WO2008068385A1

WO2008068385A1 - Arrangement and method for drilling

Info

Publication number: WO2008068385A1
Application number: PCT/FI2007/050663
Authority: WO
Inventors: Paavo Kolari
Original assignee: Terramare Oy
Priority date: 2006-12-08
Filing date: 2007-12-05
Publication date: 2008-06-12
Also published as: NO342275B1; FI20065782A0; PT2122108T; EP2122108A1; ES2605365T3; FI20065782A; EP2122108A4; FI123411B; NO20091993L; EP2122108B1

Abstract

A method for underwater drilling, in which method a drill rod assembly is inserted into a drill pipe while the drill pipe is locked to the drilling rig and the drill pipe is connected to the drill rod assembly in such a way that the rotational and impact energy received by the drill rod assembly from the drill hammer is transferable to the drill pipe. Next, a drill bit attached to the drill rod assembly and a ring bit attached to the drill pipe and the drilling rig are lowered to the sea bottom, the locking between the drill pipe and the drilling rig is opened and the drill hammer is switched on in order to begin the drilling by means of the drill bit installed to the bottom end of the drill rod assembly and the ring bit installed to the bottom end of the drill pipe. The drilling continues until the drill pipe reaches a predetermined depth into the sea bottom, after which the drill hammer is switched off, the drill pipe is locked to the drilling rig in such a way that the rotation and movement thereof in relation to the drilling rig is prevented, and the connection between the drill rod assembly and the drill pipe is released. The drill hammer is then switched on again and the drilling continues to the desired depth by means of the drill rod assembly and the drill bit.

Description

ARRANGEMENT AND METHOD FOR DRILLING

BACKGROUND OF THE INVENTION

[0001] The invention relates to equipment according to the preamble of claim 1 for underwater drilling and to a method according to the pream- ble of claim 16 for underwater drilling. In particular, the invention relates to equipment comprising a drilling rig, drill hammer, drill rod assembly formed of one or more interconnected drill rods and operationally connected at the top end thereof to the drill hammer and comprising at the bottom end thereof a drill bit and a drill pipe placed around the drill rod assembly and supported to the drilling rig, the bottom end of the drill pipe being provided with a ring bit, and to a method of drilling carried out using a drill rod assembly formed of one or more drill rods connected to the drilling rig, the drill rod assembly being operationally connected at the top end thereof to the drill hammer and comprising at the bottom end thereof a drill bit, and by means of a drill pipe mountable around the drill rod assembly and supported to the drilling rig, the bottom end of the drill pipe being provided with a ring bit.

[0002] According to the prior art, underwater drilling is conventionally carried out using a tophammer drill installed to a drilling rig that moves up and down in a stepless manner. The drilling takes place by means of one or more drill bits installed to the bottom end of a drill rod assembly consisting of one or more drill rods, while the top end of the drill rod assembly is connected to the drill hammer. The bottom end of the drilling rig is provided with a fixedly installed drill pipe that extends for a predetermined distance, for about 2 metres for example, below the bottom end of the rig and, the drill rod assembly being inserted through the pipe in such a manner that when drilling through a layer of soil on top of a rock, the drill bit is slightly below the bottom end of the drill pipe. The drill pipe is meant to prevent the layer of soil on top of the rock from falling into the drilled hole and blocking the drill hole. In other words, drilling is carried out through the drill pipe and once the desired depth is reached, the drill rod assembly is lifted upwards in such a manner that the drill bit rises above the top end of the drill pipe, the drill pipe thus being vacant for the blast to be lowered into the drill hole. The drill pipe is thus fixedly arranged in relation to the drilling rig, its downward movement being achieved by moving the entire drilling rig downward. [0003] A rock or other hard material at the bottom of the sea is often covered with a varying thickness of a softer soil through which the drill pipe is taken to prevent this softer material from collapsing or falling into the drilled hole. Accordingly, the drill bit is pressed downward by means of the drilling rig mass and the drill bit until the drill pipe reaches the surface of the rock, the drilling being then continued only by means of the drill bit installed to the drill rod assembly, while the drill pipe stays in place. However, the softer layer of soil often contains stones or other hard layers or materials, or the rock being drilled is fragmented, whereby the pushing of the drill pipe through the softer layer of soil or the fragmented rock layer is difficult and often extremely time- consuming or totally unsuccessful and thus drilling cannot be carried out at the location concerned. It is also possible that the sea bottom has to be dredged first to clean it by removing the layer of soil in question. Clean dredging is a separate work phase and increases costs significantly.

[0004] To avoid this, it is known in the art to use drill pipes directly connected to the drill hammer so as to carry out the drilling not only by means of the drill bit but also with a ring bit installed to the drill pipe. It is not advantageous to attach the drill pipe directly to the drill hammer, because it increases significantly the number of work phases as the drill pipe has to be detached from the drill hammer during the drilling, part of the drill rod assembly has to be disassembled for releasing the drill pipe for charging, the detached drill rods have to be re-installed to the drill rod assembly and the drill pipe re-attached to the drill hammer. Moreover, this renders the equipment complex and expensive.

