Patent ID: 7640984

Claim:
A method of cementing a casing string in a well, comprising: (a) providing an annular recess within a wall of the casing string in a lower portion of the casing string, the casing string having an open bore from an upper end to a lower end that has a minimum inner diameter smaller than a diameter of the annular recess; (b) providing a tubular body having an axial passage and a latch collar, pumping the body down the casing string to the recess and springing the latch collar outward into engagement with the recess; then (c) pumping cement down the casing string, through the passage and up an annulus surrounding the casing string; then (d) pumping a plug down the casing string and latching the plug to the body, thereby preventing cement in the annulus from flowing back upward in the casing string above the plug.