Hydraulic drilling jar

Details Hydraulic drilling jar Hydraulic drilling jar

2000-03-29

2001-07-24

Pezzuto, Robert E. (Department: 3671)

Boring or penetrating the earth

Below-ground impact members

Fluid-operated

Reexamination Certificate

active

06263986

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to a hydraulic drilling jar, and in particular a hydraulic drilling jar adaptable for connection between the components of a drill string used in downhole drilling.
BACKGROUND OF THE INVENTION
In downhole drilling operations, whether it be when drilling for oil, gas, or water, or for civil, geological or mining engineering purposes, typically a drill string is used to connect the surface rig to the downhole bit or motor. The drill string is usually comprised of a number of tubular sections that are threaded together such that its length can be varied as needed.
During the drilling operation the drill string can sometimes become wedged against the wall of the well casing or bore hole, often requiring the application of a high impact tensile load in order to free the wedged string. In other instances high impact tensile loading may be necessary to retrieve downhole tools that have been “set” within the well, or that otherwise have become lodged within the casing. To provide the application of high impact tensile loading for such purposes, others have developed mechanical or hydraulic jars that are capable of “jarring” or impacting the drill string in an upward or downward direction. In the case of an upwardly operating jar, a high impact load is directed upwardly to retrieve tools or dislodge a wedged drilling string. In the case of a downwardly directed jar, the impact loading is typically utilized to “set” a variety of different downhole tools with the well.
Unfortunately, such existing jars generally tend to be relatively complex mechanical and hydraulic devices that add significant capital expense to the drilling operation, and that are more prone to becoming jammed and to failure.
SUMMARY OF THE INVENTION
The invention therefore provides a hydraulic drilling jar which addresses some of the deficiencies in prior developed products. The invention provides a simple structure capable of applying high impact tensile loading to a drill string without excessive complexity, costs and with a high level of dependability.
Accordingly, in one of its aspects the invention provides a hydraulic drilling jar for use in association with downhole drilling and adaptable for connection between components of a drill string or the like, the hydraulic drilling jar comprising an outer generally hollow hydraulic housing having an enclosed first end and an open second end, said first end releasably securable to a first component of the drill string; an inner mandrel assembly having a first end releasably securable to a second component of the drill string and a second end slidably receivable within said open second end of said hydraulic housing thereby forming an internal fluid chamber between said mandrel and said housing, said mandrel assembly slidable within said outer housing from a contracted position to an extended position, said hydraulic housing and said mandrel assembly operatively connecting the first and second components of the drill string; an anvil portion and a hammer portion, one of said anvil and said hammer portions situated on said hydraulic housing and the other of said anvil and said hammer portions situated on said mandrel assembly; and, a hydraulic valve received around said second end of said mandrel assembly and within said fluid chamber, wherein upon extension of said drilling jar through the application of a tensile load between said housing and said mandrel, said valve seats against said housing and said mandrel and thereby bifurcates said fluid chamber into first and second portions while pressurizing said first portion of said fluid chamber to place said hydraulic drilling jar in a cocked configuration, such that further extension of said hydraulic drilling jar through the continued application of a tensile load causes said valve to become unseated allowing for rapid de-pressurization of said first portion of said fluid chamber and a resulting rapid further extension of said hydraulic drilling jar with high impact loading of said anvil and said hammer portions.
Further objects and advantages of the invention will become apparent from the following description taken together with the accompanying drawings.


REFERENCES:
patent: 5007479 (1991-04-01), Pleasants et al.
patent: 5033557 (1991-07-01), Askew
patent: 5123493 (1992-06-01), Wenzel
patent: 5174393 (1992-12-01), Roberts et al.
patent: 5918689 (1999-07-01), Roberts
patent: 1005810 (1977-02-01), None

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