FR2752438A1 - BLOCKING DEVICE FOR DRILL HOLES IN ALL DIRECTIONS IN SPACE IN ROCKY OVERPRESSURE FORMATIONS - Google Patents

Abstract

The sealing device allows drilled holes (1) to be drilled in all directions in space and in all rock formations, for which water or an amount of water / rock or gas is present under high pressure. To this end, according to an appropriate arrangement, a determined steel tube (5) to be inserted and cemented into the rock of the massif, a first tubular section (9) connecting thereto having lateral departures (11) connected to a single jaw safety shutter (13), a tube holding clamp (21), a double safety shutter (23) and a rotary safety shutter (25), as well as a square stem valve (29) are put in circuit together. The arrangement makes it possible to carry out all of the operating steps necessary for drilling as well as for the sampling of core samples, working under pressure.

Description

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  The object of the invention is a sealing device for drilling holes in all directions in space, in rock formations with hydraulic overpressure according to the cable coring technique and with a method using of a pressure

sweep-rinse.

  The drilling done with a double core tube in the cable coring and pressure flushing process is known. This process is used for drilling in rock, rock from which coring samples have to be taken. For, in the presence of liquid or formation gas, prevent any escape of liquid or quantities of rock / liquid out of the annular space existing between the drill string and the wall of the borehole, it is known to close the mouth of the borehole with a safety shutter. It is also known to place on the last tube of the train of

taps a tap with a square stem.

  When dealing with rock formations which are placed under high hydraulic pressure, it is not sufficient in any case to close the tube of the drill string with a tap with square rod and with a safety shutter because, after having drilled a coring path, it is necessary that the coring core having been drilled can be brought, through the tube of the drill string, to the mouth of the borehole. To take the carrot, it is then necessary to dismantle the tap with square rod. As a result, it is no longer possible to provide security preventing the escape of water and / or a quantity of rocks / water or gas

finding it under pressure.

  The object of the present invention is to create a shutter device for drilling holes, in all directions in space, in rock formations subjected to hydrostatic overpressure, a device allowing sampling without risk of coring and ensuring anytime shutter

from the borehole.

  This problem is solved by the shutter device according to the invention, which is characterized in that it

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  that it comprises a determined steel tube, to be introduced and cemented into the rock of the massif, the end of which leaves the massif carries a connecting means, a first tubular section connecting to it with lateral outlets, connected to a simple safety shutter with jaws, equipped with cutting jaws, a tube clamp, a double safety shutter and a safety shutter

  rotary valve and a tap with square stem.

  Advantageous embodiments of the invention provide: - that between the connecting means and the first tubular section is inserted a valve, which is inserted in addition to the valve, after the safety jaw simple with jaws equipped with jaws cutting, or alternatively to that; - a section between the double safety shutter and the rotary safety shutter

  intermediate tubular fitted with lateral outlets.

  The shutter device according to the invention allows under all conditions, that is to say when the borehole is placed under pressure or when it is free of pressure, to drill safely in all directions (horizontal and vertical , up and down) and take core samples without uncontrolled exit through the pipe from the drill string or through the annular space between the drill string and the tube of water or a rock / water or gas mixture. If an unforeseen event occurs, such as for example faults inside the shutter system, the exit of water or a quantity of water / rock or gas, passing through the safety shutter simple equipped with cutting jaws or as well as a ball valve would be cut in an instant. Under normal conditions, it is also possible under high overpressure to hold back by means of the seal which is of a multistage type and to take the samples.

  coring samples.

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  The invention is explained in more detail using an illustrated embodiment. The single figure represents a schematic illustration of the obturator device, mounted on an underground, horizontal borehole. In a borehole 1, which is drilled substantially horizontally in the rock 3 of a solid mass, a steel tube 5 is placed, the end of which has a connecting means, for example a thread 7. The steel tube 5 is connected over a length L to the rock 3 and is sealed in isolation, for example by cementing. The adhesion acting between the steel tube 5 and the rock 3 is of such a force that any axial displacement of the steel tube 5 under the effect of the maximum possible pressure inside the rock 3, by example a pressure of 250 bars, can be safely supported. On the thread 7 is fixed a first tubular section 9, which has lateral outlets, for example pipes 11, by means of which it is possible to withdraw or introduce by pumping the fluid, or else a manometer 12 can be mounted in order to '' check the pressure. To the tubular section 9 is connected a simple safety shutter with jaws 13 equipped with cutting jaws, allowing rapid closure of the entire borehole by the fact that the tube 27 of the drill string guided through it can be cut . To the simple safety shutter 13 fitted with the cutting jaws is connected an isolation valve, for example a ball valve 15, which allows complete closure of borehole 1, when no tube 27 of the drill string is only guided through the tap 15. Behind the ball valve 15 is connected a clamp for holding the tube 21 with hydraulic operation, with the help of which the tube 27 of the drill string can be kept subject to rotation and can withstand any pressure

  axial and be prevented from leaving the borehole 1.

