低渗透砂岩油层水驱采收率问题

On Oil Recovery in Low-Permeability Sand Reservoirs with Water Flooding

本文仅就低渗透油层采收率与渗透率的关系及采收率与驱替速度的关系进行了岩心实验研究,结果表明,对于低渗透油层,其采收率值与地层渗透率存在明显依赖关系。随着渗透率的降低,采收率明显降低。驱替速度对采收率也有明显的影响。驱替速度逐渐增大导致采收率先是显著增加,达到最大位后又趋减小,并存在使采收率最大的一最佳驱油速度。实验说明,低渗透油层中多相渗流具有某些特殊规律,它与低渗透率及地层孔隙结构特征有密切关系,对它们的研究具有重要的理论和实际意义。

In general, Oil recovery of low permeability sand reservoirs is low in the cace of water flooding. It remains an important problem that needs to be studied conscientiously. It is significant to make clear the reasons and find out the factors affecting the recovery ratio in low permeability reservoirs. This paper studies the relation among oil recovery and permeability and water flooding through experiments with core. Experiment results show that oil recovery mainly depends on the permeability of the reservoirs, It reduces greatly as permeability decreases. There is aiso a distinct relation between water flooding velocity and oil recovery in low permeability reservoirs. Oil recovery increases as water flooding velocity increases until oil recovery reaches the maximum and then reduces. There exists an optimum flood velocity that makes the recovery the best. The properties in low permeability reservoirs are different from those of the middle and high permeability reservoirs, which show that multiphase flow in low permeability reservoirs has some special laws. It relates closely to low permeability itself and the pore structure. In order to improve oil recovery, it is significant in theory and practice to study the characteristics of pore structure and multi—phase flow in low permeability reservoirs.