Patent Application
20220003062
The invention relates to an underwater drilling device for procuring drill cores of a bed of a body of water, with a base frame which is designed to be lowered in a body of water and to be placed on the bed of the body of water, a drill drive for rotatably driving a drill string about a drilling axis, wherein the drill string is constructed at least of tubular drill string elements and additionally at least one core barrel for receiving a drill core is provided in the drill string elements, in accordance with the preamble of claim 1.
The invention furthermore relates to a method for procuring drill cores of a bed of a body of water, in which an underwater drilling device with a base frame is lowered in a body of water and placed on a bed of a body of water, and a drill string consisting of at least one tubular drill string element is drilled into the bed of the body of water in a first drilling step with a drill drive, with a drill core being formed in the tubular drill string element and being received in a core barrel in the drill string element, in accordance with the preamble of claim 8.
An underwater drilling device and a method of this type are disclosed by WO 2015/172818 A1. This known underwater drilling device is designed to subject procured drill cores, directly while still under water, to a first analysis by means of at least one sensor means which is attached to the base frame of the drilling device. Thus initial findings can be obtained using the drill cores while the underwater drilling device is still on the bottom of the body of water. This may be up to several thousand meters beneath the water surface. Compared with pure analysis outside the body of water once the underwater drilling device has been retrieved, a saving can thus be made in terms of working hours and lifting and lowering operations. The drill cores obtained are stored on the drilling device and can be lifted therewith.
Further conventional underwater drilling devices are known for example from WO 2012/000077 A1 or U.S. Pat. No. 7,380,614 B1.
For certain in-depth analyses of the drill cores, in many cases it continues to be necessary to bring the drill cores to a corresponding analysis means outside the body of water and to subject the drill cores to the desired in-depth investigations. The investigations serve to obtain as accurate as possible knowledge about the structure of the bottom of the body of water, which is of interest for example for exploration of mineral resources.
It has been established that, when retrieving drill cores which are stored on a base frame of the underwater drilling device, during the retrieval operation from the bottom of the body of water changes to the drill cores may occur which may adversely affect the informative value of later investigations and analyses.
In principle, closable core barrels are known for example from DE 10 2008 049 795 A1. However, these plus the closure are located within the drill string and are closed within the drill string.
The object of the invention is to devise an underwater drilling device and a method for procuring drill cores of a bed of a body of water with which particularly reliable information about the bed of the body of water can be provided.
This object is achieved firstly by an underwater drilling device having the features of claim 1 and secondly by a method having the features of claim 8. Preferred embodiments of the invention are set forth in the respective dependent claims.
The underwater drilling device according to the invention is characterized in that the drill core, once it has been removed from the drill string, can be enclosed in pressure-tight manner in a receiving container on the base frame under water.
The invention is based on the finding that, in particular when removing drill cores from a bed of a body of water which lies several hundred or even several thousand meters beneath the water surface, changes to the state, the composition or the structure of the drill core obtained may occur merely because of the changing pressure conditions. These changes in such case may considerably adversely affect reliable information about the actual state and structure of the bottom of the body of water. This according to one finding of the invention applies particularly when the drill cores contain solids, liquids or gases which tend to change their form relatively readily in the event of a change in temperature or pressure. This applies in particular to what are called gas hydrates, in particular to methane hydrate, also known as methane ice, which occurs in large quantities in the sea bed and is of particular interest as a possible future energy source. Such methane hydrate forms from water and methane gas at a pressure of approximately 2 MPa and temperatures of 2 to 4° C. This corresponds approximately to the conditions found from a water depth of approx. 500 meters onwards. Above this water depth, therefore, methane hydrate can emerge from drill cores as a gas and volatilize.
According to the invention, securing the drill core by receiving the drill core in a receiving container and by pressure-tight closing of this receiving container is achieved still under water.
Drill cores which are therefore enclosed in pressure-tight manner while still on the bottom of the body of water thus upon later analysis permit particularly reliable information on the structure, the state and the composition of the bottom of the body of water to be obtained. Pressure-tight enclosing of the drill core outside the drill string creates space in the drill string and thus makes it possible to obtain large drill cores, which improves their informative value about the nature of the ground.
