Electro-mechanical release tool and associated methods

A release tool can include an inner mandrel, an electric motor assembly, and an engagement member. The inner mandrel is displaceable by the electric motor assembly between a position in which the inner mandrel supports the engagement member and prevents separation of portions of the release tool, and another position in which the engagement member is not supported by the inner mandrel and separation of the portions of the release tool is permitted. A method of separating portions of a release tool in a well can include transmitting an electrical signal to an electrical motor assembly of the release tool, displacing an inner mandrel of the release tool in response to the transmitting, and separating the portions of the release tool after the displacing.

TECHNICAL FIELD

This disclosure relates generally to equipment utilized and operations performed in conjunction with a subterranean well and, in one example described below, more particularly provides an electro-mechanical release tool and associated methods.

BACKGROUND

It can be advantageous to be able to disconnect upper and lower sections of a bottom hole assembly in a wellbore, for example, so that the upper section can be retrieved from the wellbore along with a conveyance used to transport the bottom hole assembly through the wellbore. The lower section can be retrieved later, such as, with a fishing operation.

It will, thus, be appreciated that improvements are continually needed in the arts of designing, constructing and operating well tools which are capable of reliably and conveniently disconnecting upper and lower sections of a bottom hole assembly. Such improvements may be useful in a variety of different well configurations, and with a variety of different bottom hole assembly configurations.

DETAILED DESCRIPTION

Representatively illustrated inFIG.1is a system10for use with a well, and an associated method, which can embody principles of this disclosure. However, it should be clearly understood that the system10and method are merely one example of an application of the principles of this disclosure in practice, and a wide variety of other examples are possible. Therefore, the scope of this disclosure is not limited at all to the details of the system10and method described herein and/or depicted in the drawings.

In theFIG.1example, a bottom hole assembly12is conveyed through a wellbore14by means of a conveyance16. The conveyance16in this example is a wireline, slickline or “e-line” of the type including at least one electrical conductor for providing power and communication between a surface control system and the bottom hole assembly12. In other examples, the conveyance16could be a coiled tubing string or another type of tubular string.

Note that it is not necessary for an electrical conductor to be provided for supplying power and communication between the surface and the bottom hole assembly12. For example, a battery or a downhole electrical generator could be used to supply power to the bottom hole assembly12, and/or various forms of telemetry (e.g., acoustic, electromagnetic, RFID, etc.) may be used for communication between the surface and the bottom hole assembly.

As depicted inFIG.1, the bottom hole assembly12includes a perforator18, a firing head20, an electro-mechanical release tool22, an instrument carrier24and an upper connection26. In other examples, different components, different combinations of components and different configurations of components may be used in the bottom hole assembly12. Thus, the scope of this disclosure is not limited to any particular components or arrangement of components in the bottom hole assembly12.

The perforator18ofFIG.1is of the type known to those skilled in the art as an explosive jet-type perforator. The perforator18includes multiple explosive shaped charges that, when detonated, form perforations28extending through casing30and cement32lining the wellbore14. Other types of perforators (such as, abrasive jet perforators, drill perforators, etc.) may be used in other examples, and it is not necessary for the bottom hole assembly12to include the perforator18.

The firing head20is used to initiate detonation of the shaped charges in the perforator18. The firing head20may actuate the perforator18in response to a signal transmitted from the surface via an electrical conductor or telemetry, or in response to another stimulus. If the perforator18does not include explosive shaped charges, or if the perforator is not used in the bottom hole assembly12, then the firing head20may not be used.

The release tool22enables the perforator18and firing head20(and any other components of the bottom hole assembly12connected below the perforator) to be disconnected from an upper section of the bottom hole assembly and the conveyance16. This will allow the upper section of the bottom hole assembly12to be retrieved from the wellbore14apart from the lower section of the bottom hole assembly, for example, in the event that the lower section becomes stuck in the wellbore.

In theFIG.1example, the release tool22is operable in response to a signal transmitted from the surface via the electrical conductor of the conveyance16. When the release tool22is actuated, an upper portion22aof the release tool can be disconnected from a lower portion22bof the release tool.

The instrument carrier24transports instruments34(such as, pressure and temperature gauges, vibration or shock sensors, or other types of sensors) in the bottom hole assembly12. Such instruments34can be relatively delicate and sensitive to shock due to detonation of the shaped charges in the perforator18. In theFIG.1example, however, the release tool22is capable of damping the shock produced when the perforator18is fired, so that the instruments34are protected from the shock.

In some examples, the instruments34could be incorporated into the release tool22. The instruments34could, for example, be positioned in or adjacent a motor section54(seeFIG.2B) of the release tool22, at which location shock should be at a minimum level. It is contemplated that shock will be less severe within the release tool22than above the release tool, but that shock above the release tool will be less severe than shock experienced below the release tool.

