Boring or penetrating the earth – With above-ground means to feed tool
Reexamination Certificate
1999-10-08
2001-11-06
Neuder, William (Department: 3672)
Boring or penetrating the earth
With above-ground means to feed tool
C166S085100, C166S379000
Reexamination Certificate
active
06311792
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a device for driving and handling a drillstring, and, in particular, for manipulating a casing string in a casing drilling environment.
BACKGROUND OF THE INVENTION
The drilling of wells, such as those for oil and gas often use a top drive to turn the drillstring. The quill of the top drive typically threads into the box end of the top joint of pipe used for drilling and in turn drives the pipe. The problem encountered is that there is potential for damage to the threads of both the drill pipe and the top drive quill. Galling of the threads is undesirable, since they have to be machined to correct the damage, which is time consuming and costly, especially given the typically remote locations that wells are drilled in. It is especially desirable to avoid damaging the threads on the top drive, since they are much more difficult and expensive to repair than drill pipe.
With the development of drilling with casing, that is using a casing string as the drill pipe, the issue of thread protection has become much more important. This is because the thread form used in casing connections is more fragile than the connections used in drill pipe, and the casing connections have to remain fluid and pressure tight once the drilling process has been completed. Other considerations are that casing typically has a thinner sidewall and is less robust than drill pipe. This is especially true in the thread area, where the casing has threads on both ends, with a corresponding reduction in section area.
While some clamps are available for gripping casing, these clamps grip the casing on the inside using expandable jaws. These clamps are therefore not suitable for use in manipulating casing during a casing drilling operation. The expandable jaws create a severe restriction on the casing's inner diameter which restricts mud flow downhole, for example, to a downhole motor which may restrict the amount of power the motor is capable of producing. In addition, the jaws are not fail safe, since a biasing agent must be continuously applied to maintain gripping force. Prior casing clamps had no means for passing fluids to the casing bore and had no means for manipulating the casing simultaneously in vertical and rotational directions.
Other prior methods of handling casing involved using the kelly or top drive to turn the casing, with the attendant risk of damage to the threaded connections. A safer and more efficient system of driving a casing string is needed.
SUMMARY OF THE INVENTION
The present invention provides a clamp for driving a drillstring where the drillstring is formed of casing pipe. While the clamp is described herein exclusively for use with casing, it should be understood that the clamp might be used in other applications. By utilising a casing clamp device of the present invention, the risk of damage to the threaded connection on the ends of the casing is minimised. The clamp includes a sealing element to enable drilling mud to be pumped down the centre of the pipe while rotating the pipe during drilling operations. In addition, the clamp permits simultaneous displacement of the pipe, either up or down, while rotating it, which is an essential requirement of drilling.
In accordance with a broad aspect of the present invention, there is provided a clamp for use with a top drive for gripping and turning a drillstring formed of pipe, the clamp comprising: slips positioned to grip the pipe, drive means for moving the slip blocks and dies radially inwardly into a pipe gripping position and radially outwardly to a pipe releasing position, and an attachment means for connecting the apparatus to a top drive.
The slips are preferably formed, for example including a toothed or otherwise knurled face, to enhance their engagement against the outer surface of a pipe. The slips can be replaceable to accommodate different sizes of pipe and to enable the gripping surface to be renewed as it wears. In one embodiment, the slips carry slip dies. The slip dies are selected to engage a pipe disposed between the slips and, therefore, can be roughened or formed with teeth to enhance their engagement with the pipe outer surface. The slip dies can be carried on the slips in such a way as to be replaceable.
In one embodiment, the slips are mounted in a slip bowl and are constrained to move along a conical taper of the slip bowl to, thereby, be moved radially inward and outward relative to the centre axis of the slip bowl. This permits the slips to be moved to grip or release a pipe positioned therebetween. The conical taper is positioned to taper downwardly such that as the weight on the pipe increases, the slips will be driven to bite with increased force into the pipe.
The drive means can be any suitable means for moving the slips radially inwardly and outwardly, for example, in one embodiment along the taper of the slip bowl. In one embodiment, the drive means includes a biasing agent such as, for example, a plurality of springs that bias the slips down the taper of the slip bowl such that they are normally in a pipe gripping, closed position. Thus, unless a force is applied against the pressure in the biasing agent, the slips remain in a pipe gripping position reducing the chance of a pipe being inadvertently released. In order to move the slips to an open position to release a pipe, the drive means includes a system for applying force against the biasing agent. The system for applying force can, for example, use hydraulics.
The clamp is attached to a top drive by an attachment means. The attachment means is selected to be capable of transferring torque from the top drive to the clamp to cause it to rotate. In one embodiment, a quill adapter is connected to the clamp and formed at its outboard end for engagement to the quill of the top drive.
In one embodiment, the clamp includes a stabbing spear extending out to fit into a pipe and align it with the slips to facilitate gripping. In another embodiment, a drilling fluid conduit is provided for conducting a flow of drilling fluid into the longitudinal bore of the pipe. Preferably, the stabbing spear is formed as a conduit so that it can also serve as the drilling fluid conduit. In such an embodiment, the stabbing spear includes seals for acting between the spear and the pipe for restricting the flow of drilling fluid outside of the pipe. The spear also acts as a mandrel, enhancing the casing's ability to withstand large inward clamping forces without deforming the pipe.
When the clamp is rotated, the slips rotate therewith and, therefore, any pipe gripped by the slips is also rotated.
In accordance with another broad aspect of the present invention, there is provided a method for drilling a well with a well casing as an elongated tubular drill string and a drilling assembly retrievable from the lower distal end of the drill string without withdrawing the drill string from a wellbore being formed by the drilling assembly, the method comprising: providing the casing as the drill string; providing a drilling assembly connected at the distal end of the drill string and being retrievable through the longitudinal bore of the drill string; gripping the drill string on its outer surface; inserting the drill string and the drilling assembly into the wellbore and driving the drilling assembly to operate to form a wellbore to a diameter greater than the diameter of the drill string.
Preferably the method further includes: removing at least a portion of the drilling assembly from the distal end of the drill sting and moving the at least a portion of the drilling assembly out of the wellbore through the drill string without removing the drill string from the wellbore, leaving the drill string in the wellbore.
The drilling assembly can be any assembly useful for drilling a wellbore through an earth formation. As would be appreciated, the drilling assembly can include a drill bit and any of, for example, measurement while drilling equipment and a downhole motor.
In a preferred embodiment, the step of gripping the
Nikiforuk Kevin
Scott Stephen F.
Bennett Jones LLP
Neuder William
Tesco Corporation
LandOfFree
Casing clamp does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Casing clamp, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Casing clamp will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2613374