Patent Application
20100059290
Not Applicable
Not Applicable
1. Field of the Invention
The invention relates generally to the field of drilling wellbores through subterranean formations. More specifically, the invention relates to devices capable of inserting instruments through drill bits used to perform certain operations in subterranean formations below the drill bit.
2. Description of the Related Art
During wellbore drilling operation, it is occasionally desirable to perform operations other than actual drilling into the formation. For instance, when drilling into a fractured or porous zone, it may be desirable to cure losses and to maintain formation strength by injecting cement and/or lost circulation material into the formation. Another example is setting a cement plug for abandonment of a well or well section, possibly followed by drilling of a branched well section. These non-drilling operations occur during the construction of a wellbore or borehole, but typically involve the use of well tools other than a drill bit. Using a drill bit for such non-drilling operations would be undesirable because, for example, attempting to pump a fluid of high density or viscosity and/or comprising coarse material through the drill string with a drill bit attached has been found to be detrimental. This is because conventional drill bits such as polycrystalline diamond cutter (PDC) bits or roller cone bits are provided with bit nozzles for discharging fluid from within a drill string into the wellbore. Such fluids create a substantial risk for the nozzles to plug up due to the high shear, rapid pressure drop, and small orifices. Nozzles normally comprise a nozzle channel with a nozzle insert, and the orifice could in principle be increased by removing the nozzle inserts from the bit. This option is however not seriously contemplated in practice because it would significantly impair the performance of the bit for progressing into the formation. Other operations such as setting a cement plug may simply not be possible with a drill bit and may require other tools.
Therefore, the drill bit is typically removed from the drill string and is replaced by a suitable tool to perform non-drilling operations. For example, when injecting fluids, a tool is used with a sufficiently large orifice in order that fluid can be introduced. This most often means that the drill string is pulled from the borehole. Before pulling the drill string out of the borehole, it is often necessary to first temporarily stabilize the borehole by introducing lost circulation material. This stabilization may often be accomplished through ports in the lower part if the drill string above the drill bit that can be opened and closed again, for example in a circulating sub. Introducing lost circulation material via the circulating sub can plug the annulus between the borehole wall and the lower part of the drill string including the drill bit, so as to require removal of the entire drill string, which may further complicate operations. The pumping of cement through the same ports is not a practical option, as a significant risk exists that the lower part of the drill string including the drill bit could be cemented in place. When the drill string then has been fully removed, the drill bit may be replaced by a cementing stinger. When the drill string is lowered again in the borehole to the desired depth, fluid can be introduced into the borehole. If it is further drilling is desired, the drill string must then be pulled from the borehole hole, so that the drill bit can be remounted.
Most procedures that involve removing the drill bit from the borehole are time-consuming and therefore often quite expensive. Typically, to remove the drill bit from the borehole, the drill string must be withdrawn from the borehole, the pipe string disassembled, then the pipe string reassembled and the drill string run back into the borehole. The foregoing process may take several hours or more depending on the depth of the borehole, among other factors. Moreover, removing the drill bit and drill string from an unstable borehole may result in borehole collapse. In these situations, it may be undesirable to remove the drill string from the borehole.
Other applications for inserting an instrument through a drill bit include the use of “well logging” devices. Well logging devices include one or more sensors for measuring one or more physical parameters of the formations outside the wellbore and/or various parameters of the wellbore itself such as geodetic trajectory. The sensors are disposed in a housing configured to move along the interior of the wellbore. In certain cases, it is difficult to insert well logging instruments into portions of the wellbore due to, for example, high inclination of the wellbore from vertical or rough surface of the wellbore wall. In such cases it is desirable to dispose the drill string within such portions to provide a conduit or passage for the well logging instrument. The instrument may be exposed to the open wellbore by opening a passage in the drill bit, such as by removing a releasable insert, and moving the instrument through the opening.
