US3399741A

US3399741A - Well jar

Info

Publication number: US3399741A
Application number: US618403A
Authority: US
Inventors: Robert C Monroe
Original assignee: Schlumberger Technology Corp
Current assignee: Schlumberger Technology Corp
Priority date: 1967-02-24
Filing date: 1967-02-24
Publication date: 1968-09-03
Anticipated expiration: 1985-09-03

Description

R. C. MONROE WELL JAR Filed Feb. 24, 1967 sept. 3, 1968 By ML ATTORNEY United States Patent 3,399,741 WELL `lAR Robert C. Monroe, Houston, Tex., assgnor to Schlumberger Technology Corporation, Houston, Tex., a corporation of Texas Filed Feb. 24, 1967, Ser. No. 618,403 5 Claims. (Cl. 175-297) ABSTRACT OF THE DISCLOSURE A hydraulic mechanism in a Iwell jar provides a time delay by means of a piston moving in a compression bore to compress a hydraulic iluid in a chamber. The piston is release-d upon its movement into an enlarged bore to produce a large jar-ring in the mechanism. A normally open bypass valve is provided in the system to increase the bypass of fluids around the piston, which limits the amount of uid pressure generated in the chamber and thereby limits the amount of the jarring force. However, the bypass valve is arranged to close upon the application of a large force to the moving piston which, in turn, permits an increased pressure and a much larger jarring force to be generated by the mechanism. Therefore, the system provides a means for selectively permitting a light or heavy jarring force to be applied to a stuck object in a well bore.

Background of the invention This invention relates to a well jar, and, more particularly, to a hydraulic well jar having means for selectively permitting -a light or heavy jarring -force to be applied to an object stuck in a well bore.

In the oil industry, jars are used on a wireline or string drill pipe for the purpose of providing, when needed, an impact force to a part stuck in a well bore. Jars operate on the principle of a hammer member striking an anvil member to deliver a large impact for-ce to the stuck part. A hydraulic jar uses a hydraulically timed delay for the purpose of developing large lforces within a hydraulic system 'in the well which, when released, impact the hammer on the anvil generating a large shock force on the stuck part. The time delay in such a System typically is provided by restricting flow of hydraulic fluids between `telescoping members while the hammer member moves toward the anvil member. This restricted flow is `dependent upon the size of a restricted orifice formed between telescoping jar members. As will be appreciated, such restriction of hydraulic fluids between the telescoping members compresses the hydraulic fluid to produce tremendous forces within the jar. Thus, the rate of such restricted uid ow is determinative of the amount of force to be developed by the jar mechanism. l

In certain applications, it is desirable to impart a light jarring force to a stuck object. A jar used in a coring operation is typical of such a situation. In a coring operation, the jarring force is used to break off a core being taken by a coring mechanism in -a well bore. In such an application, too large a jarring force willfoften damage the core. On the other hand, where the jar is used to remove a stuck piece of equipment from the well bore, a much larger jarring force is desirable.

It is, therefore, Idesirable to have a single jar mechanism which may be used in either =a light or heavy jarring situation. The all purpose jar alleviates the need of building and maintaining special purpose jars and the all purpose jar permits the application of light and heavy jarring forces at all times in any type operation. For instance, if during a coring operation, a portion of the tool string becomes stuck, a large jarring force may be applied to remove the stuck portion, while at the same time the jar. However, this method takes an undesirably long time period to operate the delay mechanism. In order to overcome this time disadvantage, a light oil is sometimes used in the jar mechanism to permit faster metering of oil through the hydraulic delay thus permitting the jar to operate faster under low pull conditions. If, however, the coring device `or other portion of the tool should become stuck in the well bore, the light oil precludes a suticient delay time to permit a heavy jarring force to be applied to the stuck object.

Accordingly, it is yan object of the present invention to provide a new and improved well jar which selectively permits a light Ior heavy jarring force to be applied to an object stuck in a well bore.

