HYDRAULIC BRAKE FOR DRILLING-BIT

Abstract

Method for blocking/braking at least one conical inlet wheel of a drilling-bit of a drilling tool, said method consisting in using at least one toothed wheel (1) of said drilling-bit as an element for driving a hydraulic pump (P) which pumps in a closed circuit (17), said circuit including a controlled distributor (9) in order to take up either an open position or a closed position; such that, in the open position, the pump runs freely without absorbing energy, and that, in the closed position, said pump (P) is hydraulically blocked, which blocks the rotation of the toothed wheel (1).

Description

The present invention relates to drilling tools for the extraction of fossil products such as crude oil or gas.

In a known manner, a drilling tool is constituted by a pipe which is completed by a drilling head, which is made up by conical wheels, provided with teeth which are mounted so as to rotate freely, the penetrating effect thereof being supplied by the rotating torque imparted to the pipe which carries the drilling head. In a usual manner, the drilling head includes three cone-shaped toothed wheels also called a drilling-bit.

Such a tool is intended for carrying out vertical drilling operations. However, it is increasingly often necessary to change and control the direction of drilling. Complicated techniques of a costly implementation are used to do this.

It has been shown that it is possible to direct a drilling operation using a classic drilling tool if it is known how to stop the toothed wheels of the tool from rotating freely, this being for the three wheels and in a manner guided by the driller.

However, up to now it has not been possible to implement said technique in a satisfactory manner as it comes up against numerous difficulties, to whit: the lack of available space in the drilling head: increased temperatures; the presence of sludge and possible impacts; to which it is necessary to add, on the one hand, the necessity of supplying a high amount of torque in order to stop a drilling wheel, and on the other hand, the necessity of having an increased braking phase frequency.

The object of the present invention is to resolve said problem.

The basic concept of the invention consists in using at least one wheel of the drilling-bit, rotating freely, as an element for driving a hydraulic pump, which discharges into a circuit which includes a controlled distributor in order to take up either an open position or a closed position; such that, in the open position, the pump runs freely without absorbing energy and that, in the closed position, it blocks the rotation of the toothed wheel up to the maximum torque imparted by the toothed wheel to the pump.

To do this, according to one embodiment, the invention supplies a method for controlling a toothed wheel of a drilling-bit, in which method the toothed wheel of said drilling-bit is used as an element for driving a hydraulic pump which pumps into a closed loop hydraulic circuit, said circuit including a controlled sealing member, the method including the steps of:

• controlling the sealing member in a forward direction in order to eliminate the hydraulic braking force exerted onto the toothed wheel, and
• controlling the sealing member in a reverse direction in order to increase, notably to create, the hydraulic braking force exerted onto the toothed wheel.

According to an embodiment of the method in which the drilling-bit is rotated, the method includes phases for braking the toothed wheel alternated with phases for releasing the toothed wheel.

The invention also supplies a drilling-bit which includes a drilling pipe, three toothed wheels mounted in a pivoting manner on said drilling pipe and at least three hydraulic brakes arranged in the drilling pipe, in which each hydraulic brake includes a closed loop hydraulic circuit, a hydraulic pump arranged in the closed loop hydraulic circuit in order to suck up a hydraulic fluid in a first portion of the hydraulic circuit and to pump out the hydraulic fluid in a second portion of the hydraulic circuit and a controlled sealing member arranged in the closed loop hydraulic circuit between the first portion and the second portion, the hydraulic pump including a rotary pumping member coupled to one of said toothed wheels in order to rotate integrally with said toothed wheel.

The present invention can, moreover, include all or part of the following arrangements.

• • a) The pump is a pump with axial pistons which are driven by a swash plate, the swash plate forming the rotary pumping member of the pump and comprising a shaft which is integral with the toothed wheel.
  • b) The shaft of the swash plate is fixed in an axial bore provided in a cylindrical support of the toothed wheel.
  • c) The pump is a pump with radial pistons which are driven by a cam which is integral with the toothed wheel.
  • d) The pump is a geared pump in the event of weak torque.
  • e) The pump is a rotary pump or any other flow generator capable of responding to the need for braking the toothed wheel and capable of supporting brutal and repeated stop/start operations.
  • f) The sealing member is controlled in an electric or mechanical manner or in another manner.
  • g) The sealing member includes a distributor having a forward state as default.
  • h) The hydraulic brake includes a pressurized and pressure-compensated hydraulic fluid reservoir in order to take account of the exterior pressure in the area where the drilling operation is located.

