WO1991019075A2

WO1991019075A2 - Double-tube core drill for inclined drilling

Info

Publication number: WO1991019075A2
Application number: PCT/BE1991/000032
Authority: WO
Inventors: Staffan Paues
Original assignee: Diamant Boart Stratabit S.A.
Priority date: 1990-05-31
Filing date: 1991-05-30
Publication date: 1991-12-12
Also published as: DE69103007T2; EP0531336A1; CA2083827A1; DE69103007D1; BE1004330A3; RU2086749C1; EP0531336B1; WO1991019075A3

Abstract

A double-tube core drill wherein the inner tube (2) is connected to the outer tube (1) by a multi-element needle and/or ball bearing (11), allows for the inner tube (2) to be made rigid and prevents it from rotating along with the outer tube (1). The extraction device (9) and the inner wall (38) of the tube are preferably covered with an antifriction coating. A set of stabilizing elements (67) are spread along the outer tube to stabilize the inner tube (2). Said inner tube has a tapered shoe (32) provided with a lower bevelled lip (14). The drill also comprises a device for indicating that the core has jammed in the inner tube (2) and a sealing device (19) designed to receive a ball (46) provided for sealing the inner tube (2) of said core drill.

Description

DOUBLE CORE FOR DEVIE DRILLING

The present invention relates to a double corer for deviated drilling.

The advantage of deviated drilling drilling lies in the possibility of taking numerous samples at great depth from a single drilling point, at various locations along a substantially horizontal oil table. These holes allow the investigation of the composition of the aquifer and its extent.

Document US-A-4467879 teaches that a deviated drilling is obtained by the implementation of one or more stabilizing sleeves mounted along a drill string. The judicious choice of the type of stabilizing sleeve and the dimensions as well as their distribution along the drill string makes it possible to adjust and control the angle of inclination of the borehole as described in document EP-A-0178709.

It is also known that a deviated drilling borehole can be carried out using a double borehole sampler as described in document BE-A-875.016. Such a corer comprises a rotary external tube provided with a sounding ring and a non-rotary internal tube provided with a shoe and an extractor spring intended to take a drilling core. The conventional embodiment of a double corer, however, has the disadvantage of not meeting the specific requirements imposed on a deviated core or a horizontal core. In fact, the inner tube of the double core barrel has, by construction, a relatively thin wall in order to extract a core of maximum section. It can therefore be seen that, during a borehole borehole drilling, the inner tube of a double core barrel, which has an inclined or horizontal position during deviated drilling, flexes inside the outer tube under the weight of the carrot during sampling.

This deflection of the inner tube makes it more difficult for the carrot to penetrate the core tube and it is frequently observed that the carrot gets stuck in the core tube. However, such jamming has the immediate effect that the thrust force during drilling, which results from the considerable weight of the entire drill string and which normally must be transmitted by the tubes outside the drill bit, is fully transmitted to the relatively thin inner core tube, which naturally causes immediate destruction of the inner core tube and the core.

The deflection mentioned above is also the cause of tensions in the ball or needle bearing connecting the rotary outer tube to the fixed inner tube. This deflection reveals friction forces between the core and the inner tube and between the inner tube and the outer tube. These frictions tend to degrade the free rotation of the outer tube relative to the inner tube and cause the inner tube to rotate. tion by causing early failure of the core barrel. The deflection of the inner tube causes a partial destruction of the sample taken by the corer.

A second drawback of conventional double borehole corers lies in the obstruction of the inlet of the inner tube at the start of drilling when the core engages in the core barrel. It also happens that an obstruction forms along the inner tube during drilling. The obstruction during operation is sometimes due to the fact that, in certain types of brittle rocks formed by strata inclined with respect to the direction of advancement of the core barrel, the carrot fractures into strips which are strongly supported against the walls of the core barrel and obstruct it by wedging. The danger of obstruction is all the greater the greater the angle of inclination of the lamellae.

In vertical or slightly inclined drilling, one realizes the blockage by the very significant decrease in the forward speed. The weight applied to the drill string is then increased, taking care not to cause internal buckling of the core barrel or overheating of the bearing, since the entire weight of the drill string affects the internal tube.

In strongly inclined drilling and a priori in horizontal drilling, the influence of the vertical forces applied to the drill string is less perceptible because these forces are transmitted by numerous contact points along the wall of the well and that only one force component intervenes. A third drawback lies in the difficulty of ensuring perfect concentricity of the inner tube of the core barrel and the outer tube. A solution fairly obvious to ensure perfect concentricity of the inner tube and the outer tube would be to distribute, along the inner tube, intermediate bearings between the inner tube and the outer tube. Conventional intermediate bearings with ball bearings have never been used in a double corer with adjustable head because they prohibit any longitudi¬ nal movement of the inner tube of the corer relative to the outer tube. However, a longitudinal displacement is necessary for adjusting the spacing between the extractor device and the sounding ring.

