Aqueous fracturing fluid
AssigneeSchlumberger Technology Corporation
InventorsIsabelle Couillet, Trevor Hughes
Life of this patent
Estimating the term…
Abstract
The invention concerns an aqueous viscoelastic fracturing fluid for use in the recovery of hydrocarbons. According to the invention, the fluid comprises a cleavable viscoelastic surfactant and a hydrophobically-modified polymer, wherein the cleavable surfactant comprises a head group and a hydrophobic tail of at least 18 carbon atoms connected through a degradable acetal, amide, ether or ester bond and wherein the concentration of the hydrophobically-modified polymer is comprised between its overlap concentration c* and its entanglement concentration ce.
Claims29
Aqueous viscoelastic fracturing fluid for use in the recovery of hydrocarbons, comprising a viscoelastic surfactant and a hydrophobically-modified polymer,
- wherein the surfactant comprises a head group and a hydrophobic tail and is of the following formula:
- R—X—Y-Z
- where R is the hydrophobic tail of said viscoelastic surfactant, which is a fully or partially saturated, linear or branched, hydrocarbon chain of at least 18 carbon atoms;
- X is a degradable acetal, amide, ether or ester bond;
- Y is a spacer group, formed by a short fully or partially saturated hydrocarbon chain of at least one carbon atom;
- and
- Z is the head group of the surfactant which can be —NR1R2R3+, —SO3−, —COO− or —N+R1R2R3—COO−
- where R1, R2 and R3 are each independently hydrogen or a linear or branched saturated aliphatic chain of at least one carbon atom, and
- wherein the concentration of the hydrophobically-modified polymer is comprised between, approximately, its overlap concentration c* and, approximately, its entanglement concentration ce.
The fluid of one of the above claims, wherein the viscoelastic surfactant forms worm-like, thread-like or rod-like micelles.
Method for recovering hydrocarbons comprising the following steps:
- providing an aqueous viscoelastic fracturing fluid comprising a viscoelastic surfactant and a hydrophobically-modified polymer
- wherein the surfactant comprises a head group and a hydrophobic tail and is of the following formula:
- R—X—Y-Z
- where R is the hydrophobic tail of said viscoelastic surfactant, which is a fully or partially saturated, linear or branched, hydrocarbon chain of at least 18 carbon atoms;
- X is a degradable acetal, amide, ether or ester bond;
- Y is a spacer group, formed by a short fully or partially saturated hydrocarbon chain of at least one carbon atom;
- and
- Z is the head group of the surfactant which can be —NR1R2R3+, —SO3−, —COO− or —N+R1R2R3—COO−
- where R1, R2 and R3 are each independently hydrogen or a linear or branched saturated aliphatic chain of at least one carbon atom, and
- wherein the concentration of the hydrophobically-modified polymer is comprised between, approximately, its overlap concentration c* and, approximately, its entanglement concentration ce;
- and
- injecting said fluid into formation rocks in order to fracture said rocks.
Dependencies are inferred from the claim text.