Foam Flooding Scheme Optimization Of Lukqin Heavy Oil Reservoir Expanded Test Area

Lukqin expanded test area is located on the TY block.During the water flooding development from 1998 to March 2015,oil well amounts to 41,water well amounts to 13,the cumulative water injection reaches 129.12×104m3,the cumulative oil production reaches 53.88×104m3,the total water ratio reaches 74.7% and EO R is only 7.32%OOIP.A large amounts of oil still remains in the reservoir and the prospect to enhance EOR greatly is considerable.In April 2015,foam flooding test was performed in the pilot test area,in which there are 4 water injection wells and 19 oil production wells.After foam flooding work,for most wells,daily oil production increases and total water ratio decreases significantly;and water injection profile improves obviously,in which,Hall curve slope of TY203 well and TY3-3 well rise obviously.Until October 2015,accumulative incremental oil production amounts to 0.9×104t3 and total water ratio decreases by 10%.Therefore,foam flooding may be one effective measure to enhance EOR of medium temperature high salinity heavy oil reservoir.According to production performance analysis of pilot test area,simulation of some oil wells is still not obviously;for these wells,foam flooding only perfoms the effect of controlling water.And even for few of the oil wells,not only does oil production not improves,but total water ratio stays at a high level.Accoring to analysis,injection/production ratio,foam slug size,gas/liquid ratio,alternating cycle and production injection rate may be principal factors of influencing EO R by foam flooding.Therefore,in order to evaluate foam flooding effect further and apply foam flooding technique in the whole Lukeqin oil reservoir better,it is significant to optimize project design of expanded area.Based on geological model of expanded test area and matching of production performance,water flooding effect was predicted that when total water ratio of the total area reaches 90%,the recovery ratio reaches 15.26% and the accumulative oil production amounts to 111.50×104t.The foam system used is CDHY-4,and the effective concentration is 0.1%(1000mg/L).After optimization of foam injection procedure,injection method and slug size,foam flooding in deep area and foam flooding were selected.For foam flooding in deep area,principal slug is 0.2PV,the effective concentration of foaming agent CDHY-4 is 0.1%,the preflush slug concentration is 0.2%,the preflush slug is 0.003 PV,gas/liquid ratio is 1.0/1.0,alternating cycle is 45 d and injection rate is 1.5 times of current injection rate.For foam flooding,principal slug is 0.45 PV,the effective concentration of foaming agent CDHY-4 is 0.1%,the preflush slug concentration is 0.2%,the preflush slug is 0.02 PV,gas/liquid ratio is 1.0/1.0,alternating cycle is 60 d a nd injection rate is 2.0 times of current injection rate.