EP0995010A1

EP0995010A1 - Core barrel

Info

Publication number: EP0995010A1
Application number: EP98933379A
Authority: EP
Inventors: Philippe Fanuel; Paul Serron
Original assignee: Dresser Industries Inc
Current assignee: DII Industries LLC
Priority date: 1997-07-08
Filing date: 1998-07-08
Publication date: 2000-04-26
Anticipated expiration: 2018-07-08
Also published as: CA2295655C; NO20000057L; BE1011266A3; DE69822466D1; NO20000057D0; NO316529B1; DE69822466T2; US6341656B1; WO1999002816A1; CA2295655A1; EP0995010B1

Abstract

The invention concerns a core barrel, in particular in the field of oil exploration, comprising at least an outer tube (2) and a core bit (3) forming an outer assembly (4) and at least an inner tube (5) forming with a drilling core optionally present therein, and optionally with part of the groups arranged under the drilling core base, an inner assembly (7), suspension and/or guiding means being provided for maintaining the inner assembly (7) inside the outer assembly (4), the suspension and/or guiding means being further arranged such that the inner assembly (7) maintains at least perpendicular to these means (9), with respect to the outer assembly (4), a predetermined axial and/or radial and/or angular freedom of movement greater than usual.

Description

"Corer"

The present invention relates to a core barrel, in particular in the field of oil exploration, comprising, on the one hand, at least one outer tube and a coring ring which form an outer assembly and, on the other hand, at least one tube interior which forms with a carrot possibly present inside thereof, and possibly with a part of the formations arranged under the foot of the carrot, an interior assembly, suspension and / or guide means being provided to maintain the interior assembly in exterior assembly. Many corers of this kind are known. Their suspension and / or guide means form, between the exterior and interior assemblies, mechanical connections of the bearing type, with radial action and built-in, and of the type with double-acting stop (s). It is then usual to have at least one upper mechanical connection, often of the type with stop at the rear end of the inner tube, considering a direction of advance S of the core barrel in the ground, and a lower mechanical connection of the type bearing and embedding (in the crown for example) at the anterior end of the inner tube. There may also be intermediate mechanical connections, usually of the bearing and embedding type, in particular in the case where the coring must be carried out in a position strongly inclined relative to the vertical or even in a horizontal position.

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

It turns out, however, that the cores obtained can be severely damaged as a result of vibrations and jerks transmitted by the drill string which controls the corer, by the phenomenon known as "whirling" or whirling of the coring ring in its hole, around its axis of rotation, and the rotation of the latter around the axis of the hole, against the pseudocylindrical internal wall of the hole with a diameter greater than that of the crown, as well as by the attachment of the latter in the core formation, etc., that is to say following an unfavorable action of the exterior assembly on the interior assembly.

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

To this end, according to the invention, the suspension and / or guide means are arranged so that the interior assembly retains at least at the location of these means, relative to the exterior assembly, a freedom of determined movement, axial and / or radial and / or angular, greater than that usual.

As a result of this, it has surprisingly appeared that brutal stresses from the external assembly are no longer transmitted, or are very reduced, to the carrot which retains its integrity only better.

It also appeared as a result of this that the core material undergoes much 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 / or guide means comprise at least one rotary stop for hanging and / or supporting the inner tube in the outer tube, this stop being mounted therewith a radial clearance and / or axial and / or angular greater than the usual clearance.

According to a particular embodiment of the invention, the suspension and / or guide means comprise hydrostatic bearing means in which pressurized coring fluid forms, during coring, one or more elastic cushions with radial location and / or axial and / or angular.

According to an advantageous embodiment of the corer of the invention, means are arranged there to maintain during coring, in cooperation with the effects of the pressure of the coring fluid on the interior assembly, the latter in lift in the external assembly between the limits of said freedom of movement and / or of the aforementioned play.

Other details and particularities of the invention will emerge from the secondary claims and from the description of the drawings which are annexed to the present specification and which illustrate, by way of nonlimiting examples, advantageous embodiments of the invention shown diagrammatically, in axial section unless otherwise indicated, with broken edges and possibly on different scales.

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

Figure 2 shows the corer 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 on a larger scale the anterior ends of the inner and outer tubes and the coring ring.

FIG. 5 shows an embodiment of an intermediate guide means implementing the present invention. Figure 6 shows another embodiment of the suspension of the inner tube in the outer tube.

