Boring or penetrating the earth – With tool shaft detail – Helix or helically arranged structure
Patent
1992-08-17
1994-08-30
Britts, Ramon S.
Boring or penetrating the earth
With tool shaft detail
Helix or helically arranged structure
1753255, E21B 1044
Patent
active
053418883
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a drilling tool intended to widen a drill well, comprising a hollow cylindrical body bordered at its ends by a first and second fixed flange, each of these flanges being provided with threaded joints so that it can be connected to a set of drill pipes.
Such a tool is used for the widening, after a time delay, of existing drill wells or, on the other hand, for immediately producing wide wells which are obtained by drilling, with a conventional drilling tool provided with a trepan or tricone bit, a narrower rough well which is directly widened into a well of larger diameter by means of a tool intended to widen a well according to the invention, which is combined with the above-mentioned conventional drilling tool.
A drilling tool intended to widen a well may also be used instead of an eccentric drilling tool or a retractable drilling tool.
The well bottom widener is designed to be introduced and lowered to a desired depth into a well drilled with an initial diameter, from which the retractable arms are unfolded to widen the well.
In the sphere of drilling, there is frequently technical and financial value in having a drill well with a large diameter in a productive zone but with a restricted diameter at the surface so that the orifice of the well can be blocked more easily should there be an ill-timed influx of pressure.
A tool for widening the bottom of a drill well is known from the document U.S. Pat. No. 4,589,504. The tool comprises a cylindrical body set into rotation by a set of drill pipes, a control device of an opening mechanism of the tool and two extendable arms. The body has a diametral cavity passing right through it. In this cavity, two extendable arms, articulated in a same longitudinal plane passing through the axis of rotation of the tool body, round pivots perpendicular to this plane.
At the rest, the arms are folded back inside the tool body. In the operating position, the arms are raised laterally to 45.degree. so as to have a cutting edge of determined shape at the lower end of the arm, the edge being profiled so as to obtain a hole profile (preferably a curved profile) for which the vertical reaction forces exerted by the ground on the arms develop round the axis of rotation of the arm a moment of forces which tends to hold the arm out and compensates the moment of forces tending to close the arm under the influence of the horizontal lateral stresses.
In this device, the tool is lubricated by a drilling fluid supplied from the surface of the ground to the tool by means of a conduit hollowed out inside the drill pipes. The drilling liquid is supplied to the vicinity of the tool in the form of jets produced by gauged nozzles directed toward the cutting edges.
The opening of the arms is controlled hydraulically by means of the drilling liquid by increasing the flow rate of the drilling fluid pumps. As soon as the hydraulic pressure of the drilling fluid exceeds a predetermined value, for example 70 bar or 7.10.sup.6 Pa, the force exerted on the piston is sufficient to displace the piston against a spring toward a stable lower position. The spring opposes the displacement of the piston under the influence of the hydraulic pressure and determines an equilibrium position. The piston drives a rack which meshes with a pinion portion, raising the arms. The arms are closed automatically as soon as the hydraulic pressure diminishes due to the fact that the precompressed spring allows the piston to rise again.
The drawback of this known tool resides in the fact that significant force has to be transmitted to the arm to enable it to move away from the tool body. This force is transmitted to the arm by means of a single tooth at a notched location which weakens the arm. The employment of the tool is dependent on the destructability of the rock and on the tendency of the tool to deviate from its axis. A second drawback is the irregular shape of the widened well and the impreciseness of the diameter obtained. Furthermore, the tool suffers from a lack of lateral stabilit
REFERENCES:
patent: 1282976 (1918-10-01), Stubbs et al.
patent: 3754609 (1973-08-01), Garett
patent: 4108256 (1978-08-01), Moore
patent: 4245709 (1981-01-01), Manuel
patent: 4549613 (1905-10-01), Case
patent: 4589504 (1986-05-01), Simpson
Britts Ramon S.
Diamant Boart Stratabit S.A.
Schoeppel Rojer J.
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