Synergistic effect of cosurfactants on the rheological performance of drilling, completion and fracturing fluids
AssigneeAkzo Nobel Chemicals International B.V.
InventorsLingling Li, James Frederic Gadberry
Life of this patent
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Abstract
The invention relates to the viscoelastic surfactant based fluids and methods for utilizing same in oilfield applications including, but not limited to gravel packing, cleanup, drilling, acidizing, fracturing and the like in a subterranean formation. The viscoelastic fluid of the invention comprises at least one amphoteric surfactant and at least one synergistic cosurfactant that increases the gel strength and extends the brine tolerance of said viscoelastic-based fluid.
Claims15
A viscoelastic fluid comprising at least one viscoelastic surfactant and at least one synergistic co-surfactant, wherein said viscoelastic surfactant is an amphoteric surfactant of the general formula (I):
- wherein R1 is a saturated or unsaturated, hydrocarbon group of from 17 to
- 29 carbon atoms, R2 and R3 are each independently selected from a straight chain or branched, alkyl or hydroxyalkyl group of from 1 to 6 carbon atoms, R4 is selected from H, a hydroxyl group, alkyl or hydroxyalkyl groups of from 1 to 4 carbon atoms;
- k is an integer of from 2-20, m is an integer of from 1-20, and n is an integer of from 0-20;
- and said synergistic co-surfactant is of the general structure (II)
- wherein R1 is a saturated or unsaturated, hydrocarbon group of from 12 to 22 carbon atoms, R2, R3 and R4 are each independently selected from a straight chain or branched, alkyl or hydroxyalkyl group of from 1 to 4 carbon atoms;
- and a hydroxyl group,
- wherein the viscoelastic fluid has a density of greater than 1.2 kg/L.
Dependencies are inferred from the claim text.