FIG. 7 shows another variant of the means for suspending and / or guiding the inner tube in the outer tube.

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

FIG. 9 shows, at the position of the rear end of the inner tube and of the suspension of the latter in the outer tube, a core barrel of the so-called "wireline" type, the anterior end of which may be similar to that shown in Figure 1. Figure 10 shows, in a view similar to that of Figure 9, an embodiment of a core barrel whose inner tube can not be removed from the outer tube by the technique of "wireline".

Figure 11 shows on a larger scale the aforementioned suspension location of Figure 10, the inner tube occupying a bearing 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 various figures, the same reference notations designate identical or analogous elements.

The core barrel 1 (FIGS. 1 and 2) of the invention comprises, on the one hand, an external tube 2 and a coring ring 3 which can be considered to form an external assembly 4 and, on the other hand, at least one inner tube 5 which can be considered to form, with a core 6 possibly present inside thereof, a interior assembly 7. It can also be considered that at least part of the formations arranged under the base of the core 6 forms part of the interior assembly 7. Means 9 for hanging and / or guiding the interior assembly 7, essentially the inner tube 5, in the outer assembly 4 are provided.

According to the invention, the suspension and / or guide means 9 are arranged so that the interior assembly 7 retains, at least at the location thereof, relative to the exterior assembly 4 a freedom of determined movement greater than that usual, whether axially and / or radially and / or angularly relative to the longitudinal axis of the exterior assembly 4.

This determined freedom, or this less severe connection than usual between the exterior 4 and interior 7 assemblies, prevents sudden movements, of a defined amplitude, of the exterior assembly 4 from being communicated to the interior tube 5 and by the latter to the core 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 formations located under it. A core 6 thus broken has artificial discontinuities with respect to the core formation and therefore does not show the real nature thereof. A core 6 thus broken and / or damaged also presents a considerable risk, directly linked to the number of discontinuities produced, of blockage in the inner tube 5 with respect to a continuous core 6, if possible in one piece.

In one embodiment of the invention, the suspension and / or guide means 9 comprise (FIG. 3) at least one rotary stop 12, for example with balls, for the suspension and / or the support of the inner tube 5 in the outer tube 2. According to the invention, this stop 12 is mounted with a radial and / or axial and / or 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, for example screwed together one inside 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 into one another and fixing a stop ring 18 (of the circlip type).

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

As shown in FIG. 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 the axial and radial clearances described with respect to FIG. 3 gives this assembly an angular clearance between the axis of the inner tube 5 and that of the outer tube 2.

In another embodiment, separately or in addition to the above, the suspension and / or guide means 9 comprise at least one bearing 20 (FIGS. 1 and 4) and / or 21 (FIG. 5) of the 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 inner 5 a radial clearance (Figures 1 and 4) and / or axial (Figures 4 and 5) and / or angular (by a combination of radial and axial clearances greater than the usually adjusted clearances). In FIG. 5, the bearing 21 has, for the part of the inner tube 5 which constitutes the shaft thereof, a barrel shape so as to increase a possible angular play between the axes of the inner 5 and outer 2 tubes, and therefore a flexibility of the mechanical connection at this location. According to a particular embodiment of the invention, the means 9 for suspension and / or guidance may comprise (FIG. 6) elastic means 22. These elastic means 22, also intended to soften the mechanical connection between the external assemblies 4 and inside 7 and to absorb a shock transmission, may include rings 23 of rubber or synthetic material arranged for example above and below the rotary stop 12 mounted, for the rest, like that of FIG. 3. These rings 23 may comprise annular beads 23A intended to cooperate with grooves in the surrounding parts in order to ensure adequate reciprocal positioning of the constituent elements thus stacked.

