Research Of A New Foaming Agent System With Salt-resistance And Oil-resistance

Surfactants are widely used in oil and gas engineering, and researches in their synthesis, structure modification and formulation design for activity improvement in this field are very important.In enhanced oil recovery (EOR) and enhanced gas recovery (EGR), the surfactant structures, functional groups, and molecular mass are decisive factors affecting their surface activities and application efficiency. The surface activities include surface tension, cmc, micelle structure, foaming performance and dispersion/emulsion ability, which are related with surfactant structure and application conditions.In gas drilling and oil drilling process the mine water absorbed in the micropores of gas- and oil-containing earth layers blockes the flow of gas/oil through these pores and reduces the recovery greatly. Surfactants are mainly used as water expellants through their low interfacial tension and high foaming ability in salt- and oil-containing medium. But ordinary surfactants with high foaming activity and low surface tension in deionised water lose their activities under drilling conditions, a newly designed surfactants with special structure and functional groups and their formulations for use in salt- and light oil-containing water for EOR and EGR are urgently required.On massive literature investigation and basis of our pre-studies, Gemini-like surfactants are designed and synthesized from maleic anhydride, polyethylene glycol, fluorinated octanoic acid, and ethylenically unsaturated carboxylic acid, and alkyl substituted 1,3-propanediamine. And one kind of comb-like polymer surfactants are also synthesized through solution polymerization from unsaturated monomer with functional groups. Introduction of different active groups such as tertiary amine group, carboxylic acid group, fluorine-containing group, sulfonate group, phosphate group etc. into one surfactant molecule greatly improved hydrophilic -hydrophobic properties and light oil dispersion in mine water. Sulfonate and phosphate groups impart surfactant excellent foaming abilities in hard water, and light oil dispersion and thus reduced defoaming abilities of oils. Cationic amine group and fluorine-containing group increased the salt-stability and thermo-stability of surfactants.For assess of surfactant application efficiency surface tension, foamability, water-carrying ability of surfactants synthesized in this study are tested by ordinary known methods. And a formulation of comb-like polymer surfactant and CBA, CHSB was designed.Experimental results show that the foaming agent system comprising the comb-like polymer surfactant, CBA, CHSB exhibits very good foaming ability and foam stability, and very high water-expelling ability in oil-containing saline water. Under the general drilling conditions of salinity of 75 thousand ppm and 10% oil volume content of aqueous medium in temperature range of 60℃to 80℃, the initial Ross-Miles foam height of the proposed surfactant formulation is 190mm to 250mm and 210mm to 350mm after 3 minutes, the foam can carry out 80% of the solution with surfactant concentration below 1%, which was superior to most of surfactants ordinarily used, and has bright application prospect in EOR and EGR.