Drop ball catcher apparatus

A drop ball catcher apparatus for use with downhole tools in oil well drilling and installation operations. A drop ball catcher apparatus is used to receive and stow a drop ball ejected from a ball-actuated downhole tool.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an apparatus for use in the oil well industry, and, more particularly, to a drop ball catcher apparatus for use with downhole tools in oil well drilling and installation operations.

2. Description of the Prior Art

Drop ball mechanisms are used in oil well drilling and installation operations typically to activate downhole tools. In U.S. Pat. No. 6,467,546, for example, a drop ball mechanism is disclosed for use in activating downhole tools and devices, namely: float equipment, flapper valves, squeeze tools, inflatable packers, running tools, adaptors, test tools, and the like. The drop ball apparatus of the '546 patent includes a drop ball and a yieldable ball seat. The yieldable ball seat is attached to an inner sleeve arranged within a downhole tool. The downhole tool is generally suspended in a borehole on a tubular string such as a drill string. To activate the downhole tool, a ball having a diameter larger than the diameter of the yieldable seat is dropped from the surface through the tubular string and into the downhole tool where it lands in the yieldable seat. The ball plugs the yieldable seat such that communication through the seat is interrupted. Drilling fluid pressure is then increased above the ball to displace the inner sleeve axially downward thereby activating the tool. In one embodiment of the '546 patent, shifting the inner sleeve axially downward launches a second ball having a diameter larger than the drill string to activate a set of flapper valves in a float collar. Once the tool is activated, drilling fluid pressure is again increased above the first ball to force the ball through the yieldable seat and out of the tool to the bottom of the borehole.

In U.S. Pat. No. 6,155,350, assigned on its face to Baker Hughes Inc., a ball seat mechanism is disclosed for use in downhole oil well tools which are also actuated by pressure build-up means. The ball seat mechanism of the '350 patent includes a ball and a ball seat supported by a rupture disc and attached to a tubular string by a set of shear pins. To actuate the downhole tool, the ball is dropped through the tubular string and into the seat to obstruct passage through the seat. Pressure is then increased by means at the surface to a predetermined level to break the rupture disc and thus shear the shear pins. The ball and seat are then displaced from the tubular string to reestablish passage.

In U.S. Pat. No. 5,960,881, a yieldable ball seat is disclosed for shifting a diverter tool used to faciliatate surge pressure reduction while running a casing liner down a borehole. The ball seat of the '881 patent is designed to yield at a particular pressure. To shift the surge pressure reduction diverter tool, a ball is dropped through a drill string to land in the yieldable seat. Drilling mud is then pressurized to a first predetermined level above the ball to shift the diverter tool from an open port position to a closed port position. Next, the drilling mud is pressurized to a second predetermined level above the ball to force the ball through the yieldable seat and out of the casing liner to land at the bottom of the borehole.

While current drop ball systems—such as those described above—provide a reliable means for actuating downhole tools, these systems do not account for the drop ball itself once the tool has been activated. Rather, in current drop ball-actuated systems, the drop ball is displaced from the downhole tool where it falls to the bottom of the wellbore. However, at the bottom of the wellbore, the drop ball becomes an obstacle for the drill bit to break up as drilling operations are resumed. This of course expends valuable time and resources.

Accordingly, the oil well industry would find desirable a drop ball apparatus for activating a downhole tool while promoting drilling operation efficiency by minimizing the proliferation of downhole debris caused by ejecting the drop ball into the wellbore. This novel and useful result has been achieved by the present invention.

SUMMARY OF THE INVENTION

In accordance with the present invention, drop ball catcher apparatus for use with downhole tools in oil well drilling and installation operations is provided.

The drop ball catcher apparatus in accordance with the present invention is used with a ball-actuated downhole tool suspended in a borehole on a tubular string. The drop ball catcher apparatus may be used with any downhole tool requiring drop ball activation including, but not limited to: downhole circulating tools, diverter tools, float equipment, flapper valves, squeeze tools, inflatable packers, running tools, adaptors, test tools, and the like. In an embodiment of the present invention, a drop ball catcher apparatus is operatively connected to the lower end of a downhole tool to receive and stow a drop ball once it is ejected from the downhole tool.

The drop ball catcher apparatus of the present invention includes a housing with an axial bore therethrough for establishing communication between the tubular string and the wellbore. The housing includes an annular recess with a diameter greater than the diameter of the axial bore of the housing.

The drop ball catcher apparatus of the present invention further includes a sliding sleeve residing within the axial bore of the housing above the recess. A ball seat having an axial bore therethrough is arranged below the lower end of the sliding sleeve. The ball seat is a receptacle for receiving and holding the drop ball that was used to activate the downhole tool. Moreover, the ball seat is moveable between: (1) a first position where the ball seat prevents the sliding sleeve from displacing axially downward, and (2) a second position where the ball seat is located in the recess of the housing and out of engagement with the sliding sleeve to allow the sliding sleeve to displace axially downward.

