Device and method for drilling with continuous tool rotation and continuous drilling fluid supply

Abstract

A device is for a drilling rig for forming of a bore hole in a subterranean structure. The drilling rig comprises a first, top driven drilling machine arranged vertically displaceable along a guide track, where a second drilling machine is arranged between the first drilling machine and the bore hole, vertically displaceable along a guide track and provided with a rotary table arranged to be able to take the weight of a pipe string. A rotary drive unit is arranged for continuous rotation of the pipe string. A fluid chamber is arranged to, in a fluid communicating way, be able to connect a pipe string end portion with a drilling liquid plant. As the fluid chamber is provided with pipe string ports comprising means arranged to, in a fluid sealing way, be able to close the pipe string ports. A power tong is arranged for continuous rotation of an element connected to the pipe string, as the power tong is arranged in the fluid chamber. Also, a method is for drilling with continuous tool rotation and continuous drilling liquid supply.

Claims

1. A system for forming a bore hole in a subterranean structure by operating a pipe string, the system comprising: a first drilling machine that is vertically displaceable along a guide track; a second drilling machine that is vertically displaceable along a guide track independently of the first drilling machine, wherein the second drilling machine is located between the first drilling machine and the borehole; a drilling liquid plant that is arranged to provide drilling liquid to both the first and second drilling machines; wherein the second drilling machine comprises a chamber having a drilling liquid inlet arranged to receive drilling liquid from the drilling liquid plant and a drain port arranged to drain drilling liquid from the chamber, a rotary drive unit located beneath the chamber and arranged to continuously rotate the pipe string, a rotary table located beneath the chamber and arranged to suspend the pipe string during rotation of the pipe string by the rotary drive unit, a lower pipe string port arranged to seal and unseal the pipe string with respect to the chamber, an upper pipe string port arranged to seal and unseal a pipe section with respect to the chamber, the pipe section being arranged for connection to and then disconnection from the pipe string, a power tong disposed in the chamber and arranged to rotate the pipe section for connection to and disconnection from the pipe string, a stop valve disposed between the upper pipe string port and the chamber, the stop valve arranged to close the upper pipe string port and to open and close to unseal and seal the chamber, respectively, the stop valve being located outside the chamber above the drilling liquid inlet and the drain port which are in continuous fluid communication with one another, wherein the rotary table, rotary drive unit, chamber, and upper and lower pipe string ports, power tong, and stop valve form a central opening extending through the second drilling machine and arranged centrically relative to the borehole as the first drilling machine rotates and displaces the pipe string into the borehole, and wherein the stop valve is arranged to open when the upper pipe string port seals the pipe string with respect to the chamber thereby allowing passage of the pipe section through the stop valve, and wherein the stop valve is arranged to close when the upper pipe string port unseals the pipe string with respect to the chamber, thereby sealing the drilling liquid in the chamber.

2. The system according to claim 1, wherein the drilling liquid plant comprises a drilling liquid reservoir, a drilling liquid pump, a pumping line which connects the drilling liquid pump to the drilling liquid reservoir, and a supply line arranged to lead the drilling liquid to the pipe string via the first and second drilling machines, the supply line comprising a primary line provided with a first valve arranged to control flow of drilling liquid to the first drilling machine, a secondary line provided with a second valve arranged to control flow of drilling liquid to the second drilling machine, and a drain line that drains drilling liquid from the drilling liquid reservoir.

3. The system according to claim 2, wherein when the first drilling machine rotates and displaces the pipe string into the borehole, the first valve is arranged to open and provide drilling liquid to the first drilling machine and the second valve is arranged to close and prevent flow of drilling liquid to the second drilling machine.

4. The system according to claim 3, wherein when the upper and lower pipe string ports seal the chamber, the second valve is arranged to open to provide drilling liquid to the chamber.

5. The system according to claim 4, wherein when the stop valve closes, the first valve is arranged to close and prevent flow of drilling liquid to the first drilling machine.

6. The system according to claim 5, wherein when the stop valve opens, the first valve is arranged to open and provide flow of drilling liquid to the first drilling machine.

7. The system according to claim 1, wherein the second drilling machine is configured to continuously downwardly move towards the borehole as the first drilling machine rotates and displaces the pipe string into the borehole.

