GB2465829A

GB2465829A - Multiple barrel corer

Info

Publication number: GB2465829A
Application number: GB0822103A
Authority: GB
Inventors: David J Smith
Original assignee: Natural Environmental Research Council
Current assignee: Natural Environmental Research Council
Priority date: 2008-12-04
Filing date: 2008-12-04
Publication date: 2010-06-09
Anticipated expiration: 2028-12-04
Also published as: GB0822103D0; GB2465829B

Abstract

Corer comprising a plurality of core barrel assemblies 100 a-j, a drive mechanism 128 and an attachment mechanism. Each core barrel assembly has a scorer (108, fig 1) which marks the core / sample obtained enabling the orientation of the sample to be determined. The attachment mechanism attaches each of the core barrel assemblies in sequence to the drive mechanism and the marking knife is oriented to a predetermined / known position. The core barrel assembly may comprise of a fixed inner barrel with the scorer on its inner surface and a rotatable outer barrel. The attachment mechanism may have a conveyor 140 to move the core barrel assemblies to the drive mechanism 128. Preferably there may be a mechanism to alter the angle of drilling. A second independent claim concerns a drive transmitting element biased to be disengaged with the core barrel assembly and move able by actuator to an engaged position.

Description

CORER

This invention concerns corers. The invention has particular, but not exclusive, application to attachment of core barrel assemblies to associated driving equipment and the acquisition of oriented cores.

Core sampling is regularly used in many industries and scientific activities including underground and undersea prospecting (e.g. for oil, gas, metals, ores or minerals), construction engineering and geological and archaeological science.

Core samples can provide a wealth of information, such as indicating the likelihood of successful prospecting, the suitability of a particular area for various types of construction, or the variations in prevailing conditions and species in a given area over geological time.

It is well known within the art that a corer might include multiple core barrel assemblies for drilling multiple cores. The core barrel assemblies can then be used one after the other by sequential attachment to driving apparatus provided. An example of such a corer is described in US4043407A. This system has the advantage that multiple cores can be drilled in multiple locations before the corer need be retrieved to the sea surface/drilling rig. This may be particularly useful where retrieval of the corer is a complicated and/or lengthy process, for example where drilling is conducted at the seabed.

It is also known within the art that oriented cores can provide significantly more valuable information than non-oriented cores. Oriented cores are those for which the orientation of the core when still present in the substrate can be ascertained following collection of the core. Oriented cores are for example more useful when it is desirable to know the strike (the course or bearing at intersection with a horizontal plane) and dip (the downward inclination in reference to the plane of the horizon) of a structural surface. A method of obtaining oriented cores is known whereby cores are scored' as they enter the core barrel assembly. If the orientation of the core barrel assembly as it drills is known, the score line in the core may be indicative of its orientation (i.e. compass readings could be assigned to the core showing its direction when still in the substrate).

Current systems do not however allow the collection of multiple oriented cores before retrieval of the corer to the drilling rig/sea surface.

Another problem currently experienced, especially in seabed core drilling, is that if power to the corer is lost during a drilling operation, it may not be possible to remove the core barrel assembly from the substrate and the whole corer may become trapped.

According to a first aspect of the invention a corer comprising a plurality of core barrel assemblies, each core barrel assembly comprising a scorer for marking a core obtained from a substrate by the core barrel assembly, a drive mechanism and an attachment mechanism arranged, in use, to attach each of the plurality of corers in sequence to the drive mechanism such that the scorer of the connected core barrel assembly is oriented in a predetermined position.

The apparatus of the invention allows multiple oriented cores to be obtained. An advantage of the apparatus is the fact that the core barrel assemblies that are attached to the drive mechanism, following disconnection of the preceding core barrel assembly/ies, are oriented in a predetermined position without it being necessary to. retrieve the drilling apparatus, for example, from the seabed. Reducing the number of times the drilling apparatus has to be retrieved may result in significant time savings when drilling multiple oriented cores. Drilling multiple orientated cores during a single visit to the substrate may be particularly useful where data from the multiple cores is combined to produce a representation of subsurface features.

Each core barrel assembly and the drive mechanism may have cooperating formations arranged such that when the core barrel assembly is connected to the drive mechanism by the attachment mechanism the scorer of the connected core barrel assembly is oriented in a predetermined position.

