Compositions and methods for completing subterranean wells

Patent metadata

Field	Value
Publication number	US-2017107420-A1
Application number	US-201515127234-A
Country	US
Kind code	A1
Filing date	Mar 31, 2015
Priority date	Mar 31, 2014
Publication date	Apr 20, 2017
Grant date	—

Abstract

Hydroxyethylcellulose (HEG) may be used to provide fluid-loss control in well-cement slurries HECs that have a molecular weight above 600,000, a degree of substitution higher than 1.9 and a molar substitution above 2.0 are particularly useful in that they not only provide fluid-loss control, but also may be used as a cement extender. Furthermore, the retardation effect may be reduced.

First claim

1 . A well cementing composition, comprising:
(i) water; (ii) a hydraulic cement; (iii) a cement dispersant; and (iv) hydroxyethylcellulose, wherein the hydroxyethylcellulose has a molecular weight between 600,000 g/mol and 1,500,000 g/mol and a molar substitution between 2.0 and 3.5 wherein the composition has a viscosity lower than 1000 cP at a shear rate of 100 s −1 .

2 . The composition of claim 1 , wherein the hydroxyethylcellulose has a degree of substitution between 1.9 and 2.5.

3 . The composition of claim 1 , wherein the cement dispersant is polynaphthalene sulfonate, present at a concentration between 0.3% and 1.5% by weight of cement.

4 . The composition of claim 1 , wherein the cement dispersant is a polycarboxylate, present at a concentration between 0.3% and 1.5% by weight of cement.

5 . The composition of claim 1 , wherein the hydroxyethylcellulose is present at a concentration between 0.4% and 1.5% by weight of cement.

6 . The composition of claim 1 , wherein the hydraulic cement is portland cement.

7 . The composition of claim 1 , wherein the composition further comprises an accelerator, a retarder, an extender, a weighting agent, an antifoam agent, nitrogen, a fluid-loss control agent or a gas generating agent, or a combination thereof.

8 . A method for cementing a subterranean well, comprising:
(i) preparing a cement slurry comprising water, a hydraulic cement, a cement dispersant and hydroxyethylcellulose, wherein the hydroxyethylcellulose has a molecular weight between 600,000 g/mol and 1,500,000 g/mol and a molar substitution between 2.0 and 3.5; and (ii) placing the slurry into the well; wherein the slurry has a viscosity lower than 1000 cP at a shear rate of 100 s −1 .

9 . The method of claim 8 , wherein the hydroxyethylcellulose has a degree of substitution between 1.9 and 2.5.

10 . The method of claim 8 , wherein the cement dispersant is polynaphthalene sulfonate or a polycarboxylate, present at a concentration between 0.3% and 1.5% by weight of cement.

11 . The method of claim 8 , wherein the hydroxyethylcellulose is present at a concentration between 0.4% and 1.5% by weight of cement.

12 . The method of claim 8 , wherein the hydraulic cement is portland cement.

13 . The method of claim 8 , wherein the composition further comprises an accelerator, a retarder, an extender, a weighting agent, an antifoam agent, nitrogen, a fluid-loss control agent or a gas generating agent, or a combination thereof.

14 . The method of claim 8 , wherein the cement slurry is placed during a primary cementing operation.

15 . The method claim 8 , wherein the cement slurry is placed during a remedial cementing operation.

Assignees

• Schlumberger Technology Corp

Inventors

• Terrier Cyril
• Couillet Isabelle
• Achtal Hafida

Classifications

• C09K8/48

  Density increasing or weighting additives · CPC title

• C04B28/04

  Portland cements · CPC title

• C04B2103/408

  Dispersants · CPC title

• C04B24/22

  Condensation {or polymerisation} products thereof · CPC title

• E21B33/14

  for cementing casings into boreholes · CPC title