Patent Description:
Oil and gas wells are generally drilled into Earth's surface or ocean bed to recover natural deposits of oil, gas, and other natural resources that are trapped within subterranean geological formations. Wellbores for reaching the natural resources may be formed by drilling systems having various surface and subterranean equipment operating in a coordinated manner. After a wellbore is formed, a metal casing string may be inserted within the wellbore, such as to protect the sidewall of the wellbore, isolate different geological formations, and help maintain control of formation fluids and well pressure during various subsequent downhole operations. The casing string may be secured within the wellbore by cement injected into an annular space between an outer surface of the casing string and the sidewall of the wellbore.

Oil and gas reservoirs located within geological formations have conventionally been accessed by vertical or near-vertical wellbores. Casing strings may be inserted into the vertical and near-vertical wellbores utilizing gravity to facilitate conveyance or movement therethrough. Oil and gas reservoirs, however, are increasingly accessed via non-vertical wellbores. Casing strings that have conventionally been inserted within vertical and near-vertical wellbores may encounter problems when inserted within non-vertical wellbores. For example, in non-vertical wellbores, gravity may be negated by frictional forces between the casing string and the sidewall of the wellbore, which may resist movement of the casing string through the wellbore. Although the casing string may be pushed along the wellbore, friction generated against the sidewall of the wellbore may be greater than the available axial force to push the casing string downhole.

Furthermore, the outer surface of the casing string may stick to the sidewall of the wellbore, or the leading edge of the casing string or the leading edges of the casing collars of the casing string may dig into or jam against the sidewall of the wellbore, impeding downhole movement of the casing string. Movement of the casing string along a non-vertical wellbore may also be impeded by presence of various obstacles along the wellbore. For example, drill cuttings, washouts, and various imperfections (e.g., bumps, uneven surfaces) in the sidewall of the wellbore may further impede or increase resistance to movement of the casing string through the wellbore.

Patent Application Publication No. <CIT> discloses roller standoff assemblies and devices that facilitate disposal of an interior tubular member radially within an exterior tubular member. A roller standoff assembly comprises a roller standoff device comprising: a roller cage to surround an interior tubular and having two cage halves that are pivotable between an open configuration wherein the roller cage is placed around an interior tubular member and a closed configuration wherein the roller cage forms a closed annular ring. The roller standoff assembly further comprises a roller supported by the roller cage to contact and roll upon an exterior tubular member, and a latch assembly for securing the roller cage in the closed position. The latch assembly comprises a latch retainer, a latching pin that is moveable between a latched position and an unlatched position to selectively latch within the latch retainer, and a compressible spring biasing the latching pin toward a latched position. Further prior art apparatuses are disclosed in <CIT>, <CIT>, <CIT> and <CIT>.

The present disclosure is best understood from the following detailed description when read with the accompanying figures.

It is to be understood that the following disclosure provides many different embodiments, or examples, for implementing different features of various embodiments. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. This repetition is for simplicity and clarity, and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. Moreover, the formation of a first feature over or on a second feature in the description that follows, may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed interposing the first and second features, such that the first and second features may not be in direct contact.

Terms, such as upper, upward, above, lower, downward, and/or below are utilized herein to indicate relative positions and/or directions between apparatuses, tools, components, parts, portions, members and/or other elements described herein, as shown in the corresponding figures. Such terms do not necessarily indicate relative positions and/or directions when actually implemented. Such terms, however, may indicate relative positions and/or directions with respect to a wellbore when an apparatus according to one or more aspects of the present disclosure is utilized or otherwise disposed within the wellbore. For example, the term upper may mean in the uphole direction, and the term lower may mean in the downhole direction.

<FIG> is a schematic view of at least a portion of an example implementation of a well construction system <NUM>, represents an example environment in which one or more aspects of the present disclosure described below may be implemented. The well construction system <NUM> is depicted in relation to a wellbore <NUM> formed by rotary and/or directional drilling from a wellsite surface <NUM> and extending into a subterranean formation <NUM>. Although the well construction system <NUM> is depicted as an onshore implementation, aspects described below are also applicable to offshore implementations.

The well construction system <NUM> includes surface equipment <NUM> located at the wellsite surface <NUM> and a casing string <NUM> comprising a plurality of casing joints <NUM> suspended within the wellbore <NUM>. The surface equipment <NUM> may be collectively operable to perform casing running operations (e.g., casing string assembly and lowering operations), which may include, receiving and positioning the casing joints <NUM>, one at a time, above the wellbore <NUM>, connecting the casing joints <NUM> to progressively assemble the casing string <NUM>, and lowering the casing string <NUM> within the wellbore <NUM> each time a new casing joint <NUM> is connected. Adjacent casing joints <NUM> of the casing string <NUM> may be connected together via corresponding casing collars <NUM>.

The surface equipment <NUM> may include a mast, a derrick, and/or another wellsite structure <NUM>. The casing string <NUM> may be suspended within the wellbore <NUM> from the wellsite structure <NUM> via hoisting equipment, which may include a crown block <NUM> connected to or otherwise supported by the wellsite structure <NUM>, a traveling block <NUM> operatively connected with the crown block via a support cable or line <NUM>, and an elevator <NUM> connected to and supported by the traveling block <NUM>. The hoisting equipment may further comprise a draw works <NUM> storing the support line <NUM>. The crown block <NUM> and traveling block <NUM> may be or comprise pulleys or sheaves around which the support line <NUM> is reeved to operatively connect the crown block <NUM>, the traveling block <NUM>, and the draw works <NUM>. The draw works <NUM> may thus selectively impart tension to the support line <NUM> to lift and lower the elevator <NUM>, resulting in vertical motion <NUM> of the elevator <NUM>. The draw works <NUM> may comprise a drum, a frame, and a prime mover (e.g., an engine or motor) operable to drive the drum to rotate and reel in the support line <NUM>, causing the traveling block <NUM> and the elevator <NUM> to move upward. The draw works <NUM> may be operable to release the support line <NUM> via a controlled rotation of the drum, causing the traveling block <NUM> and the elevator <NUM> to move downward. The surface equipment <NUM> may further comprise a torqueing device <NUM> (e.g., tongs, iron roughneck) at the rig floor (not shown). The torqueing device <NUM> may be moveable toward, away from, and at least partially around a casing joint <NUM>, such as may permit the torqueing device <NUM> to make up and break out casing joint connections to assemble and disassemble the casing string <NUM>.

