【作者】 刘岩；

【导师】 张哨楠；

【作者基本信息】 成都理工大学 ， 矿产普查与勘探， 2008， 硕士

【摘要】 镇泾区块石油资源潜力巨大,石油资源量达16039.2×10⁴t,石油资源丰度达6.38×10⁴t/km²,具有较好的勘探开发前景。现今的勘探表明镇泾油田长8¹油藏是一个大面积、低丰度、特低渗、平面和垂向上非均质性较强的油藏,向东、向南仍有较大的扩展空间,为此开展鄂尔多斯盆地镇泾油田长8段的储层特征研究,对加快该区块石油勘探开发步伐具有重要的现实意义。本次研究在岩心观察、测井资料及前人研究成果的基础上,通过对大量物性资料、测井资料的统计分析,系统研究了鄂尔多斯盆地镇泾油田延长组长8段储层特征。首先开展层序地层研究,建立镇泾油田的等时地层格架,以相控—等时原理方法进行目的层段砂层组对比,建立长8段对比框架;利用岩电关系,结合测井曲线形态和组合特征,划分测井相,综合上述各项研究的结果,确定其主要为三角洲沉积体系的三角洲前缘沉积;识别出水下分流河道沉积、水下天然堤、水下决口扇、河口坝和水下分流问湾5种微相类型;并对各微相类型的沉积特征和剖面结构进行了讨论,预测了沉积相的平面展布。通过对该区块的岩石学特征、孔隙类型和孔隙结构及四性关系进行研究后认为长8段岩性为中-细粒长石岩屑砂岩、岩屑长石砂岩,平均有效孔隙度为8.5%,平均有效渗透率0.3×10^-3μm²,该储层综合评价为低孔、低渗、中-大孔小细喉分选差型储层。通过薄片观察认为碳酸盐胶结物是破坏孔隙的最主要因素,碳酸盐胶结物主要充填剩余原生粒间孔和交代颗粒和杂基;沉积环境和成岩作用互相影响、相互制约,从而造成长8段储层在平面和垂向上具较强的非均质性。在此基础上确定了镇泾油田长8段的储层下限,研究结果表明有效储层孔喉下限为0.25μm,渗透率下限为0.1172×10^-3μm2,对应的孔隙度下限为8.5%,粒度下限为细砂岩,砂岩的厚度下限为5m。在此基础上,提出了研究区储集层的分类评价标准。并对该层段的储层进行分类,将其划分为四类储层,Ⅰ类和Ⅱ类储层在研究区极易成藏,不需要很好的闭合度;而Ⅲ类储层在研究区要聚集成藏,则需要厚砂体和相对高的闭合度,含油级别低,油气的充满度低,需经过后期改造方能具备产油能力;Ⅳ类储层由于高的H₅₀,二次运移阻力过大,油气很难进入储层,这一部分砂岩为非储层。镇泾油田Ⅰ类储层不发育,Ⅱ类储层较少,Ⅲ类储层较发育。通过比较镇泾油田长8段5个砂层组的有效砂体厚度发现:有效砂体厚度在长8^1-2小层最厚,长8^1-3最薄,各小层有效砂体厚度的差异就会导致优质储层的平面展布及发育厚度的差异,对长8段5个砂层组分别做了优质储层平面展布,认为优质储层主要发育在三角洲前缘叠置水下分流河道砂岩中。综合分析认为长8段储层发育最好的层段为长8^1-2及长8^2-2,长8^1-2小层的Ⅱ类储层发育于ZJ5井区的东部,北部也有较好的勘探前景;长8^2-2小层的Ⅱ类储层发育在镇泾油田的中部。更多还原

【Abstract】 Zhenjing area has a huge potentiality of oil resource,the amount of oil resources is 16039.2×10⁴ tons in this area,and the abundance of oil resource has reached 6.38×10⁴ t/km²,so it has a better exploration and development prospect.It can be found from the present exploration that the Chang-8 member is a reservoir with a large area,low oil abundance,and very low permeability,and the heterogeneity is strong on planar and vertical in Zhenjing oilfield.Therefore,it is of practical importance to speed up the step of research on reservoir characteristics of the Chang-8 member of the Yanchang formation in Zhenjing oilfield.On the base of core observation,logging data and the studied results of former geologists,and through statistical analysis of petrophysical data and logging data,this paper systematically studies reservoir characteristics of the Chang-8 member of the Yanchang formation in Zhenjing oilfield,Ordos Basin.Firstly,develop the sequence stratigraphic study and build the sametime sequence pattern,use the method of sedimentary facies control- sametime principle to correlate sandbody groups in the target strata,and build stratigraphic framework.Then,use logging curves to classify logging facies based on the lithology-electric property relation.According to the upper research results,the sedimentary facies is determined to be the front-delta deposition of braided river delta deposits,and five microfacies types are recognized including subaqueous distributary channel,subaqueous natural barrier,subsea crevass-splay, mouth-bar,subaqueous interdistributary embayment.The depositional characterisytics and the structure of microfacies types in sections are discussed,and the lateral distribution of the sedimental facies are predicted.Through the research of petrologic feature,pore types,pore structure and relationships among lithology,poroperm characteristics,electric properties and oilbearing properties,it is thought that the lithology are middle-fine grained feldspathic litharenite sandstone,lithic arkose sandstone.The effective porosity is 8.5%,and effective permeability is 0.3×10^-3μm² in the Chang-8 member.So it is considered after the comprehensive reservoir evaluation that it belongs to the type of reservoirs with low porosity and permeability,the fine pore throat and poor sorting.After the research on the heterogeneity of the reservoir sandstones,it can be concluded that the heterogeneity resulted from sedimentary environment and diagenesis interaction.On the basis,the lower limit of reservoir parameters of the Chang-8 member in this oilfield is determined in the paper:the lower limit of throats is 0.25urn,the low limit of permeability and porosity which are corresponding with the lower limit of throats is 0.1172×10^-3μm² and 8.5%respectively and the low limit size is 5m of fine sandstone.In light of reservoir evaluation,the reservoirs can be classified as four types.The type-Ⅰand type-Ⅱare very easy to form reservoir,and not need very thick closure.But type-Ⅲmust have thicker sand and closure,so it could have the oil producing capability after late reformation,type-Ⅳis non-reservoir because it must have high H₅₀and prevent secondary migration.The type-Ⅰ（excellent reservoirs）is not developed;type-Ⅱ（better reservoirs）is seldom and type-Ⅲis commonly found out in the research region.Compared the thickness of the effective sand bodies of the five sandbodies of the Chang-8 member of the Yanchang formation,it is found out that the thickness of sand body of Chang-8^1-2is the largest,but the smallest in Chang-8^1-3.The difference of the thickness of sand bodies would result in the difference of high-quality reservoir distribution.The high-quality reservoirs are mainly developed in the thick sandstone of subaqueous distributary channel of the front-delta deposition.At last,it is suggested that the most favorable sand body is Chang-8^1-2and Chang-8^2-2,and the exploration targets to survey the type-Ⅱreservoir which distributed in the east of the Well-5 and in northern Zhenjing Oilfield in Chang-8^1-2,and in the central part of Zhenjing Oilfield in Chang-8^2-2.更多还原