Abstract: Methods of treating subterranean zones penetrated by well bores wherein the static temperatures of the zones are as high as 400° F. and greater include using aqueous treating fluids comprised of an aqueous liquid containing one or more inorganic monovalent salts, multivalent salts or both in an amount no greater than about 5% by weight of the aqueous liquid and one or more specific synthetic hectorite clay gelling and thixotropy imparting agents.

Abstract: The present invention provides methods of treating subterranean zones penetrated by well bores wherein the static temperatures of the zones are as high as 400° F. and greater. The aqueous treating fluids are basically comprised of an aqueous liquid containing one or more inorganic monovalent salts, multivalent salts or both in an amount no greater than about 5% by weight of said aqueous liquid and one or more synthetic hectorite clay gelling and thixotropy imparting agents selected from the group of a synthetic hectorite clay having the composition by weight on a dry basis of 59.5% SiO2, 27.5% MgO, 0.8% Li2O and 2.8% Na2O, a synthetic hectorite clay having the composition by weight on a dry basis of 54.5% SiO2, 26.0% MgO, 0.8% Li2O, 5.6% Na2O and 4.1% P2O5 and a synthetic hectorite clay having the composition by weight on a dry basis of 54.5% SiO2, 26.0% MgO, 0.8% LiO2, 5.6% Na2O, 4.1% P2O5 and also containing inorganic polyphosphate peptizers.