BRIEF DISCLOSURE OF THE INVENTION [0005] It is an object of the invention to provide equipment and a method that allow the above problems to be solved. The object of the invention is achieved by means of equipment according to the characterizing part of claim 1 , the equipment being characterized in that it further comprises connecting means for optionally connecting the drill pipe to the drill rod assembly be- tween the drill hammer and the drill bit, the drill rod assembly and the drill pipe thus forming an operational unit for transferring the rotational and/or impact energy of the drill hammer from the drill rod assembly to the drill pipe, and for releasing the connection between the drill pipe and the drill rod assembly, whereby the rotational and/or impact energy received by the drill rod assembly from the drill hammer is not transferred to the drill pipe. Further, the object of the invention is achieved by a method according to the characterizing part of claim 16, the method being characterized in that it comprises the steps of

[0006] inserting the drill rod assembly with the drill bit first into the drill pipe while the drill pipe is locked to the drilling rig; [0007] connecting the drill pipe to the drill rod assembly between the bottom end of the drill rod assembly and the drill hammer in such a way that the rotational and impact energy received by the drill rod assembly from the drill hammer is transferable to the drill pipe;

[0008] lowering the drill rod assembly together with the drill bit at- tached to the bottom end thereof and the drill pipe together with the ring bit attached to the bottom end thereof to the sea bottom;

[0009] opening the locking between the drill pipe and the drilling rig;

[0010] switching on the drill hammer in order to begin the drilling by means of the drill bit installed to the bottom end of the drill rod assembly and the ring bit installed to the bottom end of the drill pipe when the drill bit and the ring bit touch the sea bottom;

[0011] continuing the drilling until the drill pipe reaches the surface of a rock or a predetermined distance into the sea bottom;

[0012] switching off the drill hammer, locking the drill pipe to the drilling rig in such a way that the rotation and movement thereof in relation to the drilling rig is prevented, and opening the connection between the drill rod assembly and the drill pipe; and

[0013] switching on the drill hammer again and continuing the drilling by means of the drill rod assembly and the drill bit into a predetermined depth by feeding the drill rod assembly through the drill pipe locked to the drilling rig.

[0014] The preferred embodiments of the invention are disclosed in the dependent claims.

[0015] The invention is based on the idea that the drill pipe and the drill rod assembly are made operationally interconnectable and disconnectable to allow drilling to be carried out either simultaneously by means of a drill bit provided at the bottom end of the drill pipe assembly and a drill pipe ring bit installed around the drill pipe assembly, or by using only the drill bit provided at the bottom end of the drill pipe assembly by feeding the drill pipe assembly through the drill pipe locked to the drilling rig. When interconnected, the drill rod assembly and the drill pipe thus form an operational assembly that pro- vides a simple and economic means for drilling through the soil, irrespective of the layers of soil. In the inventive connection achieved between the drill rod assembly and the drill pipe the drill rod assembly and the drill pipe do not need to lifted up to connect or disconnect them, but they may be connected and dis- connected when the drill rod assembly and the drill pipe are in their operational positions. Preferably the drill rod assembly and the drill pipe may be connected and disconnected by rotating the drill rod in relation to the drill pipe. Hence a hole may be drilled to the bottom of the sea by using first the drill bit on the drill rod assembly and the ring bit on the drill pipe connected to the drill rod assem- bly for receiving the impact and rotational energy of the drill hammer, the drill rod assembly and the drill pipe thus forming an operational unit. When the drilling has reached a desired depth, the drill pipe may be disconnected and released from the drill rod assembly, and the drilling may be further continued by means of the drill bit while the drill rod assembly moves through the drill pipe, without changing the configuration of the drill rod assembly. This is possible when the connecting means comprise a rod adapter on the drill rod assembly, a pipe adapter on the drill pipe and an intermediate sleeve arranged to set between the rod adapter and the pipe adapter so as to allow the rod adapter to be connected to the pipe adapter by means of the intermediate sleeve, the in- termediate sleeve transferring the rotational and impact energy of the drill hammer to the pipe adapter and further to the ring bit at the bottom end of the drill pipe, and, correspondingly, to allow the connection to the pipe adapter to be released, whereby the rotational and/or impact energy received by the drill rod assembly from the drill hammer is not transferred to the drill pipe. [0016] An advantage of the method and system of the invention is that they provide an easy and simple means for providing a connection between a drill pipe and a drill rod assembly and for releasing the connection in a short period of time in a situation where a rock or other hard material at the bottom of the sea is covered with a soft and less homogeneous layer of soil. Moreover, the structure of the equipment of the invention is simple and easy to service, because it does not contain complex parts. In addition, all the parts may be made easily replacable, which allows the connecting means to be changed according to a particular drill rod or drill pipe or damaged parts thereof to be rapidly replaced. Further still, the charging of a drill hole with ex- plosive becomes significantly faster, because a shorter drill pipe may be used than in the prior art, which means that the drill rod assembly does not need to be lifted up all the way nor to be dismantled as is the case with a drill pipe that extends to the drill hammer, but it suffices to raise the drill bit above the top end of the drill pipe for emptying the drill pipe for the charging. The accelerated drilling time brings costs savings.

