【作者】 魏刚；

【导师】 王冠民； 周心怀；

【作者基本信息】 中国石油大学 ， 矿物学、岩石学、矿床学， 2007， 硕士

【摘要】 辽西低凸起中北段目前已发现JZ20-2、JZ25-1/S等油气田,是辽东湾重要的油气产区,其含油气层位主要有东营组、沙河街组和太古界潜山,本次研究的重点是沙河街组。长期以来,影响该地区沙河街组成藏的烃源不清楚,对其输导格架、成藏动力、成藏期次等认识模糊,这极大制约了该地区的进一步勘探。本文选取辽西低凸起中北段及其相邻凹陷为研究对象,力图通过地球化学、现代石油地质学的理论和三维地震解释以及流体包裹体分析和盆地模拟分析等方法和手段来解决该地区所存在的问题。在上述理论的指导下通过油气源分析、输导系统研究以及成藏期次的综合研究确定了辽西低凸起中北部沙河街组油气的成藏机理。这对于进一步认识辽西低凸起油气的成藏过程,挖掘辽东湾地区油气勘探的巨大潜力具有重要的现实意义,同时对于丰富和发展油气成藏理论研究具有积极的作用。通过对辽西低凸起中北段沙河街组原油与辽西凹陷、辽中凹陷烃源岩甾萜烷对比分析,表明JZ25-1/S油气田原油具有与辽西凹陷烃源岩相似的甾、萜烷特征,均具有伽马蜡烷含量中等到高、4-甲基甾烷含量较高,规则甾烷呈C27>>C28<C29的偏“V”字形分布特征,证实JZ25-1/S原油来自辽西凹陷;而JZ20-2油气田原油具有两种甾、萜烷分布特征,分别为规则甾烷呈C27>>C28<C29的偏“V”字形分布特征和C27>C28>C29的偏“L”字形分布特征,证实其具有双向油源,分别来自辽西和辽中凹陷。总结来看,辽西低凸起沙河街组原油具有辽西凹陷和辽中凹陷双向油源的不对称供烃特征。对辽西低凸起中北段输导系统综合研究证实断层、砂岩输导层及不整合面共同构成了辽西低凸起沙河街组成藏的主要输导系统。该区多条断层组合成顺向屋脊断阶带、“Y”字型断层组合、边界断层下降盘断阶带和负花状构造等构造样式,断层组合的构造样式对油气的二次运移及油气再分配起到了决定性作用。砂体和不整合面为油气侧向输导提供了重要通道。根据三者的耦合关系,该地区输导系统可分为三类:①断层输导系统,进一步划分“Z”型和“T”型输导系统;②阶梯型断层-砂岩输导系统;③不整合-断层-砂岩输导系统。三类输导系统不仅为油气运移提供了通道,而且对油气藏类型也有直接影响。通过对JZ25-1/S油气田和JZ20-2油气田的输导系统及油气藏类型的综合分析,总结了输导系统类型与油气藏类型的匹配关系:①“Z”型输导系统往往形成块状油气藏;②“T”型输导系统可以形成块状或层状油气藏;③阶梯状断层-砂岩输导系统控制的油气藏类型多变,既可以形成层状油气藏,还可以形成构造岩性油气藏;④不整合-断层-砂岩输导系统往往形成层状或块状油气藏。通过对辽西低凸起JZ25-1S油气田的部分钻井进行了热史和埋藏史模拟,并结合流体包裹体均一化温度,确定了该区沙河街组成藏期在20～24Ma之间,时代上对应东一段沉积末期,且具有一次充注形成的特征。更多还原

【Abstract】 Many oilfields have been found such as JZ20-2, JZ25-1/S in mid-north Liaoxi low uplift, where was one of the most important places of oil-gas production. The Dongying formation, Shahejie formation and Archaean buried hill are the main petroliferous formations. The Shahejie formation is chosed as the priority in this paper.However, there are some primary petroleum geological problems in this region, such as the source of the existing hydrocarbon, the hydrocarbon filling periods and accumulation process still leaving unsolved. And these problems restrain the exploration steps, and more they have become the restrictions to the hydrocarbon exploration.For this reason, this paper choose Liaoxi low uplift and its adjacent sags as the target,and try to settle these puzzles mentioned above with the assistance of modern theories of geochemical and petroleum geology, strategies of 3D seismic interpretation, basin molding as well as fluid inclusions analysis. Under the direction of these theories, integrated analysis that consist of hydrocarbon-source correlation, transporting-conducting system analysis, reservoir-forming dynamic analysis and reservoir-forming periods analysis are conducted, and based on which the mechanism of hydrocarbon transportation in Liaoxi low uplift region is constructed. This study is of great practical significance to the understanding of the hydrocarbon accumulation process of the uplift as well as to taping its great exploration potential, at the same time, it has positive effect to enrich and develop the theories of the petroleum generation, migration and accumulation.This paper contrasts, oil of mid-north part of Liaoxi low uplift and hydrocarbon source rocks of adjacent sags are analyzed synthetically, the result indicates that the oil of JZ25-1/S oilfields has the same kinds of sterane and terpane as the hydrocarbon source rocks in Liaoxi sag, which has the characteristics of mid-high content of gammacerane, high content of 4-methylsterane, regular sterane C27, C28, C29 has the bias-V characteristics of C27>>C28<C29. The results confirm that the oil of JZ25-1/S oilfield is from Liaoxi sag. While the oil JZ20-2 oilfield has two kinds of sterane and terpane, regular sterane C27, C28, C29 has the bias-V characteristics and bias-L of C27>C28>C29, all these confirm JZ20-2 oilfields accumulated hydrocarbon from two different directions. As a whole, hydrocarbon in Liaoxi low uplift is accumulated from two different directions and the quantities come from each direction are of great difference.The transporting-conducting systems are composed of faults, sandbody and unconformity. Multi faults composed several structural styles such as dip fastigium terrace, Y-type faults group, downthrown terrace caused by boundary faults and positive flower structure. The structure styles of faults group made a critical function to secondary oil migration and oil redistribution. Sandbody and unconformity provide an important pathway for oil lateral transporting-conduction. Based on the coupling relationship of faults, sandbody and unconformity, the transporting-conducting system can be divided into three different types:①fault conducting system,②cascade conducting system,③fault-unconformity-sandbody compounded conducting system. Three kinds of conducting systems provides pathway for oil migration, also they influence the types of oil-gas accumulation.Based on the analysis of transporting-conducting systems and types of oil-gas accumulation in JZ25-1/S and JZ20-2 oilfield, we conclude 4 kinds of matching relationship of them:①Z-type transporting-conducting systems form massive oil-gas reservoir,②T-type transporting-conducting systems form massive or layered reservoir,③cascade conducting systems form layered reservoir or lithologic oil reservoir,④fault-unconformity-sandbody transporting-conducting systems form layered or massive reservoir.The burial history and geothermal history of some wells in JZ25-1S oilfields are reconstructed firstly and then with the combination of homogeneous temperature analysis of fluid inclusions from productive reservoir formations, periods of hydrocarbon charging are determined. The analysis of hydrocarbon accumulation period indicated that the oil of JZ25-1S oilfield has a single and relatively earlier hydrocarbon charging and accumulation period. The accumulation period of the Shahejie formation in JZ25-1S oilfield is formed between 20-24Ma which corresponds to the end of 1st menber of dongying formation sedimentary period.更多还原