Each casing joint <NUM> may have a casing collar <NUM> threadedly or otherwise connected at upper end thereof, forming a box (i.e. female) end of the casing joint <NUM>. During casing running operations, the casing joints <NUM> may be successively made up and tripped (i.e., lowered) into the wellbore until the casing string <NUM> has a predetermined length and/or reaches a predetermined depth (e.g., measured depth (MD)) within the wellbore <NUM>. For example, a new casing joint <NUM> may be conveyed to the rig floor until the casing collar <NUM> projects above the rig floor. The elevator <NUM> may then grasp the new casing joint <NUM> by the casing collar <NUM> and the draw works <NUM> may lift the new casing joint <NUM> above a previously connected casing joint <NUM> protruding from the wellbore <NUM>. A set of slips (not shown) may hold the previously connected casing joint <NUM> and, thus, the casing string <NUM>, in position suspended within the wellbore <NUM>. After a pin (i.e., male) end of the new casing joint <NUM> is positioned above and aligned with a box end of the previously connected casing joint <NUM>, the draw works <NUM> may lower the new casing joint <NUM> until the pin end of the new casing joint <NUM> is at least partially inserted into the box end of the previously connected casing joint <NUM>.

The torqueing device <NUM> may then be moved toward the casing string <NUM>, clamped around the new casing joint <NUM>, and operated to rotate the new casing joint <NUM> to threadedly engage the pin end of the new casing joint <NUM> with the box end of the previously connected casing joint <NUM> to make up the connection. In this manner, the new casing joint <NUM> becomes a part of the casing string <NUM>. The torqueing device <NUM> may then be released and moved clear of the casing string <NUM>. The slips may then be operated to an open position, and the draw works <NUM> may lower the casing string <NUM> to advance the casing string <NUM> downward (i.e., downhole) within the wellbore <NUM>. When the box end of the newly connected casing joint <NUM> is near the slips and/or the rig floor, the draw works <NUM> may stop lowering the casing string <NUM>, the slips may close to clamp the newly connected casing joint <NUM>, and the elevator <NUM> may be detached from the newly connected casing joint <NUM>.

Thereafter, another casing joint <NUM> may be conveyed to the rig floor, grasped by the elevator <NUM>, and lifted above and connected with the previously connected casing joint <NUM> protruding from the wellbore <NUM>. The slips may be opened again and the hoisting equipment may lower the casing string <NUM> to advance the casing string <NUM> downward within the wellbore <NUM>. Such casing running operations may be repeated until the casing string <NUM> reaches a predetermined length and/or reaches a predetermined depth within the wellbore <NUM>.

During the casing running operations, while the casing string <NUM> is lowered along a substantially vertical portion <NUM> of the wellbore <NUM>, gravity (i.e., the weight of the casing string <NUM>) causes the casing string <NUM> to move downwardly, perpendicularly to sidewall <NUM> of the wellbore <NUM>. Thus, while the casing string <NUM> is lowered along the substantially vertical portion <NUM> of the wellbore <NUM>, the sidewall <NUM> do not substantially impede the intended conveyance or movement of the casing string <NUM> within the wellbore <NUM>.

However, while the casing string <NUM> is lowered along a non-vertical portion <NUM> (e.g., horizontal or otherwise deviated) of the wellbore <NUM>, gravity causes the weight of the casing string <NUM> to be directed downwardly against the sidewall <NUM> of the wellbore <NUM>. As a result, the sidewall <NUM> of the non-vertical portion <NUM> of the wellbore <NUM> cause friction against the casing string <NUM> and/or otherwise impede the intended conveyance or movement of the casing string <NUM> along the wellbore <NUM>. Moreover, impacts, friction, vibrations, and other forces resulting from contact with the sidewall <NUM> may cause damage to the casing string <NUM> and/or the sidewall <NUM> when the casing string <NUM> is conveyed through the substantially non-vertical portion <NUM> of the wellbore <NUM>.

Accordingly, the present disclosure is further directed to a conveyance (e.g., rolling) apparatus (e.g., device) that may aid in conveying or otherwise moving a casing string along a non-vertical portion of a wellbore, such as the non-vertical portion <NUM> of the wellbore <NUM>. <FIG> is a schematic view of the well construction system <NUM> shown in <FIG>, but running (i.e., making up and conveying) within the wellbore <NUM> a casing string <NUM> according to one or more aspects of the present disclosure. Unlike the casing string <NUM> shown in <FIG>, the casing string <NUM> comprises or is utilized in association with a plurality of conveyance apparatuses <NUM> according to one or more aspects of the present disclosure.

Each conveyance apparatus <NUM> may form a portion of or be coupled with the casing string <NUM> and may include one or more rotatable members <NUM> (e.g., spheres, wheels, rollers, etc.) or other friction reducing members extending laterally (e.g., radially outward) from or past an outer surface of the casing string <NUM>. During casing running operations, the conveyance apparatuses <NUM> may lift, support, or otherwise offset at least a portion of the casing string <NUM> away from the sidewall <NUM> of the wellbore <NUM>, such as may reduce or inhibit contact and, thus, friction between portions (e.g., casing joints <NUM>, casing collars <NUM>) of the casing sting <NUM> and the sidewall <NUM>. For example, the rotatable members <NUM> may contact the sidewall <NUM> of the wellbore <NUM> to permit the casing string <NUM> to roll along the sidewall <NUM> of the wellbore <NUM> along a longitudinal axis of the wellbore <NUM>. The conveyance apparatuses <NUM> may thus help or otherwise facilitate conveyance of the casing string <NUM> within the non-vertical portion <NUM> of the wellbore <NUM> until the casing string <NUM> reaches a predetermined length and/or reaches a predetermined depth within the wellbore <NUM>. The conveyance apparatuses <NUM> may maintain a space or gap between an outer surface of the casing string <NUM> and the sidewall <NUM> of the wellbore <NUM> and, thus, may be utilized in addition to or instead of casing centralizers (e.g., bow-spring centralizers) during casing running operations. During subsequent cementing operations, the conveyance apparatuses <NUM> may remain coupled with the casing string <NUM> and, thus, be cemented downhole with the casing string <NUM>.

