综合分析鄂尔多斯盆地南部延长探区的岩心、测井、铸体薄片、扫描电镜、阴极发光、X衍射、压汞分析等资料,对研究区长8油层组储层特征以及影响因素进行研究.结果表明长8油层组主要为长石砂岩和岩屑长石砂岩,成分成熟度低、结构成熟度中等;储层孔隙类型多样,粒间孔和长石溶孔为主要的储集空间,喉道类型以小孔微喉型为主;物性特点为典型的低孔低渗储层;储层明显受沉积相和成岩作用的综合影响.最有利的沉积微相为沉积厚度大、粒度较粗的水下分流河道微相;同时,建设性及破坏性成岩作用对储层物性改造具有双重作用,建设性成岩作用由于溶蚀作用使得物性变好,而破坏性成岩作用由于胶结及压实致使物性变差.

Youshashan oilfield is a typical complex fault block reservoir; this kind of reservoirs have a lot of characteristics, such as complex structure, loosely scattered oil sand bodies, and difficulty in developing fault block reservoir. In this paper, based on geology, logging and developing dynamic data, distribution and controlling factors of oil sand bodies were synthetically studied. The research results not only have an important practical significance for future perfection of injection-production of the reservoir and improving waterflooding production of blocks, but also provide corresponding reference for exploration and development of the same type of reservoirs.

Because the geographical statistics cannot be used in the sparse well net area for the reservoir bed modeling of high accuracy,the paper proposes the modeling thinking of reservoir bed based on taking seismic data as constraint condition.The modeling,depending mainly on the three dimensional seismic explanation information and the prediction results of seismic inversion restricted by logging reconstruction,predicts the distribution of the reservoir sand in the well and the variation law for the physical properties of the reservoir bed to build the three dimensional model of the reservoir bed under the constraint of the prediction results by means of random modeling.This model can help to reach the required accuracy degree at the oil and gas field development stage through the onsite check,meanwhile,and provides a very good reference to the precise evaluation for the reservoir bed in the sparse well net area.