Cement isolation fluids for wellbores, methods of making, and methods of use

Patent metadata

Field	Value
Publication number	US-2016265306-A1
Application number	US-201514643138-A
Country	US
Kind code	A1
Filing date	Mar 10, 2015
Priority date	Mar 10, 2015
Publication date	Sep 15, 2016
Grant date	—

Abstract

A cement isolation fluid for use in a wellbore during a cementing operation includes an aqueous carrier fluid and a preformed synthetic polymer swellable in the carrier fluid, in an amount effective to isolate a cement slurry from another drilling fluid present in the wellbore. A method of cementing a wellbore comprising a drilling fluid includes injecting the cement isolation fluid into the wellbore; injecting a cement slurry into the wellbore; and hardening the cement in the slurry to cement the wellbore.

First claim

1 . A cement isolation fluid for use in a wellbore comprising:
an aqueous carrier fluid; and a preformed synthetic polymer swellable in the carrier fluid in an amount effective to isolate a cement slurry from another drilling fluid present in the wellbore during a cementing operation.

2 . The cement isolation fluid of claim 1 , wherein the carrier fluid comprises fresh water, salt water, aqueous acid, aqueous base, or a combination comprising at least one of the foregoing.

3 . The cement isolation fluid of claim 1 , wherein the preformed synthetic polymer is stable up to about 350° F.

4 . The cement isolation fluid of claim 1 , wherein the preformed synthetic polymer comprises poly(hydroxyC 1-8 alkyl (meth)acrylate), poly(C 1-8 alkyl (meth)acrylate), poly(meth)acrylamide, poly(vinyl pyrrolidine), poly(vinyl acetate), or a combination comprising at least one of the foregoing polymers,

5 . The cement isolation fluid of claim 1 , wherein the preformed synthetic polymer comprises
a homopolymer of (meth)acrylamide or a copolymer of (meth)acrylamide with maleic anhydride, vinyl acetate, ethylene oxide, ethylene glycol, acrylonitrile, or a combination comprising at least one of the foregoing; poly(acrylamide) having crosslinks derived from polyethylene glycol diacrylate; poly(acrylic acid) having crosslinks derived from a vinyl ester oligomer; or a poly(acrylic acid) partial sodium salt-graft-poly(ethylene glycol).

6 . The cement isolation fluid of claim 1 , wherein the preformed synthetic polymer is present in the form of particles, comprising the polymer.

7 . The cement isolation fluid of claim 1 , wherein the particles are swelled and at least about 50% of the polymer particles have an average largest diameter of about 500 to about 12,000 micrometers.

8 . The cement isolation fluid of claim 1 , wherein the preformed synthetic polymer is present in the cement isolation fluid in a concentration of about 1 pound to about 150 pounds per thousand gallons of aqueous cement isolation carrier fluid.

9 . The cement isolation fluid of claim 1 , further comprising guar, carrageenan, or a combination comprising at least one of the foregoing.

10 . The cement isolation fluid of claim 1 , wherein the preformed synthetic polymer is present in the form of a hydrated pack of swelled polymer particles.

11 . A method of cementing a wellbore comprising a drilling fluid, the method comprising
injecting the cement isolation fluid of claim 1 into the wellbore; injecting a cement slurry into the wellbore; and hardening the cement in the slurry to cement the wellbore.

12 . The method of claim 11 , wherein injecting the cement slurry is subsequent to injecting the cement spacer fluid.

13 . The method of claim 11 , further comprising injecting a cement spacer fluid to displace the drilling fluid; subsequently injecting the cement isolation fluid; and subsequently injecting the cement slurry.

14 . The method of claim 12 , further comprising injecting a second cement isolation fluid before or after injecting the cement slurry.

15 . The method of claim 11 , wherein the cement isolation fluid prevents density swapping between the cement plug and a drilling fluid, or between the cement plug and a wellbore fluid.

16 . The method of claim 11 , wherein the wellbore is a vertical wellbore.

Assignees

• Nelson Scott Gregory
• Baker Hughes Inc

Inventors

• Nelson Scott Gregory

Classifications

• C09K8/40 Primary

  Spacer compositions, e.g. compositions used to separate well-drilling from cementing masses · CPC title

• E21B33/138 Primary

  Plastering the borehole wall; Injecting into the formation · CPC title

• C09K8/426

  for plugging · CPC title

• C09K8/424

  using "spacer" compositions · CPC title

• E21B33/13

  Methods or devices for cementing, for plugging holes, crevices or the like · CPC title