Methods for producing seawater based, high temperature viscoelastic surfactant fluids with low scaling tendency

Patent metadata

Field	Value
Publication number	US-10913889-B2
Application number	US-201916580816-A
Country	US
Kind code	B2
Filing date	Sep 24, 2019
Priority date	Jul 27, 2017
Publication date	Feb 9, 2021
Grant date	Feb 9, 2021

Abstract

Embodiments of the present disclosure are directed to a method of producing a viscoelastic surfactant (VES) fluid, the VES fluid comprising desulfated seawater. The method of producing the VES fluid comprises adding an alkaline earth metal halide to seawater to produce a sulfate precipitate. The method further comprises removing the sulfate precipitate to produce the desulfated water. The method further comprises adding a VES and one or more of a nanoparticle viscosity modifier or a polymeric modifier to the desulfated seawater. Other embodiments are directed to VES fluids that maintain a viscosity greater than 10 cP at temperatures above 250° F.

First claim

What is claimed is:

1. A viscoelastic surfactant fluid comprising:
a viscoelastic surfactant comprising the general formula:

where R 1 is a saturated or unsaturated hydrocarbon group of from 17 to 29 carbon atoms, R 2 and R 3 , are each independently selected from a straight chain or branched alkyl or hydroxyalkyl group of from 1 to 6 carbon atoms, R 4 is selected from H, hydroxyl, 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;

at least one polymeric viscosity modifier with a weight average molecular weight of from 250,000 g/mol to 40,000,000 g/mol;
desulfated seawater, where the desulfated water is free of CaSO 4 precipitate; and
at least one stabilizing calcium salt.

2. The viscoelastic surfactant fluid of claim 1 , where the polymeric viscosity modifier comprises nonionic polyacrylamides, acrylamide copolymers, polyacrylamide-based terpolymers, polyacrylamide-based tetra-polymers, hydrophobically modified acrylamide-based polymers, or combinations thereof.

3. The viscoelastic surfactant fluid of claim 1 , where the polymeric viscosity modifier has a weight average molecular weight of from 2,000,000 g/mol to 8,000,000 g/mol.

4. The viscoelastic surfactant fluid of claim 1 , where the viscoelastic surfactant fluid comprises from 0.1 vol. % to 20 vol. % of viscoelastic surfactant.

5. The viscoelastic surfactant fluid of claim 1 , where the viscoelastic surfactant fluid comprises from 1 wt. % to 50 wt. % of at least one stabilizing calcium salt.

6. The viscoelastic surfactant fluid of claim 1 , where the viscoelastic fluid has a viscosity greater than or equal to 10 cP at a temperature greater than or equal to 300° F.

Assignees

• Saudi Arabian Oil Co

Inventors

• Li Leiming
• Liang Feng
• Chen Tao

Classifications

• C09K8/506

  containing organic compounds · CPC title

• C09K2208/30

  Viscoelastic surfactants [VES] · CPC title

• C09K8/86

  containing organic compounds · CPC title

• C02F1/5236

  using inorganic agents · CPC title

• C09K8/602

  containing surfactants · CPC title