The drop ball catcher apparatus of the present invention still further includes a bracket for attaching the seat to the housing, a pivot pin on which the seat rotates between the first position and second position, and a shear pin for latching the ball seat in the first position.

The drop ball catcher apparatus of the present invention also includes a drop ball for interrupting communication through the axial bore of the housing via the ball seat.

It is an object of the drop ball catcher apparatus of the present invention to minimize the proliferation of downhole debris caused by ejecting the drop ball into the wellbore.

It is an object of the drop ball catcher apparatus of the present invention to create a nonobstructed full bore flow path via the axial bore of the downhole tool.

DESCRIPTION OF SPECIFIC EMBODIMENTS OF THE INVENTION

A description of certain embodiments of the present invention is provided to facilitate an understanding of the invention. This description is intended to be illustrative and not limiting of the present invention. While the drop ball catcher apparatus is described in connection with a ball-actuated diverter tool, it is intended that the drop ball catcher apparatus may be used with any ball-actuated downhole tool.

With reference first toFIG. 1, the general components of a system in which a tool in accordance with the present invention is used are illustrated. A mast M suspends a traveling block TB. The traveling block, in turn, supports a top drive TD which moves vertically on a block dolly BD. An influent drilling fluid line L supplies the top drive TD with drilling fluid from a drilling fluid reservoir (not shown). A launching manifold LM connects to a drill string S. The drill string S comprises numerous pipe elements which extend down into the borehole BH, and the number of such pipes is dependent on the depth of the borehole BH. A surge pressure reduction bypass device or “diverter tool”100is operatively connected to the bottom end of drill string S. A drop ball catcher apparatus101in accordance with the present invention is operatively connected between the lower end of the diverter tool100and a hanger102for installing a drilling/production liner103. The drilling/production liner103is suspended from hanger102. An open guide shoe104is fastened to the bottom of the hanger102.

Solidified cement CE1fixes a surface casing SC to the surrounding formation F. The surface casing SC contains an opening O in the uppermost region of the casing adjacent to the top. The opening O controls return of drilling fluid as it travels up the annulus between the drill string S and the surface casing SC.

Solidified cement CE2fixes an intermediate casing IC to the surrounding formation F. The intermediate casing IC is hung from the downhole end of the surface casing SC by a mechanical or hydraulic hanger H.

Referring toFIG. 2, the general components of a drop ball catcher apparatus101in accordance with the present invention are illustrated. The drop ball catcher apparatus includes a housing assembly11with a top end operatively connected to the diverter tool100(FIG. 1) and a bottom end operatively connected to the drilling/production liner103(FIG.1). The housing assembly11comprises an upper housing11A, a lower housing11B, and a central housing11C. The housing assembly11has an axial bore12therethrough for establishing communication between the diverter tool and the drilling/production liner. An annular recess13formed in the central housing11C between the upper housing11A and the lower housing11B. The annular recess13has a diameter greater than the diameter of the axial bore12.

With respect toFIGS. 2 and 3, the drop ball catcher apparatus of the present invention also includes a sliding sleeve20such as a dart guide tube having an upper end and a lower end residing within the axial bore12of the upper housing11A above the annular recess13. The sliding sleeve20has a diameter smaller than the diameter of the axial bore12of the housing assembly11. The sliding sleeve20includes a protruding flange21formed on the outer surface and located at the upper end of the sliding sleeve. The flange21has a diameter equal to or slightly smaller than the diameter of the axial bore12. The flange includes a seal24, which is preferably an O-ring seal, between the sleeve20and the axial bore12. The flange further includes a spring ring25for engaging a circumferential groove14formed near the lower end of the upper housing11A. An annular volume50is formed below the flange21and between the sliding sleeve20and the axial bore12of the upper housing11A.

With respect toFIG. 3, the drop ball catcher apparatus of the present invention further includes a ball seat30having an axial bore therethrough arranged below the lower end of the sliding sleeve20. The ball seat further comprises a snap ring35for engaging a drop ball40(FIG.5). The ball seat30is moveable between a first or “obstructed” position where the ball seat engages the sliding sleeve20(as shown inFIG. 3) to prevent the sliding sleeve from displacing axially downward and a second or “recessed” position where the ball seat is located within the recess13of the housing assembly11and out of engagement with the sliding sleeve (as shown inFIG. 8) to permit the sliding sleeve to displace axially downward.

