Emulsifiers for water-based subterranean treatment fluids

A method for treating a subterranean formation comprising providing a water-based subterranean treatment fluid comprising:

• a) a continuous aqueous phase
• b) an internal oil phase
• c) from 0.1 to 15 g/100 ml, based on the total fluid volume, of an emulsifying composition comprising:
• i) from 1 to 40 wt % of a first surfactant having a HLB from 10 to 20 and ii) from 10 to 90% of at least one second surfactant obtained by reacting from 0.8 to 1.2 moles of a saturated or unsaturated C6-C30 aliphatic monocarboxylic acid, from 1 to 20 moles of ethylene oxide and from 0.8 to 1.2 moles of a hydroxyalkylamine of Formula (I)
• wherein:
• R is C2-C4-alkylene,
• X and Y are selected among H, C1-C10-alkyl, (C2-C4-alkylene)OH or (C2-C4-alkylene)NH2,
• provided that when the emulsifying composition contains less than 15 wt % of the first surfactant it also contains at least 60 wt % of the second surfactant and this second surfactant is obtained by reacting from 0.8 to 1.2 moles of a saturated or unsaturated C6-C30 aliphatic monocarboxylic acid, from 1 to 5 moles of ethylene oxide and from 0.8 to 1.2 moles of a hydroxyalkylamine of Formula (I).