Study On Optimization And Plugging Effect Of Three Phase Foam System

After long-term waterflooding development,the main oilfields in Bohai Sea have formed super-high permeability zones,which aggravate the inefficiency and ineffective circulation of oil displacement agents,and urgently need profile control and water shutoff measures to improve oil recovery.Foam system is a widely used profile control system at sea.In recent years,petroleum technology workers have found that nano particles can significantly improve foam stability as foam stabilizer,which have the characteristics of temperature resistance,salt resistance and no damage to formation,and have wide application prospects.In order to enhance the adaptability of three phase nano foam system to Bohai reservoir and improve the economic efficiency of water plugging technology,this topic carries out the optimization of the three-phase nano foam system formulatio and the evaluation of plugging performance and the research of the action mechanism based on reservoir and fluid in SZ36-1 oilfield.The results show that the best foaming agent for the three-phase foam system is anionic surfactant PO-FASD,and the stabilizer is 6# nanoparticles.Optimum formulation of three-phase nanocomposite plugging agent is as follows: foaming agent is 0.4%-0.5%,foam stabilizer is 0.3%-0.4%,"gas-liquid" ratio is 1:1-2:1,and slug size is 0.1PV-0.15 PV.Compared with the gas-liquid alternative injection mode,the gas-liquid simultaneous injection mode of three-phase nano-composite plugging agent has better foaming effect,higher injection pressure and higher plugging rate.Considering that reservoir fracture pressure and injection equipment pressure resistance will restrict injection pressure,it is suggested that alternative injection mode be adopted in field construction,and the injection pressure rise can be controlled by adjusting alternative injection period.The results also show that under the condition of saturated core oil,the water plugging effect of three phase nano foam system becomes worse.With the increase of reservoir permeability difference,the development effect of water flooding becomes worse,and the water plugging effect of three-phase nano foam system is better.With the increase of reservoir water flooding recovery rate,the diversion rate of high permeability layer decreases after water plugging by three-phase foam system and the diversion rate of low permeability layer increases.The effect of water plugging is better.With the increase of the viscosity of the crude oil,the diversion rate of the high permeable layer decreases and the diffusing rate of the low permeable layer decreases.The water plugging effect becomes worse.With the increase of injection volume,the rate of water content decreases and the recovery rate increases after water plugging.The suitable slug size of three-phase foam system should be about 0.1PV.With the increase of injection rate,the increase of water plugging recovery rate of three-phase foam system decreases so that the injection rate of ore block water injection construction should not be too high,so as not to cause damage to non target layer by blocking agent.