Summary ofthe invention Apparatus in accordance with the present invention includes a hydraulic well jar having an anvil, a hammer, and hydraulic delay mechanism. In the hydraulic delay mechanism, `when tension is -applied to the jar, a valve piston tted relative to a compression bore provides a restricted annular space which regulates the by-pass of uid while the piston compresses fluid in a chamber. An enlarged bore is 'formed at the upper end of the cornpression bore. A selectively operable secondary bypass means provides for accelerated fluid tlow around the valve piston during its movement in the compression bore. This secondary bypass means includes a spring-loaded valve which is normally open to provide for such an `accelerated iluid bypass. However, upon the application of a large tension force to the piston, the resulting pressure Igenerated in the chamber closes the secondary bypass valve so that all uid flowing past the piston must ow through the restricted annular space. The secondary valve is adjustable to permit regulation of the pressure required to close the secondary bypass. As soon as the piston exits from the compression bore into the enlarged bore, iuid freely bypasses the piston .and the hammer is accelerated and comes into contact with the anvil to provide the jarring impact force. To reset the jar, the hammer is moved back to its original position where the valve piston is in the compression bore.

The novel features of the present invention are set forth with particularity in the appended claims. The present invention, both as to its organization and manner of operation together with further objects and advantages thereof, may best be understood by way of illustration and example of certain embodiments when taken in conjunction with the accompanying drawings.

Brie)c description of the drawings FIGURE 1 is a cross-sectional view of a well jar embodying concepts of the present invention;

FIGURE 2 is an enlarged view of the hydraulic section of the apparatus shown in FIGURE 1; and

FIGURE 3 is 'an enlarged view of the secondary bypass valve shown in FIGURE 2.

Description of the preferred embodiment Referring irst to FIGURE 1, the hydraulic well jar 10 includes a telescopically mounted mandrel 11 and housing 12. The mandrel 11 at its upper end has external splines 13 received within internal splines 14 on the housing permitting rotation of the drill string through the jar and at the same time also permitting longitudinal, nonrotative movement between the housing and mandrel.

The mandrel 11 has upper and

lower sections

15, 16 of identical diameter, the upper section 15 being received within an upper borev 17 in the housing while the lower section is received within the bore 18 of an annular piston 19 slidably mounted within a bore 20 in the housing. High pressure sealing means are provided between the mandrel and housing at 12a and on the piston 19. The

equal diameter sections

15, 16 of the mandrel provide for pressure balancing of the mandrel while the piston 19 compensates for volume changes in a fluid received in a hydraulic chamber 29 between the mandrel and the housing. The mandrel 11 below the floating piston 19 is sized to a diameter somewhat less than the bore 21 of the housing to permit well bore uid access to the oating piston 19.

The housing 12 has an enlarged bore 22 which forms a downwardly facing shoulder 23, the shoulder being the jar anvil. The mandrel 11 is provided with an annular enlargement having an upwardly facing shoulder 23a forming a hammer.

The hydraulic system of the jar is shown in greater letail in FIGURE 2 and further includes valved piston means provided on the mandrel below the hammer 23a in the form of an enlarged flange 24 on the -mandrel on which a tubular metal sleeve 25 sets. The abutment of the lower end of the sleeve with the upper side of the flange forms a metal-to-rnetal fluid seal. The sleeve is normally urged toward the enlarged ange by an annular ring 26 slidably received on the mandrel 11 `and a compression spring 27 positioned between the ring 26 and lower portion of the mandrel hammer 23a. The annular ring 26 has a lower base portion slidably mounted on the mandrel, the base portion having longitudinal bypass ports 2S. The tubular sleeve 25 is slidably received within a compression bore in the housing which adjoins the lower end of the enlarged bore 22 of the fluid chamber 29. Sleeve is slidably mounted on an enlarged splined portion 32 of the mandrel. The fit between the tubular sleeve and compression bore is such that a restricted annular space is provided to meter uid past the sleeve 25. A threaded mechanism is provided at the upper end of the mandrel 11 and acts between the mandrel and housing. The mechanism 30 permits selective adjustment of the distance to which the sleeve 25 extends into the compression bore 20 thereby providing a selective adjustment of the time delay for operating the jar. The jar mechanism thus far described is set forth in greater detail in U.S. Patent No. 3,251,426.

