Fluid loss control agents for viscoelastic surfactant fluids
View Patent ↗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.
1. An aqueous viscoelastic treating fluid comprising:
an aqueous base fluid;
a viscoelastic surfactant (VES) gelling agent; and
an amount of fluid loss control agent effective to improve the fluid loss of the aqueous viscoelastic treating fluid as compared with an identical fluid absent the agent, where the fluid loss control agent is selected from the group consisting of
alkaline earth metal oxides or hydroxides selected from the group consisting of oxides or hydroxides of magnesium, calcium, strontium, barium and mixtures thereof;
transition metal oxides or hydroxides selected from the group consisting of oxides or hydroxides of vanadium, molybdenum, manganese, iron, cobalt, nickel, palladium, copper, zinc, titanium and mixtures thereof;
transition metal hydroxides selected from the group consisting of aluminum, zirconium, tin, antimony and mixtures thereof; and
combinations thereof, where the fluid loss control agent has a size ranging from about 1 nanometer to 5 microns.
2. The aqueous viscoelastic treating fluid of claim 1 where the aqueous base fluid is brine.
3. The aqueous viscoelastic treating fluid of claim 1 where the effective amount of the fluid loss control agent ranges from about 2 to about 200 pptg based on the aqueous viscoelastic treating fluid.
4. The aqueous viscoelastic treating fluid of claim 1 where the fluid loss control agent is magnesium oxide.
5. The aqueous viscoelastic treating fluid of claim 1 where the agent has a size ranging from about 1 nanometer to 1 micron.
6. An aqueous viscoelastic treating fluid comprising:
an aqueous brine base fluid;
a viscoelastic surfactant (VES) gelling agent; and
about 2 to about 200 pptg based on the aqueous viscoelastic treating fluid of a fluid loss control agent, where the fluid loss control agent is selected from the group consisting of
alkaline earth metal oxides or hydroxides selected from the group consisting of oxides or hydroxides of magnesium, calcium, strontium, barium and mixtures thereof;
transition metal oxides or hydroxides selected from the group consisting of oxides or hydroxides of vanadium, molybdenum, manganese, iron, cobalt, nickel, palladium, copper, zinc, titanium and mixtures thereof;
transition metal hydroxides selected from the group consisting of aluminum, zirconium, tin, antimony and mixtures thereof; and
combinations thereof, where the fluid loss control agent has a size ranging from about 1 nanometer to 5 microns.
7. The aqueous viscoelastic treating fluid of claim 6 where the fluid loss control agent is magnesium oxide.