Study On The Foam Combined Flooding Optimization Technology In Block Ming-15

Ming-15block in Zhongyuan oilfield is a reservoir of low water displacement recoverybecause of serious heterogeneity and high salinity, and as a result, polymer flooding is notapplicable. In this paper, according to the geological features of Ming15block, the researchis focused on a further slug of ultra-low IFT surfactant flooding after foam slug, that isfoam-surfactant combined flooding, which both have good displacement ability andsignificantly improve oil displacement efficiency.The performance of foaming was evaluated, a compound system was obtained byRolls-Mill method:0.3%surfactant A+0.12%Surfactant B+0.18%Stablizer C. The results ofthe experiments indicated that ZY-1system showed a decent performance in thermal stabilityand salt resistance, the foaming volume of ZY-1system was213mL, and the half-life timewas15.3min at70℃, under salinity of80000mg/L. Foam flooding experiments indicated agood EOR ability, and the recovery increased to16.8%, but the ZY-1system failed to reducethe interfacial tension (IFT) significantly, and only could reach to10-1mN/m.For the ZY-1system only could reach the IFT to10-1mN/m, this paper selectedsurfactant ZYBH-03by interfacial tension, emulsifying, and adsorption experiments, whichused foam-surfactant combined flooding.0.3%ZYBH-03can decrease the IFT to10-3mN/m,and the adsorption on silica sands was small, only3.4mg/g, emulsifying ability was good,little water was bleeding in80min, the results of surfactant flooding experiment showed thatZYBH-03surfactant flooding could also increase the oil recovery to11.9%.The results of single-tube physical model experimental showed that the highest recoverywas obtained when the total slug size was0.3PV, with a slug size ratio of1:1(foam slug:surfactant slug)，but alternating cycle effect is not considerable on oil recovery. Comparedwith both foam flooding and surfactant flooding, the results showed that the EOR of foamcombined flooding was the highest at the same injection. The oil recovery of heterogeneousparallel flooding increased by17.2%, which indicated that this strategy has an excellentability to raise the oil recovery in heterogeneous reservoirs.