万花-劳山区长6储层孔隙结构及物性下限研究

Research on Pore Structure and Lower Limit of Physical Properties of Chang6 Reservoir in Wanhua-Laoshan Area

万花-劳山区位于鄂尔多斯盆地一级构造单元陕北斜坡的东北部,包括下寺湾和南泥湾2个采油厂,长6油层组是该区重要含油层位之一,2个采油厂结合区域储层方面的研究,特别是储层物性下限研究较少。依据岩心、铸体薄片及扫描电镜观察,研究区长6储层岩石类型主要为细粒长石砂岩,填系物以自生矿物为主,胶结物有方解石、绿泥石等,以孔隙式胶结为主。孔隙类型以粒间溶孔为主,包括少量的剩余粒间孔、粒内孔及微裂缝,孔喉组合为中孔细—微细喉型。孔隙度主要分布区间为7.0%~16.0%,渗透率主要分布区间为0.15×10^(-3)~2.0×10^(-3)μm^2,属于低孔-超低渗储层。利用经验统计法、含油产状法及最小流动孔喉半径法等3种方法,确定了研究区储层物性下限孔隙度为8%、渗透率为0.2×10^(-3)μm^2,检验结果正确率为93.7%,为储量计算、开发生产及后期滚动试油开采提供了依据。

Wanhua-Laoshan area locates in the northeast of Shanbei slope ,first tectonic unit,Ordos Basin. Two oil production plants Xiasiwan and Nanniwan are in it.Chang6 reservoir is one of the important oil-bear- ing formations in this area.The two oil production plants lower limit of physical properties of the reservoirs.Based have few researches on regional reservoir,especially on core,casting thin sections and scanning electron microscope observation,the rock types of Chang6 reservoir in the research area are feldspar mainly fine-grained sandstone filled with the most authigenic mineral and cemented with calcite and chlorite as pore types.The main pores are intergranular dissolved pores including a few of remaining intergranular pores,intra- granular pores and microfractures.The combination of pore and throat is medium pore and fine-micro throat. The reservoirs belong to low porosity and extra-low permeability ones with the porosity ranging from 7.0% to 16.0% and the permeability ranging from 0.15×10-3 to 2.0^10-3μm2.The empirical statistical method,oil oc- currence method and minimum flow pore throat radius method were applied.And the lower limit of the physi- cal properties of the reservoir in the research area was determined as 8% of the porosity and 0.2×10-3μm2 of the permeability.The correct rate of the results is 93.7%.It provides the basis for reserves calculation,de- velopment, production and later rolling oil test.