Operation of the apparatus described thus far is briey as follows: The jar is coupled in a drill string for use in the usual Idrilling, testing or other such operations in a well bore. It the drill string becomes stuck, the operator determines the tension to be applied, pulls tension on the drill string and locks the drill string at the desired tension in the drill stand. In the jar, the housing 12 is attached to the stuck portion while the mandrel 11 has tension applied thereto. The mandrel first moves slowly upward relative to the housing because the valve piston means, including the sleeve 25, compresses the fluid contained in the fluid chamber 29. The rate of movement is controlled by the rate at which the compressed fluid bypasses the piston between the sleeve 25 and compression bore 20. Slow movement of the piston means continues until the tubular sleeve 25 exits from the compression bore 20 into the enlarged bore 22 whereupon the jar is tripped because Huid :may now rapidly bypass between the housing 12 and sleeve 25. This, in turn, permits a rapid relative movement between the mandrel and the housing which terminates with an impact of the hammer 23a upon the anvil 23. If the pipe, tool, or other object is still stuck, the operator repeats the operation. To reset the jar, the mandrel is moved downwardly and the tubular sleeve 25 will move upwardly so that uid may bypass between the sleeve 25 and mandrel and permit a quick resetting of the valve piston means to its initial position in the compression bore. By means of the threaded mechanism 30, the amount of time required for the 4 i4 l piston means to move through the compression bore 20 and exit into the enlarged bore 22 can be selectively adjusted.

As set forth in the background of the invention, some jarring applications, for example jars used in coring operations, require a relatively light force to be applied to the stuck object, i.e., the core. If the jar, however, is designed for the application of heavy loads to remove a stuck tool in the well, it is readily seen that the use of the jar for both purposes would lead to drawbacks in the operation of the tool in one or the other or both types of applications for which a jar is used. For example, if the jar is constructed to be operated with a heavy force applied to the stuck object, the piston means is designed to operate in `a certain amount of time to generate the forces required and release them thus setting up the jarring blow. lf, however, it is desired to pull a light load on the same jarring tool in order to produce a light jarring force, it would take an extremely long period of time to operate the piston means for tripping the ar. J By means of the present invention, the jar may be selectively operated to produce large jarring forces for removing stuck tools or light jarring forces to break off cores for example. To accomplish this, a secondary bypass valve 33 is provided in the hydraulic system. The secondary bypass valve communicates the hydraulic systern above and below the enlarged ange 24 on the mandrel.

The valve device 33 is shown in greater detail in FIG- URE 3 and includes a vertical passageway 34 which connects the upper side of the enlarged flange 24 with an enlarged vertical bore 36 communicating with the lower side of the enlarged flange 24. A valve housing 38 is threadedly received within the bore 36 and has seal means 39 at its upper tapered end to provide a fluid-tight seal between the valve housing and the bore 36. An annular valve seat 41 is threadedly received within a bore 35 in the valve housing 38. Seal means are positioned between the housing 38 and the valve seat 41. A passageway 40 in the upper end of the valve housing connects the bore 35 with the passageway 34. The upper end of the valve seat 41 has a frusto-conical surface 42. A valve member 43 is movably received within bore 35 between the upper end of the valve housing 38 and the valve seat 41. A frusto-conical surface 46 is formed on the lower side of the valve member 43 which, when engaged with the surface 42 on the valve seat, provides a fluid-tight seal which prevents communication of fluid through the secondary valve 33. An upper axial bore 47 is formed in the valve member 43. Ports 48 are provided in the valve member to provide fluid communication between the axial bore 47 and the exterior of the valve member. The valve member 43 is sized to provide a space 49 between the valve member and the interior bore 35 of the valve housing. The valve seat 41 has a longitudinal axial bore 52 extending therethrough. A spring retainer nut 53 is threadedly received in the lower end of bore 52. A spring 54 is positioned between the retainer nut 53 and the lower side of the valve member 43.

The operation of the secondary bypass valve 33 is as follows. If it is desired to produce a small jarring force as in the case of a coring operation, an upward pull is applied to the drill string and thus the mandrel on the jar, the housing being attached to the coring device, etc. If a light pull is applied to the string of pipe, fluid will meter between the tubular sleeve 25 and compression bore 20 in the normal fashion. In addition, lluid will also bypass through the secondary valve system 33, the spring 54 in the secondary valve system being sufliciently strong to maintain the valve member 43 spaced from the valve seat 41. This permits fluid to pass downwardly from the high pressure, upper side of the flange 24 through the passageways 34, 40 into bore 47 of the valve member 43, through the ports 48, into the annular space 49, downwardly into the bore 52 of the valve seat and through the bore of the spring retainer nut 53 which communicates with the lower or low pressure side of the flange 24. This passage of fluid through the secondary bypass valve permits the application of light forces to the jar mandrel to trip the jar in a reasonably short period of time. As the upward force is continually applied to the mandrel, the sleeve 25 and enlarged flange 24 move upwardly into the chamber 29 whereupon the mandrel accelerates upwardly to bring the hammer 23a into contact with the anvil 23 to produce the jarring force.

