The present disclosure relates in general to apparatus for launching wiper plugs, wiper darts, or other articles during cementing operations for completion of oil and gas wells.
It is well known to form a well, such as an oil or gas well, by using a drilling rig to rotate a bit attached to the end of a string of drill pipe such that the bit advances through subterranean soil formations to form a borehole of desired length and orientation. It is common practice to run a string of casing pipe into the borehole, leaving an annulus between the casing string and the borehole, and then to introduce a cement slurry into at least a portion of the borehole annulus. This is commonly called a cementing operation.
Cementing operations can be carried out in a number of different ways, but one common procedure involves introducing a first (or “lower”) wiper plug into the upper end of the casing string, and then pumping a selected quantity of cement slurry into the the casing, displacing the lower wiper plug downward within the casing. A second (or “upper”) wiper plug is then inserted into the upper end of the casing string, after which a suitable fluid (for example, a drilling fluid) is pumped into the casing, displacing the upper wiper plug, the wet cement slurry, and the lower wiper plug downward within the casing string, such that the slurry is forced out the lower end of the casing and upward into the wellbore annulus. Due to fluid density differences, the cement slurry flowing upward into the wellbore annulus will displace any drilling fluid or other fluid present in the annulus. This process is continued until the cement slurry has reached a desired level in the annulus.
The upper and lower wiper plugs provide positive separation between the cement slurry and the wellbore fluids. The lower wiper plug is typically configured such that its downward movement within the casing string will be to be stopped by a “cement shoe” provided at the lower end of the casing. The lower wiper plug has a center bore that is initially closed off by a “burst disk” that will fail (i.e., burst) at a selected differential pressure, thus allowing the cement slurry to flow through the lower wiper plug and out the bottom of the casing and up the wellbore annulus. The upper wiper plug similarly has a center bore that is initially closed by a burst disk, but with a burst pressure higher than the burst pressure of the lower wiper plug.
A cementing head (of which there are numerous known types) is used to connect the upper end of the casing string with flow lines through which cement slurry and other fluids can be pumped into the casing. As well, the cementing head typically provides a structural connection between the drilling rig and the casing string to transfer vertical hoisting loads and torsional loads into the casing string as necessary during so-called “hoist, reciprocate, and rotate” manipulations of the casing string, which are used to promote optimally effective displacement of fluids by the cement slurry, and to promote optimally uniform distribution of the slurry within the cemented region of the wellbore annulus.
The cementing head also must accommodate the introduction of the wiper plugs into the casing bore (or “dropping a plug”, as this procedure is commonly called). In accordance with one simple method, this can be achieved by disconnecting the cementing head from the upper end of the casing string and manually inserting the wiper plug. However, this simple method is feasible only where the cementing procedure being used will permit temporary stoppage of fluid flow such that the pressure at the cementing head will not exceed atmospheric pressure when the plug is dropped. Moreover, any advantages arising from the simplicity of this method of dropping a plug will typically be offset by the additional time and labor required to disconnect and reconnect the cementing head, plus the added risks of environmental damage and injuries to workers in the event of accidental and uncontained fluid spillage.
To avoid such disadvantages and risks, it is common for “plug launchers” to be incorporated into cementing heads. Plug launchers facilitate the introduction of wiper plugs and other accessory articles familiar to persons skilled in the art (e.g., balls or “darts”) into the flow path of fluids within the casing bore without needing to disconnect the cementing head or associated flow lines. As used in this patent specification, the term “plug” is to be understood as a general term encompassing articles and devices (such as but not limited to wiper plugs, wiper darts, and balls) that may be introduced into a fluid flow path within a tubing string (such as but not limited to a casing bore).
A plug launcher will typically contain the plug within the pressured envelope of the cementing head assembly, with means being provided for retaining the plug (such as by way of suitable latching means) when the plug launcher is in a closed position, and for releasing (i.e., “launching” or “dropping”) the plug when the plug launcher is in an open position. When the plug launcher is in the closed position, flowing fluid can by-pass the plug and enter the casing string bore as required by the cementing operation in preparation for dropping a plug. After the plug launcher has been moved to the open position, the continued pumping of fluid into the casing will force the plug downward within the casing bore.
Examples of prior art plug launchers are disclosed in U.S. Pat. No. 4,671,353 (Darning); U.S. Pat. No. 6,575,238 (Yokley); U.S. Pat. No. 7,066,249 (Simson); and U.S. Pat. No. 8,256,515 (Barbee).