8. The system according to claim 7, wherein the drilling liquid plant is arranged to provide drilling liquid to the first drilling machine and the pipe string as the first drilling machine rotates and displaces the pipe string into the borehole, whereafter the drilling liquid plant is arranged to provide drilling liquid to the second drilling machine and the pipe string as the first drilling machine is detached from the pipe string.

9. The system according to claim 8, wherein the upper and lower pressure seals are arranged to seal the pipe section and pipe string, respectively, as the drilling liquid plant provides drilling liquid to the pipe string.

10. The system according to claim 9, wherein the drilling liquid plant is arranged to stop providing drilling liquid to the second drilling machine when the stop valve closes.

11. The system according to claim 10, wherein the chamber defines an undivided space between the lower pipe string port and the stop valve.

12. A system for forming a bore hole in a subterranean structure by operating a pipe string, the system comprising: a first drilling machine that is vertically displaceable along a guide track and supplies pressurized drilling liquid to the pipe string; a second drilling machine that is vertically displaceable along a guide track independently of the first drilling machine, wherein the second drilling machine is located between the first drilling machine and the borehole; a drilling liquid plant that is arranged to provide the pressurized drilling liquid to both the first and second drilling machines; wherein the second drilling machine comprises a chamber having a drilling liquid inlet arranged to receive the pressurized drilling liquid from the drilling liquid plant and a drain port arranged to drain the pressurized drilling liquid from the chamber, the chamber being continuously undivided between the drilling liquid inlet and the drain port, a rotary drive unit located beneath the chamber and arranged to continuously rotate the pipe string, a rotary table located beneath the chamber and arranged to suspend the pipe string during rotation of the pipe string by the rotary drive unit, a lower pipe string port arranged to seal and unseal the pipe string with respect to the chamber, the lower pipe string port being located below and outside the chamber, an upper pipe string port arranged to seal and unseal a pipe section with respect to the chamber, the pipe section being arranged for connection to and then disconnection from the pipe string, the upper string port being located above and outside the chamber, a power tong disposed in the chamber and arranged to rotate the pipe section for connection to and disconnection from the pipe string, a stop valve disposed between the upper pipe string port and the chamber, the stop valve arranged to open and close to unseal and seal the chamber, respectively, the stop valve being located outside the chamber above the drilling liquid inlet and the drain port, wherein the rotary table, the rotary drive unit, the chamber, and the upper and lower pipe string ports, the power tong, and the stop valve form a central opening extending through the second drilling machine and arranged centrically relative to the borehole as the first drilling machine rotates and displaces the pipe string into the borehole, and wherein the stop valve is arranged to open when the upper pipe string port seals the pipe string with respect to the chamber thereby allowing passage of the pipe section through the stop valve, and wherein the stop valve is arranged to close when the upper pipe string port unseals the pipe string with respect to the chamber, thereby sealing the pressurized drilling liquid in the chamber, the first drilling machine and the second drilling machine being configured to operate such that: the first drilling machine rotates the pipe string and displaces the pipe string into the borehole while the pressurized drilling liquid is supplied to the pipe string and until the pipe string must be extended with a new pipe section; whereupon the rotary drive unit rotates at a speed of rotation that corresponds to a speed of rotation of the pipe string; whereupon the rotary drive unit is engaged with the pipe string; whereupon the chamber is sealed against one of the pipe string and a drive shaft attached to the pipe string; whereupon the power tong is rotated at a speed of rotation that corresponds to a speed of rotation of the drive shaft; whereupon the power tong is engaged with the drive shaft; whereupon the speed of rotation of the power tong is reduced relative to the speed of rotation of the rotary drive unit so that the drive shaft is disengaged from the pipe string; whereupon the pressurized drilling liquid is provided to the pipe string and not provided to the first drilling machine; whereupon the first drilling machine displaces the drive shaft out of the chamber; whereupon the first drilling machine displaces the drive shaft and a new pipe section into the chamber and the chamber is sealed with one of the pipe string and the drive shaft; whereupon the power tong is engaged with the new pipe section and rotates the new pipe section at a speed of rotation that is greater than the speed of rotation of the pipe string; whereupon the power tong is displaced towards the pipe string to connect the new pipe section with the pipe string; and whereupon the drilling liquid plant supplies the pressurized drilling liquid to the pipe string via the first drilling machine and then stops providing the pressurized drilling liquid to the chamber.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the following is described an example of a preferred embodiment illustrated in the accompanying drawings, wherein:

