Releasable ratchet latch connector

A system including a releasable connector having a housing and a split ring, and a complementary mandrel that is attachable/detachable from the connector, is provided. The mandrel is designed to be received into the housing such that a portion of the mandrel extends out of the housing for connection to a tool. The split ring is disposed in an annular space between the housing and the mandrel when the mandrel is in the housing. The split ring includes at least one set of threads and a detent formed on a radially internal surface, and the mandrel includes complementary threads. The threads on the split ring fully engage the complementary threads on the mandrel when the mandrel is in a particular axial position within the housing. The detent prevents the split ring from collapsing into engagement with the threads on the mandrel until the mandrel is in a desired axial position.

TECHNICAL FIELD

The present disclosure relates generally to connectors for downhole tools and, more particularly, to a ratchet latch connector with a twist release.

BACKGROUND

Conventional wellhead systems typically include a wellhead housing mounted on the upper end of a subsurface casing string extending into the well bore. A riser and blowout preventer (BOP) are then installed. During the drilling procedure, the BOP is installed above a wellhead housing to provide pressure control as casing is installed, with each casing string having a hanger on its upper end for landing on a shoulder within the wellhead housing. Upon completion of this process, the BOP is replaced by a Christmas tree installed above the wellhead housing, with the tree having a valve to enable the oil or gas to be produced and directed into flow lines for transportation to a desired facility.

At certain points throughout this procedure, one or more testing tools may be lowered through the BOP for connection to wellhead system components. Such testing tools are typically lowered through the BOP rams via a running tool, and placed in a desired location within the wellhead and accompanying equipment. The running tool may disconnect from the testing tool so that the path through the BOP rams is clear, and the BOP rams are then closed for the test to commence. After testing the equipment, the rams may be opened again and the testing tool removed, for example, via a retrieval tool. It is now recognized that a need exists for a more efficient process for setting and later retrieving wellhead testing equipment from a position below the BOP rams.

DETAILED DESCRIPTION

Certain embodiments according to the present disclosure may be directed to a connector that uses a ratchet latch split ring mechanism to selectively engage and disengage a complementary mandrel. The connector may be used in a well environment to selectively connect/disconnect a tool from a tubular string. The connector may be particularly useful for lowering a test tool through a BOP and into a wellhead below the BOP, disconnecting from the test tool and being pulled upward so that the BOP rams can be closed before the tool performs the test, and reconnecting to and picking up the test tool after the test is complete. The connector features a quick connect/release mechanism that may be controlled from the surface via axial and rotational movement of the tubular string.

The disclosed ratchet latch connector system includes the connector having at least a housing and a split ring, and a complementary mandrel that is selectively attachable/detachable from the connector. The housing may be coupled to a proximal end of a connector sub via a threaded connector. The mandrel is designed to be partially received into the housing such that a portion of the mandrel extends out of the housing for connection to a tool, for example. The split ring is disposed in an annular space between the housing and the mandrel when the mandrel is disposed in the housing. The split ring has some flexibility, which allows the split ring to transition between a radially expanded position and a radially collapsed position. The split ring may include at least one set of threads formed on a radially internal surface thereof, and the mandrel may include at least one set of complementary threads formed on a radially external surface thereof. The threads on the split ring may fully engage the complementary threads on the mandrel when the mandrel is in a particular axial position within the housing.

The split ring also includes a detent formed on the radially internal surface thereof adjacent the threads. The detent may prevent the split ring from collapsing into engagement with the threads on the mandrel until the mandrel is in a proper axial position. While the connector is being lowered onto the mandrel, the split ring is kept in the radially expanded position via the detent interacting with the threads on the mandrel, thereby facilitating a smooth ratcheting of the threads on the split ring over the corresponding threads on the mandrel. The detent may be positioned so as to allow the connector to be disengaged from the mandrel via a simple rotation of the connector relative to the mandrel.

The disclosed ratchet latch connector system may enable the quick and simple disconnection of a tool from a tubular string and later reattachment of the tool to the tubular string in a single trip. The release and reattachment mechanism is purely mechanical and so does not require the use of complicated hydraulic or electrical signaling. The connector provides a reliable and efficient way to land a test tool in a wellhead, operate the test tool after closing the BOP rams, and retrieve the test tool to the surface.