Each conveyance apparatus <NUM> may be, comprise, or operate as a casing collar and, thus, be utilized instead of a conventional casing collar (e.g., an instance of the casing collars <NUM> shown in <FIG>) to threadedly or otherwise couple two casing joints <NUM> together. Such conveyance apparatuses <NUM> may be coupled with corresponding casing joints <NUM> to form the box ends of the casing joints <NUM> and to couple together adjacent casing joints <NUM> of the casing string <NUM>. The conveyance apparatuses <NUM> may instead be utilized in addition to conventional casing collars <NUM>. For example, the conveyance apparatuses <NUM> may be coupled with the casing string <NUM> around or otherwise with selected ones (e.g., every, some) of the conventional casing collars <NUM>. Such conveyance apparatuses <NUM> may be coupled with the casing string <NUM> around the conventional casing collars <NUM> during casing running operations, for example, after each pin end of a new casing joint <NUM> threadedly engages a box end (i.e., a casing collar <NUM>) of a previously connected casing joint <NUM> protruding from the wellbore <NUM>. The conveyance apparatuses <NUM> may instead be coupled with the casing string <NUM> around or otherwise with selected ones (e.g., every, some) of the casing joints <NUM> between opposing conventional casing collars <NUM>. The conveyance apparatuses <NUM> within the scope of the present disclosure may be connected with every casing collar <NUM> or casing joint <NUM>, every other casing collar <NUM> or casing joint <NUM>, or at other predetermined interval(s) or rate(s).

<FIG> are perspective, side, side sectional, axial, and enlarged sectional views, respectively, of at least a portion of an example implementation of a conveyance apparatus <NUM> not forming part of the scope of protection. The conveyance apparatus <NUM> is shown coupling together or otherwise coupled between opposing upper and lower casing joints <NUM>, <NUM>. The following description refers to <FIG>, collectively.

The conveyance apparatus <NUM> may be, comprise, or operate as a casing collar and, thus, be utilized instead of a conventional casing collar (e.g., an instance of the casing collars <NUM> shown in <FIG>) to threadedly or otherwise couple two casing joints together. In the oil and gas industry, opposing ends of casing joints may be or comprise pin ends (i.e., external threats). Prior to performing casing running operations, an instance of the conveyance apparatus <NUM> may be coupled to each casing joint to form the box end of the casing joint. Thereafter, during the casing running operations, the pin ends of the new casing joints may be coupled with the box ends (i.e., conveyance apparatuses <NUM>) of the previously connected casing joints protruding from the wellbore <NUM>.

The conveyance apparatus <NUM> may comprise a body <NUM> (e.g., a sleeve, a collar, a housing) having a generally tubular geometry with an inner surface <NUM> defining an axial bore extending therethrough to permit fluid passage between the upper and lower casing joints <NUM>, <NUM> coupled with the conveyance apparatus <NUM>. The body <NUM> may comprise an upper coupling means <NUM> for mechanically coupling the conveyance apparatus <NUM> with a corresponding lower coupling means <NUM> of the upper casing joint <NUM>, and a lower coupling means <NUM> for mechanically coupling the conveyance apparatus <NUM> with a corresponding upper coupling means <NUM> of the lower casing joint <NUM>. The interface means <NUM> may be or comprise internal (i.e., female) threads configured to threadedly engage with corresponding external (i.e., male) threads of the lower coupling means <NUM>, and the interface means <NUM> may be or comprise internal threads configured to threadedly engage with corresponding external threads of the upper coupling means <NUM>.

The conveyance apparatus <NUM> may further comprise a plurality of rollable or otherwise rotatable members <NUM> rotatably connected with and distributed circumferentially around the body <NUM>. At least a portion of each rotatable member <NUM> may extend or protrude from or past an outer surface <NUM> of the body <NUM> by a predetermined distance <NUM> in a lateral or otherwise radially outward direction with respect a central axis <NUM> of the conveyance apparatus <NUM>. Each rotatable member <NUM> may be or comprise a sphere, such as a ball bearing, which may be disposed in a corresponding cavity <NUM> extending within a wall of the body <NUM>. Each rotatable member <NUM> may be retained within the corresponding cavity <NUM> via a corresponding retainer ring <NUM> having an opening that permits a portion of the corresponding rotatable member <NUM> to project or otherwise extend therethrough by the predetermined distance <NUM>. Each retainer ring <NUM> may be maintained in position against a corresponding rotatable member <NUM> via one or more bolts <NUM> connecting the retainer ring <NUM> to the body <NUM>.

Although the conveyance apparatus <NUM> is shown comprising eight rotatable members <NUM> distributed around the body <NUM>, it is to be understood that the conveyance apparatus <NUM> may comprise a lesser or a greater quantity of rotatable members <NUM>. Furthermore, although the conveyance apparatus <NUM> is shown comprising the rotatable members <NUM> distributed circumferentially around the body <NUM> along a single circumferential curve <NUM>, the rotatable members <NUM> may instead be arranged in two, three, four, or more sets of rotatable members <NUM>, each set comprising a plurality of rotatable members <NUM> distributed circumferentially around the body <NUM> along a different circumferential curve <NUM> each located at a different axial position along the body <NUM>.

During casing running operations, the conveyance apparatuses <NUM> may collectively lift or support at least portions of the casing string <NUM> at a distance from the sidewall <NUM> of the wellbore <NUM>, such as may reduce or inhibit contact and, thus, reduce friction between the portions of the casing sting <NUM> and the sidewall <NUM>. For example, the rotatable members <NUM> of each conveyance apparatus <NUM> may contact the sidewall <NUM> of the wellbore <NUM> to lift the body <NUM> and at least a portion of the casing joints <NUM>, <NUM> coupled with the body <NUM> away from the sidewall <NUM>. Each conveyance apparatus <NUM> may maintain a space or gap between the sidewall <NUM> of the wellbore <NUM> and the body <NUM> (and at least a portion of the casing joints <NUM>, <NUM> coupled with the body <NUM>) that is about equal to the distance <NUM>. The rotatable members <NUM> may further permit the corresponding portion of the casing string <NUM> to roll in an axial (i.e., longitudinal) direction along the sidewall <NUM> to reduce friction between the portions of the casing sting <NUM> and the sidewall <NUM>. The rotatable members <NUM> may also permit the corresponding portion of the casing string <NUM> to rotate (e.g., roll, turn) within the wellbore <NUM>, such as to reduce or inhibit torsional stresses along the casing string <NUM> and/or to maintain the casing string <NUM> against the low side of the wellbore <NUM>.

<FIG> are perspective, side, side sectional, axial, and enlarged sectional views, respectively, of at least a portion of an example implementation of a conveyance apparatus <NUM> not forming part of the scope of protection. The conveyance apparatus <NUM> is shown coupling together or otherwise coupled between opposing upper and lower casing joints <NUM>, <NUM>. The following description refers to <FIG> and <FIG>, collectively.

