In order to improve macro swept volume and micro displacement efficiency, a new EOR method, i.

At the late period of water injection in multi layer heterogeneous river-delta depositional system of Daqing oilfield, liquids production of partial blocks and certain well fields is high, water cut is high, producing performance is not balanced, and swept volume of conventional water injection can not be improved.

Based on fine de-scription of residual oil distribution,well pattern adjust-ment and pulse water injection were performed in Block7in Gudong oilfield to enlarge swept volume,to tap residual oil potential in low permeability zone,to reduce the area of region of bypassed oil and to improve utiliza-tion fact.

In this way, retained oil can be mobilized, the sweeping volume and use factor of injected water can be raised.

north 1 6 inspection well 27 for inspecting water flooding result and north 1 6 inspection well 26 for inspecting polymer flooding result,this paper deems that the polymer flooding only changes mobility ratio between oil and water,enlarge a sweeping volume and improves oil displacement efficiency.

A method to predict volumetric sweep efficiency and recoverable reserves of water-drive oilfields;

In addition,using the relationship among recovery percent,displacement and volumetric sweep efficiency,the equations for estimation of the volumetric sweep efficiency and.