【作者】 万友利；

【导师】 张哨楠；

【作者基本信息】 成都理工大学 ， 矿产普查与勘探， 2011， 硕士

【摘要】 鄂尔多斯盆地地处我国东西部构造区域接合区,受到东、西部构造的多期次、反复交替的拉张及挤压作用影响,形成以不整合面为界限的多构造体制、多演化阶段、多沉积体系、多原型盆地叠加的复合盆地,在我国行政区划上横跨陕西、甘肃、宁夏、内蒙古、山西5省市,面积约37×10~4km~2。构造单元上可划分为伊盟隆起、渭北隆起、西缘前陆冲断带、天环坳陷、陕北斜坡和晋西挠褶带,其中陕北斜坡面积巨大,构成了盆地以三叠系油气勘探的主体区域。鄂尔多斯盆地经过数十年的勘探开发,已经发现并投产的油田显示:盆地内部中生界地层厚度大、分布范围广,主要生、储岩系为晚三叠世延长组,其中长7油层组、长4+5油层组发育大段暗色泥岩,为半深湖—深湖沉积;长6油层组和长8油层组发育以砂岩为主的储层;储层砂体主要有东北缓坡河流三角洲沉积体系和西南陡坡区辫状河三角洲沉积体系,在西北部及南部发育少量扇三角洲沉积体系,湖盆中半深水—深水部分区域发育浊积扇沉积;地层圈闭和岩性圈闭是构成上三叠统延长组油气成藏的主体。鄂尔多斯盆地晚三叠世延长组沉积充填记录了湖盆产生、间歇震荡式湖进、湖退及消亡的兴衰演化历史。物源分析研究表明盆地在延长组沉积时期是一个多水系大型汇水盆地,古水系主要有东北190°~250°和西南50°~65°两大主流向,在盆地西北缘野外剖面的流向基本在105°~135°及正南方向,在盆地南部有正北方向股水流;轻、重矿物研究及稀土元素REE配分模式特征也表明晚三叠世沉积期盆地主要物源方向为北东向及南西向物源,同时也存在西北方向物源及南物源,但南物源影响范围不大。结合盆地沉积边界确定研究,能够为晚三叠世延长组沉积提供物源的母岩为东北方向的阴山古陆乌拉山群、集宁群,西北方向的阿拉善古陆阿拉善群,西南方向来自陇西古陆、秦岭—祁连古陆的一套中高级变质岩及花岗岩,受其控制在盆地内部相应发育形成了东北大型缓坡型复合河流三角洲沉积体系、西北扇三角洲沉积体系、西南大型陡坡型复合辫状河三角洲及扇三角洲沉积体系。成岩作用方面:延长组砂岩经历了早成岩期的压实作用和胶结作用、晚成岩期的溶蚀作用和交代作用。早成岩期的压实作用及胶结作用导致砂体储集性能降低,溶蚀作用及交代作用改善了砂体的孔隙结构和储集性能,但总体来说延长组砂体仍具有特低孔渗特征。碎屑岩储层的孔隙度既是埋藏深度和次生孔隙发育的函数,又是受物源条件和沉积环境控制的沉积物成分和结构、受构造运动控制的沉积碎屑物质埋藏史、水动力条件、孔隙流体性质及其演化阶段、地温场、与储层岩体相关的沉积体系内有机质及粘土矿物的成岩演化等一系列相关因素共同作用的结果。物源及沉积环境控制沉积物成分及结构,经历埋藏、成岩过程,延长组砂体因不同物源及沉积环境,各沉积体系的成岩作用特征也具有差异,受阴山古陆物源控制发育的东北部大型缓坡型沉积体系砂体长石及云母含量高,压实作用强烈,浊沸石胶结是本区胶结作用的主要特征,溶蚀作用阶段的长石溶蚀主要发生在三角洲平原分流河道砂体中,烃源岩生烃时产生的有机酸从盆地中心向东北方向边缘运移时沿途对浊沸石进行溶蚀形成不同溶蚀程度的环带,长石溶蚀及浊沸石溶蚀大大改善了储层性能。西南部砂体及南部砂体相较于东北砂体来说,石英含量较高,刚性颗粒对上覆地层的支撑作用更强,但上覆地层比东北部要厚的多,同时还有大量千枚岩岩屑,故西南部压实作用也较强烈,早成岩期形成的环边绿泥石对本部砂体原生孔隙具有一定的保护作用。受西北物源浅变质岩、火山岩控制的沉积体系长6油层组比长8油层的发育范围缩小很多,浅变质岩在压实作用中极易形成假杂基而堵塞孔隙,所以刚性颗粒石英的多少与储集物性有非常好的相关性。更多还原

