隙非均质较弱,而上油砂山组和下油砂山组细粒沉积岩宏孔和介孔发育,孔隙结构复杂、非均质性强。新近系细粒沉积岩成岩早期胶结作用和压实作用均较强,导致该阶段孔隙体积较小,但孔径较大;中成岩阶段有机酸产生的溶蚀作用明显,盐类物质胶结作用可抵抗压实作用的进程,因而孔隙体积有所增加,孔隙平均孔隙增大;到晚成岩作用阶段,压实作用趋于减弱,但盐类矿物的胶结作用仍明显,会进一步破坏储层,此时有机质含量高的细粒沉积岩显示了发育较多有机质孔的优势。细粒沉积岩的盐度、矿物组成、有机碳含量和热成熟度是控制孔隙发育的主要因素,表现在T0C含量与介孔体积呈正相关,碳酸盐矿物含量与比表面积、宏孔体积、介孔体积、微孔体积均呈负相关;粘土矿物与比表面积、介孔体积、微孔体积呈正相关,与宏孔体积呈负相关;盐度是控制孔隙分布的最关键因素,低-较高盐度的细粒沉积岩中的微孔较复杂,超高盐度的细粒沉积岩中微孔相对简单。综合柴西北区新近系细粒沉积岩空间展布、盐度、T0C含量、成熟度和储集物性特征,优选出干柴沟—油泉子—南翼山地区为上干柴沟组细粒沉积岩油气富集有利区;油泉子—南翼山—开特米里克及大风山以西地区为下油砂山组细粒沉积岩油气富集有利区;南翼山—开特米里克地区以及大风山以西地区为上油砂山组细粒沉积岩油气富集有利区。
[Abstract]:The Neogene in the western Qaidam basin is a typical saline lake basin. The fine grain sediments are characterized by special sedimentary characteristics, strong heterogeneity, complex hydrocarbon generation and reservoir formation mechanisms, and the degree of research is relatively weak.In this paper, by using a large number of core samples, the sedimentary distribution and lithology of fine-grained sedimentary rocks are investigated by means of a series of experiments, such as organic geochemistry X-ray diffraction, pore permeability, high pressure mercury injection, low temperature liquid nitrogen adsorption, thin slice observation and scanning electron microscope, etc.Mineral composition and reservoir properties were studied.Combined with natural evolution profile and thermal simulation experiments, the pore evolution characteristics and controlling factors are analyzed, and the diagenetic characteristics and evolution rules of fine grain sedimentary reservoir are studied by using fractal theory and method, and favorable areas for oil and gas exploration are selected.The results show that the salinity of Neogene in the northwestern part of Chaihai has a good variation law in vertical and horizontal direction. The salinity of the early sedimentary system is lower than that of the late sedimentary system, and the salinity of the sedimentary center is higher on the plane.The migration of climate and sedimentary center controls the salinity of sedimentary water and the lithologic characteristics of sediment.The carbonate and mixed rocks in the Neogene fine grained sedimentary rocks in the study area increase with the formation age, and the thickness increases in the sedimentary center of the lake basin, but the porosity and permeability decrease.The pore structure of fine-grained sedimentary rock is complex and heterogeneity is strong. The mercury injection curve shows three types: front peak type (larger than 100nm pore development, post-peak type (less than 100nm pore dominance) and multi-peak type.The mesoporous rocks of the Shangganchaigou formation have obvious mesoporous advantages and the pore heterogeneity is weak, while the macropores and mesoporous pores of the fine sedimentary rocks of the Upper Yeshaishan formation and the Lower Yeshaishan formation are developed, the pore structure is complex and the heterogeneity is strong.The early cementation and compaction of Neogene fine grained sedimentary rocks in the early diagenesis stage resulted in smaller pore volume and larger pore size in this stage, and the dissolution of organic acids in the middle diagenetic stage was obvious.The cementation of salt materials can resist the process of compaction, so the pore volume increases and the average pore size increases. At the stage of late diagenesis, the compaction tends to weaken, but the cementation of salt minerals is still obvious.The fine grained sedimentary rocks with high organic matter content show the advantage of developing more organic pores.The salinity, mineral composition, organic carbon content and thermal maturity of fine-grained sedimentary rocks are the main factors controlling pore development. The T0C content is positively related to mesoporous volume, carbonate mineral content and specific surface area, macropore volume, mesoporous volume, mesoporous volume, carbonate mineral content and specific surface area, macropore volume and mesoporous volume.There was a positive correlation between clay mineral and specific surface area, mesoporous volume and micropore volume, and a negative correlation between micropore volume and macropore volume. Salinity was the most important factor to control pore distribution.The micropores in low-high salinity fine-grained sedimentary rocks are more complex, while those in ultra-high salinity fine-grained sedimentary rocks are relatively simple.According to the spatial distribution of Neogene fine sedimentary rocks, the content of T0C in salinity, maturity and reservoir physical characteristics, the Ganchaigou-Youquanzi-Nanyishan area is selected as the favorable oil and gas enrichment area for the fine sedimentary rocks of Shangganchaigou formation.The areas to the west of Youquanzi Nanyishan Katermirik and Gengshan are favorable areas for oil and gas enrichment of fine sedimentary rocks of Lower Yeshan formation.The Nanyishan-Katermirik area and the area west of Gengshan are favorable areas for oil and gas enrichment of fine sedimentary rocks of the Upper Yeshan formation.
【学位授予单位】：中国地质科学院
【学位级别】：博士
【学位授予年份】：2017
【分类号】：P618.13

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