It is known for plug launchers to provide for a flag or release indicator disposed downstream of the location where a plug was initially retained (i.e., when the plug launcher was in the closed position), to facilitate the determination or confirmation that the plug was in fact introduced into the fluid flow path after the plug launcher was moved to the open position. The desirability of such flags or release indicators has arisen at least in part from inadequate reliability of known plug launchers in which the means for selectively retaining or releasing a plug typically uses some form of gate valve or ball valve components. As well, such prior art plug-launching devices tend to have bulky valve actuation assemblies protruding radially outward from the plug launcher body, thus creating additional hazards under rotation.
The present disclosure teaches a plug launching tool employing a collet-like mechanism that carries one or more radially-movable jaws arranged to retain a plug in a fluid flow path when the plug launcher is in a closed position, and to release the plug into the fluid flow path when the plug launcher is in an open position. Selection of the desired operational position of the plug launcher (i.e., open or closed) is effected by actuation of an axially-movable sliding sleeve.
In one embodiment in accordance with the present disclosure, the plug launcher comprises:
In another embodiment in accordance with the present disclosure, the plug launcher facilitates annular by-pass flow when in the closed position, and also facilitates selective closing-off of the annular by-pass flow when in the open position. This particular embodiment of the plug launcher comprises:
Thus arranged with the sliding sleeve in the closed position and having a plug installed in the retained plug interval, the plug launcher bore is effectively blocked off. However, the ports provided in the receiver cage above and below the retained plug interval are configured and arranged to open into the annular region, thus providing fluid communication by-passing the blocked-off plug launcher bore and facilitating fluid flow into the wellbore as may be required prior to launching the plug.
It is desirable for a plug launcher to enable the launching of plugs during fluid flow conditions. However, in prior art devices that provide annular by-pass flow closure (such as U.S. Pat. No. 8,256,515), the fully-open (i.e., plug release) position of the valve can only be achieved concurrently with annular by-pass flow closure. When attempting to launch a plug under flowing conditions, this operational limitation tends to result in excess differential pressure across the plug prior to the valve being moved into the fully-open position, with the attendant risk of premature rupture of the plug bore burst disk and resultant damage to the plug body, thereby affecting the plug's ability to wipe effectively, or causing it to jam in the plug launcher.
Plug launcher embodiments in accordance with the present disclosure mitigate or eliminate these limitations and risks, because when the sliding sleeve is displaced toward the closed position, the sleeve will be axially displaced within the annulus so as to incrementally close or to largely block the upper cage ports, thus preventing by-pass flow only after the jaw lands are retracted. This provides for flow path overlap when the sleeve is moving between its closed and open positions, allowing open-bore flow in conjunction with plug displacement before closing annular flow, thus minimizing the risk of excess differential pressure load across the plug. This arrangement thus facilitates reliable plug launching under a range of flow conditions without the operational limitations of prior art devices that either require flow stoppage or limited flow in order to protect the plug where by-pass flow restriction is provided, or require relatively high flow rates in order to reliably displace the plug where little or no by-pass flow restriction is provided.
The plug launcher may include a piston (as described above) to enable mechanical and/or fluid actuation of the sliding sleeve between closed and open positions. The piston is sealingly engageable with the bore of the outer housing along a defined interval thereof, to provide containment of wellbore fluids and thus allow through-wall openings to be placed in the housing within this interval. These openings may serve as piston actuation slots for mechanical actuation of the sleeve (with the slot length corresponding to at least the length of the sliding sleeve's stroke), or as piston actuation ports to facilitate fluid-powered actuation. The slots provide access through the housing wall for direct application of axial force to move the piston and perhaps to retain it in position.
Alternative means and methods for actuating the sliding sleeve include, but are not limited to: (1) rotary actuation about the housing axis; (2) rotary actuation about a radial axis generally normal to the housing surface; and (3) rotary actuation about a generally tangent axis. More specifically:
Additionally, remote actuation of the piston under rotation may be facilitated by providing clutch or braking devices reacting between the rotary drive sleeve and the drilling rig, such as described in U.S. Pat. No. 7,909,120 (Slack et al.)—see, for example,
In embodiments where the piston is carried by the housing, fluid actuation of the sliding sleeve may be provided by means of a double-acting hydraulic or pneumatic actuator, with the housing being configured to act as the cylinder body, and having external ports for entry of the pressurized actuating fluid, with either rigid or swiveling fluid line connections to the fluid entry ports as appropriate for particular operational requirements.
