EP0995010B1 - Core barrel - Google Patents

Description

The present invention relates to a core barrel, in particular in the field of oil prospecting, comprising, on the one hand, an outer tube and a coring ring which form a external assembly and, on the other hand, an internal tube which forms with a carrot inside of it, and with part of the formations arranged under the foot of the carrot, an interior assembly, means of suspension and guide being provided to maintain the interior assembly in the whole exterior.

We know many corers of this kind, especially according to FR-A-2,197,109. Their suspension and guide means form between the assemblies outside and inside of mechanical bearings of the bearing type, with action radial and built-in, and of the type with double acting stop (s). It is then usual to have at least one higher mechanical connection, often of the type with stop at the rear end of the inner tube, in considering a sense of advance of the corer in the ground, and a connection lower bearing and recessed mechanical type (in the crown for example) at the anterior end of the inner tube. He can also there are intermediate mechanical connections, usually of the bearing and embedding, especially in the case where the coring must be performed in a steeply inclined position relative to the vertical or even in a horizontal position.

In the search for a corer able to supply a carrot as intact as possible and as representative as possible of the formations surveyed, the skilled person tends to make it severe, that is to say by example with close tolerance, the mechanical connections between the exterior and interior assemblies defined above, in order to obtain a the most efficient guidance possible of the inner tube around the core.

It turns out, however, that the carrots obtained can be badly damaged as a result of vibrations and jolts transmitted by the drill string which controls the core barrel, by the phenomenon known as "whirling" or whirling of the crown of core drilling in its hole, around its axis of rotation, and rotation of the latter around the axis of the hole, against the pseudo-cylindrical internal wall of the hole with a diameter greater than that of the crown, as well only by the attachment of the latter in the core formation, etc., that is to say following an unfavorable action by the external assembly on the whole interior.

The inventors of the present invention resolutely chose to go against the grain with respect to the practice explained above and to consider that the inner tube and the core which is lodged there as as coring progresses must be relieved of the constraints that the above exterior assembly undergoes during the same coring and transmits to the interior assembly.

To this end, according to the invention, the suspension means and guide are arranged so that, at least at the location of these means, the interior assembly preserves, in relation to the whole exterior, a defined freedom of movement axial, radial and angular in order to isolate at at least partially the interior assembly of the brutal movements of the exterior assembly due to coring and thus protect the carrot contained in the inner tube and the formations located near the foot of said carrot.

As a result of this, he appeared surprisingly that brutal constraints of the exterior assembly are no longer transmitted, or are very reduced, to the carrot which does not retains its integrity better.

It also appeared as a result of this that the material of the corer experiences significantly less stress and is better preserved than in the past with regard to destruction by impact, by forcing pieces on top of each other, etc., and on the carrot.

According to one embodiment of the invention, the suspension and guide means comprise at least one stop swivel for suspension and support of the inner tube in the tube exterior, this stop being mounted therewith a radial, axial clearance and angular higher than the usual clearance.

According to a particular embodiment of the invention, the suspension and guide means include means for hydrostatic bearing in which pressurized core fluid form, during coring, one or more elastic cushions of radial, axial and angular localization.

According to an advantageous embodiment of the core barrel of the invention, means are arranged therein to maintain during core, in cooperation with the effects of fluid pressure coring on the interior assembly, the latter in lift in the exterior set between the limits of said freedom of movement and the aforementioned game.

Other details and features of the invention will emerge secondary claims and description of the drawings which are annexed to this memorandum and which illustrate by way of examples not limiting, advantageous embodiments of the invention shown diagrammatically, in axial section unless otherwise indicated on the contrary, with broken pieces and possibly on different scales.

Figure 1 shows an anterior end of a core barrel in which the present invention can be implemented.

Figure 2 shows the core sampler of Figure 1 at the location of the rear end of the inner tube and the suspension thereof in the outer tube.

Figure 3 shows on a larger scale the location of said suspension of the inner tube in the outer tube.

Figure 4 shows the ends on a larger scale anterior and inner tubes and the core bit.

