Preparation And Properties Of A Multi-effect Microemulsion Imbibition Agent

In order to improve the recovery rate of low-permeability and ultra-low-permeability oil fields,the surface wettability of reservoir rocks was changed and the percolation efficiency of crude oil in reservoir rock percolation channels was increased,adding surfactants to the wellbore fluid.In this paper,firstly anionic nonionic surfactant was synthesized by esterification reaction and sulfonation reaction,and used as an imbibition agent(IMS).Secondly,the oil in water micro lotion was compounded,and the micro lotion was compounded with an imbibition agent(IMS)to build a micro lotion imbibition agent system(IMP).Compared with the pure imbibition agent,this system can not only remove the organic matter pollution in the well entry area,and improve the wettability of the rock surface,but also improve the percolation efficiency of crude oil in rock pores and play a role of multiple effects with one agent.The specific research content of this paper can be summarized as the following parts:(1)Using octylphenol polyoxyethylene ether(OP-10)and maleic anhydride(MAH)as the main raw materials,p-toluenesulfonic acid as the catalyst,an absorbent(IMS)was synthesized.The end points of esterification and sulfonation reactions in different reaction periods were tested to screen out the optimal reaction conditions.The optimal reaction conditions for esterification reaction were as follows:the optimal molar ratio of OP-10 to MAH was 1.00:1.00,and the amount of p-toluenesulfonic acid accounted for 1.0%of the amount of MAH,The optimum reaction time and temperature were 3 h and 95℃,respectively;The optimum reaction conditions of sulfonation reaction were as follows:the optimum molar ratio of NaHSO3 to MAH was 1.20:1.00,and the optimum reaction time and temperature of sulfonation reaction were 3 h and 95℃,respectively.The structure of the imbibitive agent(IMS)was tested by FT-IR and 1H-NMR.The characteristic peaks and chemical shift points of each component were compared,and the molecular structure of the imbibitive agent was successfully verified.(2)In the micro lotion system,limonene was firstly chosen as the organic solvent,because it can better dissolve oil and wax.Secondly,Tween-80,Span-80 and alkyl glycosides(APG)were selected as the surfactants,and the commonly used mutual solvents for the preparation of micro lotion were screened to determine that the mutual solvents were methanol and ethylene glycol monobutyl ether.Then the micro lotion was compounded by fixing the amount of ethylene glycol monobutyl ether and alkyl polyglycoside(APG),changing the ratio of oil to water,the amount of methanol and the amount of surfactant.The results showed that the best formula of micro lotion was as follows:m(limonene):m(water):m(ethylene glycol monobutyl ether):m(alkyl glycoside):m(methanol):m(Tween-80):m(Span-80)equal to 5:5:6:5:10:6:6:6.(3)The surface interfacial tension of the aqueous solution of micro lotion and imbibition agent(IMS)was tested by mixing them in different proportions.The results showed that when the mass ratio of micro lotion to imbibition agent(IMS)was 1:9,the surface tension was the smallest,33.01 mN/m,and the interfacial tension was basically unchanged.Therefore,the optimal compounding ratio was as follows:m(micro lotion):m(IMS)is equal to 1:9,and micro lotion type imbibition agent(IMP)can be obtained.(4)The physical and chemical properties,surface interfacial tension,critical micelle concentration,particle size,wettability,contact angle,capillary rise height,surface roughness,imbibition efficiency and compatibility of imbibition agent(IMS),micro lotion and micro emulsion imbibition agent(IMP)were tested.The results showed that the wetting time of canvas discs with micro emulsion imbibition agent(IMP)in distilled water and 50000 ppm was 72 s and 82 s.Compared with the other two agents,the wetting time of canvas discs with IMP was the shortest.When the oil wet glass slide was immersed in a solution with a mass fraction of 0.3%,the contact angle of the imbibitive agent(IMS)was reduced from 106.23° to 67.57°,the contact angle of the micro lotion was reduced to 84.57°,the contact angle of the micro emulsion imbibitive agent(IMP)was reduced to 61.50°,and the rise height of the micro lotion imbibitive agent(IMP)in the oil wet capillary was 28 mm.It can be seen that IMP has good wetting improvement performance.In addition,the final imbibition efficiency of IMP can reach 41%,which has higher imbibition and replacement efficiency compared with the other two agents.