WELL CASING FLOTATION DEVICE AND METHOD

摘要

2065338 9103620 PCTABS00003 A ported float shoe (5) and a landing collar (16) are attached at a first end of a portion of a casing string (4) and a sliding air trapping insert (20) is attached at the other end. The air trapping insert (20) includes a fluid flow passageway (24) blocked by a plug (22) attached by shear pins to the insert (20) or the air trapping insert is an inflatable insert (55) having a conduit (60) providing a fluid passageway to the first end. The air trapping insert and float shoe form an air cavity (12a or 12b) within the string portion (4). The air cavity provides buoyant forces during running, cementing or other casing operations within a borehole (2), reducing running drag and the related chance of a differentially stuck casing (4). It also allows reciprocation and rotation during cementing and avoids separate removal steps.