TRAM SESSION WHEN IN COMPRESSION

FIELD OF THE INVENTION

The present invention relates to an apparatus, which enables cementing operations to be carried out with an inner work string.

BACKGROUND OF THE INVENTION

The object of the present invention is to provide an apparatus, which enables rotational torque to be transmitted from above the too! to below the too! when in tension and stroked fully open, whilst enabling no torque to be transmitted from above the tool to below the tool when in compression and stroked partially or fully closed.

The present invention is for use In; the oil Industry, particularly far cementing operations on offshore oil rigs within a work string.

A work string component such as the present invention is made up as part of a number of components attached together via connections. The present invention has connections which enabie it to be made up to any work string.

Casing strings are run and cemented into oil wells to facilitate deeper drilling operations to continue. If preferable an inner work string is sometimes run into the casing to facilitate more optimal cementing operations.

The inner work string may be attached to the base if the; leasing string via a threaded connection or latching collet which requires rotational torque to be transmitted through the string to make up the connection and to break out the connection. in the case of certain subsea wellhead systems it is required to provide rotational torque to attach components above the inner work string to the casing. In this instance it is required to provide free rotation below these components after the inner work string has been connected to the base of the casing string.

The requirement described dictates a need for a work string component which provides rotational torque when in tension but allows free rotation above the tool without torque transmission when in compression in a partially or fully stroked closed position.

SUMMARY OF THE INVENTION

There is provided a system comprising: a tool pin connection; a tool box connection below said tool pin connection; an internal barrel extending between said tool pin connection and said tool box connection; wherein said internal barrel has a cylindrical profiled section and a splined profile section; and a splined torque bushing; wherein, when said spiined torque bushing is engaged with said splined profile section, torque is transmitted from the tool box connection to said tool pin connection, and wherein, when said spiined torque bushing is engaged with said cylindrical profiled section, no torque is transmitted from said tool box connection to said tool pin connection. Advantageously, the system allows for rotational torque when in tension but allows for free rotation above the tool without torque

transmission when in compression in a partially or fully stroked closed position.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows the present invention assembly in tension in a stroked open position, with the ability to transfer torque through the present invention.

Figure 2 shows the present invention assembly in compression in a stroked partially closed position, with the ability to free rotate and not transfer torque through the present invention. Figure 3 shows the inner barrel embodiment as well as the internal barrel head of the present invention shown in figures 1 and 2.

Figure 4 shows the polished bore receptacle assembly as well as the splined torque bushing of the present invention shown in figures 1 and 2.

DETAILED DESCRIPTION OF THE INVENTION

Generally, an apparatus and a method for using the apparatus, which enables cementing operations to be carried out with an inner work string is disclosed.

A typical cementing operation of a casing string involves pumping of the fluid cement slurry down the internal diameter of the casing string, which exits the base of the casing and returns up the annulus of the casing string. Once sufficient fluid cement slurry has been pumped, a displacement fluid is pumped behind the cement slurry which forces cement slurry out of the interna! diameter of the casing string, leaving said displacement fluid internally and said cement slurry externally to the casing string. By use of a smaller diameter inner work string within the casing string, a smaller volume of displacement fluid is required to place ail of the cement slurry in the annuius and thereby optimises the cementing operation.

With subsea wellhead systems used on offshore oil wells, a running tool is required to be connected to the top of the casing string in order to install the conductor pipe (first casing string for structural support of the rest of the oil well) and surface casing pipe (second casing string run with the wellhead on the top). This running tool creates a point of fixity for the inner work string resulting in an uncertainty of the length of the inner work string. The present invention provides means of an internal barrel 7 (shown in figure 3) which can stroke relative to a polished bore receptacle 2 (shown in figure 4), providing compensation for a discrepancy between casing string and inner work string length.

