Patent ID: 11932804
Assignee: SCHLUMBERGER TECHNOLOGY CORPORATION
Field: Basic materials chemistry (Chemistry)
Classification: CPC C | IPC C

Claim 12:
13. A method, comprising:
(a) preparing a spacer fluid comprising: water, a viscosifying agent, and an expanding agent comprising calcium oxide or calcined magnesium oxide or both;
(b) during a well cementing operation, placing a drilling fluid, the spacer fluid, and a cement slurry into a well such that the spacer fluid flows between the drilling fluid and the cement slurry;
(c) causing the spacer fluid to commingle with the drilling fluid or the cement slurry, or both, thereby forming an interface; and
(d) curing the cement slurry and the interface, wherein the interface expands or does not shrink upon the curing,
wherein the expanding agent is encapsulated by a coating having a thickness between about 2 mm and 80 mm, and
wherein the coating comprises a polymer comprising a polyester, a polyacrylate, an epoxy, a polyhydroxyacid, a polypeptide, a polyesteramide, a polysulfide, a polysiloxane, a block copolymer comprising blocks joined through ester bonds, or a block copolymer comprising blocks joined through amide bonds, or a combination thereof, or silica.