Advantageously, the suspension and / or guide means 9 can comprise (FIG. 7) hydrostatic bearing means 24 in which pressurized coring fluid, arriving from the surface by a central conduit 25 and leaving by radial conduits

26 shape during coring, between a cylindrical or conical internal wall 27 of the external assembly 4 and, opposite, a cylindrical or conical external wall 28 of the internal assembly 7, one or more elastic cushions of radial and / or angular localization of this interior assembly 7 with respect to the exterior assembly 4. Adjustment and distribution of the coring fluid flow rate between the radial conduits 26 and usual connection conduits 29 supplying the fluid from the central conduit 25 at the interval between the outer 2 and inner 5 tubes makes it possible to obtain a pressure difference causing a centrifugal radial flow from the radial conduits 26, for example in oblong chambers 31 whose dimension (longitudinal) is visible in the figure 7 and the other dimension of which is visible in FIG. 8. Each oblong chamber 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 under the effect of its own weight and the pressure of the coring fluid arriving at 32 from the ground surface. In particular in this type of corer, means 33 can be arranged to maintain during coring, in cooperation with the effects of the pressure of the coring fluid pushing the inner tube 5 downward and with friction from the incoming carrot 6 in this inner tube 5, the latter in lift in the outer assembly 4 between the limits of said freedom of movement and / or the aforementioned clearance.

For this purpose, the means 33 may for example comprise a set of bristles, or another coating, (not shown) arranged on the internal wall of the inner tube 5 to oppose with a known resistance at the entry of the core 6 in this tube 5. The means 33 may alternatively comprise means for regulating the escape of a fluid contained in the inner tube 5, arranged to thus oppose by a controlled escape a known resistance to the entry of the carrot 6 in the tube 5.

The means 33 may comprise a combination of coring fluid passages 34, whose outlet orifices 35 open onto a peripheral surface of the interior assembly 7, and of interior surfaces 36 and 37 of the exterior assembly 4 which have diameters different.

The fluid outlet orifices 35 occupy at rest a position, shown in Figures 9 and 1 1, in which they face an inner surface 36 apart, so as to allow a non-throttled outlet of the coring fluid.

By the action of said known resistance, the inner tube 5 will tend to be pushed back by the core 6 in the opposite direction to the direction of advance S of the core, so as to no longer be pressed against a suspension shoulder 38 (Figures 9 and 1 1) of the outer assembly 4. As a result, the orifices 35 occupy a position shown in Figure 12, in which they gradually face another internal surface 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 rises in the exterior assembly 4. The increase in pressure will tend to push back into the direction of advance S of the core assembly the interior assembly 7 and a balance will thus be sought, away from the shoulder 38, between opposing thrusts due to said known resistance and to the increase in fluid pressure which results of its progressive throttling.

When the interior assembly 7 leaves the shoulder 38, there is in fact a fluid leak at this location (FIG. 12). The "hydrostatic" balance obtained for the lift therefore results from the self-weight of the inner tube 7 and its suspension means, from said known resistance, from the flow of coring fluid and from the leaks thereof, including through the orifices 35. Any change in the pressure of the fluid thus produced is visible on the surface for the operator of the core barrel 1 who can then act accordingly for for example, after having deduced therefrom that it is a blockage of the core 6 in the inner tube 5, modulate this pressure and try to release 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 "wireline" technique, of the interior tube 5 for at less remove it (with a core 6) from the outer tube 2.

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

FIG. 7 shows, as a variant, that the suspension and / or guide means 9 may comprise a ball joint stop 40 to increase the flexibility of the mechanical connections between exterior 4 and interior 7 assemblies. It should be understood that the invention is in no way limited to the embodiments described and that many modifications can be made to these without departing from the scope of the present invention.

Thus, Figure 4 shows that advantageously the crown 3 has an internal passage 41 whose diameter is greater than that which has 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 at this location, so as to reduce the embedding of the core 6 in the crown 3, and therefore not to stress this core 6 by unfavorable reactions of the crown 3 during work. This embedding can also be reduced by reducing as much as possible the axial length of what is called the internal guard 48 (FIGS. 1 and 4) of the crown 3 (that is to say the passage provided therein. for carrot 6). This is within the scope of the aims of the invention, namely the search for an optimal minimum number of elements and / or points of mechanical connection or contact between what has been defined above as being exterior 4 and interior 7 assemblies. Likewise, and for the same purpose, the geometric dimensions of the suspension and / or guide means 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 embedding) compared to what the skilled person has tended to do so far.

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

When the support ring 52 is supported on the suspension shoulder 38, coring fluid passing between the outer tube 2 (Figure 1 1) and the screw element 13 can practically not pass to the place of l 'support but will tend to pass through the ball stop 12 and the mounting clearances between it and the body part 50 as well as between the latter and the support ring 52. This can significantly limit the fluid flow in the mentioned path, as a function of the annular interstices organized between these parts.