A fourth drawback resulting from the use of a conventional double borehole sampler in a deviated borehole is the unexpected opening of the closure device mounted at the top of any inner tube of a double borehole.

It is generally a ball shutter device launched generally from the ground surface in order to close a seat of the shutter device. In a double class corer, the sealing ball is kept on its seat, during the coring operation, only by its own weight and by the pressure exerted on it by the drilling fluid. When the inclination of the borehole is large, even a brief interruption in the supply of drilling fluid can move the shutter ball away from its seat and cause a jet of liquid inside the core barrel. resulting in the accidental destruction of the core and the removal of the core.

The present invention aims to remedy the aforementioned drawbacks and proposes a core barrel specially adapted for deviated drilling by the use of means and accessories which reinforce the rigidity of the inner tube of the core barrel, prevent any defect in obturation, and ensure its concentricity and reliability.

It relates to a double corer for deviated drilling comprising, on the one hand, a rota¬ tive outer tube carrying a sounding ring, and on the other hand, a non-rotating inner tube, bearing at a first end, close to the crown of sounding, a carrot extraction device formed by an extractor spring and a conical shoe, while the other end is secured to the outer tube by means of a ball or needle bearing possibly adjustable in height along of said outer tube. According to the invention, this corer is characterized in that the bearing connecting the inner tube of the corer to the outer tube consists of a bearing with multiple ball bearings and / or needles housed in a sealed housing previously filled with oil or fat; the extractor device and the inner wall of the core barrel are covered with an anti-friction coating; the outer wall of the inner tube comprises a set of stabilization elements distributed along the inner tube between it and the outer tube; the conical shoe forming the lower part of the inner tube is centered in the sounding ring by centering ribs separating the flow channels; the clog is provided with a bevelled lower lip intended to facilitate the introduction of the core into the inner tube, a ball shutter device capable of holding the ball on its seat whatever the inclination of the deviated drilling.

According to a particular development of the invention, the ball or needle bearing is constituted by a bearing with multiple bearings, some of which offer four support points. The bearing consists of a ring carried by several series of ball bearings and / or aiguil¬ distributed not only concentrically around the axis of rotation but also axially along the axis sheltered from a waterproof housing containing an oil or grease bath.

The extraction device allows the carrot to be retained in the inner tube. It consists of the extractor spring and the conical shoe. The extractor spring is formed by a split ring, the inner face of which is covered with a gripping coating resting on the conical shoe which has a beveled edge widening downwards, so as to enlarge the entry section of the tube. inside up to a diameter close to the inside diameter of the crown.

The concentricity of the conical shoe supporting the extraction device relative to the crown is ensured by the beveled conical shoe which is supported on longitudinal centering ribs, separated from each other by fluid flow channels of drilling. Other details and particularities of the invention will emerge from the detailed description which follows, with reference to the attached drawings, in which:

- Figures 1A, 1B and 1C are longitudinal sections of various consecutive sections arranged from bottom to top of the double core barrel according to the invention;

- Figure 2 is a longitudinal sectional view on a larger scale of a multiple roller bearing;

Figure 3 is a longitudinal sectional view on a larger scale, of a first embodiment of a ball shutter device;

Figures 4 to 6 illustrate the various phases of movement of the ball;

FIGS. 7 and 8 are views in longitudinal section on a larger scale of a blocking indicator occupying a lower position and a higher position, and

Figures 9 and 10 are, on a larger scale, a longitudinal section of the bottom part of the core barrel having stabilizing elements and of the bottom end of the core barrel.

In these various figures, the same reference signs designate identical or analogous elements.

As illustrated in FIGS. 1A, 1B and 1C, the Double corer for deviated drilling, according to the invention, consists essentially of an external tube 1 and an internal tube 2. The external tube 1 consists of a train of hollow rods causing in rotation a sounding ring 3. At a certain distance from the ring 3, the outer tube 1 comprises a body 4 on which is fixed a bearing 10 of a ball or needle 11 bearing.

The inner tube 2 mainly comprises tubular elements screwed one after the other and arranged coaxially with the outer tube 1. The lower tubular element of the inner tube 2 carries a device 9 for extracting the core. The upper tubular element of the inner tube 2 is screwed to the non-rotating part 12 of the bearing 11, which is integral with the core barrel.