Turning now to the drawings,FIG. 1is a cross-sectional view of a connector10connected to an associated mandrel12in accordance with an embodiment of the present disclosure. The connector10may include a connector sub14, a housing16, a split ring18, a key20, and an external housing22. The connector10may include additional components to those that are illustrated in the present figure. In some embodiments, certain illustrated components of the connector10may not be present (e.g., external housing22), or may be combined into a single component (e.g., connector sub14, housing16, key20, and/or external housing22in combination).

It should be noted that all descriptions relating to axial and radial directions in the present disclosure are taken with respect to a longitudinal axis23of the connector10and associated mandrel12. A radially inward direction is one that faces toward the longitudinal axis23, and a radially outward direction is one that faces away from the longitudinal axis23. A distal direction is referring to a first (e.g., upward) axial direction taken along the longitudinal axis23, while a proximal direction is referring to a second (e.g., downward) axial direction opposite the first axial direction taken along the longitudinal axis23.

In general, the connector sub14is an elongated tubular component having a bore24formed therethrough. The connector sub14may have a threaded connector26at a distal end28thereof. The threaded connector26allows the connector sub14to be connected to a proximal end of a tubular string (not shown). The tubular string may be lowered downhole from a surface location along with the attached connector sub14, the mandrel12, and other components of the connector10.

At a proximal end30of the connector sub14, the connector sub14may form a threaded connection32with the housing16, as shown. The threaded connection32may be between external threads formed on a radially external surface of the connector sub14and internal threads on a radially internal surface of the housing16. In other embodiments, the arrangement of the connection interface between the connector sub14and the housing16may be reversed. That is, the threaded connection32may instead be between internal threads formed on a radially internal surface of the connector sub14and external threads on a radially external surface of the housing16. In still other embodiments, the connector sub14and the housing16may be formed as a single integral component.

At the proximal end30of the connector sub14, the bore24of the connector sub14may widen to a diameter sized to receive a distal end34of the mandrel12. The connector sub14may be specifically shaped at the proximal end30to match a corresponding shape of the distal end34of the mandrel12so that the mandrel12may be securely received into position within the connector10with the distal end34resting against the connector sub14. The connector sub14may be equipped with an annular seal36disposed on a radially internal surface thereof at the proximal end30so as to seal the annular space between the connector sub14and the mandrel12. An annular portion of the proximal end30of the connector sub14may extend axially downward into an annular space between the housing16and the mandrel12(when the mandrel12is positioned in the housing16) to provide a stop38or shoulder for an upper end of the split ring18.

The housing16may have a generally tubular shape, as shown. A distal end40of the housing16may include threads that form the threaded connection32with the connector sub14as described above. Below this threaded connection32, the housing16may include a stepped profile formed on a radially internal surface42of the housing16. The stepped profile of the housing16in general matches a radially external profile of the split ring18disposed in the housing16.

The stepped profile may include a number of steps44that progress the housing16from a wider inner diameter at the distal end40of the housing to a less wide inner diameter at a proximal end46of the housing16. For example, in the illustrated embodiment, the housing16includes two steps44A and44B formed along its internal surface42. However, other embodiments of the housing16may include one, three, four, or more steps44formed at this surface. The steps44A and44B may help to maintain the position of the split ring18within the housing16. The steps44A and44B moving from one inner diameter of the housing16to the next may be slanted with respect to a plane perpendicular to the longitudinal axis23. This angle forces the split ring18in the radially inward direction when it is engaged with the mandrel12to prevent inadvertent disengagement of the split ring18when the connector is under tension.

At a final portion of the stepped profile, the housing16may include a sharp stepped portion at its proximal end46. The stepped portion may generally function as a stop shoulder50to keep the split ring18positioned within the housing16at all times.

The split ring18is a ring that is not continuous around its entire circumference. The split ring18includes an open slot (split) formed at a particular circumferential position of the split ring18. The slot extends in an axial direction through the entire split ring18at this circumferential location.FIG. 1illustrates a cavity52where this split occurs. This structure of the split ring18allows the split ring18to transition between a radially expanded position (e.g., shown inFIGS. 2 and 4) and a radially collapsed position (e.g., shown inFIGS. 1 and 3). The split ring18is generally biased toward the radially collapsed position. Upon contact of a wider diameter portion of the mandrel12with a radially internal surface54of the split ring18, however, the split ring18is forced to expand radially outward into the expanded position. The steps44of the housing16may guide the split ring18to move slightly in the distal (i.e., upward) direction as it is radially expanded, or to move slightly in the proximal (i.e., downward) direction as it is radially collapsed.