FIG. 5 shows an embodiment of a means of intermediate guide implementing the present invention.

Figure 6 shows another embodiment of the suspension of the inner tube in the outer tube.

Figure 7 shows another variant of the means of suspension and / or guide of the inner tube in the outer tube.

Figure 8 shows a cross section along the plane VII-VII of figure 7.

Figure 9 shows, at the location of the posterior end of the inner tube and the suspension thereof in the outer tube, a "wireline" type corer whose anterior end can be similar to that shown in Figure 1.

Figure 10 shows, in a view similar to that of the Figure 9, an embodiment of a core barrel whose inner tube does not cannot be removed from the outer tube by the "wireline" technique.

Figure 11 shows on a larger scale the location of suspension mentioned above in Figure 10, the inner tube occupying a support position in the outer tube.

Figure 12 shows on the same scale as that of Figure 11, the same place of suspension, the inner tube occupying a so-called lift position in the outer tube.

In the different figures, the same notations of reference designate identical or analogous elements.

The core barrel 1 (Figures 1 and 2) of the invention comprises, from a share, an outer tube 2 and a core bit 3 which can be considered as forming an external assembly 4 and, on the other hand, at minus an inner tube 5 which can be considered as forming, with a core 6 possibly present inside of it, a interior set 7. We can also consider that at least part formations arranged under the foot of the carrot 6 is part of the interior assembly 7. Means 9 for suspending and guiding the interior assembly 7, essentially of the interior tube 5, in the exterior assembly 4 are provided.

According to the invention, the means 9 for suspension and guide are arranged so that the interior assembly 7 preserved, at least in the place of these, compared to the whole exterior 4 greater freedom of movement than usual, axially, radially and angularly relative to the longitudinal axis of the exterior assembly 4.

This determined freedom, or this less severe bond that usually between exterior 4 and interior 7, prevents brutal movements, of a defined amplitude, of the whole outside 4 are communicated to the inner tube 5 and by the latter to the carrot 6 which would then be damaged by these brutal movements and / or which would be broken each time, at its foot, of the part of training beneath it. A carrot 6 thus broken presents artificial discontinuities with respect to the core formation and not not show real nature. A carrot 6 thus broken and / or damaged also presents a considerable risk, directly linked the number of discontinuities produced, blocking in the inner tube 5 with respect to a continuous core 6, if possible in one piece.

• du côté de son diamètre interne, entre deux éléments 13 et 14 vissés par exemple à bloc l'un dans l'autre et supportant, par un filet mâle 15, le tube intérieur 5 proprement dit (non représenté), et
• du côté de son diamètre externe, entre deux éléments de serrage 16 et 17 du tube extérieur 4 vissés également l'un dans l'autre et fixant un anneau 18 de butée (du type circlips).

In one embodiment of the invention, the suspension and guide means 9 comprise (FIG. 3) at least one rotary stop 12, for example with balls, for the suspension and support of the inner tube 5 in the outer tube 2. According to the invention, this stop. 12 is mounted with a radial, axial and angular clearance greater than the clearance usually adjusted in the trade. To do this, the stop 12 is held, with a chosen axial clearance,

• on the side of its internal diameter, between two elements 13 and 14 screwed for example one block into the other and supporting, by a male thread 15, the inner tube 5 proper (not shown), and
• on the side of its external diameter, between two clamping elements 16 and 17 of the outer tube 4 also screwed one inside the other and fixing a stop ring 18 (of the circlip type).

To be able to be screwed into each other, it only depends of a choice and construction contingencies that element 13 carries for this purpose a male thread (Figure 3) and the element 14 a female thread or vice versa.

As shown in Figure 3, a radial clearance can also be provided between said rotary stop 12 and, on the one hand, the elements 13, 14, and, on the other hand, the clamping elements 16 and 17.

The combination of axial and radial clearances described about Figure 3 gives this assembly an angular clearance between the axis of the tube inner 5 and that of the outer tube 2.

