Sorel cement composition and method to cure loss of circulation

Patent metadata

Field	Value
Publication number	US-11148977-B2
Application number	US-201916593667-A
Country	US
Kind code	B2
Filing date	Oct 4, 2019
Priority date	Oct 4, 2019
Publication date	Oct 19, 2021
Grant date	Oct 19, 2021

Abstract

A system and method for applying a cement composition, including storing a slurry, adding magnesium oxide to the slurry to give a magnesium-oxychloride cement slurry, pumping the magnesium-oxychloride cement slurry into a wellbore, and sealing a loss circulation zone in the wellbore.

First claim

What is claimed is:

1. A method of applying a cement composition, comprising:
storing a slurry comprising a pH less than 5 for at least 24 hours comprising water, magnesium chloride, a retarder, a viscosifier, and an azo compound at a well site before application of the cement composition to a wellbore at the well site, thereby reducing time of preparing the cement composition contemporaneous with application of the cement composition to the wellbore;
adding magnesium oxide and a foam stabilizer to the slurry to form a cement composition comprising a magnesium-oxychloride cement slurry contemporaneous with the application of the cement composition to the wellbore;
pumping the magnesium-oxychloride cement slurry into the wellbore in a geological formation; and
sealing a loss circulation zone in the wellbore with the magnesium-oxychloride cement slurry.

2. The method of claim 1 , comprising specifying the storing of the slurry at the well site as an initial portion of the cement composition to be available on demand to reduce the time of preparing the cement composition contemporaneous with the application of the cement composition to the wellbore, wherein storing the slurry comprises storing the slurry as homogenous at a temperature less than 140° F. before the application of the cement composition to the wellbore, and wherein the slurry comprises a pH less than 4.

3. The method of claim 1 , wherein storing the slurry is in response to specifying storing the slurry at the well site to be available on demand for at least three days for applying the cement composition to the wellbore to reduce the time of preparing the cement composition contemporaneous with the application of the cement composition to the wellbore, wherein storing the slurry comprises storing the slurry in a vessel adjacent the wellbore, and wherein the slurry comprises at least 35 weight percent (wt %) water, at least 20 wt % magnesium chloride, and at least 0.2 wt % of the azo compound.

4. The method of claim 1 , comprising preparing the slurry comprising mixing the water, the magnesium chloride, the retarder, the viscosifier, and the azo compound, wherein preparing comprises adjusting a type of the magnesium chloride to adjust delay in a subsequent reaction that forms magnesium-oxychloride cement from the magnesium-oxychloride cement slurry, and wherein storing the slurry is in response to specifying storing the slurry at the well site to be available on demand to reduce the time of preparing the cement composition contemporaneous with the application of the cement composition to the wellbore.

5. The method of claim 1 , wherein the reducing time comprises reducing amount of time of the application of the cement composition to the wellbore by storing the slurry at the well site in advance of the application of the cement composition to the wellbore, wherein adding the magnesium oxide and the foam stabilizer comprises adding, in a batch operation, the magnesium oxide and the foam stabilizer to the slurry in a vessel at the well site comprising the wellbore.

6. The method of claim 1 , wherein storing the slurry comprises storing the slurry as homogenous and having a pH less than 4 in a vessel at the well site before the application of the cement composition to the wellbore, wherein adding the magnesium oxide and the foam stabilizer comprises adding the magnesium oxide and the foam stabilizer to the slurry in a conduit as the slurry is being pumped through the conduit into the wellbore at the time of application of the cement composition to the wellbore.

7. The method of claim 1 , comprising specifying storing the slurry at the well site to be available on demand to reduce the time of preparing the cement composition contemporaneous with the application of the cement composition to the wellbore, wherein adding magnesium oxide and a foam stabilizer to the slurry is a batch operation, and wherein sealing the loss circulation zone comprises forming magnesium-oxychloride cement from the magnesium-oxychloride slurry in fractures in the geological formation at the loss circulation zone.

8. The method of claim 1 , comprising:
specifying not incorporating the foam stabilizer in the slurry before the preparing of the cement composition contemporaneous with the application of the cement composition to the wellbore to avoid increasing pH of the slurry before the preparing of the cement composition contemporaneous with the application of the cement composition to the wellbore, wherein the foam stabilizer comprises a pH of at least 7, wherein the application of the cement composition to the wellbore comprises the pumping og the magnesium-oxychloride cement slurry into the wellbore, wherein storing the slurry comprises preparing and storing the slurry comprising a pH less than 4 before the pumping of the magnesium-oxychloride cement slurry into the wellbore; and
generating nitrogen gas in the magnesium-oxychloride cement slurry via the azo compound to expand the magnesium-oxychloride cement slurry, wherein sealing the loss circulation zone comprises filling fractures of unknown dimensions in the geological formation with the magnesium-oxychloride cement slurry via the expanding of the magnesium-oxychloride cement slurry.

9. A method of applying a cement composition, comprising:
storing a first slurry comprising a pH less than 5 for at least 24 hours at a well site having a wellbore before pumping a magnesium-oxychloride cement slurry into the wellbore, the first slurry comprising water, magnesium-chloride, a retarder, a viscosifier, and an azo compound;
adding magnesium oxide and a foam stabilizer to the first slurry to give a second slurry, wherein the second slurry forms the magnesium-oxychloride cement slurry; and
pumping the second slurry as the magnesium-oxychloride cement slurry into the wellbore in a subterranean formation to fill fractures in the subterranean formation with the second slurry to seal a loss circulation zone along the wellbore.

10. The method of claim 9 , wherein the first slurry comprises the azo compound at less than 6 weight percent (wt %) of the first slurry.

11. The method of claim 9 , wherein storing the first slurry comprises preparing wherein the first slurry comprises a pH less than 4, wherein adding the magnesium oxide and the foam stabilizer is a batch operation and comprises mixing the magnesium oxide and the foam stabilizer with the first slurry in a vessel adjacent the wellbore, wherein the foam stabilizer comprises a pH of at least 7, and wherein the method comprises specifying not adding the foam stabilizer to the first slurry as stored before contemporaneous with the pumping of the magnesium-oxychloride cement slurry to avoid increasing pH of the first slurry before contemporaneous with the pumping the magnesium=oxychloride cement slurry into the wellbore.

12. The method of claim 9 , comprising specifying storing the first slurry at the well site to reduce an amount of time of applying the cement composition comprising magnesium-oxychloride cement to the wellbore, wherein adding the magnesium oxide and the foam stabilizer comprises adding the magnesium oxide and the foam stabilizer to the first slurry flowing through a conduit into the wellbore.

13. The method of claim 9 , comprising preparing the first slurry as a portion of a loss circulation material (LCM) pill before pumping the second slurry as the LCM pill into the wellbore, wherein storing the first slurry comprises storing the first slurry as the initial portion at the well site before pumping the second slurry, wherein pumping the second slurry comprises pumping the second slurry with a centrifugal pump into a casing in

Assignees

• Saudi Arabian Oil Co

Inventors

• Thaemlitz Carl
• Santra Ashok

Classifications

• C09K8/506

  containing organic compounds · CPC title

• C09K8/5045

  containing inorganic compounds · CPC title

• C09K8/518 Primary

  Foams · CPC title

• C04B28/32 Primary

  Magnesium oxychloride cements, e.g. Sorel cement · CPC title

• C04B38/103

  the foaming being obtained by the introduction of a gas other than untreated air, e.g. nitrogen · CPC title