BRIEF DISCLOSURE OF THE FIGURES

[0017] In the following the invention will be described in greater detail in connection with preferred embodiments and with reference to the accompanying drawings, in which

Figure 1A is a schematic view of a first phase of a method of the present invention in which the drill rod assembly is connected to the drill pipe and the drilling is carried out by means of both the drill bit on the drill rod assembly and the ring bit on the drill pipe;

Figure 1B is a schematic view of a second phase of the present invention in which the drill rod assembly and the drill pipe are disconnected and the drilling is continued by means of the drill bit through the drill pipe;

Figure 1C is a schematic view of a third phase of the method of the invention in which the drill rod assembly is lifted from the drilled hole, while the drill pipe stays in place;

Figure 1 D is a schematic view of fourth phase of the method of the invention in which the drilled hole is charged with explosive;

Figure 1E is a schematic view of a fifth phase of the method of the invention in which the drill pipe is lifted from the drilled hole and a primer cable is guided up from the hole;

Figure 1 F is a schematic view of a sixth phase of the method of the invention in which the drilling equipment has been taken to a new location for drilling the next hole;

Figure 2A is a partial view of connecting means between a drill rod assembly and a drill pipe according to an embodiment;

Figure 2B shows the parts of the connecting means of Figure 2A in- terconnected.

DETAILED DISCLOSURE OF THE INVENTION

[0018] Reference is made to Figure 1A, which illustrates an example of drilling equipment of the invention to be used for underwater drilling. In the situation of Figure 1A the drilling to be carried out using the equipment and method of the invention is just about to begin. According to Figure 1A a drilling platform 32 or a similar support structure is provided with a drilling rig 2 mounted to and supported by the platform. The drilling rig 2 is mounted to the drilling platform 32 so that it is movable up and down to allow the drilling rig 2 to be moved both in a horizontal and a vertical relation to the drilling platform 32. Further, installed to the drilling rig 2 there is a drill hammer 4, which is installed to the drilling rig 2 so as to be movable in a vertical direction in relation to the drilling rig 2. The drill hammer 4 in this embodiment used as an example is a tophammer drill.

[0019] Drilling is carried out via a drill rod assembly 8, which is op- erationally connected to the drill hammer 4 and may consist of one or more drill rods 6. The drill rods 6 are interconnected by means of a screw joint, for example, that may comprise GT-60 threads. The bottom end of the drill rod assembly is provided with a drill bit 10, also known as a pilot bit, to be used for the actual drilling of the hole. The top end of the drill rod assembly 8 is further operationally connected to the drill hammer 4 that provides the drill rod assembly 8 and thereby the drill bit 10 the rotational and impact energy needed in the drilling. The drill bit 10 may be any drill bit suitable for a particular drilling to be carried out.

[0020] In addition, mounted to the bottom end of the drilling rig 2 or to the vicinity of the bottom end there is a drill pipe 12, which may consist of one long uniform drill pipe or two or more interconnected drill pipe parts. The drill pipe parts may be interconnected by means of a screw joint, for example, or a similar joint. The bottom end of the drill pipe 12 is provided with a ring bit 14 for drilling a hole. The ring bit may be any ring bit suitable for a particular drilling to be carried out. The drill pipe 12 is dimensioned so as to allow the both the drill bit 10 and the drill rod assembly 8 to inserted through the drill pipe 12 and to be moved inside the drill pipe 12 in relation to the drill pipe 12. The drill pipe 12 of the invention is mounted to and supported by the drilling rig 2 in such a way that the drill pipe 12 may be moved in a vertical direction, i.e. in the longitudinal direction of the drilling rig 2 in relation to the drilling rig 2 and rotated about its longitudinal axis in relation to the drilling rig 2 by means of the ring bit 14 for drilling to be enabled. The movability of the drill pipe 12 may be achieved by means of support bearings, rail means or other similar means. The drilling rig 2 is further provided with gripping means 30 to allow the drill pipe 12 to be locked to the drilling rig 2, when desired, to render the drill pipe 12 fixed in relation to the drilling rig and unable to move in the longitudinal di- rection of the drilling rig 2 or to rotate in relation to the drilling rig 2. Alternatively, the gripping means 30 may be implemented so that they prevent the movement of the drill pipe in relation to the drilling rig, but allow the pipe to rotate in relation to the drilling rig, or, on the contrary, allow the drill pipe to move in relation to the drilling rig and prevent the rotation thereof. The gripping means 30 may comprise curved claws, tongs or similar grippers to be placed around the drill pipe 12, for example. The gripping means 30 are preferably implemented so that they can be operated from the drilling platform 32 or from a practical control site. [0021] With further reference to Figure 1A, the rock 5 or other similar hard matter on the bottom of the sea is often covered by a softer layer of soil 3. Therefore, when a hole is to be drilled to the sea bottom 1 , it is to be taken into account that if the drill bit 10 and the drill pipe 12 are lifted from the drilled hole, the hole is filled with soil collapsing or falling into the hole from the layer of soil 3. For this reason the drill pipe 12 must be left into the hole to keep the hole clean for charging with the explosive. Often this layer of soil 3 comprises not only soft soil but also rocks or other loose hard objects and therefore in many cases the drill pipe 12 cannot be taken through the layer of soil simply by pushing. In this case drilling by means of a drill pipe 12 is advantageous, because it allows these hard areas to be penetrated.

