【作者】 邵晓岩；

【导师】 田景春；

【作者基本信息】 成都理工大学 ， 沉积学， 2009， 硕士

【摘要】 本论文在前人众多研究成果的基础上,以沉积学、沉积地球化学、石油地质学理论为指导,充分利用钻井、测井和测试分析资料,通过沉积构造、岩性组合、地球化学、砂岩微观特征以及测井响应特征综合分析,对鄂尔多斯盆地白豹—华池地区三叠系延长组长4+5油层组的沉积微相及储层特征进行了深入研究。根据沉积旋回,以K5和K6标志层进行等时性对比,将研究区长4+5油层组划分为2个亚段4个小层:即4+51、长4+52、4+511、长4+512、4+521、长4+522。利用岩性标志、沉积构造、古生物化石、粒度分布特征、测井相分析以及剖面结构等相标志分析,在研究区长4+5沉积期识别出湖泊三角洲前缘亚相、前三角洲亚相和滨浅湖亚相,可进一步划分为水下分流河道、河口坝、远砂坝、水下天然堤和水下决口扇、席状砂、分流间湾、前三角洲泥及浅湖泥等沉积微相。首次在研究区长4+5油层组中发现了震积岩沉积,论述了震积岩特征,建立了震积岩沉积序列,分析了其成因。通过大量的钻井岩心观察,在研究区长4+5油层组发现了发育大量由震积液化作用形成的砂球、砂枕、球～枕构造、微断层递变层、微裂缝、液化卷曲变形等同生变形构造,识别为震积岩,在详细研究了该区震积岩特征的基础上,建立了震积岩所具有的不同沉积序列,深入分析了其成因。通过对长4+522期～长4+511期砂体展布规律研究及岩相古地理编图,认为白豹—华池地区长4+5湖泊三角洲沉积体系属于东北水系志靖三角洲和吴旗三角洲向西南方向的延伸部分,结合沉积相标志研究、沉积类型划分及特征研究、震积岩特征研究,从而建立了研究区长4+5沉积期沉积模式。首次充分利用沉积地球化学标志,定量～半定量反演了研究区长4+5沉积期的湖盆水体性质和古气候条件,进一步论证了长4+5沉积期的沉积环境。利用沃克法(相当硼法)、亚当斯法(Admas)及元素比值法(Sr/Ba)推断出研究区长4+5沉积期为淡水沉积环境;利用铁矿物组合法和Fe2+/Fe3+比值法判断当时沉积环境为弱还原环境;通过元素组合法(Cu、Ba、Ni等)分析,认为研究区长4+5沉积期为滨湖～浅湖沉积环境;根据元素组合法(Fe、Mn、Cr、V、Ni等)和元素比值法(Sr/Ba、Fe3+/Fe2+)分析,认为研究区长4+5沉积期为潮湿气候条件。根据大量的岩心观察和测试分析资料认为,三角洲前缘的水下分流河道和河口坝以及复合成因类型的砂体是储集层发育的有利相带。研究区长4+5储集层砂岩为近物源沉积的矿物成熟度和结构成熟度较低的岩石类型,主要为长石砂岩,其次为岩屑长石砂岩。孔隙类型主要为剩余粒间孔,其次为长石溶孔。储层平均孔隙度14.36%,平均渗透率1.66×10-3μm~2,属于低孔特低渗～特低孔特低渗型储层。研究区内成岩作用主要有机械压实、压溶、胶结、溶蚀等作用,其中早期胶结和溶蚀对储层的发育具有建设性作用。对姬塬—胡尖山和白豹—华池两地区长4+5油层组进行了类比研究,论文通过两地区的岩石类型、重矿物组合、石英阴极发光、砂体展布规律、垂向相序变化以及储集砂体成因类型等特征的对比,认为姬塬—胡尖山地区主要受阿拉善古陆和阴山古陆控制物源,属于西北水系和东北水系的混合沉积区,长4+52沉积期砂体相对发育,水下分流河道及多期水下分流河道的叠置是储集砂体发育的有利相带;而白豹—华池地区主要受阴山古陆控制物源,属于东北三角洲沉积体系,长4+51沉积期砂体相对发育,有利储集相带主要是河口坝及叠置河口坝。更多还原

