Study On Surfactant Oil-displacement System For Dingbian Oil-field

The Dingbian oil-field is typically low permeability reservoir, and its recovery ratio of POR and water flooding is much lower.Surfactant oil-displacement pilot projects have got some achievements in certain reservoir of Dingbian oil-field.This paper aims mainly at preparing a new type of surfactant system with better properties to enlarge the pilot projects in more low permeability reservoir.Fluorinated surfactants were added to surfactant systems as additives, and then adsorption behaviour of each surfactant on the water-oil interface were studied. Interfacial activities, salt tolerance and temperature resistance of 15 systems(OAF0,OAF1,OAF2,OAF5,OAF7,OHF0,OHF1,OHF2,OHF5,OHF7,OLF0,OLF1,OLF2,OLF5,OLF7) have been evaluated.Wettability determination and oil-displacement experiments of 4 of them(OAF2,OHF0,OHF2,OLF1) have been done and analyzed.The results consist of:①Oil-displacement system OHF2 and OLF1 were separately chosen to be applied to Dongrengou and Jiyuan reservoir in the future.②Particular adsorption layer on the interface of hydrocarbon-fluorocarbon surfactant system and oil was illustrated,and its effect on properties of those mixture systems as well.③Hydrophilic groups of hydrocarbon and fluorocarbon surfactants play the decisive role in the properties of hydrocarbon-fluorocarbon surfactant system,such as the interfacial tension, salt tolerance and temperature resistance of them.④Effect of salt and temperature on properties of hydrocarbon-fluorocarbon surfactant system were thoroughly studied.⑤Oil-displacement surfactant systems without ultra-low interfacial tension can equally enhance oil recovery. Principles of surfactant displacement tell us that low interfacial tension has positive and negative effect on water displacement of low permeability reservoir. So ultra-low interfacial tension doesn't have to be pursued and shouldn't be either.⑥However low interfacial tension is still a crucial parameter of oil-displacement surfactant systems applicable to low permeability reservoir.⑦Compared with strong hydrophilicity reservoir,weak hydrophilicity one may have relatively high recovery ratio.Weaker hydrophilicity porous media always slow down sucking-displacement with the result that piston displacement may happen in most of the pore canal,displacement solution may drive forward more evenly, and then residual oil should be displaced more thoroughly, displacement efficiency be further improved.