[0022] According to the present invention the drilling equipment is provided with connecting means 15 to interconnect the drill rod assembly 8 and the drill pipe 12. By interconnecting the drill rod assembly 8 and the drill pipe 12 and by supporting the drill pipe 12 to the drilling rig 2 in a movable and rotatable manner the rotational and impact energy subjected by the drill hammer 4 to the drill rod assembly 8 can be transferred to the drill pipe 12, whereby drilling may be carried out by means of both the drill bit 10 mounted to the drill rod assembly and the ring bit 14 mounted to the drill pipe 12. In practice the connection between the drill pipe 12 and the drill rod assembly 8 means that they form an operational unit jointly receiving the same rotational and impact energy from the drill hammer. A further essential aspect of the invention is that the drill pipe 12 is connected to the drill rod assembly 8 between the drill hammer 4 and the drill bit 10, the length of the drill pipe 12 thus being substantially shorter than the corresponding length of the drill rod assembly 8. The drill pipe 12 may be shorter than the drill rod assembly 8, because the layer of soil 3 on top of the rock 5 usually has a limited thickness and because the drill pipe 12 is connected to the drill rod assembly 8 between the ends thereof.

[0023] The connecting means 15 are preferably implemented in such a way that the drill pipe 12 and the drill rod assembly 8 may be intercon- nected and disconnected without having to lift up the drill rod assembly and/or the drill pipe 12. In other words, the connecting means 15 are implemented so that the connection between the drill pipe 12 and the drill rod assembly 8 may be implemented and released while the drill rod assembly 8 and the drill pipe 12 and, correspondingly, the drill bit and the ring bit are in their operating posi- tion, i.e. in the water and/or lowered to the sea bottom 1. In the present application it is to be taken into account that 'sea bottom 1" refers to any bottom underneath the water of a water area. According to a preferred embodiment, the connecting means 15 are implemented so that the connection between the drill pipe 12 and the drill rod assembly 8 may be made and released by rotating the drill rod assembly 8 and the drill pipe 12 in relation to each other. This means that the connection may be achieved for example by rotating the drill rod assembly 12 in a first direction of rotation about the longitudinal axis thereof in relation to the drill pipe, in which case this first direction of rotation may correspond to a normal direction of drill rotation used during drilling. Correspond- ingly, the connection may be opened by rotating the drill rod assembly 8 in relation to the drill pipe 12 in a second direction of rotation opposite to the first direction of rotation. The drill rod assembly 8 may be rotated by means of the drill hammer 4 or by some other means of rotation. Alternatively, other type of connecting means may be used, such as pin connecting means or bolt con- necting means. What is essential is that the connecting means may be operated without lifting the drill rod assembly 8 and the drill pipe 12 from the water. [0024] Figures 2A and 2B show a solution according to the present invention for interconnecting the drill rod assembly 8 and the drill pipe 12. According to Figure 2A the connecting means comprise a rod adapter 16 con- nectable to the drill rod assembly 8 by a screw coupling. The rod adapter 16 may be fastened between two drill rods 6 of the drill rod assembly 8. In Figure 2A the drill rod 6 is provided with an external thread 7 and the rod adapter with a corresponding internal thread 17, the other end of the rod adapter 16 being, correspondingly, provided with an external thread 9, which engages with the inner thread of the next drill rod (not shown). Alternatively, the rod adapter 16, may be integrally implemented into the drill rod assembly 8 or into one of its drill rods 6. On its outer surface the rod adapter 16 comprises protrusions or shoulders 22 protruding from its surface. In a particular case the shoulders 22 may be replaced by threads, or by recesses formed to the outer surface of the rod adapter 16. In addition, the connecting means comprise an intermediate sleeve 20 arranged and dimensioned in such a way that when arranged around the drill rod assembly 8, it is capable of sliding thereon. The inner surface of the intermediate sleeve 20 is provided with protrusions or shoulders 24. The shoulders 24 of the intermediate sleeve 20 and the shoulders 22 of the rod adapter 16 are arranged so as to allow the intermediate sleeve 20 to be connected to the rod adapter 16 by bringing the intermediate sleeve 20 and the rod adapter 16 into contact with each other while the intermediate sleeve 20 is installed around the rod adapter 16 and by rotating the intermediate sleeve 20 and the rod adapter 16 with respect to each other. As a result, the shoulders 22 and 24 of the rod adapter 16 and the intermediate sleeve 20 be- come interconnected, which prevents the intermediate sleeve 20 from moving with respect to the rod adapter 16 in the direction of the longitudinal axis of the rod adapter 16. Moreover, the shoulders 22 and 24 are shaped in such a way that no matter what the position of the intermediate sleeve 20, it cannot slide entirely over the rod adapter 16 and below the rod adapter 16. [0025] The connecting means further comprise a pipe adapter 18 preferably implemented at the top of the drill pipe 12 or to the vicinity thereof. The pipe adapter 18 may be a tubular part attached to the top end of the drill pipe 12 by welding, screw coupling or by some other means. Alternatively, the pipe adapter 18 may be integrally formed into the drill pipe 12. The inner sur- face of the pipe adapter 18 is provided with protrusions or shoulders 28 formed in such a way that they are capable of locking to the shoulders 26 on the outer surface of the intermediate sleeve 20, when the intermediate sleeve 20 and the pipe adapter 18 are brought into contact with each other and the intermediate sleeve 20 and the pipe adapter 18 are rotated with respect to each other. As a result, the shoulders 28 and 26 of the pipe adapter 18 and the intermediate sleeve 20 become interconnected, whereby the movement of the intermediate sleeve 20 and also that of the rod adapter 16 and the drill rod assembly 8 in relation to the pipe adapter 18 is prevented in the direction of the longitudinal axis of the pipe adapter 18 and the drill pipe and also that of the drill rod as- sembly 8. Moreover, the shoulders 28 and 26 are shaped in such a way that no matter what the position of the intermediate sleeve 20, it cannot slide en- tirely over the pipe adapter 18 and, therefore, when the intermediate sleeve 20 is in place, the rod adapter 16 cannot slide entirely through the pipe adapter 18 either. In addition, the pipe adapter 18 and/or its shoulders 28 are dimensioned and arranged in such a way that when the intermediate sleeve 20 is not on the rod adapter 16, the rod adapter 16 and the drill rod assembly 8 are able to slide through the pipe adapter 18. In Figure 2B these connecting means of the embodiment disclosed above are in the connected position.