As mentioned above, the split ring18includes at least one set of threads56formed on the radially internal surface54. In the illustrated embodiment, for example, the split ring18includes two sets of threads56A and56B. However, it should be noted that additional or fewer sets of threads56may be utilized in other embodiments. The individual threads making up each set56may be angled as they extend radially inward from the rest of the split ring18. Specifically, the threads may each be slanted in the distal (i.e., upward) direction as they extend radially inward. This allows the threads to slide over corresponding threads of the mandrel12in a ratcheting operation until the mandrel12is at a desired location within the housing16, at which point the threads56can lock the mandrel12in place. The term “ratchet” or “ratcheting” herein refers to an action where a threaded component (i.e., split ring18) is able to slide over a complementary threaded component (i.e., mandrel12) when moving relative to the complementary component in one axial direction (e.g., proximal direction), but not in the opposite direction (e.g., distal direction).

The two sets of threads56A and56B may be interrupted by a detent58formed on the radially internal surface54of the split ring18. The detent58, as shown, extends in a radially inward direction. The detent58may extend in this radial direction about the same distance as any one of the threads (i.e., from root to crest) in the at least one set of threads56. However, the detent58extends a length in the axial direction that is multiple times the pitch of any one of the threads in the at least one set of threads56. As such, the detent58cannot be received into any of the threads on the mandrel12as the split ring18moves relative to the mandrel12. In the illustrated embodiment, the detent58is located axially between the two sets of threads56A and56B. However, in other embodiments, the detent58may be located adjacent a single set of threads, or multiple detents may be located axially between multiple sets56of threads.

The threads in each set56may progress in an axial direction as they extend around the inner circumference of the split ring18. That way, as the connector10is rotated relative to the mandrel12, the split ring18may travel in an axial direction with respect to the mandrel12. Once the detent58reaches a point of engagement with one of the corresponding threads on the mandrel12, the detent58may act as a cam to expand the split ring18into the radially expanded position and out of engaging contact with the mandrel12.

The detent58may extend around the entire inner circumference of the split ring18, and the detent58may be located at the same axial position as it extends around the split ring18. In other embodiments, the detent58may progress in an axial direction as it extends around the inner circumference of the split ring18.

The key20may be coupled to the housing and extend in a radially inward direction into the cavity52defined by the axial slot in the split ring18. The key20prevents the split ring18from rotating relative to the housing16. In some embodiments, a portion60of the split ring18on one or both sides of the open slot in the ring may be cut out to fit around the key20as well. This cutout portion60of the split ring18may be slightly longer in the axial dimension than the key20, thereby allowing the split ring18to move axially by a certain amount relative to the housing16, such as when the split ring18is expanded or collapsed.

The mandrel12, as shown, features a specific profile formed on a radially external surface62thereof. This profile is generally complementary to the profile formed on the internal surface54of the split ring18. The mandrel12includes at least one set of external threads64formed on the external surface62, and the at least one set of external threads64are positioned to interact with the corresponding internal sets of threads56on the split ring18. In the illustrated embodiment, for example, the mandrel12includes two sets of threads64A and64B. However, it should be noted that additional or fewer sets of threads64may be utilized in other embodiments.

The individual threads making up each set64may be angled as they extend radially outward from the rest of the mandrel12(similar to those threads on the split ring18). Specifically, the threads may each be slanted in the proximal (i.e., downward) direction as they extend radially outward, so as to interconnect with the threads on the split ring18when the split ring18is collapsed into engagement with the mandrel12. The angle of the threads on the mandrel12allow the split ring18to ratchet over the threads on the mandrel12until the mandrel12is at a desired location within the housing16, at which point the threads56on the split ring can lock into engagement with the threads64on the mandrel12to hold the mandrel12in place.

