Analyses of the Factors Affecting EOR of Offshore Heavy Oilfields with Weak Gel

There exist problems in blocks of L,M and N of an oilfield of Bohai Bay,namely,severe vertical and lateral heterogeneity,large water to oil mobility ratio,un-uniform water absorption for all the zones of main water injection wells and poor water flooding effect.In order to maintain reservoir energy,improve water to oil mobility ratio and control profile,the field test of profile control with weak gel is conducted in 3 well groups which are selected from the 3 blocks respectively.The factors,namely,polymer concentration,oil viscosity,permeability difference,edge water and bottom water effect,profile control time,injection rate,etc.,affecting the effect of weak gel are compared based on the different effects of the 3 well groups and the analyses of polymer property,reservoir conditions and injection parameters.The field test shows that the profile control with weak gel can adjust the water absorption of all the zones,mitigate lateral contradiction and change the direction of injected water;and the effect of profile control on field is affected by reservoir conditions,profile control time and profile control parameters.