In another embodiment, separately or in more than the above, the means 9 for suspension and guidance have at least one bearing 20 (Figures 1 and 4) and / or 21 (Figure 5) radial support of the inner tube 5 in the outer assembly 4, this bearing 20, 21 being arranged so as to allow between the outer tubes 2 and inside 5 a radial clearance (Figures 1 and 4), axial (Figures 4 and 5) and angular (by a combination of radial and axial clearances greater than games usually adjusted).

In FIG. 5, the bearing 21 presents, for the part of the tube interior 5 which constitutes the tree, a barrel-shaped so as to increase possible angular play between the axes of the inner tubes 5 and exterior 2, and therefore flexibility of the mechanical connection to this place.

According to a particular embodiment of the invention, the means 9 for suspension and guidance may comprise (FIG. 6) elastic means 22. These elastic means 22, intended for them also to soften the mechanical connection between the exterior assemblies 4 and interior 7 and to absorb shock transmission, may include rings 23 of rubber or synthetic material arranged by example above and below the mounted rotary stop 12, for the rest, like that of FIG. 3. These rings 23 can include annular beads 23A intended to cooperate with grooves in surrounding parts to ensure positioning adequate reciprocal of the constituent elements thus stacked.

Advantageously, the means 9 for suspending and guidance may include (FIG. 7) hydro-static bearing means 24 in which pressurized coring fluid, arriving from the surface by a central conduit 25 and exiting by radial conduits 26 shape during coring, between a cylindrical inner wall or conical 27 of the external assembly 4 and, opposite, an external wall cylindrical or conical 28 of the interior assembly 7, one or more cushions radial and angular localization elastic of this set interior 7 relative to the exterior assembly 4. Adjustment and distribution of the coring fluid flow between the radial conduits 26 and standard connecting conduits 29 supplying the fluid from the central conduit 25 at the interval between the outer 2 and inner 5 tubes provides a pressure difference causing a centrifugal radial flow from the radial conduits 26, for example in chambers oblong 31 whose dimension (longitudinal) is visible in Figure 7 and the other dimension of which is visible in Figure 8. Each room oblong 31 can then cause a cushion of fluid between the walls 27 and 28.

FIG. 9 shows a case of a core barrel 1 of the "wireline" type, in which the inner tube 5 is suspended in the outer assembly 4 due to its own weight and the pressure of the coring fluid arriving in 32 from the ground surface. Especially in this type of corer, means 33 can be arranged to keep in progress coring, in cooperation with the effects of fluid pressure coring pushing the inner tube 5 down and with friction carrot 6 entering this inner tube 5, the latter in lift in the exterior assembly 4 between the limits of said freedom movement and the aforementioned game.

To this end, the means 33 can include example a set of bristles, or another coating, (not shown) disposed on the inner wall of the inner tube 5 to oppose with a known resistance to the entry of the core 6 into this tube 5.

The means 33 may alternatively include means for regulating the escape of a fluid contained in the inner tube 5, arranged so to oppose by an exhaust controlled a known resistance at the entry of the core 6 into the tube 5.

Means 33 may include a combination of coring fluid passages 34, including outlet ports 35 open onto a peripheral surface of the interior assembly 7, and internal surfaces 36 and 37 of the external assembly 4 which have different diameters.

The fluid outlet orifices 35 occupy at rest a position, shown in Figures 9 and 11, in which they face an internal surface 36 separated, so as to allow an exit therefrom not throttled with the coring fluid.

By the action of said known resistance, the inner tube 5 will tend to be pushed back by the carrot 6 in opposite direction in advance S of the core drilling, so as no longer to be pressed against a suspension shoulder 38 (FIGS. 9 and 11) of the exterior assembly 4. Therefore, the orifices 35 occupy a position shown in the figure 12, in which they gradually face another surface internal 37 less spaced from the orifices 35, so as to gradually throttle the outlet of the coring fluid and therefore increase its pressure upstream of the orifices 35 as the interior assembly 7 goes up in the exterior assembly 4. The pressure increase will have tendency to push back in the direction of advance S of the core assembly interior 7 and a balance will be sought thus, away from the shoulder 38, between opposing thrusts due to said known resistance and the increase in fluid pressure which results from its constriction progressive.