Accordingly, in a first aspect the present disclosure teaches a plug-launching tool comprising: a generally axisymmetric housing having a housing bore; a sliding sleeve sealingly and coaxially movable within the housing bore; and actuation means, for axially moving the sliding sleeve between a closed position and an open position. A plug receiver bore is carried by either the housing or the sliding sleeve, with the plug receiver bore being in upstream fluid communication with the housing bore. The plug receiver bore includes a plug retainer interval configured for receiving a selected plug and to allow passage of the plug downstream of the plug retainer interval.
The plug-launching tool in accordance with this first aspect of the disclosure also includes a collet assembly coaxially disposed within the housing bore and carried by either the sliding sleeve or the housing. The collet assembly includes a collet body having a generally cylindrical bore configured to accommodate passage of the plug. The collet body carries one or more collet jaws linked to the collet body so as to be movable between a radially-inward closed position and a radially-outward open position, wherein:
The tool also includes linkage means, for linking axial movement of the sliding sleeve to radial movement of the collet jaws, such that the collet jaws will be urged toward their closed and open positions when the sliding sleeve is moved toward its closed and open positions, respectively.
In accordance with a second aspect, the present disclosure teaches a plug-launching tool comprising a generally axisymmetric housing having a housing bore, and a generally cylindrical receiver cage having a main body with upper and lower ends and defining a plug receiver bore. The receiver cage is coaxially disposed within the housing. The housing bore is configured to support the receiver cage at the upper end and/or at the lower end thereof, and defines a housing bore annulus between the housing and the receiver cage's main body. The housing bore extends through housing and the receiver cage, and is configured to allow downstream passage of a selected plug. Upper and lower sets of receiver cage ports extend through a wall of the receiver cage's main body, defining an unported receiver cage interval between the upper receiver cage ports and the lower receiver cage ports, and defining a retained plug interval in a middle region of the receiver cage's main body, with the length of the retained plug interval being at least approximately equal to the length of the selected plug.
The plug-launching tool in accordance with this second aspect of the disclosure also includes a sliding sleeve coaxially and slidably disposed within the housing bore annulus in a region generally corresponding to the upper ports in the receiver cage, wherein the sliding sleeve is movable between:
Also provided is a fluid flow path by-passing the plug receiver interval, to allow downstream fluid flow within the housing annulus to the lower receiver cage ports.
The tool further includes a collet assembly comprising a plurality of collet jaws linked to the sliding sleeve by collet arms extending axially downward from the sliding sleeve. The collet assembly is configured to axially position each collet jaw in an associated lower receiver cage lower port such that the collet jaws will extend radially inward into the plug receiver bore. The collet arms are engageable with the housing bore through a first cam interface to urge the collet jaws toward their closed position when the sliding sleeve is moved toward its closed position. The collet jaws are engageable with the receiver cage through a second cam interface between the jaw segments and surfaces of the receiver cage ports in which they move, so as to urge the collet jaws toward the open position when the sliding sleeve is moved toward its open position.
Embodiments in accordance with the present disclosure will now be described with reference to the accompanying Figures, in which numerical references denote like parts, and in which:
In the embodiment shown in
Receiver cage 1130 comprises a main body 1139 having upper and lower ends 1132 and 1133 and defining a plug receiver bore 1131, with upper and lower sets of cage ports 1134 and 1135 to allow fluid flow through the side wall b1138 of receiver cage 1130. An upper spline pattern 1136 on upper end 1132 of receiver cage 1130 engages a mating spline pattern 1107 on top cap 1100 to react against rotation of cage 1130 relative to housing 1110 and bottom cam face 1137.
The housing assembly is configured to be close-fitting with and to rigidly support cage 1130 at its upper and lower ends 1132 and 1133, including top cap 1100, bottom cap 1120, and outer housing 1110. More specifically, lower end 1133 of cage 1130 is supported by stepped face 1125, with rotational location timing being provided by engagement of cage splines 1136 and top cap splines 1106. Outer housing 1110 has an internal profile defining an annular region 1300 between outer housing 1110 and cage 1130, to thereby allow downstream passage under flow.
Lower end 1102 of top cap 1100 has external threads that are engageable with internal threads on upper end 1111 of housing 1110, for transferring hoist loads from top cap 1100 to housing 1110. Upper end 1101 of top cap 1100 is adapted for securing the assembly (by any suitable means) to components rigged into a top-drive drilling rig.