Previous devices to address the needs described above include providing a drill bit insert in the drill bit which is held in place by means of a ball-latch mechanism, detaching the drill bit insert through the use of a tool inserted into the drill string which is configured to unlatch the ball-latch mechanism, and deploying the tool through the opening in the drill bit created by removing the insert from the bit body. After completion of the task, the tool is then retracted and drill bit insert reattached to the drill bit by means of re-latching the ball-latch mechanism. The drilling activity could then re-commence. However, the foregoing drill bit with an insert does not include the use of a latch mechanism in a sealed enclosure. Drilling mud and other fluids are capable of reaching the latch mechanism in such a situation and rendering it inoperable or causing the mechanism to spontaneously unlatch. Further, in the foregoing drill bits with inserts, the tool used to disengage the latching mechanism does not lock into the latching mechanism, allowing incomplete or misaligned attempts at unlatching the latching mechanism, or worse, release of the insert from the drill bit without its positive connection to the release tool. In such cases, the insert could fall to the bottom of the well, resulting in a difficult and expensive operation to retrieve the insert.
Accordingly, there exists a need for a drill bit and release tool or “running tool” that address one or more disadvantages of the prior art.
A drill bit in one aspect of the invention includes a drill bit body defining an opening enabling longitudinal passage of an instrument therethrough, a drill bit insert disposed in the opening and a latch assembly coupled to the insert and configured to releasably retain the insert in the opening. The latch assembly is configured to operate only upon locking engagement therewith of a running tool, and the latch assembly is disposed in a substantially sealed enclosure.
A running tool in another aspect of the invention is configured to operate a latch assembly only upon locking engagement therewith. The running tool includes a running tool housing with a circumference and a longitudinal axis, a drive shaft extending along longitudinal axis of the running tool and having an outer circumference, and a mating assembly enclosed within the running tool housing and configured to lockably engage the latch assembly. The running tool further includes a shaft trigger assembly, wherein the shaft trigger assembly is enclosed within the running tool housing and the shaft trigger assembly is configured to substantially prevent rotational movement of the drive shaft and a torsion spring. The torsion spring is mechanically connected to the drive shaft and configured to motivate the drive shaft to rotate.
Other aspects and advantages of the invention will be apparent from the following description and the appended claims.
A more complete understanding of the present disclosure and possible advantages thereof may be acquired by referring to the following description taken in conjunction with the accompanying figures, wherein:
While the present invention is susceptible to various modifications and alternative forms, specific exemplary embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the invention as defined by the appended claims.
The invention enables the use of tools in a wellbore when it is undesirable or impossible to remove the drill bit. Examples of devices used in a wellbore when it is undesirable or impossible to remove the drill bit are disclosed in U.S. Pat. No. 7,287,609, filed Nov. 13, 2003, entitled “Drilling a Borehole,” and U.S. Pat. No. 7,281,592, filed Jul. 23, 2002, entitled “Injecting a Fluid into a Borehole Ahead of the Bit.”
As used herein, the term “upper” refers to a position or orientation relatively closer to the surface end of the drill string and the term “lower” is used to mean a position relatively closer to the subsurface end of the borehole during operation. The term “longitudinal” is used to refer to a direction or orientation substantially along the axis of the drill string.
Latch assembly (1) is mechanically connected (for example, by threads) to drill bit insert (2) to allow retention of the insert (2) in the bit body (206 in
As shown in
Collet assembly (22) includes collet ring (21) and collet keys (23). As shown in
Cam (11) further includes cam ring (16). Cam ring (16) concentrically contained within the collet keys (23) of collet assembly (22) so that in the engaged position the collet keys (23) are extended to lock the latch assembly (1) within the drill bit. Cam ring (16) further includes cam latch pins (28). Cam latch pins (28) project through cam ring (16) and are disposed so as to engage helical slots (18) on cam body (14) when cam ring (16) is concentrically positioned within the collet assembly (22).
Latch assembly (1) is positioned within housing (60). Housing (60) is generally cylindrical and is configured to protect latch assembly (1) from drilling mud and other wellbore fluids by forming a substantially sealed enclosure around latch assembly (1). Housing (60) is mechanically connected to bit insert (2), typically by threading housing (60) to bit insert (2), although one of ordinary skill in the art will understand alternative methods of mechanically connecting housing (60) to bit insert (2).