The conveyance apparatus <NUM> may be, comprise, or operate as a casing collar and, thus, be utilized instead of a conventional casing collar (e.g., an instance of the casing collars <NUM> shown in <FIG>) to threadedly or otherwise couple two casing joints together. Prior to performing the casing running operations, a conveyance apparatus <NUM> may be coupled to each casing joint to form the box end of the casing joints. Thereafter, during the casing running operations, the pin ends of the new casing joints may be coupled with the box ends (i.e., conveyance apparatuses <NUM>) of the previously connected casing joints protruding from the wellbore <NUM>.

The conveyance apparatus <NUM> may further comprise a plurality of rollable or otherwise rotatable members <NUM> rotatably connected with and distributed circumferentially around the body <NUM>. At least a portion of each rotatable member <NUM> may extend or protrude from or past an outer surface <NUM> of the body <NUM> by a predetermined distance <NUM> in a lateral or otherwise radially outward direction with respect a central axis <NUM> of the conveyance apparatus <NUM>. Each rotatable member <NUM> may be or comprise a wheel (e.g., having a generally cylindrical geometry) configured to rotate about a corresponding shaft <NUM> defining an axis of rotation extending substantially perpendicularly with respect to the central axis <NUM>. Each rotatable member <NUM> may be disposed in a corresponding cavity <NUM> extending within a wall of the body <NUM> and retained within the cavity <NUM> via the corresponding shaft <NUM>, which may extend through the cavity <NUM> and into the body <NUM> on opposing sides of the cavity <NUM>.

The rotatable members <NUM> may be arranged in one or more sets <NUM> of rotatable members <NUM>, each set <NUM> comprising a plurality of rotatable members <NUM> distributed circumferentially around the body <NUM> along a different circumferential curve. Each set <NUM> of rotatable members <NUM> may be located at a different axial position along the body <NUM>. The rotatable members <NUM> of one or more sets <NUM> of rotatable members <NUM> may be azimuthally offset from the rotatable members <NUM> of one or more other sets <NUM> of rotatable members <NUM>. Accordingly, although each set <NUM> of rotatable members <NUM> is shown comprising twelve rotatable members <NUM> distributed circumferentially around the body <NUM> every thirty degrees, the azimuthal offset results in the rotatable members <NUM> being distributed circumferentially around the body <NUM> every fifteen degrees, as shown in <FIG>. Although the conveyance apparatus <NUM> is shown comprising three sets <NUM> of rotatable members <NUM>, it is to be understood that the conveyance apparatus <NUM> may comprise one, two, four, or more sets <NUM> of rotatable members <NUM>. Furthermore, although each set <NUM> of rotatable members <NUM> is shown comprising twelve rotatable members <NUM>, it is to be understood that each set <NUM> of rotatable members <NUM> may comprise a lesser or a greater quantity of rotatable members <NUM>.

During casing running operations, the conveyance apparatuses <NUM> may collectively lift or support at least portions of the casing string <NUM> at a distance from the sidewall <NUM> of the wellbore <NUM>, such as may reduce or inhibit contact and, thus, reduce friction between the portions of the casing sting and the sidewall <NUM>. For example, the rotatable members <NUM> of each conveyance apparatus <NUM> may contact the sidewall <NUM> of the wellbore <NUM> to lift the body <NUM> and at least a portion of the casing joints <NUM>, <NUM> coupled with the conveyance apparatus <NUM> away from the sidewall <NUM>. Each conveyance apparatus <NUM> may maintain a space or gap between the sidewall <NUM> of the wellbore <NUM> and the body <NUM> (and at least a portion of the casing joints <NUM>, <NUM> coupled with the body <NUM>) that is about equal to the distance <NUM>. The rotatable members <NUM> may further permit the corresponding portion of the casing string <NUM> to roll in an axial (i.e., longitudinal) direction along the sidewall <NUM> to reduce friction between the portions of the casing sting <NUM> and the sidewall <NUM>.

<FIG> are perspective, side, side sectional, and axial views, respectively, of at least a portion of an example implementation of a conveyance apparatus <NUM> not forming part of the scope of protection. The conveyance apparatus <NUM> is shown coupling together or otherwise coupled between opposing upper and lower casing joints <NUM>, <NUM>. The following description refers to <FIG> and <FIG>, collectively.

The conveyance apparatus <NUM> may be, comprise, or operate as a casing collar and, thus, be utilized instead of a conventional casing collar (e.g., an instance of the casing collars <NUM> shown in <FIG>) to threadedly or otherwise couple two casing joints together. Prior to performing the casing running operations, a conveyance apparatus <NUM> may be coupled to each casing joint to form the box end of the casing joint. Thereafter, during the casing running operations, the pin ends of the new casing joints may be coupled with the box ends (i.e., conveyance apparatuses <NUM>) of the previously connected casing joints protruding from the wellbore <NUM>.

The conveyance apparatus <NUM> may further comprise a plurality of rollable or otherwise rotatable members <NUM> rotatably connected with and distributed circumferentially around the body <NUM>. Each rotatable member <NUM> may be or comprise a roller bearing having a generally cylindrical geometry and configured to rotate about a corresponding shaft (not shown) defining an axis of rotation extending substantially perpendicularly with respect to a central axis <NUM> of the conveyance apparatus <NUM>. At least a portion of each rotatable member <NUM> may be disposed past an outer surface <NUM> of the body <NUM> by a predetermined distance <NUM> in a lateral or otherwise radially outward direction with respect the central axis <NUM>.

The rotatable members <NUM> may be coupled with or otherwise supported by one or more annular members <NUM> (e.g., rings, collars, sleeves, etc.) disposed around the body <NUM>. The annular members <NUM> may be rotatably connected with the body <NUM>, such as may permit the annular members <NUM> to rotate around (i.e., about) the body <NUM> such that axis of rotation of each annular member <NUM> coincides with the central axis <NUM>. Each annular member <NUM> may be rotatably connected with the body <NUM> via a bearing assembly, such as a ball bearing, comprising a plurality of balls <NUM> disposed within opposing grooves or channels located along an inner surface of each annular member <NUM> and the outer surface <NUM> of the body <NUM>. Other means for rotatably connecting the annular members <NUM> with the body <NUM> may include roller bearings, plain bearings, and fluid bearing, among other examples.

