低渗透油藏微观孔隙结构分析

Analysis of micro pore structure in low permeability reservoirs

不同地区渗透率相近的低渗透油藏在开发动用难度、生产特征上存在很大的差异,主要原因是微观孔隙结构不同.利用恒速压汞技术研究了大庆和长庆低渗透油藏岩心的孔隙结构.结果表明:长庆低渗透油藏平均喉道半径、主流喉道半径均大于大庆低渗透油藏;大庆低渗透油藏喉道分布范围窄,峰值半径较高,而长庆则相反,存在数量较大的喉道,喉道均质性较差.单根喉道对岩心的渗透率贡献结果表明,喉道分布范围较宽,均质性较差比喉道分布集中,均质性好的油藏渗流能力强,这与所研究的低渗透油藏开发特征相吻合.

For different low permeability reservoirs with the similar permeability,there is much difference in development degree and production features.The main reason is that they have different micropore structure.Pore structure of Daqing and Changqing low permeability reservoirs is further studied using rate-controlled mercury penetration technique.The results indicate that the average throat radius and mainstream throat radius of Changqing cores are bigger than those of Daqing cores.The pore throat distribution of Daqing low permeability reservoir is narrow and the peak value radius is higher.On the contrary,there are lots of bigger throat distributions in Changqing,and the throat homogeneity is poor.For the contribution of single throat to the rock permeability,the reservoir with wider throat distribution and poorer homogeneity is more penetrative than that with centralized throat distribution and better homogeneity,which is consistent with the development characteristics of low permeability reservoirs.