COMPOSITIONS AND METHODS FOR COMPLETING SUBTERRANEAN WELLS

• US 20170107420A1
• Filed: 03/31/2015
• Published: 04/20/2017
• Est. Priority Date: 03/31/2014
• Status: Abandoned Application

• Current Assignee: Schlumberger Technology Corporation (SLB)
• Original Assignee: Schlumberger Technology Corporation (SLB)
• Inventors: Terrier, Cyril, Couillet, Isabelle, Achtal, Hafida
• Application Number:
  US15/127,234
• Publication Number:
  US 20170107420A1
• Time in Patent Office: Days
• CPC Class Codes: C04B 2103/408 Dispersants
• CPC Class Codes: C04B 2103/46 Water-loss or fluid-loss reducers, hygroscopic or hydrophilic agents, water retention agents
• CPC Class Codes: C04B 2103/50 Defoamers, air detrainers
• CPC Class Codes: C04B 22/124 Chlorides of ammonium or of the alkali or alkaline earth metals, e.g. calcium chloride
• CPC Class Codes: C04B 24/22 Condensation or polymerisation products thereof
• CPC Class Codes: C04B 24/2647 containing polyether side chains
• CPC Class Codes: C04B 24/32 Polyethers, e.g. alkylphenol polyglycolether
• CPC Class Codes: C04B 24/383 Cellulose or derivatives thereof
• CPC Class Codes: C04B 28/02 containing hydraulic cements other than calcium sulfates
• CPC Class Codes: C04B 28/04 Portland cements
• CPC Class Codes: C09K 8/46 containing inorganic binders, e.g. Portland cement
• CPC Class Codes: C09K 8/467 containing additives for specific purposes
• CPC Class Codes: C09K 8/473 Density reducing additives, e.g. for obtaining foamed cement compositions
• CPC Class Codes: C09K 8/48 Density increasing or weighting additives
• CPC Class Codes: C09K 8/487 Fluid loss control additives; Additives for reducing or preventing circulation loss
• CPC Class Codes: E21B 33/14 for cementing casings into boreholes

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.

Claims

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<sup>−

1</sup>.

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<sup>−

1</sup>.

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.