In an embodiment not described, a median tube, between the outer 2 and inner 5 tubes and substantially coaxial with them, may, as the case may be, be part of the exterior assembly 4 or of the interior assembly 7 . Legends of the figures:

S direction of advance of a coring

1 corer

2 outer tube 3 coring ring

4 outdoor set

5 inner tube

6 carrot

7 interior assembly 9 suspension and / or guide means

12 rotating 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 thrust ring 0 bearing of 9 1 bearing of 9 2 elastic means of 9 3 ring of 22 3A annular bead of 23 4 hydrostatic bearing of 9 5 central duct of 1 6 radial ducts of 24 7 internal cylindrical or conical wall of 4, 2 8 cylindrical or conical external wall of 7, 5 9 connecting conduits of 7, 5 1 oblong chambers of 24 2 place of arrival of the pressurized coring fluid lift means of 5, 7 coring fluid passages of 23 orifices of 34 internal surface of 4, 2 internal surface of 4, 2 suspension shoulder gripping means of 5, 7 ball joint internal passage of 3 knives of 3 guard internal of 3 labyrinth seal body part of 9, 14 (figure 11) annular seal on 50 support ring of 7, 5

Claims

1. Corer, in particular in the field of oil prospecting, comprising, on the one hand, at least one outer tube (2) and a coring ring (3) which form an outer assembly (4) and, on the other share, at least one inner tube (5) which forms with a core (6) possibly present inside thereof, and possibly with a part of the formations arranged under the foot of the core (6), an inner assembly (7), means (9) for suspension and / or guide being provided to hold the interior assembly (7) in the exterior assembly (4), characterized in that the means (9) for suspension and / or guide are arranged so that the interior assembly (7) retains at least at the location of these means (9), relative to the exterior assembly (4), a determined freedom of movement, axial and / or radial and / or angular, greater than that usual.

2. Corer according to claim 1, characterized in that the means (9) for suspension and / or guide comprise at least one rotary stop (12) for suspension and / or support of the inner tube (5) in the tube outside (2), this stop (12) being mounted therein with a radial and / or axial and / or angular clearance greater than the usual clearance.

3. Corer according to either of Claims 1 and 2, characterized in that the suspension and / or guide means (9) comprise at least one bearing (20, 21) for supporting the inner tube ( 5) in the exterior assembly (4), this bearing (20, 21) being arranged so as to allow between the exterior (2) and interior (5) tubes a radial and / or axial and / or angular clearance greater than the clearance usual.

4. Corer according to any one of claims 1 to 3, characterized in that the means (9) for suspension and / or guiding comprise elastic means (22).

5. Corer according to any one of claims 1 to 4, characterized in that the suspension and / or guide means (9) comprise hydrostatic bearing means (24) in which coring fluid under pressure forms, in during core drilling, one or more elastic cushions with radial and / or axial and / or angular localization.

6. Corer according to any one of claims 1 to 5, characterized in that the means (9) for suspension and / or guidance comprise at least one ball joint stop (40).

7. Corer according to any one of claims 1 to 6, characterized in that means (33) are arranged therein to maintain during coring, in cooperation with the effects of the pressure of the coring fluid on the interior assembly (7), the latter in lift in the exterior assembly (4) between the limits of said freedom of movement and / or of the aforementioned clearance.

8. Corer according to claim 7, characterized in that the means (33) for levitation comprise means arranged on the inner wall of the inner tube (5) so as to oppose a known resistance at the entrance of the carrot ( 6) in this tube (5).

9. Corer according to claim 7, characterized in that the means (33) for levitation comprise means for regulating the escape of a fluid contained in the inner tube (5), so as to oppose a known resistance to the entry of the core (6) in this tube (5).

10. Corer according to any one of claims 1 to 9, characterized in that the crown (3) has an internal passage (41) of diameter greater than that which has one or more knives (42) closest to its axis of rotation and intended to determine the external diameter of the core (6) and in that preferably the axial length of the guard (48) of the crown (3) is very short.

11. Corer according to any one of claims 2 to 10, characterized in that it comprises, on a body part (50) comprising a rotary stop (12), a ring assembly (52) and annular seal (51 ) arranged to form annular interstices between them a kind of labyrinth restricting a flow of coring fluid passing through the rotary stop (12).