In principle, the receiving container may be designed in any way whatsoever to receive the drill core. The receiving container may in principle also receive a plurality of drill cores. One particularly preferred embodiment of the invention consists in that the receiving container is formed by the core barrel or a drill string element, the barrel ends of which can be closed by means of a closing means. The closing means may in this case be in particular a manipulator means with which closure caps are applied to the barrel ends, which may also be called barrel openings or receiving openings. The direct use of the core barrel as part of the receiving container results in an overall compact configuration of the underwater drilling device.
In accordance with the preferred embodiment, drill string elements are used as the receiving container, with both ends being provided with threads for screw connection to further drill string elements. These threads which are present may be used for screwing on the closure caps.
Alternatively, according to one development of the invention it is preferred that spaced apart from the drilling axis there is provided a storage means for at least one closable receiving container for the drill core, the receiving container being designed in cartridge-like manner with a receiving opening for introducing the drill core, that a manipulating means is arranged which is designed to introduce the drill core into the receiving container, and that a closing means is provided which is designed to close the receiving opening of the receiving container once the drill core has been received. The drill core may in this case, on its own or preferably together with the core barrel in which the drill core is held, be introduced into the receiving container. By means of the closing means, which comprises in particular a manipulator, the individual receiving opening on the cartridge-like or cup-like receiving container can be closed in pressure-tight manner by applying a closure cap. For this configuration according to the invention, conventional and hence correspondingly thin-walled core barrels can be used in a drill string.
In principle, the receiving container may be closed by any closure caps whatsoever. These may be fastened to the receiving container in particular by pressing-on, pushing-on, locking, gluing or in another way in non-positive manner, in positive manner or by a material-to-material bond. According to one variant embodiment of the invention, it is particularly advantageous that the closing means has at least one rotary drive which is designed to turn a closure cap with screw thread relative to the receiving container, with a suitable thread being arranged on the barrel openings or the receiving opening. The rotary drive may in this case also be formed by the drill drive of the drilling device itself. In this case, the closing means would comprise a manipulator for holding the closure cap at least for closing a lower barrel opening on a receiving container, while the drill drive drives the receiving container in rotation to form the screw connection. To screw a closure cap onto an upper receiving opening, a corresponding closure cap can be held on the drill drive, with the receiving container then itself being secured by means of a clamping unit as part of the closing means.
Alternatively, a standalone rotary drive may also be provided on a manipulator arm which grips a closure cap, moves it into the connection position and there by applying a rotary movement screws the closure cap onto a corresponding thread on the receiving container.
The storage means may be a simple cradle for holding the receiving containers or a motor-driven storage means, for example a rotatable revolving magazine or a revolving storage chain with holding elements.
One further advantageous embodiment of the invention consists in that the core barrel can be pulled out of the drill string by means of a manipulating means, and the manipulating means and the closing means are movable relative to each other. The manipulating means may in this case be designed such that it pulls the core barrel with the drill core merely axially upwards out of the drill string and holds the core barrel in the drilling axis. Then the receiving container can be moved into the drilling axis by the manipulating means for drill string elements. By axially moving the core barrel, the latter can then be introduced into the receiving container. The axial movement may be a lowering or a raising of the core barrel depending on the position of the receiving opening of the receiving container. Then the receiving container with the received drill core can be closed by means of the closing means.
Alternatively, the manipulating means may make possible a multi-axis movement of the core barrel with the drill core. Thus the core barrel can not only be pulled out of the drill string axially but then be moved transversely to the drilling direction to a receiving container, in order there to be introduced with the drill core into the receiving container.
The manipulating means may according to the invention also consist of a plurality of movable components with a plurality of grippers, with pivoting also being possible in addition to linear movement. In particular, a multi-axis robotic arm can be used for the manipulating means.
One preferred embodiment of the underwater drilling device according to the invention consists in that the manipulating means is a cable winch with lifting cable, or has at least one lifting cylinder. The cable winch with lifting cable may be used in particular also for pulling the core barrels out of the drill string. Preferably, the cable winch means may have on the upper side of the basic cradle an extension which makes it possible to pull a core barrel upwards out of the drill string and the box-shaped base frame and thus optionally to move the core barrel also above the base frame. Alternatively or additionally, a lifting cylinder which is preferably operated hydraulically, pneumatically or electrically may also be provided for this. Usually only one core barrel is located in the drill string. If the core barrel is filled with a drill core, the core barrel is pulled out of the drill string. Then for a further drilling step an empty core barrel can be inserted into the drill string.
