A shear thickening composition which comprises a water-in-oil emulsion having dispersed in the continuous, oily phase thereof, hydratable, water-expandable hydrophillic clay, wherein said oily phase has a polyamine derivative surfactant dissolved therein and the dispersed aqueous phase comprises an aqueous solution of a polyacrylamide and polycarboxylic acid. These compositions are useful as well control fluids and may be used in deep wells.