Alkaline earth metal compounds may be fluid loss control agents for
viscoelastic surfactant (VES) fluids used for well completion or
stimulation in hydrocarbon recovery operations. The VES fluid may further
include proppant or gravel, if it is intended for use as a fracturing
fluid or a gravel packing fluid, although such uses do not require that
the fluid contain proppant or gravel. The fluid loss control agents may
include, but not be limited to, oxides and hydroxides of alkaline earth
metal, and in one case magnesium oxide where the particle size of the
magnesium oxide is between 1 nanometer to 0.4 millimeter. The fluid loss
agent appears to associate with the VES micelles and together form a
novel pseudo-filter cake crosslinked-like viscous fluid layer that limits
further VES fluid flow into the porous media. The fluid loss control
agent solid particles may be added along with VES fluids.