According to a further embodiment of the invention, it is advantageous for the base frame to be connected to a supply vessel by way of a marine umbilical. The marine umbilical may in this case be provided both for supplying power, in particular electric power or hydraulic fluid, and as a data line for data communication. Furthermore, the marine umbilical may also be designed as a cable with which the underwater drilling device can be lowered and raised again in addition to the supplying function.
The method according to the invention is characterized in that the drill core is removed from the drill string and enclosed in pressure-tight manner in a receiving container under water. The method may be carried out in particular with the underwater drilling device previously described. In this case, the advantages previously described can be obtained.
At least one closure cap is provided for closing the receiving container. This cap may be provided with any connecting means for producing a pressure-tight connection. According to a preferred variant embodiment of the method according to the invention, provision is made for at least one closure cap to be screwed on with a screw thread to close the receiving container. In this case, the receiving container may be designed in cartridge-like manner as a tubular body with a closed base. On the receiving opening of the receiving container there is arranged a corresponding thread for forming a screw connection. The receiving container may also be formed by the tubular drill string element which is open on either side, with a corresponding thread being formed on the two opposing drill barrel ends in each case, onto which thread a corresponding closure cap is then screwed. The receiving container and/or the closure cap may be provided with a pressure relief valve in order to discharge excess pressure within the receiving container which exceeds a certain value and occurs during the transport of the drill core to the water surface, in order to avoid damage to the receiving container.
According to a further method variant of the invention, it is preferred for the core barrel to be pulled out of the drill string by means of a manipulating means, for the core barrel and the receiving container to be moved and axially aligned relative to each other, and, once axial alignment of the core barrel and receiving container has taken place, for the core barrel with the drill core to be moved into the receiving container by relative axial movement of the core barrel and receiving container. In this method variant, the receiving container is preferably designed in cartridge-like manner, so that the drill core together with the core barrel can be introduced in a simple manner.
An overall compact structure can be achieved according to a further method variant of the method according to the invention in that a receiving bore for the receiving container is created beneath the base frame in the bed of the body of water, and in that the core barrel is introduced into the receiving container in the receiving bore. The cartridge-like receiving container may in this case be introduced into the drill hole already present in particular once the drill string has been removed. Alternatively, a separate receiving bore may be formed in the bed of the body of water. This bore can be created by the drill head present on the drill string or by the receiving container itself. For this case, the receiving container may be provided at its lower end with a drilling or cutting means which supports the formation of the receiving bore by soil removal and/or displacement.
Once the core barrel has been introduced into the receiving container, it, prior to or after closing of the container, may be pulled out of the receiving bore again and stored on the base frame of the underwater drilling device.
One further expedient configuration of the method according to the invention consists in that the receiving container is moved into the drilling axis. With this method, in particular the core barrel with the drill core is moved into an upper supply position by a manipulating or lifting device. This may be performed in particular by means of a cable means which is also provided for raising and lowering the core barrels. Once the receiving container has been positioned in the drilling axis approximately beneath the supply position of the core barrel, the latter can then be lowered and thus introduced into the receiving container.
In this position of the receiving container in the drilling axis, a closure cap can also be screwed, preferably by means of the drill drive, onto the receiving opening of the receiving container and thus the drill core can be closed in pressure-tight manner in the receiving container.
Alternatively, one method variant consists in that the core barrel is moved to the receiving container at the storage location and is introduced into the receiving container there. To this end, the core barrel with the drill core is moved by means of a manipulating means out of the drilling axis until it is arranged above or beneath the receiving container and is arranged axially aligned therewith. Then, by axially moving the core barrel, the latter can be introduced into the receiving container. Then the receiving container can be closed directly at the storage location by applying a closure cap.
The invention in principle also comprises a receiving container for receiving a drill core for an underwater drilling device, as has been previously described, or for a method for procuring drill cores, as has likewise previously been described. The receiving container is characterized in that it has a tubular base body with at least one receiving opening, and in that the at least one receiving opening once it has received a drill core can be closed in pressure-tight manner by means of a closure cap. Furthermore, the receiving container may have a safety valve to counteract excess pressure.