[0026] As shown in Figure 2B, when the connecting means area in a locked state, the horizontal shoulders of the rod adapter 16, the horizontal shoulders of the intermediate sleeve 20 and the horizontal shoulders of the pipe adapter 18, or the counter surfaces of these shoulders, become set one after the other and against each other in such a way that they are unable to move in relation to each other in the longitudinal direction of the drill pipe 12 and the drill rod assembly 8, thereby transmitting the impact energy subjected to the drill rod assembly 8 to the drill pipe 12. Moreover, the vertical shoulders of the rod adapter 16, the vertical shoulders of the intermediate sleeve 20 and the vertical shoulders of the pipe adapter 18 are in a locked state against each other, whereby when the drill rod assembly 8 is rotated in the direction of the drilling rotation, i.e. in a first direction of rotation, they become pressed against each other and thereby transfer the rotational energy supplied to the drill rod assembly 8 further to the drill pipe 12.

[0027] Further, the connecting means of Figures 2A and 2B are implemented so as to allow the connection between the rod adapter 16 and the pipe adapter 18 to be opened or released by rotating the rod adapter 16 and the intermediate sleeve 20 in relation to the pipe adapter 18 in a direction opposite to the direction of drilling rotation, i.e. in a second direction of rotation. Before this the drill pipe 12 can be locked to the drilling rig using the above- mentioned gripping means 30 to hold the drill pipe 12 in place in relation to the drill rod assembly 8. After the rod adapter 16 and the intermediate sleeve 20 have been rotated, the intermediate sleeve 20 and the rod adapter 16 are rotated in relation to each other to open the connection between them, and the intermediate sleeve 20 is gripped with the lifting means to lift it above the rod adapter 16, whereby it is no longer able to connect to the rod adapter 16. This allows the drill rod assembly 8 to be moved downward through the intermedi- ate sleeve 20 and the pipe adapter 18. [0028] Although an embodiment of the connecting means of the invention has been described above, it is to be kept in mind that there are also other ways of implementing the connecting means between the drill rod assembly 8 and the drill pipe. It is also to be noted that in a structure of the type disclosed here the pipe adapter 18, the intermediate sleeve 20 and the rod adapter 16 may be implemented differently so that they are interconnected in a different manner in different directions of rotation, for example, in which case the shape of the shoulders differs from that shown in Figures 2A and 2B. What is essential is that the connecting means provide a rapid and simple means of interconnecting the drill rod assembly and the drill pipe without the need to lift up the drill rod assembly and the drill pipe entirely and without complicated coupling that would be time-consuming to produce and to release.

[0029] According to the above, the invention also comprises a novel method for carrying out underwater drilling. In the following the method of the invention is disclosed with reference to Figures 1A - 1 F. Figure 1A shows the initial situation at the start of a new drilling. Before the situation shown in Figure 1A, the drill rod assembly 8 has been provided with the rod adapter 16, the drill pipe 12 with the pipe adapter 18, and the intermediate sleeve 20 has been inserted above the rod adapter 16 on the drill rod assembly 8. The drill rod as- sembly 8 and, at the same time, also the rod adapter 16 and the intermediate sleeve 20 are then lowered and rotated in relation to the drill pipe 12, which in this case is locked to the drilling rig 2 by gripping means 30. As a result of the lowering and rotation of the drill rod assembly 8, the rod adapter 16 and the intermediate sleeve 20 engage with each other and with the pipe adapter 18. Alternatively, the intermediate sleeve 20 and the rod adapter 16 may have been interconnected in advance. The connecting means are implemented to the drill rod assembly 8 and to the drill pipe 12 in such a way that when they are interconnected, the drill bit 10 at the bottom of the drill rod assembly penetrates for a predetermined distance below the bottom end of the drill pipe 12 and the ring bit 14 installed thereto.

[0030] When the drill rod assembly 8 and the drill pipe 12 have been interconnected, the locking between the drill pipe 12 and the drilling rig 2 is opened, and the drill pipe 12 remains supported by the drilling rig 2 in such a way that the drilling rig 12 is capable of moving in a longitudinal direction in relation to the drilling rig 2 and to rotate about its longitudinal axis in relation to the drilling rig 2. To start the drilling, the drilling rig 2 is lowered downward and the rotational and impact functions of the drill hammer 4 are switched on, whereby the drilling takes place by means of a drill bit 10 installed to the drill rod assembly 8 and the ring bit 14 installed to the drill pipe 12, the rotational and impact energy of the drill hammer 4 being transmitted via the connecting means 15 to the drill pipe and further to the ring bit 14. The drilling carried out by means of the drill bit 10 and ring bit 14 continues until the drill pipe 12 and the ring bit 14 installed thereto have been drilled through the soil layer 3 on the rock 5 and/or for some distance into the rock 5.

