Repair of microannuli and cement sheath
AssigneeHalliburton Services
InventorsKirk L. Harris, Edward F. Vinson, Daniel L. Bour, David P. Ewert, Richard R. Gerke
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Abstract
This invention relates to a method of repairing holes, channels, voids and microannuli in a cement sheath situated in the annular space between a casing and the wall of a wellbore penetrating a subterranean earth formation, which method involves the use of a hydraulic cement consisting of discrete particles having a particle size not greater than about 30 microns. The cement, which is utilized in a water slurry, has a low density, good thixotropic properties and, in one embodiment, expansive characteristics.
Claims19
A method for repairing a hole in a cement sheath disposed in the annular space between a casing and a wellbore said method comprising the steps of:
- locating said hole in said sheath;
- producing a perforation in said casing to intersect said hole;
- isolating said hole by defining a space within said casing in communication with said hole via said perforation;
- introducing into said space a volume of a slurry of hydraulic cement in water;
- permitting said slurry to enter into said hole from said space via said perforation;
- and
- maintaining said slurry in said hole for a time sufficient to enable said slurry to form a rigid plug of cement in said hole;
- wherein said slurry is comprised of a mixture of water and said hydraulic cement in the ratio of from about 0.5 to about 5.0 pounds of water per pound of cement, the particle size of said hydraulic cement is not greater than about 30 microns, and the Blaine Fineness of said hydraulic cement is no less than about 6000 cm.sup.2 /grama dn furher wherein said hydaulic cement is slag.
A method for terminating the flow of fluid through a hole in a cement sheath disposed in the annular space between a casing and a wellbore said method comprising the steps of:
- producing a perforation in said casing to intersect said hole;
- placing within said casing adjacent said perforation a volume of a slurry of hydraulic cement in water said volume being in an amount at least sufficient to fill said hole;
- forcing said slurry to penetrate into said hole via said perforation;
- and
- maintaining said slurry in said hole for a time sufficient to enable said slurry to form a rigid plug of cement in said hole;
- wherein said slurry is comprised of a mixture of said hydraulic cement and water in the ratio of from about 1.0 to about 1.75 pounds of water per pound of cement, said particles size of said cement is not greater than about 17 microns, the Blaine Fineness is no less than about 7000 cm.sup.2 /gram, 90 percent of said particles have a diameter not greater than about 10 microns, 50 percent of said particles have a diameter not greater than about 6 microns and 20 percent of said particles have a diameter not greater than 3 microns and further wherein said hydraulic cement is slag.
A method for repairing a hole in a cement sheath disposed in the annular space between a casing and a wellbore said method comprising the steps of:
- locating said hole in said sheath;
- producing a perforation in said casing to intersect said hole;
- isolating said hole by defining a space within said casing in communication with said hole via said perforation;
- introducing into said space a volume of a slurry of hydraulic cement in water;
- permitting said slurry to enter into said hole from said space via said perforation;
- and
- maintaining said slurry in said hole for a time sufficient to enable said slurry to form a rigid plug of cement in said hole;
- wherein said slurry is comprised of a mixture of water and said hydraulic cement in the ratio of from about 0.5 to about 5.0 pounds of water per pound of cement, the particle size of said hydraulic cement is not greater than about 30 microns, and the Blaine Fineness of said hydraulic cement is no less than about 6000 cm.sup.2 /gram;
- and further wherein said hydraulic cement is Portland cement or a blend of Portland cement and slag.
A method for terminating the flow of fluid through a hole in a cement sheath disposed in the annular space between a casing and a wellbore said method comprising the steps of:
- producing a perforation in said casing to intersect said hole;
- placing within said casing adjacent said perforation a volume of a slurry of hydraulic cement in water said volume being in an amount at least sufficient to fill said hole;
- forcing said slurry to penetrate into said hole via said perforation;
- and
- maintaining said slurry in said hole for a time sufficient to enable said slurry to form a rigid plug of cement in said hole;
- wherein said slurry is comprised of a mixture of said hydraulic cement and water in the ratio of from about 1.0 to about 1.75 pounds of water per pound of cement, said particles size of said cement is not greater than about 17 microns, the Blaine Fineness is no less than about 7000 cm.sup.2 /gram, 90 percent of said particles have a diameter not greater than about 10 microns, 50 percent of said particles have a diameter not greater than about 6 microns and 20 percent of said particles have a diameter not greater than about 3 microns;
- and further wherein said hydraulic cement is Portland cement or a blend of Portland cement and slag having at least 10 percent Portland cement by weight of blend.
Dependencies are inferred from the claim text.