【作者】 张道锋；

【导师】 李文厚；

【作者基本信息】 西北大学 ， 矿物学、岩石学、矿床学， 2006， 硕士

【摘要】 陕北斜坡南部延长组是鄂尔多斯盆地最主要的含油层系。依据野外剖面露头观察、岩芯描述、单井测井相分析和连井剖面对比,结合岩石类型、沉积结构、构造、古生物、沉积旋回等多种手段,识别出陕北斜坡南部上三叠统延长组主要由河流沉积体系、湖泊沉积体系、三角洲沉积体系组成,并进一步分为11种亚相,22种微相,详细研究了研究区内的三角洲沉积体系,认为研究区内存在辫状河三角洲和曲流河三角洲沉积,并识别出研究区内发育两种不同地层样式的湖泊三角洲沉积:深水盆地型三角洲和浅水台地型三角洲。 研究表明,延长组存在东北部和西南部两大物源,其中东北部物源来源于盆地北缘的阴山、大青山地区的太古界乌拉山群和下元古界二道凹群中的深变质结晶片岩、片麻岩,西南部物源来源于盆地西南缘秦岭区的震旦亚界和上、下古生界的浅海相碎屑岩及碳酸盐岩。另外,盆地西北方向也存在一支规模较小的物源。 陕北斜坡南部延长组主要发育东北、西南两大沉积体系,东北部以曲流河三角洲沉积体系为主,而西南部以辫状河三角洲沉积体系为主,并在庆阳-合水一带发育浊积扇沉积。纵向上从长10-长2总体呈现向南进积的趋势,而长1期基底的不断上升,局部地方出现差异沉降,形成了内陆闭塞的浅水小湖泊,全区普遍大面积沼泽化,从而导致湖盆最后枯竭,结束了延长组的沉积历史。沉积体系平面展布特征控制砂体展布,东北沉积体系砂体连片性好,以席状、朵状为主,呈北东向展布;西南沉积体系的砂体形态为条带状,呈东西向或北东向展布。延长组沉积过程经历了湖盆发育初期的平原河流,中期的湖泊环境,晚期的泛滥平原至湖泊消失三个阶段。 研究区烃源岩和生油中心的分布均与深湖区的分布有良好的对应关系。储集层性能与分布均受沉积体系的控制。河道砂体、三角洲平原分流河道砂体、三角洲前缘水下分流河道砂体和浊积扇砂体是有利储集体。频繁的湖进和湖退,为形成良好的生、储、盖空间组合提供了条件。综合沉积相带和砂体展布、构造特征和储集层性能等多方面因素分析,优选出延长组主要油层组有利勘探区。更多还原

【Abstract】 The yanchang formation in the south of the slope of shanbei is important oil-bearing series in Ordos basin. Based on outcrop observation , core description , single log facies analysis and connecting-well section , combined with the rock types , depositional texture , structure , paleontology and sedimentary cycle , etc , the Upper Triassic Yanchang formation is composed of the fluvial system , the lacustrine system and the delta system in the south of the slope of shanbei ,which are farther divided carefully them into 11 types sediment subfacies and 22 types sediment micfacies .and After researching carefully the delta system in research aera , There are two types delta sedimentary . It is braided river delta sedimentary and meandering river delta sedimentary , and two different types of stratigraphic modes was identified in lacustrine - delta system , that is , the deep water delta and the water platform delta .The study showed , the yanchang formation has the southewest and norheast provenances , the northeast provenance come from the Archeozic Wulashan group and lower proterozic Erdaoao group of high-grade metamorphic crystalline schist and gneiss in Yinshan mountain and Daqing mountain in the north part of Ordos basin , the southwest provenance come from the Simian and Paleozoic neritopelagic detrital rock and carbonatite . In addition , there are subprovenancs in the northwest, but their size are small.The study showed , the yanchang formation in the south of the slope of shanbei have two main deposition systems , that is , the northeast and southwest deposition system , the deposition system in the northeast of the research area is the main of meandering river delta deposition system , the deposition system in the southwest of the research area is the main of braided river delta deposition system , while , the turibidite fan appears in Qingyang—Heshui in the southwest. There is a general trend of progradation to the south in the cross section from changlO to chang2 period , however , because the basement was uplifted , the part of region appeared differential subsidence ,the continental shallow small lake was formed in chang 1 period .Because the large region appeared paludification , the lake disappeared at last, so the history of yanchang formation deposition ended . The characteristics of distribution of sedimentary system in plane controls the distribution of sand body , the northeast sedimentary system’s sand body has a good continuity and presents silllike of northeast-southwest trend in the plane , the southwest sedimentary system’s sand body presents a band shape of east -west or northeast-southwest trend . The procession of Yanchang formation sediment come through three stages, that is , plain-river environment in the early lacustrine basin development era , lacustrine environment inthe metaphase era ,and the flood plain-river plain environment ,and then lacustrine disappear in the late era.The source rock and the distribution of the centre of oil generation all have well coincidence relation with the distribution of deep lake in research area . The property and distribution of reservoir is controlled by sedimentary system , the stream channel sandbody , deltaic plain distributary channel sand body , deltaic front subaqueous distributary channel sand body and turbidite fan sand body are good reservoirs . The favorable source-reservoir-caprock group can be formed for the frequency of lacustrine transgression and regression . Through analysis of sedimentary facies , the distribution of sandbody , the character of structure and the property of reservoir, etc , the favorable exploration area can be found out in the main oil-bearing beds in Yanchang formation .更多还原