【摘要】：鄂爾多斯盆地南部地區(qū)上三疊統(tǒng)延長組是盆地主要的產(chǎn)油層位。但是,延長組油層具有低孔特低滲、特低孔超低滲的特征,造成油氣藏比較隱蔽進而產(chǎn)量低,增加油氣勘探開發(fā)的難度。成巖作用直接控制儲層的微觀孔隙結(jié)構(gòu),決定儲層的孔滲條件。因此,在對長8油層組成巖作用進行研究的基礎(chǔ)上,找到造成儲層低孔低滲的因素,并對儲層物性演化做定量分析,可以進一步加深對儲層的認識。鎮(zhèn)涇油田位于鄂爾多斯盆地天環(huán)拗陷的南端,毗鄰渭北隆起,地層平緩,構(gòu)造簡單,局部發(fā)育范圍較小的鼻狀隆起,低幅度鼻狀隆起為油氣相對富集提供了有利條件。研究區(qū)長8油層組巖性為粉、細砂巖與泥巖互層。沉積相為水下分流河道、分流間灣微相,形成的砂體層厚,分布廣,物性好,形成了鎮(zhèn)涇地區(qū)主要的儲油層。通過鑄體薄片分析、電鏡分析等實驗手段,分析研究區(qū)儲層巖石學(xué)特征和成巖作用,得出:(1)砂巖以細粒為主,分選中等-好,次棱狀磨圓,成分上石英含量相對較低,巖石定名為長石巖屑砂巖和巖屑長石砂巖。(2)通過鏡下觀察,認為綠泥石膠結(jié)作用對儲集巖的孔滲性能起到有利作用,而方解石膠結(jié)作用及壓實作用使儲集巖孔滲性能降低,在儲層原生孔隙保存較好的層段,溶蝕作用對儲層物性的影響較大。根據(jù)各種鏡下成巖作用現(xiàn)象,確定成巖序列,判斷儲層成巖階段達中成巖A期。(3)研究區(qū)從東往西依次劃分出綠泥石膜-方解石膠結(jié)相帶、長石-濁沸石溶蝕相帶、泥質(zhì)雜基填隙相帶、長石溶蝕相帶以及高嶺石相帶等五個大的成巖相帶,各成巖相帶物性有所差異。儲層以粒間孔為主,其孔隙度值約為10.1%。結(jié)合對儲層孔隙類型、喉道特征及孔隙結(jié)構(gòu)特征的研究,分別從沉積、成巖和構(gòu)造三方面討論儲集體孔滲條件的控制因素。通過分選系數(shù)的計算對儲層初始孔隙度進行恢復(fù),經(jīng)壓實作用、溶蝕作用以及膠結(jié)作用等一系列成巖作用過程,在對成巖儲層做成巖相分類的基礎(chǔ)上,繪制各個成巖相中儲層孔隙度的演化曲線。
[Abstract]:The Yanchang formation of Upper Triassic in southern Ordos Basin is the main oil-producing zone in the basin. However, the Yanchang formation has the characteristics of low porosity and low permeability and ultralow permeability, which leads to the subtle reservoir and low production, which makes exploration and development of oil and gas more difficult. Diagenesis directly controls the microscopic pore structure of the reservoir and determines the pore and permeability conditions of the reservoir. Therefore, on the basis of the study of the formation rock action of Chang 8 oil reservoir, the factors that cause the low porosity and low permeability of the reservoir and the quantitative analysis of the evolution of the reservoir physical properties can further deepen the understanding of the reservoir. Zhenjing oilfield is located at the southern end of Tianhuan depression in Ordos basin, adjacent to Weibei uplift. The formation is smooth, the structure is simple, the local development range is small, and the low amplitude nasal uplift provides favorable conditions for the relative enrichment of oil and gas. The lithology of Chang 8 oil formation in the study area is silt, fine sandstone and mudstone interbedded. The sedimentary facies are subaqueous distributary channel and interdistributary bay microfacies, forming thick sand body, wide distribution and good physical properties, forming the main reservoir in Zhenjing area. The petrological characteristics and diagenesis of reservoirs in the study area are analyzed by means of casting thin slice analysis and electron microscope analysis. The results show that: (1) the sandstone is mainly fine-grained, the separation is medium to good, the secondary prism is round, and the content of quartz in the composition is relatively low. The rock is named feldspathic lithic sandstone and lithic feldspathic sandstone. (2) through microscopic observation, it is considered that chlorite cementation plays a beneficial role in the porosity and permeability of reservoir rock, while calcite cementation and compaction make reservoir pore and permeability performance lower. In the reservoir where the primary pores are well preserved, the dissolution has a great influence on the reservoir physical properties. According to various diagenesis phenomena under the mirror, diagenesis sequence is determined, and the diagenetic stage of reservoir reaches diagenesis A stage. (3) from east to west, the study area is divided into chlorite film-calcite cementation facies zone, feldspar and clinopalite dissolution facies zone. There are five large diagenetic facies belts, such as muddy complex base filling gap zone, feldspar dissolution facies belt and kaolinite facies belt, and the physical properties of each diagenetic facies belt are different. The reservoir is dominated by intergranular pore, and its porosity is about 10.1. Based on the study of reservoir pore types, throat characteristics and pore structure characteristics, the controlling factors of reservoir pore and permeability conditions are discussed from three aspects: deposition, diagenesis and structure. Through the calculation of sorting coefficient, the initial porosity of reservoir is restored. After a series of diagenesis processes, such as compaction, dissolution and cementation, the diagenetic reservoir is classified into lithofacies. Draw the evolution curve of reservoir porosity in each diagenetic facies.
【學(xué)位授予單位】：山東科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：P618.13

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