Preparation And Properties Of Temperature-Resistant And Low-Interfacial Tension Micro-Foam System

Foam flooding has achieved good results in the application of oil reservoirs because of the Jamin effect.However,the foam liquid film of ordinary foam is very thin,and it is easy to rupture and has poor stability due to liquid film drainage and foam extrusion.In addition,due to the large size of ordinary foam,the injection performance is poor in low-permeability reservoirs,resulting in high injection pressure and limited application.The micro-foam system with smaller foam size and better stability has the advantages of ordinary foam flooding through the compounding of polymer and surfactant.On the one hand,foam has better stability in high temperature formation environment.On the other hand,the size of micro-foam generated by polymer and surfactant through high-speed stirring is smaller than that of ordinary foam,which makes it have the characteristics of low injection pressure and good injection performance,which can be applied to The penetration range is wider.In this paper,foaming experiments at 90℃were carried out to study the foaming volume,foam half-life,interfacial tension,foam particle size and other parameters of 7kinds of surfactants and 3 kinds of polymers at different complex proportions.By carrying out the screening of surfactant,surfactant complex screening,polymer screening and the determination of optimal concentration,screening at 90℃conditions,Finally,the salt resistance,aging resistance and oil displacement performance of the microfoam system were evaluated.The research results show that the final micro-foam system obtained through screening is:The foam volume of 205m L was 0.5%wt DHSB+0.7%wt APG+0.2%wt DG,the half-life was 65.03min,the interfacial tension was 0.09825m N/m,and the average particle size was 49.44μm.In terms of salt resistance and aging resistance,the microfoam system still maintained good foam performance when Na Cl concentration was less than 30,000 mg/L,and the foam volume and half-life decline rate increased when Na Cl concentration was higher than 30,000 mg/L.The foaming volume was 183m L,the half-life was 52.66min and the interfacial tension was 0.1364m N/m on the 28th day,which still showed good foaming and interfacial properties.Microfoam flooding experiments were carried out on cores with different permeability of 32.86×10^-3μm² and 468.32×10^-3μm².After injection of 0.3PV microfoam,the recovery was increased by 14.56%and 17.5%respectively under the two conditions when the water content reached 100%,showing good recovery performance.In addition,after 0.3PV microfoam was injected into low and medium permeability core,subsequent water flooding pressure continued to increase,indicating that foam blocked the dominant channel inside the core,expanded sweep volume,and improved subsequent water flooding recovery.