| In this article,focused on chemical plugging methods,formation condition of Qi 40 heavy oil block in Liaohe oilfield is used as reference,problems about injected steam channeling along high permeability zone can be solved by preparing a high temperature plugging agent used in multi-medium steam driving.Combined with practical formation condition,a plugging agent system in form of gel carrying particle is prepared.At first,strength and rheological property of gel are measured under 80? in lab static evaluation,to conduct comparative study on two kinds of gel in different concentration of polymer,and plugging agent #A is selected as optimal gel.Then,study on injecting system of plugging agent is conduct.Combined with results of evaluation of high temperature endurance for gel,and sedimentation experiment of solid particle,the combination of injected slugs,namely “polymer front slug + gel/solid particle main slug + gel sealing slug”,is designed,constitute and injected volume of each kind of slug are ensured.By dynamic evaluation experiments in lab,injection parameters of plugging agent system are optimized,to verify effects of profile control.In plugging experiments of single tube,it is obtained that optimal injected volume of main slug is 0.2PV,and optimal aging time is 5d,which has most ideal plugging performance and scouring resistance.In selective plugging experiments of multi-tube parallel,this plugging agent is proved that it have good selective plugging performance,which can significantly reduce permeability of high permeability zone,and hardly reduce permeability of middle and low permeability zone.Finally,steam and air are together injected with mass ratio 98:2,simulating multi-medium steam driving process.Results show that in process of multi-medium steam driving for heavy oil,compared with no injection of plugging agent,this plugging agent system can significantly enhance recovery of heavy oil,which increase oil recovery by 9.23%. |
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