By way of a non-restricting example and in order to facilitate the understanding of the invention, the attached drawings are as follows:

FIG. 1—shows a perspective view illustrating a known-type drilling-bit which includes three conical wheels provided with teeth.

FIG. 2—shows a sectional view of the toothed wheels of FIG. 1.

FIG. 3—shows a schematic view illustrating an implementation of the method according to the invention.

FIG. 4—shows a sectional view illustrating the toothed wheel of FIG. 2 modified so as to be associated with an axial pump with a swash plate.

FIG. 1 shows a drilling head or drilling-bit, of the known type, which includes three conical toothed wheels mounted on a body 20. FIG. 2 is a sectional view of one of the three toothed wheels of FIG. 1.

Said wheel is made up by a conical body 1, the surface of which is provided with teeth 2; said conical body being threaded on a cylindrical support 3 which penetrates into a corresponding cylindrical bore 4. A ball bearing 5 allows the conical body 1 to run freely on its support 3, when the drilling pipe which carries the toothed wheels is made to rotate. The type of toothed wheel 2, widely known, does not include any means for braking or immobilization.

The method according to the invention is illustrated by the schematic diagram of FIG. 3.

The conical wheel 1, provided with teeth 2, drives, by any appropriate means which will be described below, a pump P, the delivery 6 of which is connected to the suction 8 thereof by means of a circuit 7. Downstream of the outlet 6, the circuit 7 includes a distributor 9 which can take up two positions: an open position (shown) and a closed position.

When the distributor 9 is in the open position, the pump P runs freely without offering any resistance to the rotation of the toothed wheel 1.

Contrary to this, when the distributor 9 is in the closed position, it is no longer possible for hydraulic liquid to circulate in the circuit 7 and the pump P is blocked from rotating. As it is mechanically connected to the toothed wheel 1, the latter is also blocked from rotating up to the torque admitted by the pump P.

It can be seen that in this way it is possible, by acting on the distributor 9, to block and unblock the toothed wheel 1 at will. A hydraulic fluid reservoir 19 is connected to the circuit 7 upstream of the pump P in order to compensate for fluid losses. Said reservoir is acted upon by an elastic member in the manner of a pressure accumulator in order to maintain a pressure in the circuit 7, for example approximately 2 bar, and to ensure pressure compensation for the pressure prevailing in the shaft at the place where the drilling-bit is located.

FIG. 4 illustrates a first method of implementing the method according to the invention.

The cylindrical support 3 of the toothed wheel 1 is provided, along the rotational axis thereof, with an axial cylindrical bore 13 in which a shaft 12 is fixed, carrying a swash plate 11 which can run in a cylindrical chamber 10, which is arranged in the cylindrical support 3. The shaft 12 is made to rotate integrally with the toothed wheel 1 by means of a pin 14 or other methods of rotational connection.

A plurality of hollow pistons 15, co-axial with respect to the shaft 13, are supported against the face of the swash plate 11 by means of contacts 16 and are supplied with hydraulic liquid, prevailing in the chamber 10, by means of the suction lunule cut on the face of the swash plate 11.

As said distribution of hollow axial pistons 15 resting by means of contacts 16 against the face of a swash plate and supplied by means of a lunule on the face of said plate has been known and commercialized for very many years by the applicant, it will not be described in detail.

The rotational movement of the toothed wheel 1 drives the rotation of the swash plate 11, which prompts the hollow pistons 15 into an alternative movement pumping hydraulic liquid located in the chamber 10 inside which the plate 11 runs.

The pumped liquid is drained off through the outlet 6 and returns into the pump through the inlet 8.

As has been explained beforehand in connection with FIG. 3, when the distributor 9 is open, the pump, made up by the swash plate 11 and the pistons 15, pumps the liquid circulating freely in the circuit 7 when the toothed wheel 1 rotates.

Contrary to this, when the distributor 9 is in the closed position, it is no longer possible for any hydraulic liquid whatsoever to circulate: this results in the swash plate 11 no longer being able to turn, therefore the shaft 13 which carries it is no longer able to turn, which immobilizes the toothed wheel 1 which is pinned onto the shaft 13 of the pump.