At least a portion of each rotatable member <NUM> may extend or protrude from or past an outer surface of a corresponding annular member <NUM> in a lateral or otherwise radially outward direction with respect the central axis <NUM>. Each rotatable member <NUM> may be disposed in a corresponding cavity <NUM> extending into the outer surface of the annular member <NUM> and retained within the cavity <NUM> via a corresponding shaft (not shown), which may extend through the cavity <NUM> and into the annular member <NUM> on opposing sides of the cavity <NUM>. Each annular member <NUM> may carry one or more sets <NUM> of rotatable members <NUM>, each set <NUM> comprising a plurality of rotatable members <NUM> distributed circumferentially around the body <NUM> along a different circumferential curve. Each set <NUM> of rotatable members <NUM> may be located at a different axial position along the annular member <NUM> and with respect the central axis <NUM>. The rotatable members <NUM> of one or more sets <NUM> of rotatable members <NUM> may be azimuthally offset from the rotatable members <NUM> of one or more other sets <NUM> of rotatable members <NUM>. Accordingly, although each set <NUM> of rotatable members <NUM> is shown comprising twelve rotatable members <NUM> distributed circumferentially around the body <NUM> every thirty degrees, the azimuthal offset results in the rotatable members <NUM> of the conveyance apparatus <NUM> being distributed circumferentially around the body <NUM> every fifteen degrees, as shown in <FIG>. Although the conveyance apparatus <NUM> is shown comprising two annular member <NUM> carrying the rotatable members <NUM>, it is to be understood that the conveyance apparatus <NUM> may comprise one, three, or more annular member <NUM> carrying the rotatable members <NUM>. Furthermore, although each annular member <NUM> is shown supporting two sets <NUM> of rotatable members <NUM>, it is to be understood that each annular member <NUM> may support one, three, or more set <NUM> of rotatable members <NUM>. Also, although each set <NUM> of rotatable members <NUM> is shown comprising twelve rotatable members <NUM>, it is to be understood that each set <NUM> of rotatable members <NUM> may comprise a lesser or a greater quantity of rotatable members <NUM>.

During casing running operations, the conveyance apparatuses <NUM> may collectively lift or support at least portions of the casing string <NUM> at a distance from the sidewall <NUM> of the wellbore <NUM>, such as may reduce or inhibit contact and, thus, reduce friction between the portions of the casing sting <NUM> and the sidewall <NUM>. For example, the rotatable members <NUM> of each conveyance apparatus <NUM> may contact the sidewall <NUM> of the wellbore <NUM> to lift the body <NUM> and at least a portion of the casing joints <NUM>, <NUM> coupled with the body <NUM> away from the sidewall <NUM>. Each conveyance apparatus <NUM> may maintain a space or gap between the sidewall <NUM> of the wellbore <NUM> and the body <NUM> (and at least a portion of the casing joints <NUM>, <NUM> coupled with the body <NUM>) that is about equal to the distance <NUM>. The rotatable members <NUM> may further permit the corresponding portion of the casing string <NUM> to roll in an axial (i.e., longitudinal) direction along the sidewall <NUM> and, thus, reduce friction between the portions of the casing sting <NUM> and the sidewall <NUM>. The ability of the annular members <NUM> to rotate about the body <NUM> may permit the casing string <NUM> to rotate (e.g., roll, turn) within the wellbore <NUM>, such as to reduce or inhibit torsional stresses along the casing string <NUM> and/or to maintain the casing string <NUM> against the low side of the wellbore <NUM>.

<FIG> are perspective, side, sectional side, and two sectional axial views, respectively, of at least a portion of an embodiment of a conveyance apparatus <NUM> according to the invention. The conveyance apparatus <NUM> is shown coupled between and partially around opposing upper and lower casing joints <NUM>, <NUM>. The conveyance apparatus <NUM> is utilized in addition to a conventional casing collar (e.g., an instance of the casing collars <NUM> shown in <FIG>) for threadedly or otherwise coupling together the upper and lower casing joints <NUM>, <NUM>. The conveyance apparatus <NUM> is coupled with the casing string <NUM> around, with, or otherwise in association with an instance of the casing collar <NUM> forming the casing string <NUM>. The following description refers to <FIG> and <FIG>, collectively.

The conveyance apparatus <NUM> comprises a body <NUM> (e.g., a sleeve, a collar, a housing) having a generally tubular geometry. The body <NUM> comprises an inner surface <NUM> defining an axial bore extending therethrough for receiving or accommodating the casing collar <NUM> and the casing joints <NUM>, <NUM>. The body <NUM> is configured to engage the casing collar <NUM> and/or the casing joints <NUM>, <NUM> in a manner preventing axial movement of the conveyance apparatus <NUM> with respect the casing collar <NUM> and the casing joints <NUM>, <NUM>. The inner surface <NUM> comprises a larger inner diameter portion <NUM> (e.g., a channel extending into the inner surface <NUM> in a radially outward direction with respect to a central axis <NUM> of the conveyance apparatus <NUM> and circumferentially along the inner surface <NUM>) configured to receive or accommodate the casing collar <NUM> when the conveyance apparatus <NUM> is coupled around the casing collar <NUM> and the upper and lower casing joints <NUM>, <NUM>. The inner surface further comprises smaller inner diameter portions <NUM>, <NUM> on opposing sides of the larger inner diameter portion <NUM> configured to receive or accommodate portions of the upper and lower casing joints <NUM>, <NUM>, respectively, when the conveyance apparatus <NUM> is coupled around the casing collar <NUM> and the upper and lower casing joints <NUM>, <NUM>. A transition surface or shoulder <NUM> extends radially between each smaller inner diameter portion <NUM>, <NUM> and the larger inner diameter portion <NUM>. Accordingly, when the conveyance apparatus <NUM> is coupled around the casing collar <NUM> and the upper and lower casing joints <NUM>, <NUM>, each shoulder <NUM> contacts an opposing edge or shoulder of the casing collar <NUM> extending laterally from the upper and lower casing joints <NUM>, <NUM> to prevent or otherwise limit axial movement of the conveyance apparatus <NUM> with respect to the casing collar <NUM> and, thus, prevent or otherwise limit longitudinal movement of the conveyance apparatus <NUM> along the casing string <NUM>.