When the interior assembly 7 leaves the shoulder 38, it actually produces a fluid leak at this location (Figure 12). The balance "hydrostatic" obtained for lift therefore results from the dead weight inner tube 7 and its suspension means, said resistance known, coring fluid flow and leakage thereof, including included through the openings 35. Any change in fluid pressure thus produced is visible on the surface for the operator of the corer 1 which can then act accordingly for for example, after deducing it is a blockage of the core 6 in the inner tube 5, modulate this pressure and try to unblock the core 6 by this.

In FIG. 9, the interior assembly 7 comprises at the rear end of its suspension and / or guide means 9 a gripping means 39, known per se in the technique of "wireline", from the inner tube 5 to at least remove it (with a core 6) of the outer tube 2.

In Figure 10, the interior assembly 7 is similar to that of FIG. 9, except that it does not include any means gripping 39 because, for example due to a diameter restricted interior of the outer tube 4 upstream of the interior assembly 7 (considering the direction of flow of the coring fluid in the core barrel), the interior assembly 7 cannot be reassembled by said "wireline" technique. Following this, the configuration of the conduits passage of the coring fluid from location 32 and directed towards the anterior end of the core barrel 1 may be different from that of Figure 9 and present for example a funnel shape. Pressure of this fluid at location 32 is transformed into the pushing force of the tube inside 5 in direction S towards said anterior end of the core barrel 1, in the coring position, to the exclusion of all mechanical means.

FIG. 7 shows, as a variant, that the means 9 of suspension and guide may include a ball joint 40 for increase the flexibility of mechanical connections between assemblies exterior 4 and interior 7.

It should be understood that the invention is in no way limited to the embodiments described and that many modifications can be made to them without departing from the scope of this invention.

Thus, Figure 4 shows that advantageously the crown 3 has an internal passage 41 whose diameter is greater than that that presents one or more knives 42: closest to its axis of rotation and intended to determine the external diameter of the core 6. This is intended to give play to this place, so as to reduce a embedding the carrot 6 in the crown 3, and therefore not solicit this carrot 6 by unfavorable reactions from the crown 3 during work. This embedding can also be reduced by reducing as much as possible the axial length of the so-called the internal guard 48 (FIGS. 1 and 4) of the crown 3 (that is to say the passage provided in it for the carrot 6).

This falls within the scope of the aims of the invention, know how to find an optimal minimum number of elements and / or points of mechanical connection or contact between what has been defined above as being the exterior 4 and interior 7 sets. Similarly, and for the same purpose, the geometric dimensions of the means of suspension and guide 8 are preferably optimized in particular to increase clearances between these exterior 4 and interior 7 assemblies, to reduce diameters and / or lengths (for example to reduce or avoid as soon as built-in) compared to what the skilled person has tendency to do so far.

It can be noted, in particular in FIGS. 11 and 12, a labyrinth seal 49 disposed on a body part 50 of the means suspension 9, below the rotating ball stop 12 (or, if applicable ball joint). The labyrinth seal 49 may consist, for example, of an annular seal 51, mounted tight on the body part 50, and a ring support 52 which, for example, cooperates with the suspension shoulder 38 as described above and which has an annular groove in which the annular seal 51 can be housed with annular games.

When the support ring 52 is in contact with the shoulder suspension 38, coring fluid passing between the outer tube 2 (Figure 11) and the screw element 13 can practically not pass to the place of support but will tend to pass through the stopper balls 12 and the mounting clearances between the latter and the body part 50 as well as between the latter and the support ring 52. This can significantly restrict the flow of fluid in the mentioned path, as a function of the annular gaps organized between these parts.

In an embodiment not described, a middle tube, between the outer 2 and inner 5 tubes and substantially coaxial to these, may, as the case may be, be part of the exterior assembly 4 or of the interior assembly 7.

