鄂尔多斯盆地姬塬地区长2低阻油层分布及成藏控制因素研究

发布时间：2018-10-15 08:14

【摘要】：鄂尔多斯盆地姬塬地区延长组长2段发现一些油井,但油层电阻率较低,难以识别,且不同区块石油富集程度存在差异,长2低阻油层分布及成藏控制因素不详。论文在油层低阻成因分析的基础上,结合前人低阻识别方面的研究成果,建立研究区长2低阻油井识别图版,明确研究区长2低阻油井的平面分布,并通过油源对比和石油运聚特征分析,总结研究区长2油层成藏控制因素。研究区长2油水层电阻率对比表明：研究区长2段油层电阻率绝对值和电阻增大率普遍较低,且电阻率在平面上分布无规律；长2油层低阻主要受高地层水矿化度和高束缚水饱和度的影响,而与导电矿物含量及淡水泥浆的侵入无关；此外,碎屑颗粒粒度偏细、孔隙结构复杂、黏土矿物含量及其阳离子附加导电性对研究区长2油层低阻也有一定的影响。通过对研究区长2段油层低阻成因分析,建立了用侵入因子与电阻率交汇图以及侵入因子与声波时差值的交汇图来识别研究区长2段低阻油层的识别图版；明确了研究区平面上长2低阻油井的分布。研究区长2段石油三降藿烷参数Ts/Tm大于1,重排甾烷丰度较高,与下伏延长组长7段烃源岩抽提物三降藿烷参数特征相似,而与延长组长6及长4+5特征不同,但三降藿烷参数Ts/Tm的比值及重排甾烷含量较长7段源岩抽提物低,表明：研究区长2段石油主要来自于其下伏长7段烃源岩,但同时还存在长6段及长4+5段源岩产物的混和。研究区长2段下伏层位中局部发育的裂缝系统及垂向叠置的砂体是研究区延长组长7源岩生成产物向上运聚的通道；长7段烃源岩生成的石油沿输导体系运移至长2段储层的过程中,以垂向运移为主,并在长2段低渗透砂体中发生局部小规模的侧向运移；长7源岩层段的异常压力是烃源岩生成产物沿裂缝及垂向叠置砂体向上运移的动力,而浮力是石油在长2储层内部发生小范围侧向运聚的动力。研究区长2低阻油层成藏受烃源岩分布、垂向上发育的裂缝系统、单斜背景下鼻状隆起和储层渗透率的控制。
[Abstract]:Some oil wells were found in the second member of Yanchang formation in Jiyuan area, Ordos Basin, but the resistivity of reservoir is low, it is difficult to identify, and the degree of oil enrichment is different in different blocks. The distribution of Chang2 low resistivity reservoir and the controlling factors of reservoir formation are unknown. Based on the analysis of the formation cause of low resistivity in oil reservoir and the research results of previous research on low resistivity identification, the recognition chart of Chang2 low resistivity oil well in the research area is established, and the plane distribution of the low resistivity oil well in the study area is determined. Through oil source correlation and oil migration and accumulation analysis, the controlling factors of reservoir formation in Chang2 reservoir are summarized. The comparison of resistivity of Chang2 oil-water layer in the study area shows that the absolute value of resistivity and the increase rate of resistance are generally lower and the resistivity distribution is irregular in the plane. The low resistivity of Chang2 reservoir is mainly affected by the water salinity and high irreducible water saturation in the highland layer, but not by the content of conductive minerals and the invasion of fresh water mud, in addition, the grain size of clastic particles is thin and the pore structure is complex. The content of clay and the additional conductivity of cations also have some effects on the low resistivity of Chang2 reservoir in the study area. Based on the analysis of the formation causes of the low resistivity of the Chang-2 formation in the study area, the identification chart of the low resistivity reservoir in the study area is established by using the intersection map of the invasion factor and the resistivity, and the intersection diagram of the invasion factor and the acoustic time difference value to identify the low resistivity oil layer of the Chang-2 formation in the study area. The distribution of 2 long and low resistivity wells on the plane of the study area is determined. In the study area, the Ts/Tm of the second member of the study area is greater than 1, and the abundance of the rearrangement sterane is higher, which is similar to that of the source rock extract of the lower Changchang formation, but is different from the characteristics of the Chang 6 and Chang 45. However, the ratio of Ts/Tm and the content of rearrangement sterane are lower than those of the source rocks of the Chang2 formation, which indicates that the source rocks of the Chang2 formation mainly come from the source rocks of the Lower Changchang formation, but at the same time there is a mixture of the source rock products of the Chang 6 member and the Chang 45 member. The fracture system developed locally in the underlying bed of the Chang-2 formation and the vertical overlay sand body are the channels for the upward migration and accumulation of the products of the source rocks in the Chang 7 formation of the study area. In the process of oil migration from source rock of Chang7 formation to Chang 2 reservoir, vertical migration is dominant, and local small-scale lateral migration occurs in low permeability sand body of Chang 2 member. The abnormal pressure in source rock formation of Chang 7 is the driving force of hydrocarbon source rock generation products moving upward along fractures and vertical superimposed sand bodies, while buoyancy is the power of lateral migration and accumulation of oil in a small range in Chang 2 reservoir. Reservoir formation in Chang2 low resistivity reservoir is controlled by source rock distribution, vertical fracture system, nasal uplift and reservoir permeability in monoclinic background.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P618.13

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