As shown in <FIG>, the conveyance apparatus <NUM> may further comprise a plurality of rollable or otherwise rotatable members <NUM> distributed along the inner surface <NUM> of the body <NUM>, such as may permit the conveyance apparatus <NUM> to rotate about the casing collar <NUM> and the upper and lower casing joints <NUM>, <NUM>, as indicated by arrows <NUM>, when the conveyance apparatus <NUM> is coupled around the casing collar <NUM> and the upper and lower casing joints <NUM>, <NUM>. The rotatable members <NUM> may be arranged in one or more sets of rotatable members <NUM>, each set comprising a plurality of rotatable members <NUM> distributed circumferentially along the inner surface <NUM> of the body <NUM>. Each set of rotatable members <NUM> may be located at a different axial position along the body <NUM>. Each rotatable member <NUM> may protrude laterally inward (i.e., radially inward with respect the central axis <NUM>) from the inner surface <NUM> of the body <NUM> by a predetermined distance to form an annular space or offset between the body <NUM> and the casing collar <NUM>, the upper casing joint <NUM>, and the lower casing joint <NUM>, and, thus, prevent or inhibit contact between the body <NUM> and the casing collar <NUM>, the upper casing joint <NUM>, and the lower casing joint <NUM>. Each rotatable member <NUM> may be disposed in a corresponding cavity <NUM> extending into the inner surface <NUM> within a wall of the body <NUM> and retained within the cavity <NUM> via a corresponding shaft (not shown), which may extend through the cavity <NUM> and into the wall of the body <NUM> on opposing sides of the cavity <NUM>. Each shaft may define an axis of rotation extending substantially parallel to the central axis <NUM> of the conveyance apparatus <NUM>. Each rotatable member <NUM> may be or comprise a roller bearing having a generally cylindrical geometry. However, it is to be understood that the rotatable members <NUM> may be or comprise other rotatable members, such as ball bearings and wheels.

The conveyance apparatus <NUM> may further comprise a plurality of rollable or otherwise rotatable members <NUM> rotatably connected with the body <NUM> and extending laterally outward (i.e., radially outward with respect the central axis <NUM> of the conveyance apparatus <NUM>) from an outer surface <NUM> of the body <NUM>. The rotatable members <NUM> may collectively facilitate rolling along the sidewall <NUM> of the wellbore <NUM> and thereby facilitate axial conveyance of at least a portion of the casing joints <NUM>, <NUM> and casing collar <NUM> coupled with the conveyance apparatus <NUM>. A plurality of conveyance apparatuses <NUM> may form a portion of or be coupled with a casing string <NUM> and, thus, collectively facilitate axial conveyance of the casing string <NUM> within the wellbore <NUM>. Each conveyance apparatus <NUM> may be configured to support the corresponding casing joints <NUM>, <NUM> at an intended offset distance from the sidewall <NUM>. The rotatable members <NUM> may extend laterally outward from the outer surface <NUM> of the conveyance apparatus <NUM> by a predetermined distance <NUM>. Each rotatable member <NUM> may be or comprise a wheel configured to rotate about a corresponding shaft <NUM> extending laterally from the outer surface <NUM> of the body <NUM> and defining a corresponding axis of rotation <NUM> extending substantially perpendicularly with respect to the central axis <NUM>. Each rotatable member <NUM> may be disk or bowl shaped, comprising curved outer surfaces or profiles (e.g., viewed from a perspective along the central axis <NUM>) each representing a segment of a spheroid having a radius that may be smaller than a radius of a cross-section of the sidewall <NUM> of the wellbore <NUM>. A ball bearing <NUM> or another bearing may reduce rotational friction between each shaft <NUM> and a corresponding rotatable member <NUM>.

The rotatable members <NUM> may be arranged in pairs <NUM>, with each rotatable member <NUM> connected on an opposing side of the body <NUM>. The axes of rotation <NUM> of each pair <NUM> of rotatable members <NUM> may coincide (i.e., be collinear with), as shown in <FIG> and <FIG>. Each pair <NUM> of rotatable members <NUM> may be located at a different axial position along the body <NUM>. Although the conveyance apparatus <NUM> is shown comprising two pairs <NUM> of rotatable members <NUM>, it is to be understood that the conveyance apparatus <NUM> may comprise one, three, or more pairs <NUM> of rotatable members <NUM>. Furthermore, the rotatable members <NUM> may not necessarily be arranged in pairs <NUM>. Accordingly, each rotatable member <NUM>, corresponding shaft <NUM>, and corresponding axis of rotation <NUM> may be located at a different axial position along the body <NUM> such that the axis of rotation <NUM> of each rotatable member <NUM> on one side of the body <NUM> does not coincide with the axis of rotation <NUM> of another rotatable member <NUM> on an opposing side of the body <NUM>. The axes of rotation <NUM> may extend substantially perpendicularly with respect to the central axis <NUM>.

<FIG> shows the conveyance apparatus <NUM> and a portion of the casing string <NUM> (i.e., casing joint <NUM>) during casing running operations disposed within the non-vertical portion <NUM> of the wellbore <NUM> extending through the subterranean formation <NUM>. The axes of rotation <NUM> of the rotatable members <NUM> may be radially offset from the central axis <NUM> of the conveyance apparatus <NUM> by a predetermined distance <NUM>. The central axis <NUM> of the conveyance apparatus <NUM> may coincide with the center of mass of the casing joints <NUM>, <NUM> and the casing collar <NUM>. Accordingly, the radial offset <NUM> between the central axis <NUM> and the axes of rotation <NUM> of the rotatable members <NUM> can create a mechanical instability when the central axis <NUM> is not located below the axes of rotation <NUM> of the rotatable members <NUM>. Such mechanical instability can result in the gravitational force <NUM> (i.e., weight of the casing joints <NUM>, <NUM> and the casing collar <NUM>) causing a torque <NUM> that urges rotation <NUM> of the conveyance apparatus <NUM> around its geometric center <NUM> toward a mechanically stable and, thus, intended rotational position (i.e., orientation) in which the conveyance apparatus <NUM> is rotatably oriented <NUM> such that the central axis <NUM> is below the axes of rotation <NUM> of the rotatable members <NUM> and the rotatable members <NUM> are in contact with the sidewall <NUM> of the wellbore <NUM>. The mechanically stable rotational position of the conveyance apparatus <NUM> is shown in <FIG>. The torque <NUM> and, thus, the tendency of the conveyance apparatus <NUM> to rotate, may be directly proportional to the distance <NUM> between the central axis <NUM> and the axes of rotation <NUM>.

During casing running operations, the conveyance apparatuses <NUM> may collectively lift or support at least portions of the casing string <NUM> at a distance from the sidewall <NUM> of the wellbore <NUM>, such as may reduce or inhibit contact and, thus, friction between the portions of the casing sting <NUM> and the sidewall <NUM>. For example, the rotatable members <NUM> of each conveyance apparatus <NUM> may contact the sidewall <NUM> of the wellbore <NUM> to lift the body <NUM> and at least a portion of the casing joints <NUM>, <NUM> coupled with the body <NUM> away from the sidewall <NUM>. Each conveyance apparatus <NUM> may maintain a space or gap between the sidewall <NUM> of the wellbore <NUM> and the body <NUM> (and at least a portion of the casing joints <NUM>, <NUM> coupled with the body <NUM>) that is about equal to the distance <NUM>. The rotatable members <NUM> may permit at least portions of the casing string <NUM> supported by the conveyance apparatuses <NUM> to roll in an axial (i.e., longitudinal) direction along the sidewall <NUM> to reduce or inhibit friction between the portions of the casing sting <NUM> and the sidewall <NUM>. The rotatable members <NUM> may permit the corresponding portion of the casing string <NUM> to rotate (e.g., roll, turn) within the wellbore <NUM>, such as to reduce or inhibit torsional stresses along the casing string <NUM> and/or to maintain the casing string <NUM> against the low side of the wellbore <NUM>.