The cooperating formations may provide a keying arrangement to ensure that the core is attached to the drive mechanism with the scorer aligned in the predetermined position. The cooperating formations may connect together by any one of a snap fit, meshing lock and key arrangement, cooperating threads, cooperating formations, electromagnets or any other suitable arrangement or mechanism, provided that the scorer of each core barrel assembly, once the core barrel assembly is connected to the drive train, is oriented in a predetermined position.

Each core barrel assembly may comprise a fixed inner barrel and a rotatable outer barrel, where the inner barrel contains the scorer on its inner surface arranged to mark the core sample and where the outer barrel is operably connectable to the drive mechanism for drilling through the substrate. This arrangement may relieve the outer barrel, the primary function of which may be to drill through the substrate, from having to provide the core with a mark indicative of its orientation when still in the substrate.

The inner barrel may be fixed relative to a base of the core barrel assembly, at least a portion of the base of the core barrel assembly providing one of the cooperating formations of a keying arrangement for ensuring that the scorer is oriented in a predetermined position when the core barrel assembly is connected to the drive mechanism.

It may be that the inner barrel is inset within the outer barrel to the extent that substantially only the scorer impinges on the core as it enters the core barrel assembly. This may reduce wear and tear on the core barrel assembly and reduce the power that must be supplied by the drive train.

A portion of the outer surface of the outer barrel may be provided with teeth for engagement with cooperating teeth of the drive mechanism.

This may represent a relatively uncomplicated solution to driving the outer barrel, while the inner barrel remains substantially stationary.

The attachment mechanism may comprise a conveyer to transport core barrel assemblies to and from the drive mechanism. This may allow used core barrel assemblies to be transported away from the drive train, while an unused core barrel assembly is positioned so as to be ready for attachment to the drive train. Although used core barrel assemblies may then continue to move as unused core barrel assemblies are sequentially connected to the drive train, they need play no further part in the drilling process and are essentially dormant until the apparatus is retrieved or until cores are removed from the used core barrel assemblies.

The conveyer may be a carousel. A carousel may be a particularly space efficient and yet uncomplicated way of transporting the core barrel assemblies to and from the drive train.

The apparatus may comprise a tilt mechanism arranged to vary a drilling angle of the core barrel assemblies. The apparatus may comprise a feed mechanism arranged to support each core barrel assembly when the core barrel assembly is connected to the drive mechanism to control movement of the core barrel assembly into and from the substrate and the tilt mechanism may be arranged to vary the drilling angle by raising or lowering the angle of a feed mechanism supporting the core barrel assembly.

This may be desirable where the substrate is not substantially horizontal, or where it is thought that sub surface features will be more usefully revealed by drilling at an angle. It may also be that the feed drive and/or core barrel assembly is attached to an extender drive that may extend the feed mechanism and/or core barrel assembly so as to be clear of a main body of the apparatus and/or the ROY (if provided).

The feed mechanism may comprise a feed table for supporting the core barrel assembly and the drive mechanism and a feed drive connected to the drive mechanism for controlling movement of the drive mechanism and a core barrel assembly connected to the drive mechanism relative to the feed table and the tilt mechanism may be arranged to adjust the angle

of the feed table.

It may be that core drilling and/or sequential connection of core barrel assemblies is remotely controllable. This may be advantageous where the core drilling site is inaccessible to operators or where remote control offers greater flexibility or increased safety.

It may be that a core drilling sequence perhaps including sequential connection of cores may be performed automatically, perhaps by computer. It may for example be possible to program the computer to utilise the apparatus to drill a particular pattern of cores in particular locations. This system may allow for greater efficiency and accuracy of core drilling, as the apparatus under computer control may perform more quickly and with smaller operational tolerances than when under manual control.

The apparatus may be arranged to retrieve core samples from a seabed.

The apparatus may be particularly useful for seabed core drilling, where it is frequently very time consuming to retrieve the drilling apparatus.

Furthermore the unpredictable nature of the sea may mean that there is only a brief window of opportunity to retrieve as much data as possible.