During the pumping of a fluid cement slurry an upward force is experienced at the base of the inner work string which unless connected would drive the connection out of the base of the casing string. This is overcome by threading a connection of using a latching coilet oh the base of the inner work string which positively connects the base of the casing string to the inner work string. This threaded connection or latching collet is made up as the inner work string is run into the casing string and it interacts with the base of the casing string. The present invention is at a position above the base of the inner work string in tension and in a stroked open position. Rotational torque can be transmitted through the present invention as the box connection 1 (shown in figure 1) is rotated from above, transmitting torque through the polished bore receptacle 2 (shown in figure 1) and spiined torque bushing 3 (shown in figure 4) complete with one or more spline profiles. The spiined torque bushing 3 (shown in figure 1) mates with the spiined profile section of the internal barrel 6 (shown in figure 3) complete with the one or more spline profiles, typically the same figure as those on the spiined torque bushing 3 (shown in figure 4), which transmits rotational torque into the cylindrical profile section of the internal barrel 7 (shown in figure 3) and through the pin connection 8 (shown in figure 1). Confirmation of the successful mating of the threaded connection or latching collet at the base of the inner work string with the base of the casing string can be confirmed by means of attempting to pull the inner work string and creating additional tension in the inner work string. The running tool of the casing string can then be lowered into position at the top of the casing string, in turn causing the present invention to undergo a compressional force and stroking partially closed as the internal barrel head 5 (shown in figure 2) rides up internally within the polished bore receptacle 2 (shown in figure 2). The running tool is required to be rotated to engage the top of the casing string which can be achieved without rotating the inner work string as the spiined torque bushing 3 (shown in figure 4) is rotating freely around the cylindrical profile section of the interna! barrel 7 (shown in figure 3), therefore no engagement of the spiined profile section of the internal barrel 6 (shown in figure 3) with the spiined torque bushing 3 (shown in figure 4) is established and no torque is transferred through the tool.

The casing string is then run to the required depth using additional pipe, and cementing operations are performed through the additional pipe and inner work string to place cement slurry in the annulus of the casing string. The fluid cement slurry is pumped internally through the inner work string as well as through the present invention which provides pressure containment with a seal stack assembly 4 (shown in figure 1 ) mounted around the internal barrel head 5 (shown in figure 1).

Following successful cementing operations, the running tool is removed from the top of the casing string by applying rotational torque. This rotational torque is experienced at box connection 1 (shown in figure 1), the polished bore receptacle 2 (shown in figure 1) and the spiined torque bushing 3 (shown in figure 1) of the present invention. This rotational torque is not experienced by the internal barrel 7 (shown in figure 3) or the inner work string underneath the pin connection 8 (shown in figure 3). This is as a result of the spiined torque bushing 3 (shown in figure 4) rotating around the cylindrical profile section of the internal barrel 7 (shown In figure 3) causing no physical engagement or interaction. Once the running tool is removed and raised the present invention experiences a tensile force due to the base of the inner string still being engaged at the base of the casing string via the threaded connection or latching collet. This tension in the present invention strokes open the tool and engages the spiined torque bushing 3 (shown in figure 4) with the spiined profile section of the internal barrel 6 (shown in figure 3). Rotational torque can now be transmitted through the string from above which will provide rotational torque through the inner work string and disengage the threaded connection or latching collet at the base of the inner work string. in a preferred embodiment, the material of the tool body, is steel. Of course, the tool box connection 1 (shown in figure 1), polished bore receptacle 2 (shown in figure 1), spiined torque bushing 3 (shown in figure 4), interna! barrel head 5 (shown in figure 1), spiined profile section of inner barrel 6 (shown in figure 3), cylindrical profile section of inner barrel 7 (shown in figure 3) and pin connection 8 (shown in figure 3) could be made of other materials, such as X56, L80, P110. S135, V150 (various grades of steel). The seal stack assembly 4 (shown in figure 1 ) can be any polymer or steel material to provide hydraulic sealing whilst the internal barrel head 5 (shown in figure 1) Is in various positions within the polished bore receptacle 2 (shown in figure 2). Although the invention has been described in terms of preferred embodiments as set forth above, it should be understood that these embodiments are illustrative only and that the claims are not limited to those embodiments. Those skilled in the art will be able to make modifications and alternatives in view of the disclosure which are contemplated as failing within the scope of the appended claims.