Seal grooves 1103 and 1104 are provided on the outer and inner diameters, respectively, of top cap 1100 at lower end 1102 thereof. A suitable seal element installed in external seal groove 1103 seals against the upper section of housing 1110 above piston actuation slots 1116 to prevent contaminants from entering annular space 1310 from above. A wiper groove 1105 is provided on the inner diameter of top cap 1100, just above inner seal groove 1104, with a suitable wiper being installed in the groove along the articulating surface between a generally cylindrical piston 1140 and top cap 1100. Seal groove 1117 and wiper grooves 1118 contain suitable seal and wiper elements to prevent the exit of contaminants or fluid from the fluid bore section of tool 100.
Upper end 1121 of the bottom cap 1120 has external threads 1123 that engage internal threads 1115 on lower section 1112 of housing 1110. Upper end 1121 of bottom cap 1120 is configured for mating engagement with lower end 1133 of receiver cage 1130. Lower end 1122 of bottom cap 1120 is threadingly engageable with a casing string. As shown in
The sliding sleeve assembly includes a sliding sleeve 1161 coaxially disposed within an annular region 1300 at an axial position generally corresponding to the position of upper receiver cage ports 1134. In the illustrated embodiment, the sliding sleeve assembly includes a generally cylindrical piston 1140 that is axially movable within a cylindrical interval of the bore of housing 1110, with the length of this cylindrical bore interval being sized to accommodate the axial stroke of piston 1140 and sliding sleeve 1161 of a collet assembly 1160 (described below). Piston 1140 has an upper end 1141, a lower end 1142, and a radially-extending, stepped middle section 1143 with threaded lug holes 1144 and a top lug hole 1145. A seal element installed in inner seal groove 1104 seals against the outer diameter of upper section 1141 of piston 1140.
Sliding sleeve 1161 is configured to interact with upper cage ports 1134 such that when sleeve 1161 is in the closed position (as seen in
Collet assembly 1160 in the illustrated embodiment comprises collet jaws 1163 linked to sliding sleeve 1161 by axially-extending arms 1164 that preferably are elastically resilient or otherwise configured to bias collet jaws 1163 toward the radially-open position. In the illustrated embodiment, sliding sleeve 1161 is generally cylindrical and has a top lug hole 1162, with each collet arm 1164 having a collet ramp 1165. This arrangement is configured to axially position jaws 1163 in receiver cage ports 1135, allowing them to extend radially through the receiver cage wall, so as to partially protrude into the receiver bore on the inner diameter of cage 1130, and thus to provide a land for the selected wiper plug 1170 and to retain it in the receiver bore.
Collet ramps 1165 on collet arms 1164 are engageable with the profiled bore of housing 1110 on housing ramp 1113. These surfaces act as a first cam interface forcing collet jaws 1163 into the closed position when sliding sleeve 1161 is moved to its closed position. Cam surface 1137 on cage 1130 and collet jaw bottom ramps 1166 on collet jaws 1163 define a second cam interface as sleeve 1161 is moved to the open position, with collet arms 1164 tending to force jaws 1163 radially outward and thus removing the protrusion into the receiver bore. As such, the land for the selected plug is effectively removed from the receiver bore and no longer provides means for retaining plug 1170.
Sliding sleeve 1161 is provided with axial movement means, for moving sleeve 1161 axially within and relative to housing 1110 for purposes of actuating the plug-launching tool 100 between the closed and open positions. As best seen in
Piston 1140 may be actuated by a variety of different means, and embodiments in accordance with the present disclosure are not limited or restricted to the use of any particular actuation means, whether disclosed herein or not. By way of non-limiting example, the piston actuation means may comprise a mechanical gear reduction assembly that mounts directly onto the outside of plug-launching tool 100.
Rotary drive sleeve 1220 has a seal groove 1221 and an external driving thread 1222 which is close-fitting with and coaxially mounted to the exterior of housing 1110, reacting against lock sleeve 1260 to prevent axial translation. A generally cylindrical stroking drive sleeve 1270 with seal grooves 1271 and 1272, an internal thread 1273, and a lug hole 1274 threadingly engages with rotary drive sleeve 1220 (as described later herein).