If, on the other hand, it is desired to apply a large jarring force to an object which is stuck in the well bore, for example, if the coring device should become stuck in the well bore, such large force is applied as follows. A heavy pull is taken on the pipe string and thus applied to the mandrel of the jar. Such heavy pull generates a large llow of oil to create a pressure increase in the passageway 40 which is suicient to overcome the force of spring 54. Thus, the valve member 43 is moved downwardly against the force of the spring 54 to mate the surface 46 on the valve member with the surface 42 on the valve seat thereby providing a metal-to-metal seal and preventing passage of iluid through the bore 52 in the valve seat. It is readily seen that the greater the pull on the mandrel, the greater the ow through passageway 40, with the resulting higher pressure acting on the valve members to create a tighter seal. With the secondary passage closed, uid can only bypass between the sleeve 25 and compression bore 20 thus permitting a heavy load to be applied to the jar mechanism due to the increased restriction, which in turn generates a large jarring force.

The spring retainer plug 53 is threadedly received within the bore 52 of the valve seat to permit a selective pretensioning of the spring 54 so that the secondary bypass 33 may be adjusted to operate at any desired pressure differential, thereby determining the amount of force which is necessary to close the secondary bypass which in turn changes the operation of the jar from a low force to a high force jar.

While a particular embodiment of the present invention has been shown and described, it is apparent that changes and modilications may be made without departing from this invention in its broader aspects and, therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of this invention.

What is claim is:

1. A hydraulic well jar including telescopically mounted mandrel and housing members movable between contracted and extended positions, said members having anvil and hammer means thereon, said anvil means being spaced from said hammer means when said members are in said contracted position and arranged for contact when said members are in said extended position, a sealed hydraulic chamber between said members and adapted to receive a hydraulic fluid, hydraulic means in said chamber coupled to one of said members and movable relative to the other of said members, said hydraulic means cooperating with said members during movement over a rst relative distance from said contracted position toward said extended position to compress fluid in said chamber and permit a limited bypass of fluid and cooperating with said members when moved beyond :said first distance to permit a relatively free bypass of fluid, and selectively operable valve means in said hydraulic means for bypassing uid in addition to said limited bypass of fluid as said hydraulic means is moved through said first relative distance.

2. A well jar apparatus comprising: telescopically arranged mandrel and housing members adapted for limited relative movement between contracted and extended positions; and hydraulically operable means including piston means on one of said members and first bypass means for -bypassing tluid between said piston means and the other of said members to retard relative movement of said members during a portion of said relative movement between said positions, said hydraulically operable means further including second bypass means which can be selectively operated in order to bypass uid past said piston means in order to vary the retarding effect of said hydraulically operable means.

3. The apparatus of claim 2 wherein said second bypass means includes valve means responsive to fluid pressure generated on one side of said piston means for c011- trolling llow rate past said piston means.

4. The apparatus of claim 3 further including means for adjusting said valve means to operate at preselected pressures.

5. A well jar `apparatus. comprising: inner and outer members arranged for longitudinal relative movement between contracted and extended positions, said members having means engageable in one of said positions to provide a jarring 'blow to an object connected to one of said members; and hydraulic means for retarding relative movement `of said members toward said one position only during a portion of said relative movement, said hydraulic means including irst and second normally open bypass means, one of which is closable in response to a preselected force applied to the other of said members.

References Cited UNITED STATES PATENTS 2,678,805 5/ 1954 Sutlif 175-297 3,087,559 4/1963 Hazen et al. 175-297 3,251,426 5/1966 Lebourg 175-297 3,349,858 10/ 1967 Chenowe'th 175-297 DAVID H. BROWN, Primary Examiner.