Patent Application
20090308593
This document relates to jar compounders, in particular to double-acting jar compounders.
Jar compounders are used in tandem with jarring devices in order to enhance the jarring impact of the jarring device. Jar compounders use inner spring mechanisms in order to store the additional energy that is released to increase the jar. U.S. Pat. No. 5,931,242 describes a compounder that incorporates a movable piston disposed within a fluid chamber between inner and outer cylindrical assemblies to provide compounding in either jarring direction.
A double-acting jar compounder is disclosed having a first end and a second end, and comprising an outer housing, an upper mandrel, and a lower mandrel. The upper mandrel defines the first end. The upper mandrel is at least partially disposed telescopically within the outer housing to define an uphole fluid chamber between the upper mandrel and the outer housing, the upper mandrel defining the second end. The lower mandrel is at least partially disposed telescopically within the outer housing to define a downhole fluid chamber between the lower mandrel and the outer housing. The uphole fluid chamber and the downhole fluid chamber each contain fluid, have a variable stroke-dependent volume, and are sealed at an uphole end and a downhole end. The upper mandrel has a first shoulder engagable with and facing a second shoulder of the lower mandrel to move the lower mandrel during at least a portion of a downjar or upjar stroke.
These and other aspects of the device and method are set out in the claims, which are incorporated here by reference.
Embodiments will now be described with reference to the figures, in which like reference characters denote like elements, by way of example, and in which:
Immaterial modifications may be made to the embodiments described here without departing from what is covered by the claims.
Jars provide a large transient force impact to a tubing string in either an upward or downward direction. A jar may have, for example, an inner tubular disposed within an outer tubular, defining a chamber in between the two. The chamber may contain hydraulic fluid in the form of gas or liquid, for example. In some cases, a mechanical spring may be used. A tensile or compressive force is applied, through the tubing string, to either the outer tubular or the inner tubular of the jar, forcing the outer tubular and inner tubular to move relative to one another. The relative movement between the two is initially restricted within the chamber, such that the energy of the tensile or compressive force builds up in the tubing string. As soon as the outer tubular and inner tubular move far enough relative to one another to clear the initial restriction, the energy built up in the tubing string is transferred into rapid relative motion between the inner tubular and the outer tubular. Jarring shoulders on both the inner tubular and outer tubular then impact one another, releasing a large amount of kinetic energy into the tubing string and causing a striking blow to the tubing string.
A double-acting jar may be used with a double-acting jar compounder, in order to compound the jarring force of the jar in both directions. A jar compounder may be connected, for example, either directly or indirectly to the jar in the tubing string. By applying a compressive or tensile force to the tubing string, the jar compounder uses, for example, a fluid or mechanical spring to allow additional force to be built up prior to the release of that force in either an up or a down jar. Jar compounders are useful additions with, for example, a coiled tubing jarring operation, because they allow additional force to be built up and stored in the compounder to be transferred during a jar, without imposing additional strain on the already limited compressive and tensile stress of the tubing string itself.
The double-acting jar compounder disclosed herein may be used with coiled tubing. Adapting such a tool to a coiled tubing application presents some challenges to overcome. A coiled tubing operation may involve, for example, the use of a single continuous pipe or tubing. The tubing, which is coiled onto a reel and uncoiled as it is lowered into the well bore, can be used for, for example, drilling or workover applications. However, coiled tubing presents a number of working constraints to existing tool design. First of all, due to the limited size of the coiled tubing, limited compressive loads can be placed on the tubing by the rig operator. Essentially, this means that downhole tools which require compressive force to operate, such as a jarring tool, must be capable of operating with the limited compressive load capability of coiled tubing. In addition, in coiled tubing application the overall length of the downhole tool becomes significant since there is limited distance available between the stuffing box and the blowout preventor to accommodate the bottom hole assembly. A typical bottom hole assembly may include, for example, a quick disconnect, a sinker bar located below the quick disconnect to provide weight to the bottom hole assembly, the jar, a release tool below that of some type, and then an overshot. Other tools may also be present, as required. Thus, the length of any tool used itself becomes particularly significant since the entire bottom hole assembly may be required to fit within the limited distance between the stuffing box and blowout preventor to introduce it into a pressurized well. Furthermore, within these confines, the jar compounder may be required to have a large enough internal bore to permit pump-down tools to pass. Thus, the coiled-tubing jar compounder may have a limited overall wall thickness in view of limited outer diameter conditions.
As in the case with conventional drill pipe, coiled tubing or other down hole tools, these items may get stuck in the well bore at times. Under these circumstances, repetitive upjarring or downjarring with a jarring tool may be useful. Many traditional double-acting jar tools do not perform this function, as upon resetting from a jar in one direction, only a jar in the opposite direction may be subsequently enacted. The double acting jar compounder disclosed herein allows a user to enhance the jarring force for a jar in either direction. Further, the double-acting jar compounder disclosed herein allows a user to subsequently repetitively jar in either direction. In some embodiments this jar compounder design may be adapted for use in a conventional drill string as well.