As shown in
As shown in
As shown in
Running tool (100) is shown in
Running tool housing (102) is approximately cylindrical and encloses mating assembly (101), drive shaft (110), shaft trigger assembly (130) and torsion spring (160) and is configured to protect these elements from drilling mud and other fluids that may exist within central longitudinal passageway (208).
Drive shaft (110) is aligned along the longitudinal axis of running tool housing (100) and circumferentially encompassed by running tool housing (102). Drive shaft (110) includes shaft (112) and shaft head (114). Shaft head (114) is mechanically connected to drive shaft (110) and is configured to rotate with rotation of shaft (112). Shaft head (114) includes shaft head splines (116).
Mating assembly (101) is configured to lockably engage running tool (100) with latch assembly (1). Mating assembly (101) includes upper collet assembly (140), upper collet support ring (150), and collet body (148) with guide slots (149). Upper collet support ring (150) circumferentially encloses and is mechanically connected to drive shaft (110). Upper collet assembly (140) includes upper collet frame (142), a ring that is configured to circumferentially enclosing drive shaft (110) such that drive shaft (110) can rotate and pass longitudinally therethrough, and upper collet keys (144), which extend from the upper surface of upper collet frame (142). The inner diameter of upper collet frame is larger than the outer diameter of upper collet support ring (150); therefore, upper collet support ring (150) is configured so as to be capable of longitudinally passing through upper collet frame (142). Upper collet keys (144) are prevented from contacting the surface of drive shaft (110) by upper collet support ring (150) when drive shaft (110) passes longitudinally therethrough.
Upper collet (140) is seated against a ledge in the collet body (148). The collet body is mated to the Shaft Trigger assembly (130) so that the collet (140), collet body (148) and Shaft Trigger assembly (130) are able to move axially as a single unit within the Running tool Housing (102). The collet (140) is configured so that it is held in engaged in the running tool housing (102) and as such restrains the Shaft Trigger assembly (130) and collet body (148) until such time as it is activated by engagement with the latch assembly (1) as described below. Rotational translation by upper collet (140) within running tool housing (102) is substantially prevented by mechanical contact between the outer diameter of upper collet frame (142) and the inner diameter of running tool housing (102).
Upper collet keys further include upper collet key latch mechanisms (146). Upper collet key latch mechanisms (146) are configured so as to mechanically engage inner diameter groove (40) of housing (60). When mechanically engaged, inner diameter groove (40) longitudinally fixes running tool (100) with respect to latch mechanism (1). Upper collet mechanisms (146) and inner diameter groove (40) will not properly engage unless will not properly engage unless guide slots (149) and alignment keys (34) are mechanically engaged. The upper collet (146) is further configured so that proper engagement in the inner diameter groove (40) allows the shaft trigger assembly (130) to move axially with respect to the running tool housing (102).
As shown in
As further shown in
To unlatch and move latch assembly (1) to the unlatched position as shown in
Upon moving latch assembly (1) to the unlatched position, latch assembly (1) may be pushed longitudinally along borehole (202) by mechanical pressure applied by drive shaft (110). In this way, latch assembly (1) may be completely disengaged from bit body (206), allowing drive shaft head (114) to longitudinally traverse the interior of housing (60). When disengaged, latch assembly (1) with insert attached (2) may be moved out from the bit body (206) enabling passage of the running tool and any instrument coupled to the running tool to be moved into the wellbore through the passage in the bit body. Typically, the tool, instrument and/or the running tool will include a “no-go” or similar device having a size larger than the diameter of the passage (210) in the bit body so that the instrument will be suspended by the drill string in the open wellbore below the drill bit. The instrument may be moved along the interior of the wellbore, for example, by withdrawing the drill string from the wellbore.
The examples disclosed herein have generally been described in the context of a subsea installation. One of ordinary skill in the art with the benefit of this disclosure will appreciate that examples of the present invention would be suitable for surface and land-based installation. Additionally, it is explicitly recognized that any of the features and elements of the examples disclosed herein may be combined with or used in conjunction with any of the examples disclosed herein.
The particular examples disclosed above are illustrative only, as the present invention may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the foregoing disclosure. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular illustrative examples disclosed above may be altered or modified and all such variations are considered within the scope of the present invention, as defined only by the claims appended hereto. Also, the terms in the appended claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined herein.