During casing running operations, a bottom side portion <NUM> of the body <NUM> may be located below points of contact <NUM> between the rotatable members <NUM> and the sidewall <NUM> and, thus, in close proximity to the sidewall <NUM> at the low side of the wellbore <NUM>. When the wellbore diameter increases, clearance or spacing between the bottom side portion <NUM> of the body <NUM> and the sidewall <NUM> may progressively decrease and may contact the sidewall <NUM>. Accordingly, the bottom side portion <NUM> of the body <NUM> may be thinner than as shown in <FIG>, such as indicated by phantom line <NUM>. Furthermore, the body <NUM> may extend around a portion of the casing collar <NUM> and/or the casing joints <NUM>, <NUM>, but not around the entire circumference of the casing collar <NUM> and/or the casing joints <NUM>, <NUM> as shown in <FIG>. For example, the bottom side portion <NUM> of the body <NUM> may be at least partially cut off or otherwise omitted, such as along phantom lines <NUM>.

Each conveyance apparatus <NUM> may be coupled with the casing string <NUM> around a corresponding casing collar <NUM> during casing running operations before each pin end of the upper (i.e., new) casing joint <NUM> threadedly engages a box end (e.g., the casing collar <NUM>) of the lower (previously connected) casing joint <NUM> protruding from the wellbore <NUM>. For example, each conveyance apparatus <NUM> may be split along a plane extending radially with respect to the central axis <NUM>, forming opposing upper and lower halves of the conveyance apparatus <NUM> that may be slipped onto the casing joints <NUM>, <NUM> before the casing joints <NUM>, <NUM> are coupled via the casing collar <NUM>. The upper and lower halves may then be coupled together around the casing collar <NUM>, such as via bolts and/or corresponding threading of each half of the conveyance apparatus <NUM>. Each conveyance apparatus <NUM> may also or instead be coupled with the casing string <NUM> around a casing collar <NUM> during casing running operations after each pin end of the upper casing joint <NUM> threadedly engages the box end of the lower casing joint <NUM> protruding from the wellbore <NUM>. For example, each conveyance apparatus <NUM> may be split along a plane extending along (i.e., coinciding with) the central axis <NUM>, forming opposing left and right halves of the conveyance apparatus <NUM> that may be brought together around the casing joints <NUM>, <NUM> and the casing collar <NUM> after the casing joints <NUM>, <NUM> are coupled via the casing collar <NUM>. The left and right halves may then be coupled together, such as via bolts extending through each half of the conveyance apparatus <NUM>.

<FIG> and <FIG> are side and sectional side views, respectively, of at least a portion of an example implementation of a conveyance apparatus <NUM> not forming part of the scope of protection. The conveyance apparatus <NUM> may be utilized in association with a conventional casing string <NUM> comprising a plurality of casing joints <NUM> (e.g., upper and lower casing joints <NUM>, <NUM>) connected together via a plurality of casing collars <NUM>. The conveyance apparatus <NUM> is shown disposed around a lower casing joint <NUM> and in contact with the casing collar <NUM>. The following description refers to <FIG>, <FIG>, and <FIG>, collectively.

The conveyance apparatus <NUM> may comprise a body <NUM> (e.g., a sleeve, a collar, a housing) having a generally tubular geometry. The body <NUM> may comprise an inner surface <NUM> defining an axial bore extending therethrough for receiving or accommodating a casing joint <NUM>, such as the lower casing joint <NUM>. The inner surface <NUM> may have an inner diameter <NUM> that is slightly larger than an outer diameter <NUM> of the lower casing joint <NUM>, permitting the conveyance apparatus <NUM> to slide axially (i.e., longitudinally) along an outer surface of the lower casing joint <NUM>, as indicated by arrows <NUM>. The inner diameter <NUM> may be smaller than an outer diameter <NUM> of the casing collar <NUM>, preventing the conveyance apparatus <NUM> from sliding or otherwise moving over or past the casing collar <NUM>. The body <NUM> may comprise an upper shoulder <NUM> configured to contact a lower shoulder <NUM> of the casing collar <NUM> in a manner preventing upward axial movement of the conveyance apparatus <NUM> along the lower casing joint <NUM> after such contact is made. The body <NUM> may further comprise a lower shoulder <NUM> configured to contact an upper shoulder <NUM> of another casing collar (not shown) at the bottom of the lower casing joint <NUM> in a manner preventing downward axial movement of the conveyance apparatus <NUM> along the lower casing joint <NUM> after such contact is made. Accordingly, when the conveyance apparatus <NUM> is connected with, installed on, or otherwise disposed around the lower casing joint <NUM>, the conveyance apparatus <NUM> is permitted to slide axially along the lower casing joint <NUM> between casing collars <NUM> at opposing ends of the lower casing joint <NUM>.

The conveyance apparatus <NUM> may further comprise a plurality of rollable or otherwise rotatable members <NUM> rotatably connected with and distributed circumferentially around the body <NUM>. At least a portion of each rotatable member <NUM> may extend or protrude from or past an outer surface <NUM> of the body <NUM> by a predetermined distance <NUM> in a lateral or otherwise radially outward direction with respect a central axis <NUM> of the conveyance apparatus <NUM>. Each rotatable member <NUM> may be or comprise a wheel (e.g., having a generally cylindrical geometry) configured to rotate about a corresponding shaft <NUM> defining an axis of rotation extending substantially perpendicularly with respect to the central axis <NUM>. Each rotatable member <NUM> may be disposed in a corresponding cavity <NUM> extending into the body <NUM> and retained within the cavity <NUM> via the corresponding shaft <NUM>, which may extend through the cavity <NUM> and into the body <NUM> on opposing sides of the cavity <NUM>.