[0031] When the drill pipe reaches the rock 5, as disclosed above, the drill hammer 4 is switched off and the drill pipe 12 is fixedly locked to the drilling rig 2 by gripping means 30 so that the movement and rotation of the drill pipe 12 in relation to the drilling rig 2 is prevented. Next, the connection between the drill pipe 12 and the drill rod assembly 8 is released while the drill pipe 12 is kept in place in the drilled hole. The connection may be opened by rotating and lifting the drill rod assembly 8, whereby the intermediate sleeve 20 is disconnected from the rod adapter 18. The rotation is preferably carried out in a direction opposite to the direction of rotation of the drilling. The rotating of the drill rod assembly 8 then continues in the direction opposite to the direction of rotation of the drilling until the vertical surfaces of the inner shoulders of the intermediate sleeve 20 and the vertical shoulders of the rod adapter 16 come into contact with each other. The intermediate sleeve 20 is then lifted up at least above the vertical shoulders of the rod adapter 16 by lifting means that grab the intermediate sleeve 20 by means of a lifting fork or shoulders and hold it in place for as long as necessary. The lifting means may comprise a hydraulic cylinder and/or a lifting fork or some other structure. In that case the lifting fork may be coupled to a vertically operating hydraulic cylinder.

[0032] However, it is to be noted that the connection may be released or it may open also so that first opens the connection between the rod adapter 16 and the intermediate sleeve 20 and only then the connection be- tween the intermediate sleeve 20 and the pipe adapter 18. The order in which the connection opens is influenced by the difference in the frictions between the intermediate sleeve 20 and the rod adapter 16 and between the intermediate sleeve 20 and the pipe adapter 18 and the fact that the unwinding force to the connection comes from the inside through the rod adapter. [0033] After the connection has been opened the drill hammer 4 is switched on again and drilling continues only by means of the drill rod assem- bly 8 and the drill bit 10 installed thereto, as shown in Figure 1 B. When there is no connection, the drill pipe 12 stays in place and the drill rod assembly 8 moves downward through the drill pipe 12, the rod adapter 16 coming along as a part of the drill rod assembly 8. When a hole of a desired depth has been drilled into the rock 5, the drill rod assembly 8 is lifted up by means of the lifting mechanism of the drill hammer 4, for example, to a sufficient height to extract the drill bit 10 entirely from the drill pipe 12 as shown in Figure 1C. As the drill rod assembly 8 is lifted up the intermediate sleeve 20 on the rod adapter 16 rises with it. The drill pipe 12 is further kept in place to prevent the soil layer 3 from falling into the drilled hole 34.

[0034] When the drill rod assembly 8 has been lifted above the drill pipe 12, the drill pipe 12 is empty and the drilled hole 34 may be charged with explosive through the drill pipe 12, as shown in Figure 1D, by means of charging devices 38. The charging may be carried out manually or by pumping the explosive into the hole 34. Before the explosive is lowered into the hole 34, a primer is placed therein.

[0035] After the charging the drilling rig 2, and with it the drill pipe 12, are lifted to the upper position and the fuse 36 extending from the hole 34 is lifted onto the drilling rig 32 and combined with other blasting cables possibly used, as shown in Figure 1 E. Finally, the explosive charge may be detonated for excavating the rock. Alternatively, a plural number of holes may be drilled and charged and all the drilled holes may be exploded simultaneously. The work then proceeds to a new drilling point and the method starts from the beginning, as shown in Figure 1 F. It is to be noted that the drilling rig may com- prise one or more drilling apparatuses of the invention to allow a plural number of holes to be drilled and charged simultaneously.

[0036] A person skilled in the art will find it apparent that as technology advances the basic idea of the invention may be implemented in various ways. The invention and its embodiments are therefore not restricted to the above examples but may vary within the scope of the claims.

Claims

1. Equipment for underwater drilling, the equipment comprising a drilling rig (2), drill hammer (4), drill rod assembly (8) formed of one or more interconnected drill rods (6) and operationally connected at the top end thereof to the drill hammer (4) and comprising at the bottom end thereof a drill bit (10) and a drill pipe (12) placed around the drill rod assembly (8) and supported to the drilling rig (2), the bottom end of the drill pipe being provided with a ring bit (14), connecting means (15) for optionally connecting the drill pipe (12) to the drill rod assembly (8) between the drill hammer (4) and the drill bit (10) for transferring the rotational and/or impact energy of the drill hammer (4) from the drill rod assembly (8) to the drill pipe (12), and for releasing the connection between the drill pipe (12) and the drill rod assembly (8), whereby the rotational and/or impact energy received by the drill rod assembly (8) from the drill hammer (4) is not transferred to the drill pipe (12), c h a r a c t e r i z e d in that the connecting means (15) comprise a rod adapter (16) on the drill rod assembly (18), a pipe adapter (18) on the drill pipe (12) and an intermediate sleeve (20) arranged to set between the rod adapter (16) and the pipe adapter (18) so as to allow the rod adapter (16) to be connected to the pipe adapter (18) by means of the intermediate sleeve (20), the intermediate sleeve (20) transfer- ring the rotational and impact energy of the drill hammer (4) to the pipe adapter (18) and further to the ring bit (14) at the bottom end of the drill pipe (12), and, correspondingly, to allow the connection to the pipe adapter (18) to be released, whereby the rotational and/or impact energy received by the drill rod assembly (8) from the drill hammer (4) is not transferred to the drill pipe (12).