The present invention facilitates rapid accumulation of useful data by providing the facility to obtain multiple orientated core samples during only one visit to the seabed.

The apparatus may be provided as part of a remotely operated vehicle (ROy). The ROV may allow an operator to move the apparatus around almost at will. This may be particularly useful where it is desirable to have the flexibility to choose drilling sites when the apparatus is proximate to the substrate. This may be especially true where the ROV is also able to send back information about the substrate.

According to a second aspect of the invention a drive mechanism arranged to be used with a corer, the drive mechanism comprising a drive transmitting element arranged to be movable to a first position, in which the drive transmitting element is operably engaged with a corresponding element on a core barrel assembly to transmit drive to the core barrel assembly. and a second position, in which the drive transmitting element is disengaged with the corresponding element on the core barrel assembly, a biasing element arranged to bias the drive transmitting element to the second position and a power driven actuator for moving the drive transmitting element to the first position against the biasing when power is supplied to the actuator and release the drive transmitting +1 element to move under the biasing when no power is supplied to the actuator.

This drive mechanism may be advantageous in that, when used on a drilling apparatus, the drive mechanism automatically releases from the core barrel assembly when there is a loss of power allowing the drilling apparatus to be retrieved even if the core barrel assembly is trapped in the substrate.

The biasing element may comprise a spring to bias the drive transmitting element to the second position.

It may be that the drive transmitting element is mounted on a hinged base portion, whereby the hinging of the base portion allows the drive transmitting element to be brought into or out of operative engagement with the corresponding element of the core barrel assembly. This may provide a relatively uncomplicated method of disconnecting the core barrel assembly from the rest of the apparatus. The hinged base portion may be biased by the spring to a position in which the drive transmitting element is out of operative engagement with the corresponding element of the core barrel assembly.

Embodiments of the invention will now be described in more detail, by way of example only, with reference to the accompanying drawings, in which: Figure la is a schematic representation of one embodiment of an inner barrel of a core barrel assembly; Figure lb is a schematic representation of one embodiment of an outer barrel of a core barrel assembly; Figure ic is a schematic representation showing the relationship between inner and outer barrels of a core barrel assembly; Figure id is a schematic representation of a core barrel assembly; Figures 2a to 2c are schematic representations showing connection of a core barrel assembly to a drive mechanism; Figure 3 is a schematic representation showing part of one embodiment of the invention including a conveyer arrangement for transporting core barrel assemblies to and from a drive mechanism; Figures 4a to 4c are schematic representations illustrative of a core barrel assembly being oriented for drilling; Figures 5a to 5e are schematic representations illustrative of a core barrel assembly being oriented for drilling when the drilling apparatus includes a remotely operated vehicle (ROy); and Figures 6a to 6f are schematic representations illustrative of the angle of the core barrel assembly being varied for drilling.

Referring first to figures la to id, a core barrel assembly is generally provided at 100. The core barrel assembly comprises a cylindrical inner barrel 102 with a hollow body and an opening 104 at its distal end 106.

Running along the length of the inner barrel 102 on its inner wall is a scorer 108. Moulded around the proximal end 110 of the inner barrel 102 is a cuboid inner barrel base portion 112. Base portion 112 is fixed relative to inner barrel 102 such that there is substantially no relative movement between them.

The core barrel assembly 100 also comprises a cylindrical outer barrel 114 with a hollow body and an opening 116 at its distal end 118. The diameter of the outer barrel 114 is greater than the diameter of the inner barrel 102. The distal end 118 of the outer barrel 114 has cutting surfaces (not shown). The proximal end 120 of the outer barrel 114 is attached via a bearing (not shown) to a cuboid outer barrel base portion 122. The bearing allows the outer barrel 114 to rotate freely relative to the outer barrel base portion 122 about its axial length. Close to the proximal end of the outer barrel there is also a series of longitudinally oriented teeth 124 arranged to cooperate with a cog of a drive mechanism (described later).

The inner barrel 102 is received within the outer barrel 114, and the outer barrel base portion 124 is attached to the inner barrel base portion 112 to form a base portion generally provided at 126. The inner wall of the outer barrel 114 contains a recess (not shown) into which the inner barrel 102 is received. When the inner barrel is received in the recess of the inner wall of the outer barrel 114, only the scorer 108 protrudes radially inwards beyond the non-recessed portions of the inner wall of the outer barrel 114.