(2) FIG. 1 shows a side view of a drilling rig comprising two cooperating drilling machines where the lower drilling machine is sectioned;

(3) FIG. 2 shows schematically at a smaller scale a drilling liquid plant connected to the drilling machines;

(4) FIGS. 3 to 7 shows side views of different steps of a continuous drilling operation, whereby arrows and black, solid hachure indicate the unit being active and also where drilling fluid is flowing, as

(5) FIG. 3 shows the drill string operating by means of the lower drilling machine, and a pipe string section made ready for connection to the first drilling machine;

(6) FIG. 4 shows the pipe string section connected to the first drilling machine and introduced into the upper port of the fluid chamber and sealingly enclosed by the port pressure seal;

(7) FIG. 5 shows the pipe string section led through the fluid chamber stop valve and connected to the power tong set in rotation;

(8) FIG. 6 shows the pipe string section disengaged from the power tong and connected to the pipe string row disengaged from the rotary table and driven by the first drilling machine, while the fluid chamber is being drained of drilling liquid; and

(9) FIG. 7 shows the pipe string driven by the first drilling machine and in free rotation relative to the lower drilling machine.

DETAILED DESCRIPTION OF THE DRAWINGS

(10) In the drawings the reference numeral 1 indicates a per se known top drive, in the following also called the first drilling machine. It is in a normal manner provided with a drive shaft 11 and a drive shaft extension 12 and also a drilling liquid inlet 13 and is attached to a rig derrick 2 displaceable in the vertical direction along a guide track 21. The drilling machine 1 is arranged centric relative to the central axis 62 of a bore hole 6.

(11) Between the first drilling machine 1 and the bore hole 6 is arranged a second drilling machine 3 attached to a second rig derrick 4 and displaceable in the vertical direction along a guide track 41.

(12) A pipe string 5 extends downward in the bore hole 6 (see FIG. 2) and is composed of multiple pipe string sections 52 by threadable joining with an end portion 51 of the pipe string 5. The pipe string section 52 comprises a drive pipe 521 provided with a portion 521a having a polygonal cross-section arranged for releasable engagement with the second drilling machine 3. The pipe string 5 is provided with a drill bit 53.

(13) The bore hole 6 extends front a wellhead 61 downward in a subterranean structure 63.

(14) The drilling machines 1, 3 are in a fluid communicating way connected to a drilling liquid plant 7 comprising a drilling liquid pump 71, a supply line 72 arranged to lead pressurised drilling liquid to the drill bit 53 via the drilling machines 1, 3 and a central opening in the pipe string 5, a pumping line 73 which in a fluid communicating way connects the drilling liquid pump 71 with a drilling fluid reservoir 74, and a return line 75 connects the wellhead 61 and the drilling fluid reservoir 74.

(15) The supply line 72 comprises a primary line 721 provided with a first stop valve 723 arranged to in a controlled way to lead drilling liquid to the first drilling machine 1, and a secondary line 722 provided with a second stop valve 724 arranged to in a controlled way to lead drilling liquid to the second drilling machine 3. A drain line 76 connects the second drilling machine with the drilling fluid reservoir 74.

(16) The second drilling machine 3 comprises a rotary table 31 provided with power slips 311 arranged for suspension of the pipe string 5 in the rotary table 31 in a per se known way. Connected to the rotary table 31 is arranged a rotary drive unit 32 arranged for by releasable attachment to the polygonal portion 521a of the drive pipe 521 to be able to rotate the pipe string 5 about its central axis when it is suspended in the rotary table 31. Above the rotary table 31 is arranged a power tong 33 arranged for continuous rotation. The power tong 33 is enclosed in a fluid chamber 34 provided with a lower and an upper pipe string port 341 and 343 respectively. The pipe string ports 341, 343 are each provided with a pressure seal 342 and 344 respectively, arranged to by enclosing abutment against a portion of a portion of the pipe string 5, a pipe string section 53 or the drive shaft extension 12 of the first drilling machine to close the pipe string ports 341, 343. Between the fluid chamber 34 and the upper pressure seal 344 is arranged a stop valve 345, which in an open position is arranged for leading through of a pipe string section 52 and at least a downward extending end portion of the connected drive shaft extension 12.