The two sets of threads64A and64B may be interrupted by an indentation66formed on the radially external surface of the mandrel12. The indentation66, as shown, generally extends in a radially inward direction. The indentation66may extend in this direction about the same distance as any one of the threads (i.e., from root to crest) in the at least one set of threads64. However, the indentation66has a length in the axial direction that is multiple times the pitch of any one of the threads in the at least one set of threads64. That way, the indentation66is able to capture the corresponding detent58of the split ring18when the split ring18is in the axial position relative to the mandrel12where the split ring18collapses into engagement with the mandrel12. In the illustrated embodiment, the indentation66is located axially between the two sets of threads64A and64B. However, in other embodiments, the indentation66may be located adjacent a single set of threads, or multiple indentations may be located axially between multiple sets of threads. In still other embodiments, the mandrel12may not have an indentation at all, but may instead feature an elongated flat portion of the external surface62that functions to receive the detent58of the split ring18.

The external housing22may be included in the connector10to provide a protective housing for the internal components of the connector10and the mandrel12. The external housing22, as shown, may be disposed around the proximal end30of the connector sub14, the entire housing16, split ring18, and key20, and the distal end34of the mandrel12. The external housing may include two or more pieces that are bolted together to form the protective housing. The external housing22has a bore formed therethrough. As illustrated, the external housing22includes an opening at its proximal end, and the opening may feature sloped walls68(i.e., angled relative to the longitudinal axis23). The sloped walls68at the opening in the proximal end of the external housing22may help to guide the mandrel12into the housing16(and split ring18) as the connector10is moved axially toward the mandrel12for receiving and connecting to the mandrel12.

Having described the structure of the disclosed connector10and associated mandrel12, a detailed description of a method for operating the connector10to selectively connect to and release the mandrel12will now be provided.FIG. 1illustrates the connector10being connected to and fully engaged with the mandrel12via the collapsed split ring18. The split ring18is held in place within the housing16via the stop shoulder50and the steps44A and44B of the housing16. The split ring18is in the collapsed configuration such that the at least one set of threads56A and56B of the split ring18fully engage the at least one set of threads64A and64B of the mandrel12. The angle of the threads on both components ensures that the force due to gravity on the mandrel (and any connected downhole tools) is transmitted through the threads to the split ring18, the housing16, and the connector sub14. Thus, the connector10is able to hold the weight of the mandrel12and other connected components. It is in this connected configuration that the connector10and attached mandrel12may be initially lowered toward or through a well.

At some point, the mandrel12may be lowered to a desired position for being released from the connector10, such as a location at which a tool coupled to the mandrel12is landed (e.g., in a wellhead). To release the mandrel12from the connector10, an operator may rotate the uphole tubular string that is coupled to the connector sub14, thereby rotating the entire connector10. This is shown inFIG. 2, where an arrow110indicates the rotation (e.g., right hand turn) of the connector10relative to the mandrel12. The mandrel12may remain in place due to a tool at its lower end being landed and secured at a desired location. As such, the connector sub14, housing16, split ring18, key20, and/or external housing22may rotate relative to the mandrel12.

As a result of this rotation, the connector10may begin to move axially upward (arrow112) relative to the mandrel12, as the rotation causes the set(s) of threads56on the split ring18to traverse the corresponding set(s) of threads64on the mandrel12. At some point in traveling up the threads64on the mandrel12, the split ring18reaches an axial position relative to the mandrel12where the detent58abuts a lower surface of one of the mandrel threads. Further rotation of the connector10and resulting axial movement of the split ring18relative to the mandrel12causes the detent58to act as a cam forcing the split ring18from its collapsed configuration to its expanded configuration, as shown inFIG. 2. At this point, the split ring18is disengaged from the threaded profile of the mandrel12, and the connector10is able to be axially lifted off the mandrel12. In the expanded configuration, the threads56and detent58of the split ring18are able to slide over the threads64on the mandrel12.

Further upward movement of the connector10disconnects the connector10entirely from the mandrel12such that the mandrel12remains at the location at which it was landed and the connector10is retrieved to an upward location, as shown inFIG. 3. This figure shows that once the connector12has been removed from the mandrel12, the split ring18is biased back to its initial collapsed position within the housing16. The housing16maintains the split ring18in place via the stop shoulder50and the steps44A and44B.

