【作者】 李珊；

【导师】 朱玉双；

【作者基本信息】 西北大学 ， 矿物学、岩石学、矿床学， 2013， 硕士

【摘要】 鄂尔多斯盆地内长7油藏具有自生自储的成藏特点,日益成为重要的勘探开发目的层系,目前已落实多个长71、长72油藏,这些油藏具有分布范围广、增储潜力大的特点；同时部分区域(如安83井区等)长7已经投入开发,具备良好的开发效益。为更加全面地认识胡尖山地区长7储层,有必要对研究区长7储层孔隙结构与渗流特征研究进行深入剖析,搞清孔隙结构、水驱油的渗流规律和剩余油的形态及其形成机理,为油田的开发提供科学依据。本次研究通过常规压汞、铸体薄片和扫描电镜等技术定量地表征孔喉的大小、形态、类型、分选情况以及之间的连通性；同时结合相渗测试以及微观真实砂岩渗流实验模拟长7储层中流体的运移以及水驱油结束后残余油赋存状态,系统分析驱油效率、驱油效率影响因素、剩余油分布、剩余油影响因素以及残余油赋存类型等情况；在此基础上,研究储层孔隙结构与渗流特征二者之间的关系。研究结果表明：胡尖山长7储层主要为致密储层和特低孔超低渗储层,岩性以灰色、灰褐色极细-细粒、细粒岩屑质长石砂岩为主,含少量长石砂岩。孔隙类型主要为粒间孔、长石溶孔、岩屑溶孔以及少量晶间孔、微裂隙,其中长石溶孔较为发育,与粒间孔含量相当；喉道类型主要有孔隙缩小型喉道、缩颈型喉道以及片状或弯片状喉道；孔喉组合类型主要为小孔-微喉、中孔-微喉型。整体来看,长7储层较为致密,孔喉细小,连通性较差。微观水驱油形态以非均匀状驱替为主,驱替压力大驱替时间长,水驱结束后残余油类型主要有绕流形成的簇状、片状残余油。储层物性的大小并不是驱油效率的唯一决定因素,而是要结合微观孔隙结构、微观非均质性、粘土矿物含量、驱替压力和驱替倍数等因素综合分析。不同的孔隙类型以及孔喉组合类型对应不同的驱油效率和驱替类型,并且会对残余油赋存起到一定的影响作用。研究区长石溶孔发育的区域驱替效果较好,驱油效率为56.1%,比粒间孔和微孔发育的区域平均高出8.42%,驱替类型主要为网状驱替；孔喉组合以小孔微喉型最佳,驱替类型也以网状为主,驱油效率为57.1%,比中孔微喉、小孔微细喉高出10%以上。综上所述,长7致密储层、特低孔超低渗储层具有溶蚀孔较为发育,孔喉连通较差,非均质性强,渗流能力差,最终采收率较低的特点。更多还原

【Abstract】 The chang-7reservior in Ordos Basin, which play a vital part in exploration area nowadays, is authigenic and promising. The chang71and chang72eservior are widespread and productive; meanwhile, some areas (such as An-83oilfield) have already brought into operation and reveal a favourable benefit. In order to study the subject reservior comprehensively and provide scientific foundation for reasonable exploitation, it is necessary to do research on pore structures and micro-flow characteristics of chang-7reservoir to know the relationships between pore structures and micro-flow characteristics, shape of remaining oil and its formation mechanism.Based on the technique of conventiona mercury penetration, cathodeluminescence, cast thin section analysis, particle size analysis and scanning electron microscope, the size, shape, type, degree of sorting and connectedness of pore and throat are well described; at the same time, the experiment of permeability ratio curve, wettability, sensitivity and real sandstone micromodels are well studied to evaluate the fluid movement, shape of remaining oil and micro-flow characteristics. On the basis of pore structures result, the saturation of bound water, moving fuid saturation, oil displacement efficiency and its affecting factors, distribution of remaining oil and its affecting factors are well analysied. On this condition, deal with the relationship between pore structures and micro-flow characteristics.The paper shows that chang-7reservoir which belongs to tight oil reservoir is made of grey and grey-brown aphanocrystalline and fine grain syrosem feldspar-porphyry sandstone with little feldspar-porphyry sandstone. The compositional maturity is low while the texture maturity is medium. The main type of cementation is pore and pore-membrane. Intergranular pore and feldspar dissolved pore which have same cont are the major pore type and throat type include pore constriction, constriction, flaky and curved lamellar。 The constent combination is microbore-microthroat and mesopore-microthroat. To sum up, chang-7reservoir is tight with minute pore throat and bad connectedness.Nonhomogeneous form is ubiquitous in this area and the displacement pressure is high while the displacement time is long. The shape of remaining oil is diverse from cluster type to flaky type.The displacement efficiency not only lies on permeability and porosity, it is the combination of physical property, pore structure, microscopic heterogeneity, displacement pressure, total injection volume and so on. Different pore and pore-throat type has different displacement efficiency and displacement type, also have effect on shape of remaining oil. Feldspar dissolved pore and microbore-microthroat area has relatively high displacement efficiency in this region, which is8.42%and10%higher than other type.In summary, chang-7reservoir has the unique feature of bad physical property, mature emposieu, bad pore-throat connectedness, strong heterogeneity, poor displacement ability and low displacement efficiency.更多还原