1. Field of the Invention
Embodiments of the present invention generally relate to running a casing into a wellbore. Particularly, embodiments of the present invention relate to a fill up tool for use during a casing running operation. More particularly, embodiments of the present invention relate to a fill up tool adapted to seal the casing for fill up or circulation of fluid during casing running operations.
2. Description of the Related Art
To obtain hydrocarbons from an earth formation, a wellbore is typically drilled to a predetermined depth using a drill string having a drill bit attached to its lower end. The drill string is then removed, and thereafter a casing is lowered into the wellbore to line the wellbore. The casing may be a casing section or, in the alternative, a casing string including two or more casing sections threadedly connected to one another.
While the casing is being lowered into the wellbore during the casing running operation, the pressure within the wellbore is typically higher than the pressure within the bore of the casing. This higher pressure within the wellbore exerts stress on the casing as it is being lowered into the wellbore, thereby risking damage or collapse of the casing during run-in. A casing fill-up operation is performed to mitigate these stresses. The casing fill-up operation involves filling the bore of the casing being run into the wellbore with a fluid (such as “mud”) in an attempt to equalize the pressure inside the casing with the pressure outside the casing (i.e., the pressure within the wellbore) and thereby prevent collapse of the casing during the run-in operation. Pressurized fluid is typically input into the bore of the upper end of the casing using a fill line from the existing mud pumps at the well site.
At various times during the casing running operation, the casing may get stuck within the wellbore. To dislodge the casing from the wellbore, a circulating operation is performed by utilizing a circulation tool, where pressurized drilling fluid is circulated down the casing and out into the annulus to remove the obstructing debris. To “rig up” the circulating tool for circulating operation, the circulating tool is inserted into the bore of the casing at the upper end of the casing. A sealing member on the circulating tool is then activated to seal the circulating tool with the casing, forming a path for fluid flow through the circulating tool and out into the bore of the casing. Specifically, in a circulation operation, fluid is introduced into the circulating tool, flows through the bore of the casing and out the lower end of the casing to remove the obstructing debris, and then the fluid having the debris therein flows up the annulus to the surface of the wellbore.
After the circulation operation, the circulating tool is removed from the casing, and the casing fill-up operation is restarted to run casing into the wellbore. During the casing running and fill-up operations, air is allowed to escape through the bore of the casing to prevent over-pressurizing the bore of the casing. To vent the air from the bore of the casing, the circulating tool is removed from the casing prior to the fill-up operation. To remove the circulating tool, the sealing member is de-activated, and the circulating tool is lifted from the bore of the casing. The casing may then be lowered further into the wellbore while filling the casing with fluid to prevent collapse of the casing.
The casing running operation generally requires the sealing member on the fill up or circulation tool to be repeatedly inserted and removed from the interior of the casing. The constant movement of the sealing member against the wall of the casing over time may damage the integrity of the sealing member. In the respect, the sealing member's capacity to seal against a pressure kick in the wellbore is adversely affected.
There is, therefore, a need for a fill up tool suitable for fill up operations while maintaining capacity to seal against pressure fluctuations. There is also a need for a fill up tool having a sealing member arrangement capable of sealing against pressure fluctuation.