Piston 1140 has an upper end 1141, a lower end 1142, and a middle radially-extended stepped section 1143 with threaded lug holes 1144 and a top lug hole 1145. In order to axially move the sliding sleeve 1161, pinion gear 1180 is rotated (such as by a socket wrench or other suitable torque application means), causing the gear teeth of pinion gear 1180 to engage ring gear teeth 1201 to rotate ring gear 1200 about the longitudinal axis of housing 1110, thus rotating rotary drive sleeve 1220 by load transfer through ring gear lugs 1230. This causes stroking drive sleeve 1270 to stroke axially along the exterior of housing 1110 as the rotation of rotary drive sleeve 1220 is converted to axial movement or stroke due to the threaded engagement of rotary drive sleeve 1220 and stroking drive sleeve 1270.
As best seen in
Piston actuation slots 1116 provide a reaction face against rotation for linkage 1280 and stroking drive sleeve 1270. Accordingly, piston 1140 strokes axially along with stroking drive sleeve 1270 and is further locked with the previously-described sliding sleeve assembly by lugs threaded into holes 1145 and extending into sliding sleeve holes 1162. To avoid premature actuation of this stroking mechanism, lock key 1240 is mounted to the radially exterior face of anchor lock sleeve 1260 and arranged such that it is locked in place between teeth 1201 and secured with lock key lug 1250, thereby preventing rotation of ring gear 1200 and rotary drive sleeve 1220.
Anchor lock sleeve 1260 has an internal splined section 1261 engageable with splines 1106 on top cap 1100 and external splined section 1119 on housing 1110, and thus is capable of transferring torque from top cap 1100 and housing 1110. Anchor lock sleeve 1260 has a lower external face mating onto the upper end of rotary drive sleeve 1220, and stroking drive sleeve 1270 seals against the outer diameter of housing 1110. Circumferential seal grooves 1262, 1221, and 1271 and 1272 are provided in anchor lock sleeve 1260, rotary sleeve 1220, and stroking drive sleeve 1270, respectively.
When plug-launching tool 100 has been fully assembled and rigged into a top-drive-suspended casing string, fluids such as drilling fluid and cement slurry can be pumped through plug-launching tool 100. When tool 100 is in the closed position as shown in
After tool 100 has been moved into its open position as shown in
There is often a need in cementing operations to launch multiple plugs down the casing string.
Plug-launching tool 200 shown in
This “stacked” embodiment's ability to launch multiple plugs is not limited to two plugs. Theoretically, there is no limit to the number of plugs that can be accommodated by modifying tool 200 to include an additional housing stage for each additional plug, with each housing stage stage having its own set of actuation components (1140, 1160, 1270, 1220, 1260, 1280) and its own receiver cage 1130.
Disclosed embodiments of the plug-launching tool may be readily adapted for pneumatic or hydraulic actuation (or other actuation means) by modifying the disclosed housing and piston assemblies in accordance with technology and methods within the knowledge and capabilities of persons skilled in the art, such that pneumatic or hydraulic components can be used to apply the stroking forces necessary to move the sliding sleeve between the closed and open positions and thus to launch the plug.
By way of non-limiting example,
It will be readily appreciated by those skilled in the art that various modifications to embodiments in accordance with the present disclosure may be devised without departing from the scope of the present teachings, including modifications which may use equivalent structures or materials hereafter conceived or developed. It is to be especially understood that the scope of the present disclosure is not intended to be limited to described or illustrated embodiments, and that the substitution of a variant of a claimed or illustrated element or feature, without any substantial resultant change in functionality, will not constitute a departure from the scope of the disclosure.
In this patent document, any form of the word “comprise” is to be understood in its non-limiting sense to mean that any item following such word is included, but items not specifically mentioned are not excluded. A reference to an element by the indefinite article “a” does not exclude the possibility that more than one of the element is present, unless the context clearly requires that there be one and only one such element. Any use of any form of the terms “connect”, “engage”, “couple”, “attach”, or any other term describing an interaction between elements is not meant to limit the interaction to direct interaction between the subject elements, and may also include indirect interaction between the elements such as through secondary or intermediary structure.
Relational and conformational terms such as “perpendicular”, “coaxial”, and “cylindrical” are not intended to denote or require absolute mathematical or geometrical precision. Accordingly, such terms are to be understood as denoting or requiring substantial precision only (e.g., “substantially perpendicular”) unless the context clearly requires otherwise. Wherever used in this document, the terms “typical” and “typically” are to be interpreted in the sense of representative of common usage or practice, and are not to be understood as implying essentiality or invariability.
Filing Document | Filing Date | Country | Kind |
---|---|---|---|
PCT/CA2017/000072 | 3/31/2017 | WO | 00 |
Number | Date | Country | |
---|---|---|---|
62319262 | Apr 2016 | US |