In a preferred embodiment, the drop ball catcher apparatus comprises a bracket31for attaching the seat30to the upper housing11A and a pin32on which the seat pivots between the first position and the second position. A shear pin33is used to latch the ball seat in the first position. The bracket31includes a bracket attachment device34to operatively connect the bracket to the upper housing11A and a bore seal52to prevent incidental communication around the seat30when in the first position. A set of radial ports51are formed on the on the upper end of the bracket such that the annular volume50can vent into the annular recess13when the sliding sleeve20is displaced axially downward. The set of ports51prevents a pressure build-up in the annular volume which would resist the downward shifting of the sleeve20. While this embodiment includes a shear pin to hold the ball seat in the first position, it is intended that any conventional connecting device can be used including but not limited to a latch, a snap, or a hook.

The drop ball catcher apparatus of the present invention also includes a drop ball40for interrupting communication through the axial bore12of the housing assembly11via the ball seat30. In an embodiment of the present invention, the drop ball is located at the surface on a drilling rig and is dropped down the tubular string to shift the diverter tool. Once the diverter tool has been shifted, the drop ball is received by the drop ball catcher apparatus.

Referring now toFIGS. 2-9, the operation of the drop ball catcher apparatus is described. The drop ball catcher apparatus is operatively connected to the lower end of a downhole tool, such as a diverter tool, and is run down a borehole on a tubular string, such as a drill string. To activate the downhole tool, the drop ball40is dropped from the surface and into the downhole tool via the tubular string. Once the ball is used to activate the downhole tool, it is ejected from the tool and lands in the ball seat30of the drop ball catcher apparatus101. The ball40is held in the ball seat30by the snap ring35, and drilling fluid pressure is then increased above the drop ball40to a predetermined level to shear the shear pin33and release the bracket31of the ball seat30. At this time, the bracket31rotates around the pivot pin32. Once the ball catcher apparatus has rotated out of engagement with the sliding sleeve20and into the annular recess13, the sliding sleeve is displaced axially downward. As the sliding sleeve shifts axially downward, drilling fluid is swept from the annular volume50by the flange21via the set of radial ports51. The lower end of the sliding sleeve20engages the lower housing and the spring ring25protracts radially outward as it reaches the circumferential groove14thereby preventing the sliding sleeve from shifting axially upward. Once locked in place, the sliding sleeve20traps the drop ball40in the annular recess13and forms an unobstructed flow path through the housing assembly11.

While an embodiment of the present invention is described with respect to a single drop ball catcher, it is intended that a plurality of drop ball catchers may be operatively connected in series to receive and stow drop balls ejected from a downhole tool requiring multiple drop ball activation.

In another embodiment of the present invention, the drop ball catcher may be integrated with a downhole tool—such as a diverter tool, liner hanger, or circulating tool—and used as a primary activation device. For example,FIGS. 10 and 11show the drop ball catcher apparatus integrated with a surge pressure reduction diverter tool which may be used to run a drilling/production liner103(FIG. 1) down a borehole. The housing assembly11of the tool includes a set of flow holes15to facilitate surge pressure reduction as the tool is run on a drill string down a wellbore filled with drilling fluid. The sliding sleeve20is moveable between: (1) an open port position whereby a flow path F1is formed to establish communication between the axial bore12of the housing assembly11and the annulus outside the housing assembly to facilitate surge pressure reduction (as shown in FIG.10), and (2) a closed port position whereby a flow path F2is formed to establish full bore communication via the tool (as shown in FIG.11). When the sleeve is in the open port position, drilling fluid flows upward from the borehole (open hole) into the drilling/production liner, from the drilling/production liner to the running tool, from the running toll to the diverter tool, and from the diverter tool into an annular space between the drill string and the borehole (cased hole). When the sleeve is in the closed port position, the flow path is altered such that drilling fluid flows downward from the drilling rig to the drill string, from the drill string to the diverter tool, from the diverter tool to the running tool, from the running tool to the drilling/production liner, and from the drilling/production liner into the borehole (open hole). In this embodiment, the drop ball catcher apparatus as described above is used not only to catch and stow the ball, but also to activate the diverter tool to shift the sleeve axially downward from the open port position to the closed port position.

In the specification and appended claims, the term “operatively connected” is used to mean “in direct connection with” or “in connection with via another element;” the term “set” means “one or more elements;” and the term “dropped” is used to mean “released” or “pumped.”

Moreover, in oilfield applications, a “drilling/production liner” and a “sub-sea casing” are tubular members which are run on drill pipe. The term “sub-sea casing” is used with respect to offshore drilling operations, while the term “drilling/production liner” is used with respect to both land and offshore drilling operations. For ease of reference in this specification, the present invention is described with respect to a “drilling/production liner.” However, it should be appreciated that the present invention may also be used in connection with a sub-sea casing down a borehole. In the appended claims, the term “tubular member” is intended to embrace either a “drilling/production liner” or a “sub-sea casing.”