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济阳坳陷深层稠油成因机理、储层评价与成藏规律

Formation Mechanism, Reservoir Evaluation and Accumulation of Deep Viscous Oil

【作者】 张善文

【导师】 傅家谟; 盛国英;

【作者基本信息】 中国科学院研究生院(广州地球化学研究所) , 地球化学, 2002, 博士

【摘要】 深层稠油是指油藏深度大于1800m的稠油。在胜利油田分布广泛,罗家-垦西地区是深层稠油重要分布区域。本论文从石油地质、地球化学和地球物理多方面系统研究了济阳坳陷(尤其是罗家-垦西地区)深层稠油的物性、地球化学特征、储层特征以及源岩地球化学特征,探讨本区域深层稠油的形成机理和分布、富集规律。 罗家-垦西地区的典型稠油在物性上具有高密度、高粘度和高凝固点等特点。在化学组成上具有含硫量高、胶质和沥青质含量高,而饱和烃、芳烃含量低。稠油物性与含硫量和族组成之间具很好的相关关系。由于这两个地区同时又有稀油及稀、稠混合原油分布。因此,在整体上,这两个地区原油物性、含硫量和族组成变化很大。 罗家—垦西地区稠油饱和烃色谱、色谱-质谱分析结果展示:(1)正构烷烃具有明显的偶奇优势;(2)类异戊二烯烷烃具有较强的植烷优势,姥姣烷/植烷(Pr/Ph)比值远小于1;(3)伽玛蜡烷相对含量(相对于C30藿烷)普遍很高;(4)C35升藿烷明显高于C34、甚至C33升藿烷;表现出膏盐湖相生物标志物的组成特征。油源对比研究表明,罗家-垦西深层稠油来源于沾化凹陷沙四段膏盐相源岩。 罗家-垦西稠油大部分样品饱和烃中正构烷烃分布十分完整,不具有生物降解特征。这表明这两个地区深层稠油属原生稠油,不是由于生物降解、地表氧化、水洗等次生作用形成的。生物标志物成熟度指标显示稠油具有中低成熟度,相对低于来源于沙三段源岩稀油成熟度。因此,深层稠油可能是沙四段膏盐相源岩早期生烃的产物。由于后期埋深,稠油成熟度指标有所增高,但稠油物性和族组成变化不大。 济阳坳陷也有典型次生稠油分布,这类稠油具有明显的生物降解特征。两类稠油生物标志物组成也有明显的差异,次生稠油主要由来源于沙三段源岩的正常原油(稀油)经生物降解、地表氧化、水洗等次生作用形成的,并且成熟度指标相对较高。 罗家—垦西地区储层主要分布于巨厚的洪积砂砾岩体中,物性变化大,采用地质统计分析与地球物理方法相结合的研究思想,在巨厚的复杂砂砾岩体中描述出可信度很高的储层空间展布,应用测井多参数综合分析方法识别油、水、干层,进而描述了罗家—垦西地区油藏空间展布,经开发准备井钻探证实,储层预测和含油气预测都是准确的。 在系统研究的基础上,指出了济阳坳陷具有很大的深层稠油资源潜力及不同类型深层稠油的勘探方向。

【Abstract】 Deep viscous crude oils,with depth more than 1800m,widely occur in Jiyang Depression,especially in Loujia-Kenxi region. Here,based on geological,geochemical and geophysical data,these oils were described and studied extensively in physical properties,sulfur contents,gross compositions,geochemical characteristics and reservoir features. Finally,we discussed the formation mechanism and outlined some exploration strategies of these viscous oils.The typical deep viscous oils in Loujia-Kenxi area are characterized by a high density (or low API gravity),a high viscosity,a high sulfur content and low amounts of saturates and aromatics as compared to resins and asphaltenes. The physical properties of these crude oils are closely related to their sulfur contents and gross compositions,hi addition to viscous oils,there are also some normal oils and intermediate oils between the normal and viscous types. As a result,the physical property,sulfur content and bulk composition of crude oils in this area vary significantly.Based on GC and GC-MS analyses,the geochemical characteristics of these typical deep viscous oils are listed as follows:(1) strong preference of even n-alkanes over odd n-alkanes;(2) strong preference of phytane over pristane,i.e. Pr/Ph ratio1;(3) high abundance of gammacerane relative to Caohopanes;(4) much more amounts of C35 pentakishomohopanes than C34 tetrakishomohopanes and even C33 trishomohopanes. Oil source correlation results demonstrate that these deep viscous oils are derived from the Es4 evaporite source rocks.Most of these deep viscous oils in Loujia-Kenxi region show no sign of biodegradation effects based on n-alkane and acyclic isoprenoid distributions. It appears that biodegradation,oxidation and water washing near the surface are not responsible for the high density and high viscosity of these deep viscous heavy oils,In addition,biomarker parameters demonstrate maturities of these viscous oils are relatively low to that of the normal oils derived from the Es3 source rocks in this area. It is possible that these deep viscous oils were generated from the Es4 evaporite source rocks during the early oil generation stage. After further burial,their maturity parameters increased while their physical properties remained unchanged.hi addition to these native viscous oils,there are also typical altered viscous ones in Jiyang Depression,of which the gas chromatograms show clearly the features of biodegradation effects. The biomarker characteristics of these two types of viscous oils are distinctive. Oil source correlation results show the altered viscous oils were generated from the Es3 source rocks and subsequently suffered biodegradation,oxidation and water washing effects near the surface.There exists huge thick alluvial glutinite in Luojia-Kenxi area,with various physical properties. By applying the comprehensive study idea of geostatistical analysis and geophysics,the reliable reservoir distribution is described in the complicated thick glutinite body. By comprehensive analyzing log multi-parameters,oil,gas and dry layer are identified,and the reservoir distribution in Luojia-Kenxi area is further described. The reservoir and hydrocarbon prediction are reliable provedby the drilling of production preparing wells.On the basis of systematic research,it is shown that there exist great resource potential and different exploration targets in deep viscous crude of Jiyang depression.

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