2. Equipment according to claim 1 , c h a r a c t e r i z e d in that the connecting means (15) are implemented so as to allow the drill pipe (12) to be connected to the drill rod assembly (8) and the connection to the drill rod assembly (8) to be released by rotating the drill rod assembly (8) in a first and, correspondingly, second direction of rotation in relation to the drill pipe (12).

3. Equipment according to claim 2, c h a r a c t e r i z e d in that the first direction of rotation for connecting the drill pipe (12) to the drill rod assembly (8) corresponds to the normal drilling direction of rotation of the drill rod assembly (8) and the second direction of rotation for releasing the connection between the drill pipe (12) and the drill rod assembly (8) is a direction of rota- tion opposite to the first direction of rotation.

4. Equipment according to any one of the preceding claims 1 to 3, characterized in that the rod adapter (16) is a separate piece installed between two successive drill rods (6) of the drill rod assembly (8), or that the rod adapter (16) is implemented integrally with a drill rod (6).

5. Equipment according to any one of the preceding claims 1 to 4, characterized in that the rod adapter (18) is a separate intermediate tube attached to the top end of the drill pipe (12) or that the pipe adapter (18) is implemented integrally with the top end of the drill pipe (12) or to the vicinity thereof.

6. Equipment according to any one of the preceding claims 1 to 5, characterized in that the intermediate sleeve (20) is dimensioned to be at least partly placeable inside the drill pipe (12), to be movable around the drill rods (6) and to be able to at least partly receive the rod adapter (16) therein.

7. Equipment according to any one of the preceding claims 1 to 6, characterized in that the outer surface of the rod adapter (16) comprises shoulders (22) or threads arranged to connect with shoulders (24) or threads provided on the inner surface of the intermediate sleeve (20), when the drill rod assembly (8) is rotated in the first direction of rotation in relation to the intermediate sleeve (20), the rod adapter (16) thus locking the intermediate sleeve (20) to the drill rod assembly (8) in the axial direction thereof and in the first direction of rotation.

8. Equipment according to any one of the preceding claims 1 to 7, characterized in that the outer surface of the intermediate sleeve (20) comprises shoulders (26) or threads arranged to connect with shoulders (28) or threads provided on the inner surface of the pipe adapter (18), when the intermediate sleeve (20) is rotated in the first direction of rotation in relation to the drill pipe (12), whereby the intermediate sleeve (20) becomes locked to the drill pipe (12) in the axial direction thereof and in the first direction of rotation.

9. Equipment according to any one of the preceding claims 1 to 8, characterized in that the rod adapter (16) and the pipe adapter (18) and the drill pipe (12) are dimensioned so that the drill rod assembly (8) and the rod adapter (16) are movable through the pipe adapter (18) and the drill pipe (12).

10. Equipment according to any one of the preceding claims 1 to 9, characterized in that the equipment comprises support means for sup- porting the drill pipe (12) to the drilling rig (2) in such a way that the drill pipe (12) is movable in the longitudinal direction of the drilling rig (2) in relation to the drilling rig (2) and rotatable in relation to the drilling rig (2).

11. Equipment according to claim 10, characterized in that the support means comprise support bearings.

12. Equipment according to any one of the preceding claims 1 to 11 , characterized in that the equipment comprises gripping means (30) arranged to the drilling rig (2) for locking the drill pipe (12) to the drilling rig (2) so as to prevent the drill pipe (12) from moving in relation to the drilling rig (2).

13. Equipment according to any one of the preceding claims 1 to 12, characterized in that the equipment comprises lifting means for lifting the intermediate sleeve (20) upwards around the drill rod assembly (8) while the locking between the intermediate sleeve (20) and the rod adapter (16) is released.

14. Equipment according to claim 13, characterized in that lifting means comprise a hydraulic cylinder and a lifting fork or a lifting shoulder.

15. Equipment according to any one of the preceding claims 1 to 14, characterized in that the equipment further comprises charging means (38) for charging a drilled hole (34) with explosive.

