Research On Profile Control Effect Of Weak Gel Profile Control System In Block G18 Oil Field

The weak gel system of G18 oilfield affected by the water quality of this block seriously and the effect of weak gel profile control is not ideal, in order to solve this problem, we did some experimental research about system optimization and profile control system which mixed by output water. The experimental results show that the reasonable scope about the polymer concentration of oil displacement system was ranged from 0.15% to 0.2%, and the crosslinking agent concentration was ranged from 0.15% to 0.25%. All of these three kinds of output water which are existing in the G18 oilfield, mixed in different proportion can become gel,but the gel strength are differences.In order to get the factors about water quality which affect the system gelling performance,we carry out some experiments,though the analysis of the experiment result,we can find that with the greater the particle size of solid phase particles and high content in liquid water, the poorer performance in gelling, but they all can gel and has certain gel strength. The content of suspended particles in the formulated water should equal or less 30 mg/L.and the size of suspended particles should equal or less 8μm. The effects of salinity to the gel properties of the weak gel profile control system are very serious, as the increase of salinity, the gelling performance of oil displacement system becomes poorer, when the salinity come to 7000 mg/L,it can’t be gel; the oil content in liquid water should equal or less than 20 mg/L, and when the content of SRB bacteria equal or less than 102/ml, it has no effect on the gel properties of the system; the best value of pH in the liquid water should be 7.The results of the experiments shows that with the increase of the injection of oil displacement system,the oil recovery increased, the descend range of water cut increased, the highest displacement pressure increased, and the total oil recovery rate increased. Integrated balance the effect of oil displacement and the benefit of economic,we choose 0.2 PV as the best injection volume; When the water come to high water-cut stage, the earlier displacement, the higher oil recovery incease, and we can undertake displacement in advance if possible, in this time we can shorten the production time; And with the increase of oil displacement system injection rate, the oil recovery of decreases, the descend range of water cut decreased, the biggest displacement differential pressure increased, and the total oil recovery efficiency decreased.