When the distributor 9 is electric-driven, for example a solenoid valve, it is very easy to program the openings/closings thereof in a sequential manner, and therefore the stopping/rotating phases of the toothed wheel 1.

The three toothed wheels 1 of a drilling head are preferably equipped in this manner.

The pump described in the present invention is an axial piston pump, it would perhaps be possible according to the space available to accommodate a radial piston pump.

According to the torque to be supplied, other pump technologies could be used, such as, for example, rotary pumps, gear pumps or other flow generators.

It is understood that if the means for driving the pump P is integral with the toothed wheel 1, all blocking, or braking, of the flow of the pump P by means of the distributor 9 brings about a blocking or braking of the toothed wheel 1, whatever the pump P may be.

In the closed position of the distributor, the hydraulic pump is going to supply a braking torque in proportion to the cubic capacity of the pump and to the internal pressure generated by the pump, thanks to the friction torque imparted to the pump by the input wheel of the drilling-bit.

The connection between the ground and the tool could be effected inside the pipe which carries the drilling tool. Thus, thanks to a control program for opening/closing the distributor, the operator on the surface will be able to stop or release the toothed drilling wheels.

In one embodiment, when the rotational torque supplied by the rotation of the toothed wheel is in excess of the torque supplied by the pump, the latter will slide, that is to say that the sliders by means of which the pistons are supported against the swash plate 11 will slide.

EXAMPLE

A pump having a cubic capacity of 8 cm³ is arranged on a drilling-bit used in an active drilling operation; the wheel of the drilling-bit rotating between 200 and 400 t/min on average.

To do this, the different components of the pump are calibrated so that it can supply an instantaneous pressure of 2000 bar at 200 t/min.

Claims

1. Method for controlling a toothed wheel of a drilling-bit, in which method the toothed wheel (1) of said bit is used as an element for driving a hydraulic pump (P) which pumps in a closed loop hydraulic circuit (7), said circuit including a controlled sealing member (9), the method including the steps of:

controlling the sealing member in a forward direction in order to suppress the hydraulic braking force exerted onto the toothed wheel (1), and

controlling the sealing member in a reverse direction in order to increase the hydraulic braking force exerted onto the toothed wheel (1).

2. Method according to claim 1, in which the drilling-bit is rotated, the method including phases for braking the toothed wheel alternated with phases for releasing the toothed wheel.

3. Drilling-bit including a drilling pipe (20), three toothed wheels (1) mounted in a pivoting manner on said drilling pipe and at least three hydraulic brakes arranged in the drilling pipe (20), in which each hydraulic brake includes a closed loop hydraulic circuit (7), a hydraulic pump (P) arranged in the closed loop hydraulic circuit in order to suck up a hydraulic fluid in a first portion (8) of the hydraulic circuit and to pump out the hydraulic fluid in a second portion (6) of the hydraulic circuit and a controlled sealing member (9) arranged in the closed loop hydraulic circuit between the first portion and the second portion, the hydraulic pump (P) including a rotary pumping member coupled to one of said toothed wheels (1) in order to rotate integrally with said toothed wheel.

4. Drilling-bit according to claim 3, characterized in that the pump (P) is a pump with axial pistons (15) which are driven by a swash plate (11), the swash plate forming the rotary pumping member of the pump and including a shaft (13) which is integral with the toothed wheel (1).

5. Drilling-bit according to claim 4, characterized in that the shaft (13) of the swash plate (11) is fixed in an axial bore (14) which is provided in a cylindrical support (3) of the toothed wheel (1).

6. Drilling-bit according to claim 3, characterized in that the pump (P) is a pump with radial pistons which are driven by a cam which is integral with the toothed wheel (1).

7. Drilling-bit according to claim 3, characterized in that the pump (P) is a geared pump or another flow generator.

8. Drilling-bit according to claim 3, characterized in that the sealing member (9) is controlled in an electric or mechanical manner.

9. Drilling-bit according to claim 3, characterized in that the sealing member (9) includes a distributor having a forward state as default.

10. Drilling-bit according to claim 3, in which the hydraulic brake includes a pressurized and pressure-compensated hydraulic fluid reservoir (19) connected to the first portion (8) of the hydraulic circuit (7).

11. Drilling-bit according to claim 3, including three toothed wheels and three hydraulic brakes in order to brake the rotation of each of said toothed wheels independently.