Research And Evaluation Of Air Foam System For Lukeqin Heavy Oil Extraction

With the development of heavy oil fields, when they came into mid-to-late period of producing, water cut of reservoir rose, the recovery of water flooding became low, the development of oilfield was increasingly difficult, and the mining costs was raised. Integrating air flooding with foam flooding, air foam flooding has a dual function of profile control and displacement. For its specific performance of flow and displacement of reservoir oil, people attached more and more importance to air foam flooding.Now, water flooding is the main development technology of LKQ oil field, whose depth is 2000m-4800m, temperature is 80～100℃ and salinity of the formation water is about 5×104～18×104mg/L. However, the water flooding blocks are convex type, which have a high heterogeneity, high oil water viscosity ratio, serious fingering phenomenon, and fast increase of water cut. It was turned out that the enhanced oil recovery of water flooding was low.In this paper, using the Warring Blender to study a better foam system for LKQ reservoir. Then, for the foam system, temperature tolerance, salt tolerance, and oil resistance were measured, while oil sands static adsorption loss of the foaming agent was investigated. By sand-packed model, influencing factors on blocking ability of the foam system were explored. Simultaneously, the contribution of enhanced oil recovery by air foam flooding was conducted.For the CXF foam system, which the temperature was 80℃, salinity was 18×104mg/L and oil content was 20% reflected the following phenomena that the foaming volume was 410 mL, and half-life was 28min.Thus, the system had good foaming performance. we conducted the blocking ability of the foam system based on sand-packed model, the results shown that: blocking ability will enrich with the increase of concentration of foaming agent; the blocking ability increased at first and then decreased with the gas-liquid ratio increasing, When the ratio of gas-liquid was 1:1, the blocking ability reached the best effect. Moreover, as permeability improved, the blocking ability increased; while the increase of oil saturation, its blocking ability gradually decreased.Air foam flooding could enhance oil recovery by 8.06%, and decrease water cut of produced fluids, water cut decreased from 98.12% to 60.34% through the single tube experiment results. The founding of two-tube parallel displacing oil experiments shown that, in the stage of water flooding, the rate of oil producing was quite fast in the hypertonic tube, and the recovery reached 53.64%, while the recovery of hypotonic tube was 10.94%. In addition, the oil recovery of hypertonic tube increased from 53.64% to 62.27% in the air foam flooding stage; while hypotonic tube oil recovery increased from 10.94% to 20.31%; meanwhile, due to the blocking profile effect of foam, the total water cut decreased from 98.23% to 65.89%. After foam flooding, the reservoir took water flooding again by injecting water. It made oil production continued to increase, eventually the total recovery reaching 51.18%.