Cement squeeze well tool

1. A well tool for cementing a portion of a well, the well tool comprising:

a cement retainer assembly configured to be disposed within a wellbore, the cement retainer assembly comprising a ported sub, the ported sub comprising a port to flow cement out of the cement retainer assembly and into an annulus of the wellbore; and

a capsule connected to the cement retainer assembly and comprising a body defining an interior chamber of the capsule, the interior chamber configured to retain a fluid, the capsule configured to be disposed at a location within the wellbore and downhole of the cement retainer assembly, the capsule comprising a one-way check valve at a first longitudinal end of the capsule and a vent structure at a second longitudinal end of the capsule opposite the first longitudinal end, the one-way check valve configured to allow fluid to enter the interior chamber of the capsule, and the vent structure configured to expel gaseous fluid from within the interior chamber out of the interior chamber of the capsule.

2. The well tool of claim 1 , wherein the body of the capsule is comprised of fiberglass.

3. The well tool of claim 1 , wherein the capsule comprises centralizers extending radially outwardly from the body, the centralizers to position the capsule proximate to a radial center of the wellbore.

4. The well tool of claim 1 , wherein the capsule comprises a first connection structure at a first longitudinal end of the capsule and a second connection structure at a second longitudinal end of the capsule opposite the first longitudinal end.

5. The well tool of claim 4 , wherein the first connection structure comprises a threaded pin-type connection or a threaded box-type connection, and the second connection structure comprises a threaded pin-type connection or a threaded box-type connection.

6. The well tool of claim 4 , wherein the first connection structure directly couples the capsule to the cement retainer assembly.

7. The well tool of claim 6 , wherein the first connection structure directly couples the capsule to the ported sub of the cement retainer assembly.

8. The well tool of claim 6 , wherein the second connection structure directly couples to a second capsule configured to be disposed at a location within the wellbore and downhole of the first-mentioned capsule, the second capsule comprising a second body defining a second interior chamber of the second capsule.

9. The well tool of claim 1 , wherein the one-way check valve comprises a spring-loaded check valve.

10. The well tool of claim 1 , wherein the vent structure comprises a ball member and a ball seat, the ball member having a specific density less than the fluid in the interior chamber.

11. The well tool of claim 1 , wherein the vent structure comprises a one-way check valve.

12. The well tool of claim 1 , wherein the body is substantially cylindrical, and an outer diameter of the cylindrical body of the capsule is between 65 percent and 80 percent of an inner diameter of an inner wall of the wellbore.

13. The well tool of claim 1 , wherein the cement retainer assembly comprises a packer element to seal against an inner wall of the wellbore.

14. The well tool of claim 1 , wherein the wellbore is a cased wellbore, and an inner wall of the wellbore comprises an inner wall of a casing.

15. The well tool of claim 1 , wherein the ported sub comprises a plurality of ports to flow cement out of the cement retainer assembly, the plurality of ports comprising the port of the ported sub.

16. A method for cementing a portion of a well, the method comprising:

running a well tool into a wellbore, the well tool comprising:

a cement retainer assembly comprising a ported sub, the ported sub comprising a port; and

a capsule connected to the cement retainer assembly and comprising a body defining an interior chamber of the capsule, the capsule disposed downhole of the cement retainer assembly;

receiving well fluid disposed in the wellbore into the interior chamber of the capsule to fill the interior chamber with the well fluid, wherein receiving well fluid into the interior chamber of the capsule comprises flowing well fluid through a one-way check valve at a first longitudinal end of the capsule to fill the interior chamber of the capsule with well fluid and expelling gaseous fluid from within the interior chamber out of the interior chamber through a vent structure at a second longitudinal end of the capsule opposite the first longitudinal end; and

flowing cement through the port of the ported sub out of the cement retainer assembly and into an annulus between the capsule and an inner wall of the wellbore.

17. The method of claim 16 , wherein the cement retainer assembly comprises a packer element to seal against an inner wall of the wellbore, the method comprising:

prior to flowing cement through the port of the ported sub, engaging the inner wall of the wellbore with the packer element to isolate the wellbore downhole of the packer element.

18. The method of claim 17 , further comprising positioning the packer element of the cement retainer assembly uphole of a perforation in the inner wall of the wellbore.

19. The method of claim 16 , wherein the wellbore is a cased wellbore, the inner wall of the wellbore comprises an inner wall of a casing, and flowing cement into the annulus between the capsule and the inner wall of the wellbore comprises flowing the cement into the annulus between the capsule and the inner wall of the casing.

20. A capsule for a cement squeeze well tool, the capsule comprising:

a body defining an interior chamber configured to retain a fluid;

a connection structure at a first longitudinal end of the body, the connection structure configured to couple to a cement squeeze well tool;

a one-way check valve at a second longitudinal end of the body opposite the first longitudinal end and fluidly connected to the interior chamber, the one-way check valve configured to flow fluid into the interior chamber; and

a vent structure at the first longitudinal end of the body and fluidly connected to the interior chamber, the vent structure to expel gaseous fluid out of the interior chamber.

21. The capsule of claim 20 , wherein the connection structure comprises a threaded pin-type connection or a threaded box-type connection.

22. The capsule of claim 20 , wherein the body is substantially cylindrical.