To reattach the connector10to the mandrel12, the connector10may be lowered back down over the distal end of the mandrel12, as shown inFIG. 4. The sloped walls68at the proximal end of the external housing22may guide the distal end of the mandrel12into the housing16and split ring18. As the mandrel12enters the split ring18, the radially external surface62of the mandrel12comes into contact with the radially internal surface54of the split ring18, thereby forcing the split ring18from the collapsed configuration to its expanded configuration. In this expanded configuration, the internal threads56of the split ring18are able to ratchet downward over the threads64of the mandrel12as the connector10is moved axially downward with respect to the mandrel12. The internal profile of the split ring18with the detent58prevents the threads56of the split ring18from engaging the threads64on the mandrel12until the split ring18reaches an axial position relative to the mandrel12where the detent58is received in the indentation66. When the detent58reaches the indentation66and the corresponding threads of the split ring18and mandrel12are in alignment, the split ring18collapses into a secure engagement with the mandrel12(seen inFIG. 1). As a result, the connector10is fully connected in a load bearing manner to the mandrel12. The connector sub14may then be raised upward to retrieve the connected mandrel12(and any attached tools) to the surface.

Examples of the types of tools that may be lowered downhole, disconnected from, reconnected to, and retrieved to the surface via the disclosed connector10are provided and illustrated inFIGS. 5A, 5B, 6A, 6B, 7A, 7B, 8A, and 8B.

FIGS. 5A, 5B, 6A, 6B, 7A, 7B, 8A, and 8Billustrate different systems that may utilize the connector10and the mandrel12described above. The mandrel12in these figures may be coupled to a BOP test tool210for positioning within a wellhead212. As shown inFIGS. 5A, 5B, 6A, and 6B, the mandrel12may be coupled to the BOP test tool210via a tubular214connected between the mandrel12and the test tool210. In other embodiments, as shown inFIGS. 7A, 7B, 8A, and 8B, the mandrel12may be directly coupled to the BOP test tool210.

InFIGS. 5A and 5B, the test tool210may be designed to test a wellhead212. As shown, the wellhead212is disposed within and extends downward into a conductor housing216. The test tool210may be operated to ensure that the wellhead212is securely positioned and sealed within the conductor housing216.

InFIGS. 6A and 6B, the test tool210may be designed to test a casing or tubing hanger310(e.g., a 14″ hanger) located in the wellhead212. As shown, the wellhead212is disposed within and extends downward into a conductor housing216, and the hanger310is disposed within and extends downward through (and beyond) the wellhead212. The test tool210may be operated to ensure that the hanger310is securely positioned and sealed within the wellhead212.

InFIGS. 7A and 7B, the test tool210may be designed to test a wear busing410(e.g., a 13⅜″ wear bushing) located in the wellhead212. As shown, the wellhead212is disposed within and extends downward into a conductor housing216, a hanger310is disposed within and extends downward through (and beyond) the wellhead212, and the wear bushing410is disposed within the wellhead212and supported by the hanger310. The test tool210may be operated to ensure that the wear bushing410is securely positioned and sealed within the wellhead212.

InFIGS. 8A and 8B, the test tool210may be designed to test a wear sleeve510(e.g., a 18/16″ wear sleeve) located in the wellhead212. As shown, the wellhead212is disposed within and extends downward into a conductor housing216, and the wear sleeve510is disposed within the wellhead212. The test tool210may be operated to ensure that the wear sleeve510is securely positioned and sealed within the wellhead212.

To perform the desired testing in any one of these embodiments ofFIGS. 5A, 5B, 6A, 6B, 7A, 7B, 8A, and 8B, it may be desirable for a series of BOP rams220located uphole of the wellhead212to be closed prior to performing the test. As such, the connector10and above tubing may lower the mandrel12through the open rams220to a position where the attached test tool210is landed in the wellhead212(FIGS. 5A-5B). The connector10may then be disconnected from the mandrel12, via rotation as described above, and withdrawn upward (FIG. 6A—arrow112) to a position above the BOP rams220so that the rams220can be closed and the desired test performed in the wellhead212. Once the test is finished, the rams220may be reopened, the connector10lowered back down onto the mandrel12(FIG. 7A) until it is fully connected to the mandrel12(FIG. 8A), and the mandrel12and connected test tool210retrieved to the surface.