Note that, in theFIG.1example, the release tool22is connected in the bottom hole assembly12between the perforator18and the instrument carrier24. If the instrument carrier24is used in the bottom hole assembly12without the perforator18, then it may be desirable to position the release tool22above the instrument carrier. Thus, the scope of this disclosure is not limited to any particular position of the release tool22relative to any other component(s) of the bottom hole assembly12.

Referring additionally now toFIGS.2A-C, cross-sectional views of a more detailed example of the release tool22is representatively illustrated. TheFIGS.2A-Crelease tool22may be used in the system10and method ofFIG.1, or it may be used with other systems and methods.

In theFIGS.2A-Cexample, the upper portion22aof the release tool22includes a top sub36and a collet sub38. The top sub36provides for connecting the release tool22to components (such as the instrument carrier24or the upper connector26) above the release tool22.

An electrical connector40connects to the electrical conductor in the conveyance16, via the instrument carrier24or any other components connected between the conveyance and the release tool22. In this manner, an electrical conductor42of the release tool22is in electrical communication with the conductor of the conveyance16. If, however, the release tool22is provided with electrical power via batteries or a generator, the electrical connector40may not be used.

The collet sub38includes downwardly extending and circumferentially spaced apart flexible collets44having radially enlarged engagement members46. The engagement members46are radially outwardly engaged with a radially enlarged recess or profile48formed in an outer generally tubular body50of the lower portion22b.

The lower portion22bof the release tool22includes the body50, an inner mandrel52, an electric motor assembly54and a lower connector56. The lower connector56mechanically and electrically connects the release tool22to components of the bottom hole assembly12below the release tool (such as the firing head20and perforator18).

The inner mandrel52includes an inner passage58extending longitudinally through most of the inner mandrel, so that the conductor42can extend through the passage from the upper connector36to the electric motor assembly54. Seals60are provided on opposite ends of the inner mandrel52to isolate the passage58from well fluids and pressures.

The electric motor assembly54includes an electric motor62, a gearbox64and a motor controller68. The motor controller68is electrically connected to the conductor42, so that when an appropriate electrical signal is transmitted via the conductor42, the motor controller68actuates the motor62to produce rotation of an output shaft connected to an input shaft of the gearbox64. The motor controller68may include a hardware or software “switch” that supplies electrical power to the motor62when the appropriate electrical signal is received via the conductor42.

An output shaft of the gearbox64is connected to the inner mandrel52. Thus, when the motor62is supplied with an appropriate electrical signal, the motor rotates, the gearbox64reduces an output speed and increases an output torque of the motor, and the inner mandrel52is thereby rotated.

The inner mandrel52has multiple circumferentially spaced apart radially enlarged lobes66formed thereon. As depicted inFIG.2B, the lobes66are radially aligned with and radially outwardly support the collet engagement members46in engagement with the profile48in the outer body50. Thus, the outer body50and the remainder of the lower portion22bof the release tool22is prevented from separating from the collet sub38and the remainder of the upper portion22aof the release tool.

However, when the inner mandrel52is rotated by the motor assembly54, the lobes66will no longer be radially aligned with the engagement members46of the collets44. At that point, the lobes66will no longer radially outwardly support the collet engagement members46in engagement with the profile48in the outer body50, and the upper and lower portions22a,bof the release tool22will then be able to separate from each other.

In other examples, the inner mandrel52could be longitudinally displaced, so that the lobes66are no longer longitudinally aligned with the engagement members46of the collets44. In this manner, the lobes66will no longer radially outwardly support the collet engagement members46in engagement with the profile48in the outer body50, and the upper and lower portions22a,bof the release tool22will then be able to separate from each other. The inner mandrel52can be displaced in any direction electro-mechanically (as in the example of the electric motor assembly54), or hydrostatically (e.g., using a piston drive and well pressure).

Referring additionally now toFIG.3, a cross-sectional view of the release tool22, taken along line3-3ofFIG.2Bis representatively illustrated. In this view, the manner in which the inner mandrel52can be rotated relative to the collet sub38, so that the upper and lower portions22a,bof the release tool22are either secured to each other or released from each other can be more clearly seen.

As depicted inFIG.3, the inner mandrel52has been rotated relative to the collet sub38, so that the lobes66on the inner mandrel are no longer radially aligned with the engagement members46of the collets44. The lobes66no longer support the engagement members46in engagement with the profile48. The collets44can flex radially inward out of engagement with the profile48, so that the upper connector36and collet sub38can be withdrawn from the outer body50and the remainder of the lower portion22bof the release tool22.