(17) The fluid chamber 34 is further provided with a drilling liquid inlet 35 in fluid communicating connection with the secondary line 722. A closable fluid chamber drain port 351 is arranged to foe able to drain the fluid chamber 34 to the drilling liquid reservoir 74 via the drain line 76. A fluid chamber ventilator 352 is arranged in the upper portion of the fluid chamber 34 and is arranged to be able to ventilate the fluid chamber 34 for air and other gases when the fluid chamber is filled with or emptied for drilling liquid.

(18) The rotary table 31, the rotary drive unit 32, the power tong 33 and the fluid chamber pipe string ports 341, 343 form a central opening 36 extending through the second drilling machine 3 and is arranged centrically relative to the bore hole 6 central axis 62.

(19) When a drilling operation is carried out with a drilling rig arranged according to the invention, the pipe string b is rotated and displaced in a first phase by means of the first drilling machine 1, as the pipe string 5 extends through the central opening 36 of the second drilling machine 3 and moves freely relative to the second drilling machine 3 (see FIG. 7). The drilling liquid is circulated via the drilling liquid inlet 13 of the first drilling machine 1 to the drill bit 53 and returns to the drilling liquid reservoir 74 via an annulus 54 (see FIG. 2), the wellhead 61, the return line 75 and necessary processing equipment (not shown) for per se known treatment of the drilling liquid. The second drilling machine 3 is displaced in the vertical direction to an upper starting position.

(20) When a drive pipe 521 arranged uppermost in the pipe string 5, is positioned with its polygonal drive pipe portion 521a enclosed by the rotary drive unit 32 of the second drilling machine 3, this is set in rotation corresponding to the pipe string 5 and is led to engagement with the pipe string 5. The pipe string 5 is suspended in the rotary table 31 by means of the power slips 311 in a per se known way. The power tong 33 is set in rotation corresponding to the pipe string 5 and is led to engagement with the drive shaft extension 12 extending through the power tong. The rotation of the pipe string may now be carried out by the second drilling machine 3, as the drive gear of the first drilling machine 1 is disengaged.

(21) In the next phase the lower and upper pressure seals 342, 344 and also the fluid chamber port 351 are closed, and drilling liquid is supplied to the fluid chamber 34 in that the respective stop valve 724 in the supply line 72 is opened. By means of a speed reduction in the power tong 33 relative to the rotary drive unit 32 the connection between the drive shaft extension and the pipe string is broken, and the drilling liquid is now supplied via the fluid chamber 34 and the open pipe string end portion 51. The drilling fluid supply to the first drilling machine 1 stops when the respective stop valve 723 in the supply line 72 is closed. The pipe string rotation and displacement of the pipe string 5 is for the time being carried out by the second drilling machine 3.

(22) The first drilling machine 1 is now displaced away from the second drilling machine 3, as the stop valve 345 of the second drilling machine 3 is closed as soon as the drive shaft extension 12 is pulled out of the central run of the stop valve 345, while the upper pressure seal 344 is still closing pressure sealingly a round the drive shaft extension 12. Thereafter the upper pressure seal 344 is pulled back and the drive shaft extension 12 is pulled away from the second drilling machine 3 for connection to the next pipe string section 52 (see FIG. 3).

(23) The first drilling machine 1 is displaced toward the second drilling machine 3 until a lower end portion of the pipe string section 52 is enclosed by the upper pressure seal 344 which is then being activated to close pressure sealingly around the pipe string section 52 (see FIG. 4). Thereafter the stop valve 345 is opened, and the first drilling machine 1 and the power tong 33 are set in rotation corresponding to the pipe string 5. Drilling liquid supply to the first drilling machine 1 is opened (see FIG. 5). The power tong 33 rotational speed is increased relative to the rotary drive unit 32 as the drive gear of the first drilling machine 1 is disengaged and the pipe string section 52 is displaced toward the pipe string 5 end portion 51 and connected to the pipe string 5. The closing of the respective stop valve 724 stops the supply of drilling liquid to the fluid chamber 34.

(24) The rotary drive unit 32, the power tong 33 and the power slips 311 are disengaged from the extended pipe string 5 as the first drilling machine 1 is set in operation. The fluid chamber 34 is emptied of drilling liquid through the fluid chamber drain port 351 and the drain line 76, and the pressure seals 342, 344 are disengaged from their pressure sealing abutment against the pipe string 5.

(25) The process is repeated until the desired position of the drill bit is reached.

(26) It is obvious for a person skilled in the art to provide the drilling rig according to the invention with relevant monitoring and operating means for synchronising the various operations described above.