【Abstract】 Ordos Basin tectonic area was located in the west in China by landing zone of east and west structure in many times, alternately repeatedly pull zhang and extrusion effect with unconformity, forming the many tectonic system for boundaries, evolutionary stages and sedimentary system and more complex basin superposition prototype basin in China, administrative divisions over the shaanxi, gansu, ningxia, Inner Mongolia, shaanxi 5 provinces, an area of about 37×10~4km~2. The tectonic units can be divided into YiMeng uplift, considered uplift, west margin foreland thrust belt and tianhuan depression, shanbei slope and jinxi fold belt, including shanbei slope area, constitute a huge oil and gas exploration in the basin subject area Triassic.Ordos basin, after decades of exploration and development, has been found and put in oilfield shows: basin internal Mesozoic strata large thickness, distribution scope, main birth, porosity are late Triassic to extend groups, among which chang 7 reservoir group, chang 4+5 reservoir development section of the dark mudstone, to half deep lake - deep lake sedimentation; chang 6 reservoir group and chang 8 in sandstone reservoir development mainly of reservoir; Reservoir sandbody mainly northeast river delta depositional system and slope southwest steep slope area braided delta depositional system, in the northwestern and south fan delta depositional system development, a semi-deep-lake deep-water - deep-water part in half regional development turbidite fan deposition; Stratigraphic traps and lithologic trap is composed of upper Triassic prolong the subject of hydrocarbon accumulation.Ordos basin late Triassic to prolong the deposition of the filling record semi-deep-lake to produce, intermittent concussion type lake lake withdrew into, and evolution history of and extinct. The provenance analysis research shows that basin during the deposition in prolonging the group is more than a stream large catchment basin, ancient water system mainly northeast 190°~250°and 50°~65°southwest to two mainstream in basin, the flow of the field profiles at 105°~ 135 basic°and south direction, in basin in the south north direction strands of flow; Light and heavy mineral research and rare earth elements stable REE distribution pattern characteristics also suggests that the late Triassic depositional period basin the primary provenance direction as north east to the west and south material sources, but also the existence the provenance and northwest, but south south the provenance is the provenance influenced range. Combined with the basin sedimentation, can determine the research for border late Triassic provide extended the deposition of the material sources of the parent rocks northeast of yinshan for ancient land castrated2 mountains, JiNing group, the ancient land ALaShan northwest, southwest direction ALaShan group of ancient land, from west gansu qinling - a set of ancient land dang senior metamorphic rocks and granite, suffer its control in basin formed inside the corresponding development of composite northeast large slope river delta depositional system, northwest fan delta depositional system, southwest large steep type composite braided river triangle and fan delta depositional system.Diagenesis aspects: extend the sandstone of the experience of heavy rain and high winds compaction effect rock period and cementation, late diagenetic stage of dissolition and explaination role, precocious rock period compaction effect and cementation cause sand body reservoir property is reduced, dissolition and explaination role improved sand body reservoir pore structure and properties, but overall extend group sand body still have extra-low permeability and porosity features. Of clastic reservoir porosity is buried depth and secondary porosity function, is also subject to the provenance conditions and sedimentary environment control of sediments composition and structure, by structural motion control sedimentary clastic particle burial history, hydrodynamic conditions and pore fluid properties and evolutionary stages, geothermal field, and reservoir rock within the sedimentary system related to organic matter and clay mineral and so on a series of diagenetic evolution related factors the result of joint action.The provenance and sedimentary environment control in composition and structure, experience sediments buried, diagenetic process, extend for different objects of sand body source and sedimentary environment, the diagenesis of depositional system also has difference, the characteristics of ancient land content source control west-to-east deelopment of type of large slope sedimentary system northeast sand body feldspar and mica content high, compaction effect, turbidity zeolite cementation is strong in the main characteristics of cementation, dissolition stage of feldspar dissolution mainly in delta plain distributary channel sand, hydrocarbon source rock hydrocarbon generation when from the center to organic along the northeast edge of turbidity zeolite when migration on dissolution dissolution degree form different band, and feldspar dissolution and turbidity zeolite dissolution has greatly improved the reservoir properties. Southwest sand body and south sand body compared to the northeast sand body speaking, quartz content is higher, rigid particle on the overlying strata support action, stronger, but the upper stratum of the northeast to more than thick, and still a large number of thousand pieces rock cuttings compaction effect, so southwest stronger also, precocious rock formation of ring (for part edge chlorite primary porosity of sand body has certain protective effect. Northwest things by source shallow metamorphic rock, and volcanic rocks control sedimentary system long and six reservoir group than in the development of reservoir long 8 narrowed down a lot, shallow metamorphic rock in compaction effect easily in the miscellaneous base and jam formed false pore, so rigid particles with the amount of quartz reservoir physical property has a very good correlation.更多还原