  Behind the hydraulic tube clamp 21 is placed a double safety shutter 23 which ensures a tight closure of the borehole 1 in the annular space when the drill string is introduced as well as after extraction of the last tube 27 of the drill string,

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  sealing being ensured over the entire cross section. As the last member or link of the shutter device then comes a rotary safety shutter 25 serving to hold with possibility of rotation the tube 27 of the drill string inserted in the borehole 1, during the progression and drilling operations, and to seal off the annular or intermediate space between the fixed parts of the obturator device and the tube 27 of the drill string, and to allow the coring process with exit from the borehole

  in the event that there is an overpressure.

  It is also possible to insert a ball valve 15 ′ behind the first tubular section 9 equipped with outlets 11. This can be provided, in addition or as a variant of the ball valve 15, before the

  hydraulic tube clamp 21.

  In addition, one can insert before the rotary safety shutter 25 an intermediate tubular part 33 provided with outlets 35 allowing the introduction and

  water diversion from borehole 1.

  The single-jaw safety shutter 13 with the cutting jaws, the rotary shutter 25 and the groups placed in the intermediate position are mounted

  preferably on a common frame 37.

  Already, at the start of the core drilling work, so after the introduction and penetration of the steel tube 5, the obturator device or the safety device for the borehole must be mounted. To carry out core drilling in a borehole 1 which is not under pressure or which is under pressure, in the example shown is inserted a system not comprising a cable and working according to the locking process with scanning pressure . The cost of setting up a lock or airlock at the time of the coring work is significantly reduced thereby in the hole

drilling 1 placed under pressure.

  As a variant, of course, a cable lock can be mounted, behind a tap with a square rod 29 which is screwed onto the last tube 27 of the drill string.

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  (sealing sleeve) so that you can also work

  under pressure in the cable core drilling process.

  After drilling the borehole 1 over a length L, the steel tube 5 is placed with a cementation, so that it is securely anchored to prevent any expulsion of the solid mass under the effect of the pressure maximum possible high that may occur. Then, the rest of the parts of the device are mounted on the thread 7

steel tube 5.

  The drill string, which is located in the borehole 1 and which is equipped with the annular space sealing device provided in the rotary safety shutter 25, is closed at the end of the last tube 27 of the drill string. rod, by means of the square rod tap 29 and, after drilling a length of coring, it is withdrawn from the soil with its screw connection vis-à-vis the last train tube 27 of the rod train until that the sealing device is in the double safety shutter 23. The hydraulic tube holding clamp 21 is now tightened around the section of tube which is for the most part still in the borehole 1. The unscrewing is carried out using the rotary head of the drilling installation (not shown) between the last tube 27 of the drill string and the tubular section still located in the borehole 1 and blocked by means of the hydraulic tube clamp 21. The last tube 21 of the drill string and the square rod valve 29 are retracted somewhat through the rotary safety shutter 25, so that the jaws of total closure can be closed by means of the safety shutter 23. Pressure is discharged, via the square rod tap 29, the area behind the total closure, then the tube 27 of the drill string is pulled together with the square rod tap 29, out of the shutter of rotary security 25. The supply of the sliding force exerted on the unscrewed assembly is ensured until the pressure is relieved, by means of the rotary head of the drilling installation. Now, in known manner, a recovery tool (not shown), which can be pumped and

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  for the inner tube of the cable core drill (not

  visible), is introduced into the tube 27 of the drill string.

  The introduction, with an airlock of the last tube 27, of the drill string with the pumpable recovery tool, as well as the tap with square rod 29, takes place in the reverse order of succession to what has been indicated. beforehand for the outing. After establishing the pressure by means of the square rod tap 29, the total closure provided in the double safety shutter 23 is opened and, after re-establishing the screw connection, the recovery tool is pumped by the tap rod

square 29.

  In addition, by inserting the intermediate tubular section 33 between the double safety shutter 23 and the rotary safety shutter 25, any introduction of water or quantities of water / sand or gas is stopped. Due to the increase in pressure compared to the pressure that appears from the borehole in all the preparatory steps inside the system (obturator), the penetration of the

mixture in the latter.

  Of course, the invention is not limited to the embodiment described; we could on the contrary conceive

  various variants without departing from its framework.

"'7

Claims (3)

  1. Closing device for boreholes (1) in all directions in space, in rock formations with hydraulic overpressure according to the cable coring technique and with a process using pressure sweep-rinse, characterized in that it comprises a determined steel tube (5), to be introduced and cemented into the rock of the massif, the end of which comes out of the massif carries a connecting means (7), a first tubular section (9) connecting to it with lateral outlets (11), connected to a simple safety shutter with jaws (13), equipped with cutting jaws, a tube holding clamp (21), a shutter for double safety (23) and a rotary safety shutter (25) as well as a tap square rod (29).   2. Sealing device for boreholes according to claim 1, characterized in that after the first tubular section (9) is inserted a tap (15 '), which is inserted in addition to the tap (15) located after the safety jaw with single jaws (13) fitted   with cutting jaws, or alternatively.   3. Shutter device according to one of   claims 1 and 2, characterized in that between   the double safety shutter (23) and the rotary safety shutter (25) is inserted a tubular section   intermediate (33) equipped with lateral feeders (35).