难采油田不同区块储层物性特征及分类评价

 以柴达木盆地3个难采区块为例,针对其储层物性差、注水效果差、微观结构认识不深入等问题,应用恒速压汞、核磁共振及非线性渗流等室内实验技术,对研究区3个主力区块储层的物性特征及微观孔隙结构特征进行了系统研究。在低渗透油田储层分类系数评价方法的基础上,加入表征裂缝发育程度的的评价参数--脆性指数,形成了符合难采油田开发现状的六元分类系数评价方法。研究表明:难采油田储层整体属于典型的低孔、特低渗透储层,不同区块储层物性特征与孔喉特征参数的差异,均归因于储层微观孔隙结构的差异。开展柴达木盆地难采油田相对富集区块的开发潜力分析评价,其分类结果与油田实际开发生产效果相吻合。

Physical properties and classifications of different reservoirs in difficult recovery oilfields

In view of the poor physical property and the complicated geological conditions of the difficult recovery reservoir in Qaidam Basin, the physical properties and the micro pore structure characteristics of the reservoir in 3 main blocks are systematically studied by means of the constant-rate mercury injection technique, the nuclear magnetic resonance and the nonlinear seepage experiment. In the comprehensive evaluation of low-permeability reservoirs, we add a new parameter, the brittleness index. Thus, a comprehensive evaluation method for the low-permeability & difficult recovery reservoir is proposed. It is indicated that the difficult recovery reservoir is typically a low porosity and ultra-low permeability reservoir. The differences of the physical properties and the pore-throat characteristic parameters of the reservoir in different blocks are due to the differences of the micro-pore structures of the reservoir. Meanwhile, the exploitation potential of the difficult recovery reservoir of Qaidam Basin is analyzed and evaluated. The classification results are consistent with the actual development and production of the oilfield.