Spring devices – Fluid – Expansible-contractible chamber device
Reexamination Certificate
1999-09-11
2001-10-30
Oberleitner, Robert J. (Department: 3613)
Spring devices
Fluid
Expansible-contractible chamber device
C267S137000, C175S300000, C175S322000
Reexamination Certificate
active
06308940
ABSTRACT:
TECHNICAL FIELD
This invention relates to an energy absorbing device for tubular members, specifically to such devices for arresting both longitudinal and torsional shocks on tubular members used in drilling operations.
BACKGROUND ART
In the process of rotary drilling of wells, a variety of abnormal forces can cause stress on the drill string members which comprise the drill string assembly. If these abnormal forces or loads occur repetitively, they can cause failure of the drill string assembly. Down hole vibration and torque have long been associated with bit-failure and drill string failure. These various events are described as stick/slip, bit whirl, bit bounce, and bottom-hole-assembly (BHA) whirl and resonance. Although highly cost-effective, the development and deployment of new slimhole drilling techniques has been hampered by mechanical problems resulting from bit whirl and stick-slip problems.
Directional drilling programs have introduced other problems associated with various shock fatigue factors. The use of downhole motors for driving the drill bit has also been delayed because of vibrational problems associated with the forces described herein.
Although these events have long been recognized as a cause of drill string failures and a variety of tools have been developed to limit or eliminate these shocks, no generally acceptable device has been developed which is capable of absorbing the damaging overload stresses from repetitive longitudinal and rotary shocks.
A number of prior art devices have been proposed to absorb shocks in a drill or pipe string. For example, U.S. Pat. Nos. U.S. Pat. No. 2,212,153 to Eaton (1940) (relating to sucker rod vibrations only), U.S. Pat. No. 2,756,022 to Sturgeon (1956), 3,871,193 to Young (1975), U.S. Pat. No. 3,998,443 to Webb (1976), 4,600,062 to Teng (1986) and U.S. Pat. No. 4,844,181 to Bassinger (1989), each describe devices or combinations of devices to absorb axial or longitudinal shock, yet allow torque transmission to the drill string. U.S. Pat. No. 3,998,443 to Webb (1976) discloses an arrangement to absorb both longitudinal and torque shock, but limited excessive torque by translation of the torque into longitudinal movement. Thus, this patent did not independently absorb both torque and longitudinal shock in the drill string.
DISCLOSURE OF THE INVENTION
The present invention provides an shock/vibration-absorbing tool that will effectively act to reduce or eliminate abnormal shocks from being transmitted through the drill string irrespective of the source of the shock. Abnormal energy can be imparted to the drill string by a number of sources or causes. These energy loads can manifest themselves as longitudinal movement in the drill string, or torsional movement in the drill string, or both. The present invention provides a tool which acts intermediate the drill string and the bottom-whole assembly (BHA) or bit to allow progressively resistive longitudinal movement to absorb longitudinal or axial shocks as from bit bounce. Independently of that feature, the tool is designed to absorb abnormal rotation of the drill string as from bit whirl. This invention thereby prevents this abnormal energy from either source from propagating throughout the drill string assembly. The tool consists of a mandrel attached through an intermediate assembly to the lower sub assembly which both absorbs unusual energy which is transmitted, yet permits continuous torque to be transmitted to the drill bit from the surface drive means.
If the source of the energy shock originates above the tool, the mandrel is compressively moved telescopically into the drive cylinder which allows continued rotational movement, while simultaneously absorbing (through both mechanical and hydraulic means), the initial energy loading of the shock. The shock is dampened by the movement of the mandrel into the annular space provided by the drive cylinder, connector sub and compression cylinder which cooperatively and progressively resist the shock and the damaging movement of the drill string by resilient cooperating mechanical and hydraulic means.
If the source of the energy shock originates below the tool, the energy is transmitted to the tool which drives the lower sub and compression cylinder up, causing compression of the lower resilient assemblies, which in turn move the compression mandrel against the hydraulic and mechanical energy absorbing means in the drive cylinder. The dampening effect of the present invention from both directions, and independent of the rotational energy which may be continued to be imparted the drill string, realizes the long-desired but unobtained goal of a device which absorbs rotational and longitudinal shocks. The tool continues to provide rotational energy which is required to maintain movement of the drill bit on the well bottom.
A further object of this tool is to provide a tool in which the longitudinal axial shock absorbing means is separate and apart from the torque shock absorbing means.
A still further object of this tool is to provide a tool in which the longitudinal shock means will address both light and heavy shock loads.
Another object of this tool is to provide a tool in which the torque-shock absorbing means has the ability to absorb at least two complete 360° turns.
An additional object of this tool is to provide a tool for use with polycrystalline diamond compact bits in which the torque-shock absorbing means will address bit whirl, both clockwise and counterclockwise.
Another object of this tool is to provide an energy absorbing device in which the pump-out or thrust means has a low effective piston area.
Another object of this tool is to provide a tool which will absorb abnormal energy conditions in the drill string to provide the elimination of excessive torque on drill string joints, which will lessen the need for excessive force in loosening joints upon recovery of the well string.
The transmission of energy through the tool is symmetrical whether the compressive energy originates at the bit end of the tool or from above the tool. Since damage can be experienced to the mechanical top-drive units from abnormal torsional shocks, the placement of the energy-absorbing drive mechanism of the invention may be used to absorb abnormal energy being transmitted up the drill string to the drive unit.
Other objects and advantages of the tool will become apparent from a consideration of the following description and the drawings.
REFERENCES:
patent: 4139994 (1979-02-01), Alther
patent: 4257245 (1981-03-01), Toelke et al.
patent: 4462471 (1984-07-01), Hipp
patent: 5033557 (1991-07-01), Askew
patent: 5224898 (1993-07-01), Johnson et al.
patent: 5323852 (1994-06-01), Corette et al.
patent: 5372548 (1994-12-01), Wohlfeld
Hayden Jack W.
Henkel Sean C.
Kramer Devon
Noah Wesley T.
Oberleitner Robert J.
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