Four of the collet engagement members46and four of the lobes66are depicted inFIG.3. However, in other examples, any number of engagement members and lobes may be used.

It may now be fully appreciated that the above disclosure provides significant advancements to the art of designing, constructing and operating well tools which are capable of reliably and conveniently disconnecting upper and lower sections of a bottom hole assembly. In one example described above, the release tool includes an electrical motor assembly that displaces an inner mandrel to release upper and lower portions of the release tool from each other.

The inner mandrel may have a series of circumferentially spaced apart lobes formed thereon which are initially radially aligned with engagement members formed on a collet sub. The lobes may radially outwardly support the engagement members in engagement with a profile formed in an outer body of the lower portion of the release tool.

The lobes, when rotated by the electrical motor assembly, may no longer be radially aligned with the engagement members. The lobes, when rotated by the electrical motor assembly, may no longer radially outwardly support the engagement members in engagement with the profile formed in the outer body of the lower portion of the release tool.

An electrical conductor may extend through an inner passage formed in the inner mandrel. The inner passage may be isolated from well fluids and pressures by seals on each opposite end of the inner mandrel.

The above disclosure provides to the art a release tool22for use in a subterranean well. In one example, the release tool22can include an inner mandrel52, an electric motor assembly54, and at least one engagement member46. The inner mandrel52is displaceable by the electric motor assembly54between a first position (seeFIG.2B) in which the inner mandrel52supports the at least one engagement member46and prevents separation of first and second portions22a,bof the release tool22, and a second position (seeFIG.3) in which the at least one engagement member46is not supported by the inner mandrel52and separation of the first and second portions22a,bof the release tool22is permitted.

The electric motor assembly54may be configured to rotate the inner mandrel52between the first and second positions. In other examples, the electric motor assembly54may be configured to longitudinally displace the inner mandrel52between the first and second positions.

The “at least one” engagement member46may include multiple circumferentially distributed engagement members46. The engagement members46may be formed on respective ones of multiple flexible collets44.

The inner mandrel52may include multiple circumferentially distributed lobes66that radially outwardly support respective ones of the multiple circumferentially distributed engagement members46. The lobes66may be radially aligned with the respective ones of the engagement members46in the first position of the inner mandrel52.

In the first position, the inner mandrel52may support the engagement member46in engagement with a profile48formed in an outer body50of the release tool22. The second portion22bof the release tool22may include the outer body50.

The release tool22may include an electrical conductor42extending through an inner passage58formed longitudinally through the inner mandrel52, and seals60at opposite ends of the inner mandrel52. The seals60may isolate the inner passage58from fluid communication with an exterior of the release tool22.

Also provided to the art by the above disclosure is a method of separating first and second portions22a,bof a release tool22in a subterranean well. In one example, the method can include transmitting an electrical signal to an electrical motor assembly54of the release tool22; displacing an inner mandrel52of the release tool22in response to the transmitting; and separating the first and second portions22a,bof the release tool22after the displacing step.

The displacing step may include rotating the inner mandrel52.

The displacing step may include displacing the inner mandrel52from a first position in which the inner mandrel52supports at least one engagement member46of the release tool22to a second position in which the inner mandrel52does not support the at least one engagement member46. The displacing step may include the electrical motor assembly54rotating the inner mandrel22from the first position to the second position.

The “at least one” engagement member46may include multiple circumferentially spaced apart engagement members46, the inner mandrel52may include multiple circumferentially spaced apart lobes66, in the first position the lobes66are radially aligned with respective ones of the engagement members46, and in the second position the lobes66are not radially aligned with the respective ones of the engagement members46.

The transmitting step may include transmitting the electrical signal via an electrical conductor42in an inner passage58of the inner mandrel52. The method may include positioning seals60at opposite ends of the inner mandrel52, thereby isolating the inner passage58from fluid communication with an exterior of the release tool22.

The method may include connecting the release tool22between a perforator18and an instrument carrier24. The method may include connecting the release tool22in a bottom hole assembly12conveyed by a conveyance16in the well.

The first portion22aof the release tool22may include a collet sub38, the engagement member46may be formed on a collet44of the collet sub38, and the second portion22bof the release tool22may include the inner mandrel52and the electrical motor assembly54. The separating step may include separating the collet sub38from the inner mandrel52and the electrical motor assembly54in the well.

In the above description of the representative examples, directional terms (such as “above,” “below,” “upper,” “lower,” “upward,” “downward,” etc.) are used for convenience in referring to the accompanying drawings. However, it should be clearly understood that the scope of this disclosure is not limited to any particular directions described herein.