Legends of the figures :

S

advance direction of a core drill

1

corer

2

outer tube

3

coring crown

4

outdoor set

5

inner tube

6

carrot

7

interior set

9

suspension and / or guide means

12

rotary stop

13

screwed element of 7.5

14

screwed element of 7.5

15

male thread of 14

16

clamping element of 4, 2

17

clamping element of 4, 2

18

stop ring

20

9 step

21

9 step

22

elastic means of 9

23

22 ring

23A

ring bead 23

24

hydrostatic bearing of 9

25

central duct of 1

26

radial ducts of 24

27

cylindrical or conical internal wall of 4, 2

28

cylindrical or conical outer wall of 7.5

29

connecting conduits of 7, 5

31

oblong chambers of 24

32

location of pressurized coring fluid

33

lift of 5, 7

34

coring fluid passages of 23

35

34 holes

36

internal surface of 4, 2

37

internal surface of 4, 2

38

suspension shoulder

39

gripping means of 5, 7

40

ball bearing

41

internal passage of 3

42

knives of 3

48

internal guard of 3

49

labyrinth seal

50

body part of 9, 14 (figure 11)

51

ring seal on 50

52

7.5 ring support

Claims (10)

1. Core barrel comprising, on the one hand, an outer tube (2) and its coring bit (3), called hereinafter outer assembly (4), and, on the other hand, an inner tube (5) and the drilled core (6) present therein and being a portion of the formations under its base, called hereinafter inner assembly (7), suspension and guidance means (9) being provided to keep the inner assembly (7) inside the outer assembly (4),
      characterized in that the suspension and guidance means (9) are arranged in such a way that the inner assembly (7) retains, at least at the location of these means (9), with respect to the outer assembly (4), a predetermined freedom of axial, radial and angular movement in order to isolate at least partially the inner assembly (7) from the harsh movements of the outer assembly (4) resulting from the core-drilling and so to protect the drilled core (6) contained in the inner tube (5) and the formations located in the proximity of the base of said drilled core (6).
2. Core barrel according to Claim 1, characterized in that the suspension and guidance means (9) comprise at least one rotary thrust bearing (12) for suspending and supporting the inner tube (5) in the outer tube (2), this thrust bearing (12) being mounted therein with a radial, axial and angular clearance that is greater than the usual clearance.
3. Core barrel according to one or other of Claims 1 and 2, characterized in that the suspension and guidance means (9) comprise at least one bearing (20, 21) for supporting the inner tube (5) in the outer assembly (4), this bearing (20, 21) being arranged in such a way as to allow a radial, axial and angular clearance greater than the usual clearance between the outer tube (2) and the inner tube (5).
4. Core barrel according to any one of Claims 1 to 3, characterized in that the suspension and guidance means (9) comprise elastic means (22).
5. Core barrel according to any one of Claims 1 to 4, characterized in that the suspension and guidance means (9) comprise hydrostatic bearing means (24) in which pressurized core-drilling fluid forms, during core drilling, one or more elastic cushions for the radial, axial and angular location.
6. Core barrel according to any one of Claims 1 to 5, characterized in that the suspension and guidance means (9) comprise at least one spherical thrust bearing (40).
7. Core barrel according to any one of Claims 1 to 6, characterized in that means (33) are arranged therein so as, during core drilling, and in collaboration with the effects of the pressure of the core-drilling fluid on the inner assembly (7), to keep the latter hydrostatically suspended within the outer assembly (4) within the limits of the said freedom of movement and of the aforementioned clearance.
8. Core barrel according to Claim 7, characterized in that the hydrostatic-suspension means (33) comprise means arranged on the interior wall of the inner tube (5), to offer known resistance to the entry of the drilled core (6) into this tube (5).
9. Core barrel according to Claim 7, characterized in that the hydrostatic-suspension means (33) comprise means for regulating the escape of a fluid contained in the inner tube (5) so as to offer known resistance to the entry of the drilled core (6) into this tube (5).
10. Core barrel according to any one of Claims 1 to 9, characterized in that the bit (3) has an internal passage (41) of a diameter greater than the one exhibited by one or more cutters (42) closest to its axis of rotation and intended to determine the outside diameter of the drilled core (6), and in that the axial length of the clearance (48) of the bit (3) is extremely short.

Images