The rotatable members <NUM> may be arranged in one or more sets <NUM> of rotatable members <NUM>, each set <NUM> comprising a plurality of rotatable members <NUM> distributed circumferentially around the body <NUM> along a different circumferential curve. Each set <NUM> of rotatable members <NUM> may be located at a different axial position along the body <NUM>. The rotatable members <NUM> of one or more sets <NUM> of rotatable members <NUM> may be azimuthally offset from the rotatable members <NUM> of one or more other sets <NUM> of rotatable members <NUM>. Accordingly, although each set <NUM> of rotatable members <NUM> is shown comprising twelve rotatable members <NUM> distributed circumferentially around the body <NUM> every thirty degrees, the azimuthal offset results in the rotatable members <NUM> being distributed circumferentially around the body <NUM> every fifteen degrees (similarly as shown in <FIG>). Although the conveyance apparatus <NUM> is shown comprising three sets <NUM> of rotatable members <NUM>, it is to be understood that the conveyance apparatus <NUM> may comprise one, two, four, or more sets <NUM> of rotatable members <NUM>. Furthermore, although each set <NUM> of rotatable members <NUM> is shown comprising twelve rotatable members <NUM>, it is to be understood that each set <NUM> of rotatable members <NUM> may comprise a lesser or a greater quantity of rotatable members <NUM>.

Each conveyance apparatus <NUM> may be coupled with the casing string <NUM> around a corresponding casing joint <NUM> during casing running operations before each pin end of a new casing joint <NUM> (e.g., upper casing joint <NUM>) threadedly engages a box end <NUM> (e.g., the casing collar <NUM>) of a previously connected casing joint <NUM> (e.g., lower casing joint <NUM>) protruding from the wellbore <NUM>. For example, after a pin end of a new casing joint <NUM> is positioned above and aligned with a box end <NUM> of a previously connected casing joint <NUM>, a conveyance apparatus <NUM> may be slipped onto the new casing joint <NUM> via the pin end of the new casing joint <NUM>. Thereafter, the draw works <NUM> may lower the new casing joint <NUM> until the pin end of the new casing joint <NUM> is at least partially inserted into the box end <NUM> of the previously connected casing joint <NUM>. The torqueing device <NUM> may then be moved toward the casing string <NUM>, clamped around the new casing joint <NUM>, and operated to rotate the new casing joint <NUM> to threadedly engage the pin end of the new casing joint <NUM> with the box end <NUM> of the previously connected casing joint <NUM> to make up the connection. In this manner, the conveyance apparatus <NUM> is connected with the casing string <NUM> around the new casing joint <NUM> between opposing casing collars <NUM>. The draw works <NUM> may then lower the casing string <NUM> to advance the casing string <NUM> downward within the wellbore <NUM>. When the box end <NUM> of the newly connected casing joint <NUM> is near the slips and/or the rig floor, the draw works <NUM> may stop lowering the casing string <NUM>, the slips may close to clamp the newly connected casing joint <NUM>, and the elevator <NUM> may be detached from the newly connected casing joint <NUM>.

Thereafter, another casing joint <NUM> may be conveyed to the rig floor, grasped by the elevator <NUM>, and lifted above the previously connected casing joint <NUM> protruding from the wellbore <NUM>. Another conveyance apparatus <NUM> may be slipped onto the new casing joint <NUM> via the pin end of the new casing joint <NUM>. The new casing joint <NUM> may then be coupled with the previously connected casing joint <NUM>. The slips may be opened again and the draw works <NUM> may lower the casing string <NUM> to advance the casing string <NUM> downward within the wellbore <NUM>. A conveyance apparatus <NUM> may be disposed around every casing joint <NUM>, every other casing joint <NUM>, or at another predetermined interval or rate. Such casing running operations may be repeated until a predetermined number of conveyance apparatuses <NUM> are coupled with the casing string <NUM> and/or the casing string <NUM> reaches a predetermined length and/or reaches a predetermined depth within the wellbore <NUM>. While the casing string <NUM> is assembled and lowered along the wellbore, each conveyance apparatus <NUM> may encounter friction against the sidewall <NUM> of the wellbore <NUM>, causing each conveyance apparatus <NUM> to stop moving downward with the casing string <NUM> or to move downward at a slower rate than the casing string <NUM> until each conveyance apparatus <NUM> contacts a casing collar <NUM> located at an upper end of the casing joint <NUM> having the conveyance apparatus <NUM> connected to or disposed thereon.

During casing running operations, each conveyance apparatus <NUM> may lift or support a corresponding portion of the casing string <NUM> at a distance from the sidewall <NUM> of the wellbore <NUM>, such as may reduce or inhibit contact and, thus, reduce friction between each portion of the casing sting <NUM> and the sidewall <NUM>. For example, the rotatable members <NUM> of each conveyance apparatus <NUM> may contact the sidewall <NUM> of the wellbore <NUM> to lift the body <NUM> and at least a portion of the casing string <NUM> contacting the body <NUM> away from the sidewall <NUM>. Each conveyance apparatus <NUM> may maintain a space or gap between the sidewall <NUM> of the wellbore <NUM> and the body <NUM> (and at least a portion of the casing string <NUM> supported by the conveyance apparatus <NUM>) that is about equal to the distance <NUM>. Each rotatable member <NUM> may further permit at least a portion of the casing string <NUM> supported by a conveyance apparatus <NUM> to roll in an axial direction along the sidewall <NUM> to reduce friction between the supported portion of the casing sting <NUM> and the sidewall <NUM>.

Claim 1:
An apparatus comprising:
a conveyance device (<NUM>) for connecting with a casing string (<NUM>) having a plurality of casing joints (<NUM>) coupled together via a plurality of casing collars (<NUM>), wherein the conveyance device comprises:
a sleeve (<NUM>); and
a plurality of rotatable members (<NUM>) connected with the sleeve and extending from the sleeve in a radially outward direction;
characterized in that:
the sleeve comprises an inner surface (<NUM>) defining a central bore configured to accommodate the casing string;
the inner surface comprises a larger inner diameter portion (<NUM>) and smaller inner diameter portions (<NUM>, <NUM>) on opposing sides of the larger inner diameter portion (<NUM>);
the larger inner diameter portion defines a channel extending circumferentially along the inner surface of the sleeve;
a transition surface (<NUM>) extends radially between each smaller inner diameter portion (<NUM>, <NUM>) and the larger inner diameter portion (<NUM>);
the channel is configured to accommodate an instance of the casing collars;
the conveyance device comprises a first conveyance device half and a second conveyance device half;
the first conveyance device half and the second conveyance device half are separable;
the first conveyance device half and the second conveyance device half are connectable around the casing string such that the instance of the casing collars is within the channel;
the conveyance device is configured to connect to the casing string by disposing the conveyance device around the casing string such that the casing string is within the central bore and the instance of the casing collars is within the channel; and
each transition surface is configured to contact a corresponding shoulder of the instance of the casing collars to inhibit movement of the conveyance device longitudinally along the casing string.