【Abstract】 With the comprehensive analysis of the sedimentary structures,lithologic composition,geochemistry,micro-characteristics of sandstone as well as the characteristics of the log response,based on many previous research results,using sedimentology,petroleum geology theory,this paper makes full use of information of the drilling,well logging and testing analysis to study the sedimentary microfacies and reservoir characteristics of the chang4+5 oil-bearing Intervals of the Triassic Yanchang formation in the Baibao—Huachi region in Ordos Basin.According to sedimentary cycles,contrasted stratum’s isochronism with K5 and K6 marker bed,the chang4+5 oil bearing intervals is divided into two sub-paragraphs and four layers which are chang 4+51,chang 4+52,chang 4+511,chang 4+512,chang 4+521,chang 4+522.Use of the facies marker such as lithology, sedimentary structures, fossils, particle size distribution, log-phase analysis and profile structure of analysis of,etc,it can be recognized delta front, the former delta and shallow lake subfacies in chang4+5 oil-bearing intervals in the research area,and can be more identified diversified sedimentary microfacies such as underwater distributary channels, mouth bars, distal bars, subsea natural barriers and crevasse splays, sand sheets, separate inter-bays, the former delta muds and shallow lake muds and so on.For the first time seismites,deposition is discovered in the chang4+5 oil-bearing intervals in research district,while discussing the characteristics seismites, establishing seismites sedimentary sequence and analysising its causes. Through the observation for the cores, many syndepositional deformational structures such as sand balls,sand pillows,ball-and-pillows, graded micro-faults, micro-cracks, fluidified convolute deformational beddings have been greatly discovered in the lake delta front deposition in the chang4+5 oil-bearing intervals,which are recognized as seismites.On base of the detailed sduty of the seismites characteristics, it can be established different sedimentary sequences,and in-depth analysed its causes. Study on the sandbody distribution and lithofacies palaeogeography mapping from the chang4+522 to chang4+511 sedimentary period suggest that depositional system of the Baibao- Huachi area in chang4+5 sedimentary period is belong to the extension of the northeast Zhi Jing Delta and Wuqi delta to south-west direction.Chang4+5 sedimentary depositional model.is established on combining with study of sedimentary facies marks,sediment type characteristics and dividing as well as characteristics of seismites.For the first time the paper have a quantitative or semi-quantitative study on inversion of the chang4+5 sedimentary depositional environment and paleo-climatic conditions taking full advantage of the sedimentary geochemistry signs.Using the walker method (equivalent boron method),the Adams method and the elemental ratio method(Sr/Ba) conclude that it was the freshwater depositional environment in the period of chang4+5. Using iron mineral assemblage method and Fe2+/Fe3+ method determine that sedimentary environment was the weak reduction condition at that time.Using the method of the combination of elements (Cu,Ba,Ni,etc.) suggest that the sedimentary environment was from lakeshore to shallow lake in depositional period of chang4+5;Using the method of the combination of elements(Fe,Mn,Cr,V,Ni,etc.) and the elements ratio (Sr/Ba, Fe3+/Fe2+) inferred that it was humid weather conditions in the chang4+5 depositional period.Observation of a large number of core and various test analysis conclude that underwater distributary channels and mouth bars, as well as sand bodys which have the complex genetic types in the delta front are favorable facies for development of the reservoir. The rock types of the reservoir sandstone of the chang4+5 oil-bearing intervals in the research area are mainly feldspar,following feldspar sandstone debris.which have lower the mineral maturity and the maturity structure because of the near source deposition. The main porosity types are the remainder inter-particle-hole,following feldspar dissolution porosity.With an average porosity of 14.36% and average permeability of 1.66×10-3μm~2.the reservoir is belong to low porosity and low permeability or ultra-low permeability reservoir Diagenesis of the study area have mechanical compaction, pressure solution, cementation, dissolution,etc,in which early cementation and dissolution have a constructive role in development of the reservoir.Contrasting Jiyuan-Hu Jianshan and Baibao-Huachi with rock types,heavy mineral assemblages,quartz cathodoluminescences,sandbody distribution laws,changes in vertical facies sequence,as well as the causes of the reservoir sandbody suggest that the provenance of the Jiyuan-Hu Jianshan is controlled mainly by Yinshan oldland and Alashan oldland,belonging to the mixed deposition zone of the northwest and northeast river system, in which the sandbody of the chang4+52 deposition period develope relatively.The underwater distributary channels and the overlays of the multi-phase underwater distributary channels are favorable development facies zones of the reservoir sandstone.While the provenance of the Baibao-Huachi is mainly controlled by the Yinshan oldland,belonging to the depositional system of the northeast delta,in which the sandbody of the chang4+51 deposition period is relative development.Favorable reservoir facies zones are the mouth bars and the overlay.of the mouth bars.更多还原