Referring to
Lower mandrel 20 is at least partially disposed telescopically within outer housing 16 to define a downhole fluid chamber 24 between lower mandrel 20 and outer housing 16. In some embodiments, lower mandrel 20 is disposed entirely within outer housing 16. Uphole fluid chamber 22 and downhole fluid chamber 24 each contain fluid, have a variable stroke-dependent volume, and are sealed at uphole ends 26, 30, and downhole ends 28, 32, respectively. Variable stroke-dependent volume refers to the fact that, for example, due to the respective dimensions of upper mandrel 18 and outer housing 16 that define uphole fluid chamber 22, relative longitudinal movement between upper mandrel 18 and outer housing 16 acts to increase the volume of uphole fluid chamber 22 in one direction, and decrease the volume in the other direction. Similarly, due to the respective dimensions of lower mandrel 20 and outer housing 16 that define downhole fluid chamber 24, relative longitudinal movement between lower mandrel 20 and outer housing 16 acts to increase the volume of downhole fluid chamber 24 in one direction, and decrease the volume in the other direction. This way, motion in one direction will expand the volume, and thus the fluid contained within, and motion in the other direction will compress the volume and thus the fluid contained within. Energy may be stored in chambers 22 and 24 during either expansive or compressive movements. The fluid contained within uphole and downhole fluid chambers 22 and 24 may be, for example, hydraulic fluid. In some embodiments, the fluid may be compressible, for example compressible hydraulic liquid. The fluid creates a fluid spring within chambers 22 and 24, in which the jar compounding energy may be stored to enhance the jarring impact. A floating seal 25 may be present at least one of uphole end 26, 30 and downhole end 28, 32 of at least one of uphole fluid chamber 22 and downhole fluid chamber 24. In some embodiments, uphole fluid chamber 22 may comprise floating seal 25 at least one of uphole and downhole ends 26 and 28, respectively. downhole fluid chamber 24 may comprise floating seal 25 at least one of uphole and downhole ends 30 and 32, respectively. Floating seal 25 allows pressure differentials between either or both of chambers 22 and 24 and outside of compounder 10 to equalize. This may prevent, for example, either or both of chambers 22 and 24 from collapsing under the extreme fluid pressures that may be experienced downhole. Either or both of chambers 22 and 24 may be annular in shape. In some embodiments, there may be one or more of either or both chambers 22 and 24 (plural fluid chambers), each one operating according to the embodiments disclosed herein for compounding operation. At least one of upper mandrel 18, lower mandrel 20, and outer housing 16 may be individually composed of, for example, one or more units connected together. Each unit may be, for example, threadably connected together as is well known in the art, and as is illustrated in the figures. At least one of outer housing 16, upper mandrel 18, and lower mandrel 20 may be, for example, tubulars.
Upper mandrel 18 has a first shoulder 34 engagable with and facing a second shoulder 36 of lower mandrel 20 to move lower mandrel 20 during at least a portion of a downjar or upjar stroke. Referring to
Referring to
Referring to
Uphole fluid chamber 22 may be configured to increase or decrease in volume during downward movement relative to outer housing 16. Similarly, downhole fluid chamber 24 may be configured to increase or decrease in volume during downward movement relative to outer housing 16. In some embodiments, if the volume of one of chambers 22 or 24 is configured to expand during a downjar, the volume of the other of chambers 22 or 24 will be configured to compress during a downjar. This way, when upper mandrel 18 is in the process of moving lower mandrel 20, a greater jar enhancement may be achieved without relying solely on the expansion of one of chambers 22 or 24. This reduces the overall expansion of one of the chambers 22 or 24 required to give the same level of jar enhancement on its own. Due to the extreme pressures experienced downhole, the larger the reduction of pressure within a sealed chamber, the greater the pressure differential between the chamber and outside the compounder 10, and hence the greater the likelihood that compounder 10 may be crushed. In some embodiments, first shoulder 34 is engagable with second shoulder 36 to move lower mandrel 20 during at least a portion of a downjar. In this embodiment, downhole fluid chamber 24 may be configured to decrease in volume during a downjar, in order to create the downjar compounding force by a combination of the expansion of fluid in uphole fluid chamber 22 and the compression of fluid in downhole fluid chamber 24. This way, uphole fluid chamber 22 will be configured to decrease in volume during upward movement relative to outer housing. Thus, an upjar enhancement may be achieved by upward movement of upper mandrel 18 relative to outer housing 20, and a downjar enhancement may be achieved by a combined downward movement of upper mandrel 18 and lower mandrel 20 relative to outer housing 16.
Referring to
The operation of one embodiment of compounder 10 will now be described. Referring to
Jar compounder 10 of the type disclosed herein may be used in, for example, fishing operations, drilling operations, coiled tubing, and drill strings. The use of up or down in this document illustrates relative motions within jar compounder 10, and are not intended to be limited to vertical motions, or upward and downward motions. It should be understood that jar compounder 10 may be used in any type of well, including, for example, vertical, deviated, and horizontal wells.
In the claims, the word “comprising” is used in its inclusive sense and does not exclude other elements being present. The indefinite article “a” before a claim feature does not exclude more than one of the feature being present. Each one of the individual features described here may be used in one or more embodiments and is not, by virtue only of being described here, to be construed as essential to all embodiments as defined by the claims.