16. A method for underwater drilling, the drilling according to the method being carried out using a drill rod assembly formed of one or more drill rods connected to a drilling rig, the drill rod assembly being operationally connected to a drill hammer and comprising at the bottom end thereof a drill bit, and by means of a drill pipe mountable around the drill rod assembly and sup- ported to the drilling rig, the bottom end of the drill pipe being provided with a ring bit, the method comprising the steps of inserting the drill rod assembly with the drill bit first into the drill pipe while the drill pipe is locked to the drilling rig; connecting the drill pipe to the drill rod assembly between the bot- torn end of the drill rod assembly and the drill hammer in such a way that the rotational and impact energy received by the drill rod assembly from the drill hammer is transferable to the drill pipe; lowering the drill rod assembly together with the drill bit attached to the bottom end thereof and the drill pipe together with the ring bit attached to the bottom end thereof to the sea bottom; opening the locking between the drill pipe and the drilling rig; switching on the drill hammer in order to begin the drilling by means of the drill bit installed to the bottom end of the drill rod assembly and the ring bit installed to the bottom end of the drill pipe when the drill bit and the ring bit touch the sea bottom; continuing the drilling until the drill pipe has reached the surface of the rock or bored into the sea bottom for a predetermined distance; switching off the drill hammer, locking the drill pipe to the drilling rig in such a way that the rotation and movement thereof in relation to the drilling rig is prevented, and opening the connection between the drill rod assembly and the drill pipe; and switching the drill hammer on again and continuing the drilling by means of the drill rod assembly and the drill bit into a predetermined depth by feeding the drill rod assembly into the drilling rig through the locked drill pipe, c h a r a c t e r i z e d in that the connection implemented between the drill rod assembly and the drill pipe by means of the connecting means is optionally produced by rotating the drill rod assembly of the drill rod assembly and the drill pipe in a first direction of rotation in relation to the drill pipe in a second direction of rotation in such a way that the rod adapter on the drill rod assembly and the intermediate sleeve placed between the pipe adapter and the rod adapter on the top end of the drill pipe both rotate in relation to the pipe adapter for connecting the intermediate sleeve and thereby the rod adapter to the pipe adapter, and in that the connection implemented between the drill rod assembly and the drill pipe by means of the connecting means is optionally opened by rotating the drill rod assembly of the drill rod assembly and the drill pipe in a second direction of rotation in relation to the drill pipe in a second direction in such a way that the rod adapter on the drill rod assembly and the intermediate sleeve placed between the pipe adapter and rod pipe adapter on the top end of the drill pipe both rotate in relation to the pipe adapter for disconnecting the intermediate sleeve and thereby the rod adapter from the pipe adapter.

17. A method according to claim 16, c h a r a c t e r i z e d in that the first direction of rotation corresponds to the normal direction of rotation of the drill rod assembly and the second direction of rotation for releasing the connection between the protective tube and the drill rod assembly is a direction of ro- tation opposite to the first direction of rotation.

18. A method according to claim 16 or 17, characterized in that when the drill rod assembly is being connected to the drill pipe the shoulders or threads on the outer surface of the rod adapter are connected to the shoulders or threads on the inner surface of the intermediate sleeve by rotating the drill rod assembly in first direction of rotation in relation to the intermediate sleeve, and the shoulders or threads on the outer surface of the intermediate sleeve connect with the shoulders or threads on the inner surface of the rod adapter when the intermediate sleeve is rotated in the first direction of rotation in relation to the drill pipe, whereby the intermediate sleeve becomes locked to the drill pipe in the direction of its axis and in the first direction of rotation.

19. A method according to any one of the preceding claims 16 to 18, characterized in that to release the connection between the drill rod assembly and the drill pipe, the intermediate sleeve is lifted upwards along the drill rod assembly to a position above the rod adapter.

20. A method according to any one of the preceding claims 16 to 19, characterized in that after the hole has been drilled to a desired depth, the drill hammer is switched off and the rod assembly is lifted upwards until the drill bit is above the top end of the drill pipe and then the drilled hole is charged with explosive through the drill pipe.

21. A method according to any one of the preceding claims 16 to 20, characterized in that when the drill pipe is connected to the drill rod assembly, the drilling rig is arranged to support the drill pipe in such a way that in relation to the drilling rig the drill pipe is rotatable and movable in the longitudinal direction of the drilling rig.

22. A method according to any one of the preceding claims 16 to 21 , characterized in that when the drill pipe is disconnected from the drill rod assembly the drill pipe is locked to the drilling rig by gripping means so as to prevent the drill pipe from being rotatable or movable in relation to the drilling rig.

23. A method according to any one of the preceding claims 16 to 22, characterized in that it comprises the steps of installing the intermediate sleeve around the rod adapter on the drill rod assembly before the drill rod assembly is placed into the drilling position inside the drill pipe; inserting the drill rod assembly with the drill bit first into the drill pipe, while the drill pipe is locked to the drilling rig, so that the drill bit reaches a po- sition at a predetermined distance below a ring bit installed to the bottom end of the drill pipe; interconnecting the drill pipe and the drill rod assembly by means of the pipe adapter on the drill pipe, the rod adapter on the drill rod assembly and the intermediate sleeve to be placed between them in such a way that the rotational and impact energy delivered to the drill rod assembly by the drill hammer is transmitted from the drill rod to the drill pipe; lowering the drill bit connected to the drill rod assembly and the ring bit connected to the drill pipe and the drilling rig to the bottom of the sea while the drill pipe is locked in relation to the drilling rig and the drill rod assembly and the drill pipe are interconnected into a single functional unit; releasing the locking between the drilling rig and the drill pipe; switching on the drill hammer to begin the drilling by means of the drill bit installed to the bottom end of the drill rod assembly and the ring bit in- stalled to the bottom end of the drill pipe to penetrate a layer of soil covering a rock or other hard surface until the ring bit comes into contact with the rock or other hard surface or reaches a predetermined drilling depth inside the rock or other hard surface; switching off the drill hammer, locking the drill pipe to the drilling rig with the gripping means in such a way that the rotation and movement thereof in relation to the drilling rig is prevented and releasing the connection between the drill rod assembly and the drill pipe; switching on the drill hammer again and continuing the drilling by means of the drill rod assembly and the drill bit to a predetermined depth by taking the drill rod assembly through the drill pipe locked to the drilling rig; switching off the drill hammer and lifting the drill rod assembly upwards until the drill bit is above the top end of the drill pipe as the intermediate sleeve rises with the drill rod assembly on the rod adapter, the drilled hole being then charged with explosive through the drill pipe; and lifting the drilling rig to its upper position and moving to the next drilling location.