The at least one closure cap may be connected to the receiving opening in any suitable manner. Preferably, a pressure relief valve may also be provided on the closure cap, so that upon lifting the closed receiving container any excess pressure beyond a specified limit pressure which may possibly arise due to a change in the state of aggregation of elements in the drill core is avoided.
One advantageous development of the receiving container according to the invention consists in that a temperature control means is provided on the base body, with which means an interior of the receiving container can be heated and/or cooled. As a result, the temperature and hence the pressure within the receiving container can be influenced directly. In particular, by cooling the receiving container sublimation for example of methane hydrate or another substance out of the drill core and hence a pressure increase in the receiving container can be counteracted.
The invention will be described further below with reference to preferred examples of embodiment, which are illustrated schematically in the drawings. The drawings show:
In a first embodiment of the underwater drilling device 10 according to the invention of
In the illustration of
Once the core barrel 34 has been pulled out of the drill string 30 into an upper position, as illustrated in
To close a lower barrel end 35 of the core barrel 34, a cap-like or cup-shaped closure cap 46 is picked up from a magazine 56 and pivoted into the drilling axis 31 beneath the core barrel 34 by means of a lower manipulator arm 52 of the closing means 50, as illustrated clearly in
The closure cap 46 has at its upper end an internal screw thread which corresponds to an external thread on the lower barrel end 35 of the core barrel 34. By actuating the drill drive 20 and the lifting device 68, the core barrel 34 can be screwed into the screw thread of the closure cap 46. This is done in such a way that the lower barrel end 35 is closed in pressure-tight manner. Preferably a corresponding sealing means, in particular a sealing ring, can be provided on the screw connection.
If further drill string elements 32 and further core barrels 34 are present, these method steps for pressure-tight enclosing of the drill core in a collecting container 40 can be repeated until all the core barrels 34 with drill cores are obtained. Upon dismantling the drill string 30, the outer drill string elements 32 can likewise be pulled out of a drill hole again in known manner and conveyed back into the corresponding storage region 14 on the base frame 12.
For pressure-tight enclosing of the core barrels 34 with the drill cores located therein, first of all a cartridge-like receiving container 40 is picked up out of the storage means 70, which may also be the storage region 14 for the drill string elements 32, by means of a manipulating means 60 with at least one gripper arm 62 and introduced into a receiving bore 7 in the bed of the body of water 5, as illustrated clearly in
By means of a manipulating means 60, which may in particular comprise a lifting cable 67, a core barrel 34 can be removed from the storage means 70 and, once it has been introduced into the drilling axis, can be introduced through the receiving opening 42 into the cup-like receiving container 40, as is illustrated in
According to
A third embodiment of an underwater drilling device 10 according to the invention emerges from
Once the drilling-out has been terminated, or after each drilling advance which corresponds to the length of one drill string element, the drill drive 20 is moved upwards along the base frame 12 on a corresponding linear guide and then spaced apart laterally from a drilling axis, as can be inferred from
Then an empty receiving container 40 can be removed from a carousel-like storage means 70 by way of a manipulating means 60 with a gripper arm 62, and positioned in the region of the drilling axis beneath the core barrel 34 which has been pulled upwards, as can be seen from
Once the receiving position of the receiving container 40 illustrated in
Then the closed receiving container 40 can be brought back into the storage means 70 by way of the gripper arm 62, after which a further core barrel 34 can be introduced into the drill string 30. Prior to or after this, a further drill string element 32 can be placed on the existing drill string 30 and be screw-connected thereto. After renewed drilling, a further method step for closing a further core barrel 34 can be carried out.
One further variant embodiment of the invention emerges from
From this transfer position illustrated in
By means of a closing means 50 which has a movable manipulator arm, a receiving container 40 is moved out of a storage means 70 upwards to above the base frame 12 and moved laterally over the core barrel 34 into the closure position.
In contrast to the embodiments previously described, the receiving container 40 has an inverted position, with the closed base 44 of the cylindrical base body 41 being at the top, while the receiving opening 42 is directed downwards to the core barrel 34. Then with a gripping and displacement unit 58 of the closing means 50 the receiving container 40 can be moved downwards over the core barrel 34 which is located thereunder, as illustrated clearly in
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2018/086116 | 12/20/2018 | WO | 00 |
