鄂尔多斯盆地陇东地区致密油储层特征研究——以鄂尔多斯盆地长7段为例

Characteristics of Tight Oil Reservoirs in Ordos Basin——A Case Study of Chang-7 Member of Longdong Area,Ordos Basin

鄂尔多斯盆地陇东地区目前的勘探开发已经进入立体化勘探开发阶段,长7段致密油资源丰富,具有很大的勘探开发潜力。本文应用岩石薄片、铸体薄片、扫描电镜、压汞试验等测试分析资料,对鄂尔多斯盆地陇东地区长7储层特征进行了研究。结果表明,研究区长7储层的岩性特征以中细粒岩屑长石砂岩和长石岩屑砂岩为主,岩屑砂岩和长石砂岩含量较少,填隙物主要为绿泥石、伊利石和铁方解石,孔隙主要为粒间孔隙,但也有部分为长石溶蚀孔和岩屑溶蚀孔。陇东地区长7储层的平均渗透率是0.15mD,平均孔隙度为8.64%。长7储层喉道多为微米—纳米级,长71属于小孔微喉型储层,具有相对"高孔低渗"特征;长72属于小孔微细喉储层,具有"低孔高渗"特征。

At present,the exploration and development of Longdong area in Ordos basin has entered the stage of stereoscopic exploration and development.The dense oil resources of Chang-7 member are abundant and have great exploration and development potential.In this paper,the characteristics of Chang-7 reservoir in Longdong area of Ordos basin were studied by using the test and analysis data of rock slice,casting slice,scanning electron microscope and mercury injection test.The results showed that the lithological characteristics of Chang-7 reservoir in the study area are mainly medium-fine lithic feldspar sandstone and feldspar lithic sandstone,with fewer lithic sandstone and feldspar sandstone.The fillings are mainly chlorite,illite and iron calcite.The pore is mainly intergranular pore,but some of them are feldspar dissolution pore and lithic dissolution pore.The average permeability and porosity of Chang-7 reservoir in Longdong area are 0.15 mD and 8.22%.The throats of Chang-7 reservoir are mostly micron- nanometer,and Chang-7 1 reservoir belongs to microporous and microlaryngeal reservoir,which has relatively high porosity and low permeability,while Chang-7 2 reservoir belongs to microporous and microlaryngeal reservoir,which has the characteristics of low porosity and high permeability.