Referring now to figures 2a to 2c a core barrel assembly is generally provided at 100. Drive is transmitted to the core barrel assembly via a drive mechanism 128 mounted on a base plate 137. The drive mechanism 128 comprises a motor 130, a substantially cuboid base portion 132, and a hinging element 134. The motor 130 includes a drive transmitting element (in this case a cog 136) with longitudinally oriented teeth 138 designed so as they can mesh with the longitudinally oriented teeth 124 of the outer barrel 114.

The hinging element 134 allows cog 136 of motor 130 to be moved into a first position shown in Fig 2a, in which the cog 136 engages with the longitudinally oriented teeth 124 of the outer barrel 114 and a second position shown in Fig 2c, in which the cog 136 is out of engagement with the teeth 124. In this embodiment the hinging element 134 is biased by a spring (not shown) to the position in which the drive transmitting element is out of operative engagement with the longitudinally oriented teeth 124 of the outer barrel 114. An actuator (in this case a hydraulic ram (not shown)) moves the hinged element 134 to the first position when power is supplied to the actuator. If no power is supplied to the hydraulic ram the hinging element 134 is allowed to move freely and moves under the biasing of the spring such that the cog 136 of motor 130 is in the second position.

Referring now to figure 3, ten core barrel assemblies lOOa to lOOj are provided on a conveyer 140. Core barrel assemblies lOOa to lOOg are yet to be used for drilling and are awaiting use. Core barrel assemblies lOOi and lOOj have already been used for drilling and both contain a core (not shown). Core barrel assemblies lOOi and lOOj are deemed to be dormant.

Core barrel assembly lOOh is aligned with a drive mechanism 128 and is ready to be prepared for drilling.

The conveyor 140 acts as an attachment mechanism for locating the core barrel assembly lOOh on the base plate 137. The cuboid shaped base portions 112 and 122 act as cooperating formations that cooperate with the flat base plate 137 such that the orientation of the core barrel assembly lOOh is as desired. As the inner barrel 102 is fixed to the base portion 112, positioning of the core barrel assembly lOOh on the base plate 137 ensures that the scorer 108 is orientated in a predetermined position.

The drive mechanism 128 is shown in an out of operative engagement position (see fig 2a), but may be controlled to adopt an operative engagement position (see fig 2c), so as to drive the outer barrel 114 of the core barrel assembly lOOh. The core barrel assembly lOOh and drive mechanism 128 sit atop a feed table 142 to which is also mounted a support guide 144, with a cylindrical hole through which the outer barrel 114 extends when the core barrel assembly is drilling. Once core barrel assembly lOOh has been used to drill a core, the conveyer 140 moves core barrel assembly lOOg into a position where it is ready to be prepared for drilling. This process continues, until all core barrel assemblies contain a core or until further drilling is not required. The core barrel assemblies lOOa to lOOj present on the conveyer 140 are arranged such that the scorer 108 of each conveyer is orientated in a predetermined position.

Movement of the core barrel assemblies lOOa to lOOj along the conveyer 140 does not alter the orientation of the scorer 108. When a core barrel assembly is ready to be prepared for drilling, movement of the drive mechanism 128 to the operative engagement position does not change the orientation of the scorer 108 and the core barrel assembly base portion 126 is locked into position, preventing alteration to the orientation of the scorer 108. Following drilling, when the drive mechanism 128 is moved out of the operative engagement position and the core barrel assembly lOOa to lOOj is moved along the conveyer 140, the scorer 108 orientation is not changed.

Figures 4a to 4c show a feed mechanism according to an embodiment of the invention. The feed mechanism comprises a feed table 142 for supporting a core barrel assembly 100. Associated with the feed table 142 is a feed drive 146, in this embodiment a rotatable helical thread is in engagement with base plate 137 such that rotation of the thread causes movement of the base plate 137. The feed drive 146 is used to extend and retract the core barrel assembly in a direction parallel to the feed table 142, so that the core barrel assembly 100 may be extended into and retracted from a substrate.