In a manner known per se, the non-rotating part 12 of the bearing 11 comprises a closure device 19 intended to receive a ball 46 as shown in FIGS. 3 to 6.

The purpose of this closure device is known (see document BE-A-8700395). At the start of drilling it is essential to pass the drilling liquid in the direction of the arrows X through the inner tube 2 in order to remove the scree that has accumulated in the inner tube 2 and at the bottom of the well. This clearing is obtained by using the fully open core barrel, that is to say not yet provided with the sealing ball 46, so as to allow the drilling liquid to pass through the inner part of the inner tube 2.

When the downhole clearing operation is completed, the flow of drilling liquid is deflected in the direction of the arrows Z towards the outside of the inner tube 2 through the openings 52 in an annular space 47 surrounding the latter, as illustrated in FIG. 5, by launching freely from the surface of the ground, the ball 46 intended to close off a seat 48 provided in the non-rotating part 12 of the bearing 11. A first embodiment of the closure device specially adapted to the double corer for deviated drilling is illustrated in Figure 3. This device is made up of a metal basket 49 without bottom flared upwards. The side wall of the basket 49 is formed of elastically deformable curved fingers 50. These fingers are retained by the upper edge 51 of the basket 49. They have the function of keeping the ball on its seat whatever the inclination of the deflected borehole.

Figure 3 illustrates the approach of the ball driven by the drilling fluid. To accelerate the descent of the ball 46 it is known to increase the flow rate of the drilling liquid.

Figure 4 shows how the ball crosses the basket by spreading the fingers thanks to the inertia acquired by the ball 46. The resistance of the fingers 50 to elastically deform brakes the ball 46 and reduces the impact of the ball 46 on the seat 48. When it is applied to the seat 48, the ball 46 closes the inner tube 2 (FIG. 5).

The curved shape of the fingers 50 allows the ball

46 to deviate to a limited extent from its seat 48 so as to allow the elimination of any overpressure in the core barrel by releasing, in the direction of the arrows Y, the drilling liquid or any other fluid trapped in the inner tube 2 (Figure 6).

The non-rotating part 12 of the ball or needle bearing 11 is extended by inner tube elements 2 of constant diameter.

The bearing 11 is made up of a series of concentric ba¬ gues-bearings 7 housed in a sealed annular housing 21 filled with oil or grease 22 (FIG. 2). The concentric bearing rings 68 re¬ hold captive between them balls 69 and / or needles 50. The outer part of the housing 21 is therefore not driven in rotation. The housing 21 is sealed by baffles 25 and by a seal 26.

A first embodiment of the core barrel according to the invention, for deviated or horizontal drilling, is, in its operating principle, derived from the double core barrel described in Belgian patent No. 875.016. The core barrel has an adjustable head whose position is adjusted by moving, by rotation, a sleeve 13 of the upper part of the bearing 11 in either direction, along a thread 5 of the body 4 of the outer tube 1. This succeeds in correcting the spacing between the conical shoe 32 of the extractor spring 8 and the sounding ring 3 (see FIG. 10). The purpose of this adjustment is to compensate for the differences in length of the interior and exterior assemblies due to manufacturing tolerances and differential thermal expansion, in particular when using an interior tube 2 in aluminum or fiberglass.

When the above-mentioned spacing reaches the desired value, a blocking cap 18 is put in place in order to prevent any subsequent relative displacement between the inner tube and the outer tube (FIG. 1C). The locking cap 18 having at least one lug 20 allows angularly blocking the rotating part 12 of the ball bearing 11 or needle on the threaded body 4 of the outer tube 1 and thus prevent the relative rotation of the latter one relative to each other around their common vertical axis, thanks to a pair of diametrically opposite longitudinal grooves 17 of the sleeve 13 of the upper part of the bearing 11 and two diametrically opposite notches 6 of the threaded bore of the body 4 of the outer tube 1 (see BE-A-875.016)

The body 4 of the outer tube 1 is mounted on the outer tube 1 by a seal 29 called security, consisting of a single thread of square section. Preferably, this thread is undone in the case where the outer tube 1 is driven in reverse rotation with a view for example to unlock a part of the core barrel when the latter is jammed.

The end opposite to that of the cap 18 is suitable for serving to wedge the bearing rings 7 and the bearings with four abovementioned support points.

In order to prevent the second drawback, the extraction device 9 and the inner wall 38 of the inner tube 2 are covered with an anti-friction coating composed for example of a film of film. flon. However, it happens that despite this precautionary measure, certain types of rock cleave and get stuck inside the inner tube 2 or at the entrance thereof, between the conical shoe 32 and the drill bit 3 of the extraction device 9.

