Synthesis Of CO₂-Philic Surfactants And Their Extraction Porperties In Oil Recovery And Dry-Cleaning

For the later contenting high-water and heavy oil reservoirs,scCO₂ flooding technology can greatly increase oil recovery.At the same time,it also solved the problem of CO₂ storage to achieve a win-win situation for effectively developing oil fields and reducing CO₂emissions.However,for most domestic reservoirs,the minimum miscibility pressure?MMP?of crude oil-CO₂ system is too high to directly achieve the miscible CO₂ flooding.Based on the principle of water flooding with surfactant,an amphiphilic compound with CO₂-philic and lipophilic might be enhance the interaction between CO₂ and crude oil to reduce the MMP.In this paper,the long-chain alkyl ether modified heptamethyltrisiloxane?A_n-TS?was designed and synthesized by taking silicon-oxygen structure as the CO₂-philic end and alkane structure as the lipophilic end.The solubility was measured at the reservoir temperature?359K?.The results showed that the longer the alkyl chain of A_n-TS was,the higher the dissolved pressure was;the solubility of A_n-TS had logarithmic linear increasing relationship with the density of pure scCO₂.Therefore,the solubility of A_n-TS under any pressure conditions could be calculated by the fitted parameters of the Chrastil equation,which provides data support for the study of their extraction performances.The effect of A_n-TS on the material exchange between CO₂ and crude oil was studied by the interfacial tension?IFT?of CO₂/C₂₈H₅₈ and CO₂/crude oil,experiments of CO₂ extraction from crude oil.According to the corresponding data,the following conclusions were drawn:Under certain pressure,A_n-TS would speed up material exchange between them and the optimal dosage is 80 mg/L.Once exceeded this amount,when the pressure exceeds 20 MPa,A_n-TS would compete with crude oil for CO₂,resulting in no longer changes in CO₂ and crude oil components not to reduce the IFT;When P<20 MPa,A_n-TS with short alkyl chain has interacted with light components of crude oil,which contributes to transfer light component to CO₂;However,as pressure increases,CO₂ has extracted intermediate components.A_n-TS with a longer alkyl chain would interact with heavy components of crude oil to reduce the IFT;Compared with C12-4,A₄-TS can obviously help the transfer of C⁺₂₅from crude oil to CO₂ at 10 MPa and favor the transfer of C^-₃₀ to CO₂ at 20 MPa.Due to the close polarities between the components of crude oil and soiled fabric with protein and carbon black,they could be studied together.In view of the problems of difficult removal of particulate soils and few researches on detergent formulation,the influence of different compounding systems on liquid CO₂ dry-cleaning was studied.From a practical and economic point of view,compared with no surfactant,Glu-C12&C16?3?had the best cleaning effect and could increase the detergency value from 4.6 to 8.32.When the molecular volume is moderate and pro-fabric get balance with pro-CO₂,the non-ionic surfactant combined with Glu-C12 has better cleaning effect.This provides experimental basis for surfactant used in liquid CO₂ dry-cleaning.