The feed table 142 is connected to a skid portion 152 by a hinge 148 and a tilt mechanism 150, in this embodiment a piston, controls pivotal movement of the feed table 142 relative to the skid portion 152. The tilt mechanism 150 allows the core barrel assembly 100 to be tilted to a desired drilling angle relative to the skid portion 152 that remains substantially horizontal. Associated with the skid portion is an extender drive 154 which can be used to extend or retract the skid portion 152 and so the feed table 142. In this embodiment, the extender drive 154 is a rotatable helical thread in engagement with the skid portion 152 such that rotation of the thread causes movement of the skid portion 152.

Referring now to figures 5a to 5e a use of the extender drive 154 is shown when a remotely operated vehicle (ROy) 156 is provided as part of the apparatus. The extender drive 154 is used to extend the skid portion 153 and feed table 142 out of the ROV 156 housing. The tilt mechanism can then be used to tilt the core barrel assembly 100 to a desired drilling angle relative to the skid portion 152. Finally (as shown in fig 5e) the extender drive 154 may be used to further alter the degree of extension of the skid portion 152, so as to increase stability of the apparatus or to alter the drill site.

Referring now to figures 6a to 6f the core barrel assembly 100 is shown in a retracted and extended state for three different drilling angles. The core barrel assembly 100 is extended or retracted by the feed drive 146.

It will be appreciated that the tilt mechanism 150 is capable of providing the feed table 142 with substantially any angle (between at least 0 and 90 degrees) relative to the skid portion 152, and that the angles reproduced in the figures are therefore exemplary only.

In use the corer is positioned in close proximity to a substrate to be drilled (this may be by means of an ROV 156). A drilling site is selected and the conveyer 140 positions the first core barrel assembly lOOj so as to be ready to be prepared for drilling. The drive mechanism 128 is then brought into its operatively engaged position such that the motor 130 cooperates via teeth 138 of cog 136 with teeth 124 of the outer barrel 114 of the core barrel assembly lOOj. Through the action of the conveyer 140 and the operative engagement process of the drive mechanism 128 the orientation of the scorer 108 of the core barrel assembly lOOj is in a predetermined position. The extender drive 154 may then be engaged to move the feed table 142 (and so the core barrel assembly lOOj and drive mechanism 128) clear of the body of the apparatus. The tilt mechanism may then be engaged to alter the angle of the feed table 142, and so the drilling angle. The extender drive 154 may then be engaged once more to stabilise the apparatus and or to alter the drilling site. A power source is then engaged which transmits power via the drive mechanism 128 and onto the outer barrel 114 of the core barrel assembly lOOj. The inner barrel 102 does not rotate with the outer barrel 114. The feed drive 146 is then engaged to lower the core barrel assembly lOOj into the substrate such that a core may be drilled. As the core enters the core barrel assembly it is marked by the non-rotating scorer 108. In this way, if the orientation of the apparatus is known, and given that the orientation of the scorer is in a predetermined position, the orientation of the core when still in the substrate can be determined following retrieval of the core.

Once the core has been drilled the feed drive 146 is engaged to remove the core barrel assembly lOOj and the core from the substrate. If at any point during the drilling process power is lost, the drive mechanism 128 will automatically return to the state of non-operative engagement, such that if desirable the core barrel assembly lOOj may be abandoned in the substrate and the rest of the apparatus retrieved.

Following removal of the core barrel assembly lOOj from the substrate the tilt mechanism 150 and extender drive 154 are engaged appropriately so as to return the core barrel assembly lOOj to its starting position. The drive mechanism 128 is returned to a state of non operative engagement and the conveyer 140 activated to move the first core barrel assembly lOOj away from the drive mechanism 128 and to move the next core barrel assembly lOOi into position such that it is ready to be prepared for drilling.

The process is repeated with further core barrel assemblies, until the desired numbers of cores have been drilled or until all core barrel assemblies lOOa to lOOj have been used. Crucially the conveyer and drive mechanism 128 combine to ensure that the orientation of the scorer on 108 on each core barrel assembly lOOa to lOOj used is orientated in a predetermined position. All of the steps mentioned above might be performed by a computer program, by remote control or manually.

