【作者】 马海勇；

【导师】 周立发；

【作者基本信息】 西北大学 ， 矿产普查与勘探， 2013， 博士

【摘要】 近年来,鄂尔多斯盆地中西部延长组下组合油层组勘探取得了重大突破,显示出较好的勘探前景。许多学者对该区延长组下组合油层进行了构造单元、地层格架、沉积展布等方面的研究,但对该区延长组下组合油藏的分布规律以及成藏控制因素等方面的问题认识还不够明晰。这些问题的解决不仅能够进一步完善对鄂尔多斯盆地中生界湖盆油气成藏规律的认识,而且对于鄂尔多斯盆地中西部下组合油藏的勘探也具有指导意义。本次研究充分利用最新的录井、测井、化验分析等资料,对鄂尔多斯盆地中西部延长组下组合油藏的主控因素进行了系统研究,从控制储层形成的沉积相、储层特征等静态要素和影响油藏形成的成岩作用过程、油气运聚成藏过程、圈闭形成过程等动态过程两个方面进行综合研究。在静态要素研究方面,利用层序地层学方法对鄂尔多斯盆地延长组地层沉积旋回进行划分,确立了该区延长组下组合地层三维地质模型。通过研究区下组合储层砂岩的轻重矿物组合特征、微量元素配分模式、成像测井古水流分析等资料对研究区物源进行分析,认为该区受西北、东北两个方向的物源控制,其主要受西北物源的控制。本文结合鄂尔多斯盆地中生界湖盆演化过程和沉积相标志综合研究,认为晚三叠世早期湖盆基底处于沉降阶段,研究区距离物源较近,长9期发育辫状河三角洲沉积体系,辫状河三角洲平原为主要的沉积亚相,长8期发育浅水三角洲沉积体系,浅水三角洲平原和浅水三角洲前缘沉积为主要的沉积亚相。本文在对铸体薄片、扫描电镜等相关分析化验资料统计的基础上,分析得出延长组下组合储层砂体主要为岩屑长石砂岩、长石岩屑砂岩,长9储层砂岩粒度较粗,粒间孔发育,平均孔隙度11.27%,平均渗透率3.80mmD。长8储层砂岩以细砂岩为主,粒间孔、长石溶孔发育,平均孔隙度8.5%,平均渗透率0.61mD。在动态过程研究方面,盆地中西部延长组下组合油藏储层砂岩的成岩作用过程的研究结果表明延长组下组合油层储层砂岩经历了压实作用、胶结作用、交代作用和溶蚀作用等成岩作用,储层砂岩已进入晚成岩A期。利用单因素分析多因素综合的方法进行成岩相分析,将研究区延长组下组合油层成岩相划分为长石溶蚀成岩相、绿泥石膜-粒间孔成岩相、碳酸盐胶结成岩相、压实成岩相等四种类型；长石溶蚀成岩相和绿泥石膜-粒间孔成岩相为建设性成岩相,有利于储集空间的形成。根据包裹体镜下观察和均一温度频率分布特征,结合盆地中生界构造演化史的综合分析,发现盆地中西部延长期发育两期包裹体,分别代表了晚侏罗世-早白垩世、白垩世末的两次构造抬升过程中的油气成藏事件。在研究区延长组下组合地层砂岩裂缝的发育特征和平面分布规律研究的基础上,本文认为研究区主要发育E-W、NE-SW向裂缝,在天环坳陷轴部裂缝走向为NE-SW:天环坳陷东西两侧和邻近伊陕斜坡区为E-W向。受NEE-SWW向现今应力场的影响,NE-SW向裂缝为主要的渗流方向。鄂尔多斯盆地延长组长7烃源岩的生烃增压作用产生的过剩压力是石油横向、纵向运移的动力,过剩压力从高值区向低值区聚集,过剩压力低值区是油气聚集的场所。与油藏伴生的地层水水型、矿化度、物化参数的平面分布规律反映了油藏保存条件,研究区延长组下组合油藏伴生的地层水平面分布受燕山期构造运动的影响较大,不同区域地层水的化学性质明显不同,天环坳陷东侧靠近伊陕斜坡、三角洲河道砂体发育区地层水矿化度高、钠氯系数、脱硫系数低,油藏保存条件好；天环坳陷轴部、靠近西缘冲断带断层、裂缝发育区,由于受后期构造运动改造封闭性变差,地层水矿化度低,钠氯系数、脱硫系数都偏高,油藏保存条件相对较差。本文在对鄂尔多斯盆地中西部延长组下组合油藏形成的静态要素和动态过程系统研究的基础上,根据油藏的分布规律和主控因素,在研究区延长组长8油层优选了四个有利目标区。更多还原

