| Foam drive is a technical means to improve the recovery with certain potential in the tertiary oil recovery,relying on the bubble to have the selective plugging effect of water blocking without oil blocking,which can expand the volume of the oil washing while improving the efficiency of oil washing.However,the effect of conventional foam flooding system under high temperature reservoir conditions is not ideal,and the effective substances in the system are seriously limited by temperature.Therefore,it is necessary to improve the stability of the foam under high temperature conditions,study the effect of temperature-resistant foam system to improve the recovery under high temperature conditions,and open up a new path for the development of high-temperature reservoirs.In this paper,a Janus functional nanoparticle was prepared by Dockering emulsion method as a bubble stabilizer,and the comparative analysis with conventional bubble stabilizer found that the nanoparticles increased the stability of the liquid film under high temperature conditions.By evaluating the temperature,mineralization,oil content and aging time,two kinds of temperature-resistant foam systems(0.3%JNS-3+0.2%WP-21)and(0.2%FN-28+0.3%WP-21)with relatively good foam performance were preliminarily screened out.Through the determination of surface interface tension,rheological properties,Zeta potential,and dynamic adsorption experiments,comparative analysis found that(0.3%JNS-3+0.2%WP-21)had good performance,and the surface tension reached 24.2m N/m at 95°C.Oil-water interface tension is 0.00643m N/m;In the frequency range of 0.05 to 1.0Hz,the viscosity modulus and elastic modulus are high,and they have a certain degree of anti-adsorption ability.Subsequently,two temperature-resistant nano-foam systems were studied experimentally in the room.By adjusting the parameters such as gas-liquid ratio,injection amount,and injection method,the injection parameters of the temperature-resistant nano foam system can be optimized.The two-pipe parallel oil flooding model is used to verify the sealing performance of the system and analyze the oil displacement mechanism.Among them,the core permeability grade difference is one of the control factors affecting the oil displacement effect of the foam system.As the permeability gradient decreases or the seepage resistance increases,the system's effect on hyperosmolar core closure increases.Under the temperature of 95°C,two different permeability combinations,(100/25×10-3?m2)permeability combined with low permeability core water flooding can increase the recovery rate by 23.04%,high permeability core increased recovery value of 15.10%;(100/50×10-3?m2)permeability combination of low permeability core can improve the recovery rate by 19.05%,and high permeability core can improve the recovery value by 14.73%.It is proved that the temperature-resistant nanofoam system relies on the Jiamin effect generated by the superposition of bubbles to form an effective sealing in the hyperpermetic layer,so that the subsequent foam system flows to the low permeability layer,and a small number of bubbles accumulate at small pores,which plays an excellent modulation and driving effect. |
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