It will be understood that the invention is not limited to the embodiment above-described and various modifications and improvements can be made without departing from the various concepts described herein. The attachment mechanism between the drive mechanism and core barrel assembly might for example be substantially different. The crucial factor is only that the orientation of the scorer associated with each core barrel assembly is oriented in a predetermined position. Another example concerns the feed and extender drives which may be formed by any suitable mechanism, for example a ball screw, chain drive or hydraulic ram. Another possible variation is the provision of a carousel arrangement for the conveyer arrangement. It should also be noted that

L

the arrangement is not intended to be limited to ten core barrel assemblies and that more or less core barrel assemblies may be provided. Any of the features may be employed separately or in combination with any other features and the invention extends to and includes all combinations and sub-combinations of one or more features described herein in any form of corer.

Claims

CLAIMS1. A corer comprising a plurality of core barrel assemblies, each core barrel assembly comprising a scorer for marking a core obtained from a substrate by the core barrel assembly, a drive mechanism and an attachment mechanism arranged, in use, to attach each of the plurality of core barrel assemblies in sequence to the drive mechanism such that the scorer of the connected core barrel assembly is oriented in a predetermined position.
2. A corer according to claim 1, wherein each core barrel assembly and the drive mechanism have cooperating formations arranged such that when the core barrel assembly is connected to the drive mechanism by the attachment mechanism the scorer of the connected core barrel assembly is oriented in a predetermined position.
3. A corer according to claim 2, wherein the cooperating formations provide a keying arrangement.
4. A corer according to any one of the preceding claims, wherein each core barrel assembly comprises a fixed inner barrel and a rotatable outer barrel, where the inner barrel contains the scorer on its inner surface and where the outer barrel is operably connectable to the drive mechanism for drilling through the substrate.
5. A corer according to claim 4 as dependent on claim 3 wherein the inner barrel is fixed relative to a base of the core barrel assembly, at least a portion of the base of the core barrel assembly providing one of the cooperating formations of the keying arrangement for ensuring that the scorer is oriented in a predetermined position when the core barrel assembly is connected to the drive mechanism.
6. A corer according to claim 4 or claim 5, wherein a portion of the outer surface of the outer barrel is provided with teeth for engagement with cooperating teeth of the drive mechanism.
7. A corer according to any preceding claim wherein the attachment mechanism comprises a conveyer to transport core barrel assemblies to and from the drive mechanism.
8. A corer according to claim 7 wherein the conveyer is a carousel.
9. A corer according to any preceding claim, comprising a tilt mechanism arranged to vary a drilling angle of the core barrel assemblies.
10. A corer according to claim 9 comprising a feed mechanism arranged to support each core barrel assembly when the core barrel assembly is connected to the drive mechanism to control movement of the core barrel assembly into and from the substrate and the tilt mechanism is arranged to vary the drilling angle by raising or lowering the angle of a feed mechanism supporting the core barrel assembly.
11. A corer according to any one of the preceding claims arranged such that core drilling and sequential connection of core barrel assemblies is remotely controllable.
12. A corer according to any one of claims 1 to 10 comprising a computer for controlling automatically a core drilling sequence including sequential connection of core barrel assemblies.
13. A corer for retrieving multiple core samples from a seabed according to any of the preceding claims.
14. A remotely operated vehicle (ROy) comprising drilling apparatus according to any one of the preceding claims.
15. A drive mechanism arranged to be used with a corer, the drive mechanism comprising a drive transmitting element arranged to be movable to a first position, in which the drive transmitting element is operably engaged with a corresponding element on a core barrel assembly to transmit drive to the core barrel assembly, and a second position, in which the drive transmitting is disengaged with the corresponding element on the core barrel assembly, a biasing element arranged to bias the drive transmitting element to the second position and a power driven actuator for moving the drive transmitting element to the first position against the biasing when power is supplied to the actuator and release the drive transmitting element to move under the biasing when no power is supplied to the actuator.
16. A drive mechanism according to claim 15, wherein the biasing element comprises a spring to bias the drive transmitting element to the second position.
17. A drilling apparatus comprising a drive mechanism according to claim 15 or claim 16.
18. A corer substantially as described herein with reference to the accompanying drawings.
19. A drive mechanism substantially as described herein with reference to the drawings.