【Abstract】 In recent years, the lower Yanchang formation exploration in the middle of west Ordos basin is making a breakthrough and displaying preferable prospect. Many scholars studied the lower formation of Yanchang formation reservoir of the area tectonic units, stratigraphic framework, sand spread characteristic, but the less study of the distributive regularity and control factors of the lower formation of Yanchang formation reservoir and which restricts the exploration process. The results of these programs improve the understanding of Ordos Basin in Mesozoic accumulation theories, but also direct the exploration of the area.Utilizing the latest drilling data, the research analyses the main controlling factors the lower formation of Yanchang formation reservoir in the middle of west Ordos basin. The comprehensive research includes two aspects which were static elements controlling reservoir formed and dynamic elements which destructed and transformed reservoir. Static elements are formed by deposition phase, characteristics and source rock conditions. These dynamic elements are consist of diagenesis, hydrocarbon migration, accumulation reservoir, trap formation, and the reservoir destruction and transformation.Static factor analysis, the sequence stratigraphy method is used to divide Yanchang formation reservoir into sedimentary cycles, establish the lower Yanchang formation reservoir3D geological model. Used light and heavy mineral assemblages, trace elements, imaging logging paleocurrent direction to analysis provenance direction. The conclusion is that the provenance direction of in the middle of west Ordos basin subject to the control of the direction of the northwest and northeast provenance, and the northwest provenance is the mainly control. Combination the basin evolution and sedimentary facies characteristic comprehensive analysis that early Late Triassic lake basin base was in descending stage. The middle of west Ordos basin is closer to provenance, Chang9was developed braided river delta sedimentary system, and Chang8was developed shallow water delta. Analysis of the statistics shows that the lower Yanchang formation mainly sandstone is Lithic arkose, feldspathic lithic sandstone. The Grain Size of Chang9sandstone is coarse, the average porosity of the sandstone is11.27%, and the average permeability is3.8OmD. Chang8sandstone is fine sandstone, The dominating pore type of Chang8reservoirs is intergranular pore and feldspar dissolved pore, the average porosity is8.5%, and the average permeability is0.61mD.Dynamic factor analysis, the lower Yanchang formation sandstones are in the A period of the late diagenetic stage. This set of sandstone experienced compaction, cementation, metasomatism and dissolution diagenesis. Used the single factor analysis and multifactor comprehensive method to analysis diagenetic facies zone of the area. The result is that the feldspar dissolution diagenetic facies, chlorite intergranular pore diagenetic facies is a constructive diagenetic facies. Two different phases of hydrocarbon inclusions have been identified according to the microscopic characteristics of sandstone type U-deposit and homogeneous temperature distribution characteristics and referring to the tectonic evolution history of the Ordos Basin. It represents Late Jurassic and end of the Cretaceous tectonic uplift process hydrocarbon accumulation event. Based on the characteristics of tectonics evolution, the well drilling, log information and microscopic, high resolution boreholemicro resistivity image logs were used to investigate the flat distribution regulation and genesis of the fractures.The research shows that the E-W and NW-SE regional fractures are developping well. It is found that E-W fractures developed well where closed to Yishan Slope, and NW-SE fractures developed well neared Tianhuan depression or faults.The directions of the present tectonic stress fields in the basin were NEE-SWW which controlled the fractures expanded and permeability. Hydrocarbon source rocks of Chang7increased pressure from hydrocarbon generation expanding which was the dynamic force for the oil transverse and vertical migration.The oil migrated from higher pressure area to lower pressure area and accumulated in lower pressure area. Chemical characteristics of formation water were used to study the condition about the oil and gas migration and preservation of the lower Yanchang formation in the middle of west Ordos Basin. It is found that the formation water type is CaCb, the formation water salinity is high, ratio of Na+and Cl-and coefficient of desulphuration is low where develop shallow-water deltas in sandstones and closed to Yishan Slope. The formation water salinity is low, ratio of Na+and Cl-and coefficient of desulphuration is high where neared Tianhuan depression or faults. Conclusion The formation water distribution was influenced by Yanshan movements, closed geological environment is good for oil to be preserved where the formation water salinity is high, ratio of Na+and Cl-and coefficient of desulphuration is low.Analysing those static elements and dynamic elements of the controlling factors of the lower assemblage of Yanchang formation reservoir, four targets were selected in Chang8reservoir to provide the orientations of exploration.更多还原