When the drilling tool no longer progresses, all the weight applied to the outer tube 1 and to the crown 3 is reflected on the inner tube 2. Depending on whether the inner tube 2 is made of fiberglass or steel, the transfer to the inner tube 2 of the forces applied to the outer tube 1 during the blocking of the core barrel, causes either the buckling of the inner tube 2, or the rupture of this tube. In case of blocking of the core barrel, the weight transferred to the inner tube 2 is so considerable that we sometimes witness the crushing of the bearing 11, even if it is a multiple bearing. However, the resistance to crushing of a multiple bearing 11 is far greater than that of a single bearing since it allows the axial forces taken up by the bearing to be distributed over several stages of balls or needles. The deterioration of the bearing 11 en¬ inevitably leads to the destruction of the core since the inner tube 2 is then inevitably rotated by the outer tube 1.

In horizontal drilling, the influence of the force applied to the outer tube 1 and the crown 3 is difficult to perceive due to the fact that only one component of the vertical force is involved. Simultaneous variations of the numerous parameters and the high number of points of contact of the external tube 1 with the wall of the well in horizontal drilling make the conduct of drilling extremely difficult. The operator generally realizes too late that the drilling speed has decreased. When he notices this, the survey equipment may already be irreparably damaged.

The present invention provides a means for detecting the blockage of the inner tube 2 using a pressure gauge provided by a device generally designated by the reference sign 55. It is a blocking indicator mounted in head of the inner tube 2. As illustrated in FIG. 1B, the blocking indicator 55 comprises a sleeve 56 opening into a gap 58 provided between the flow distributor tube 27 and a deflecting envelope 59 which facilitates the passage of the li¬ quide of drilling feeding the lower zone of the corer in order to cool the tool during the coring and to evacuate the drilling debris.

The deflector casing 59 is fixed to the distributor tube 27 (see FIG. 4). It is limited by a biased edge 60 cooperating with a biased edge 61 of a protuberance of the sleeve 56 so as to delimit an annular slot 62 of variable width - constituting a restriction of an annular channel for passage of the drilling liquid, during an axial movement of the sleeve 56 relative to the deflecting envelope 59 which surrounds it. This restriction makes it possible to cause an increase in pressure which can be read on a surface pressure gauge by an operator.

In the event of a blockage, the inner core barrel 2 tends to rise inside the outer barrel 1 at the same time as the core, while the outer barrel 1 can no longer progress in its descent (Figures 7 and 8).

The inner tube 2 of the core barrel then drives up a suspension ring on which a spring 63 made up of Belleville washers 64 rests, allowing the inner tube a certain freedom of sliding limited downwards by the stops 65. The spring hardly crushed pushes the sleeve up against the stops 66 and engages a biased edge 61 of the sleeve 56 in the annular gap 58 so as to restrict the section of the annular slot 62.

The increase in pressure, which results from this restriction and which is read on the pressure gauge, informs the operator of a possible blockage of the core in the inner tube 2.

The inner tube comprises a set of stabilizing elements 67 distributed along the inner tube 2 between the latter and the outer tube 1. This set of stabilizing elements 67 makes it possible to center the inner tube 2 correctly. the outer tube 1 possibly also provided with stabilizing elements 35 and, when the corer is in a horizontal position, it reduces the deflection of the inner tube 2 under the effect of its own weight and that of the carrot (FIG. 9 ). These stabilizing elements 67 constitute intermediate bearings with smooth friction bearing on the inner wall of the outer tube 1. The stabilizing elements 67 in no way prevent the adjustment of the spacing between the lower ends of the conical shoe 32 and sounding ring 3, since they can slide longitudinally the along the inner wall of constant diameter of the outer tube 1.

In a preferred embodiment, illustrated in FIG. 9, each set of stabilization elements 67 carries a ring 28 of self-lubricating material bearing against the inner wall of the outer tube 1. When adjusting the spacing of the shoe conical 32 and crown 3, the self-lubricating ring 28 can slide along the outside tube 1.

The stabilizing elements 67 contribute to maintaining the straightness of the inner tube 2, one end of which can be considered to be embedded, in free rotation, in the outer tube 1 by means of the ball or needle bearing 11 formed by a bearing multiple bearings with four support points for example. These four support points help to make the inner tube 2 rigid, preventing it from bending.

By preventing any excess tension in the ball or needle roll, the stabilizing elements 67 reduce the friction forces in the bearing 11 and eliminate the risks of entrainment in rotation of the inner tube 2, which rotation would destroy the carrot.

The self-lubricating ring has the same role. It prevents torsional forces on the inner tube 2.

