Patent ID: 8517102

Claim:
A method of delivering a thickened aqueous composition to a subterranean location accessible via a wellbore, comprising steps of: i. providing a biphasic aqueous mixture comprising two aqueous solutions which, at surface temperature and pressure, are able to co-exist as separate aqueous phases in contact with each other, the two phases containing a plurality of dissolved solutes which segregate between the two phases such that at least one first solute is present at a greater concentration in the first aqueous phase than in the second aqueous phase while at least one second solute is present at a greater concentration in the second aqueous phase than in the first aqueous phase; ii. pumping said biphasic aqueous system down the wellbore to the subterranean location, and iii. converting the biphasic mixture below ground so that its phases combine into a single aqueous phase which is more viscous than the biphasic mixture.