The lower part of the inner tube 2, formed by the conical shoe 32, is centered in the crown of sounding 3 by centering ribs 34 separating the flow channels 33 (FIG. 10).

The shoe 32 is extended by a lower lip 14 guiding the drilling liquid longitudinally relative to the crown. The lip 14 is bevelled and flared downwards so as to facilitate the introduction of the carrot into the inner tube 2. The outer lateral wall 39 of the conical shoe 32 is covered with an anti-friction coating intended to prevent the rotation of the inner tube 2 by the crown 3. The combined shapes of the outer side wall of the conical shoe 32 and the inner face of the crown 3 guide the drilling liquid parallel to the axis of the core.

The extractor spring 8 (FIG. 10) is formed of a split ring, the inner face of which is covered with a gripping coating 36. At the end of the coring, the ring closes on the carrot by cone effect, in bearing on the conical shoe 32 when the inner tube is removed 2. The extraction device makes it possible to break the carrot and to rete¬ nate the sample in the inner tube while the inner tube 2 is brought up to the surface of the ground.

The corer according to the invention has the merit of making it possible to carry out a horizontal drilling which has the advantage of making it possible to correctly determine the extent of an oil deposit made up of large-scale oil slicks but of low height, where a vertical survey would only give summary survey results and clearly insufficient to give an estimate correct profitability of the eventual exploitation of a deposit.

A horizontal borehole also has the major advantage of speeding up the extraction of petroleum and increasing the flow of petroleum which can access the extraction tube in a horizontal petroleum deposit since it makes it possible to sample, by a large number distinct orifices distributed along the oil table, the crude oil which conceals the water table. This clearly improves the profitability of the exploitation of a horizontal deposit since it prevents the oil from having to migrate over significant distances through sufficiently permeable layers of land before reaching the immediate vicinity of the tube. extraction, as could be the case in a vertical survey.

Claims

1. Double corer for deviated drilling comprising, on the one hand, a rotary external tube (1) carrying a sounding ring (3), and, on the other hand, an internal non-rotary tube (2) bearing at a first end, next to the sounding ring (3), a carrot extraction device (9) formed by an extractor spring (8) and a conical shoe (32) while the other end is screwed on a par¬ non-rotating tie (12) of a ball or needle bearing (11), fixed to the outer tube (1), evenly adjustable along the latter, characterized in that:

the bearing (11) connecting the inner tube (2) to the outer tube (1) consists of a series of concentric bearing rings (7) aligned on the same axis and holding captive balls (68) and / or needles (69) housed in a sealed housing (21) filled with oil (22) or grease;

the extraction device (9) and the inner wall (38) of the inner tube (2) are covered with an anti-friction coating;

- The outer wall of the inner tube (2) comprises a set of stabilizing elements (67) distributed along the outer tube (1) between the outer tube (1) and the inner tube (2); the conical shoe (32) forming the lower part of the inner tube (2) is centered in the sounding ring (3) by centering ribs (34) separating the flow channels (33), the shoe being provided with a lower lip (14) bevelled and flared towards the outside so as to facilitate the introduction of the core into the inner tube (2), and

- a ball shutter (19) capable of holding the ball (46) on its seat (48) regardless of the inclination of the deflected borehole.

2. Corer according to claim 1, characterized in that the set of stabilizing elements (67) carries a ring (28) of self-lubricating material pressed against the outer tube (1).

3. Corer according to claim 1 or 2, characterized in that the bearing (11) is a multiple bearing consisting of two bearing rings (7) at least aligned along the same axis in order to offer several points which make the inner tube (2) more rigid.

4. Corer according to any one of the preceding claims, characterized in that the extraction device (9) is centered relative to the sounding ring (3) by a conical shoe (32) which is supported on longitudinal ribs (34) separated from each other by channels (33) for flow of drilling liquid.

5. Core sampler according to any one of the preceding claims, characterized in that the closure device (19) with ball (46) is a basket (49) formed of metal fingers (50) retained by the upper edge ( 51) of the basket (49) and bent inwards, elastically deformable and capable of deviating under the thrust of the ball (46) to determine an orifice (52) wider than the ball (46) and form a barrier for the ball (46) when the fingers (50) return to the initial position.

6. Corer according to any one of the preceding claims, characterized in that it comprises a blocking indicator consisting of a sleeve (56) opening into an annular gap (58) provided between a distributor tube (27) and an envelope deflector (59) mounted on the distributor tube (27) and limited by a biased rim (60) cooperating with a biased edge (61) of an annular protuberance of the sleeve (56) to delimit an annular slot (62 ) of variable width, during sliding of the sleeve (56) relative to the deflecting envelope (59).