Abstract
Disclosed is a drilling system and a method for drilling a well. The drilling system includes a coilable drill string; a first reel for storing the coilable drill string; a drive means for driving the coilable drill string into the well from the first reel and out of the well to the first reel; and a deflection means for directing the coilable drill string between the first reel and into the well centre. The drilling system further includes a top drive. The coilable drill string is provided with: a first connection at a first end for connecting the coilable drill string to a bottom-hole-assembly and a second connection at a second end for connecting the coilable drill string to the top drive.
Claims
1. Drilling system for drilling a well, the drilling system having a well centre through which a drill string may be run into and pulled out of the well, said drilling system comprising: a coilable drill string; a first reel for storing said coilable drill string; a drive means for driving said coilable drill string into the well from said first reel and out of the well to said first reel; a deflection means for directing said coilable drill string between said first reel and into said well centre; a top drive; wherein said coilable drill string is provided with: a first connection at a first end thereof for connecting the coilable drill string to a bottom-hole-assembly; and a second connection at a second end thereof for connecting the coilable drill string to said top drive.
2. Drilling system according to claim 1, wherein said coilable drill string comprises a composite material.
3. Drilling system according to claim 1, wherein said coilable drill string comprises metal.
4. Drilling system according to claim 1, wherein said coilable drill string comprises a plurality of connected drill pipes.
5. Drilling system according to claim 4, wherein said first reel comprises recesses configured to accommodate joints between connected pipes, said joints having a larger diameter than said drill pipes.
6. Drilling system according to claim 1, wherein said deflection means is slidable to and from said well centre.
7. Drilling system according to claim 1, wherein said top drive is connectable to said second end of the coilable drill string via a drill stand.
8. Drilling system according to claim 1, wherein said drilling system further comprises a second reel for storing a coilable string.
9. Drilling system according to claim 1, wherein said first reel has a diameter in the range 10-15 metres.
10. Drilling system according to claim 1, wherein said drilling system further comprises a cooling means for cooling said coilable drill string at or near said deflection means.
11. Drilling rig comprising a drilling system according to claim 1.
12. Method for operating a drilling system according to claim 1, said method including the steps of: placing said first reel and said deflection means in an operating position; connecting said first end of the coilable drill string to a bottom-hole-assembly; spooling out said coilable drill string from the first reel for lowering said bottom-hole-assembly into the well; reaching a target depth; securing said coilable drill sting in said well centre; disconnecting said first reel from said second end of the coilable drill string; and connecting said top drive to said second end of the coilable drill string.
13. Method according to claim 12, wherein the step of connecting said top drive to said second end includes the sub-steps of: presenting a stand to the well centre and connecting said stand, directly or indirectly, to said second end of the coilable drill string; and latching said top drive to the stand.
14. Method according to claim 12, wherein the step disconnecting said first reel from said second end of the coilable drill string includes the step of rotating the coilable drill string on the well-side of the coilable drill string, while keeping said coilable drill string substantially fixed on the reel side of the coilable drill string.
15. Method according to claim 12, wherein the method further comprises the step of drilling the well by rotating said coilable drill string with the top drive.
16. Drilling system according to claim 1, wherein said drilling system further comprises a lubrication means for lubricating said coilable drill string at or near said deflection means.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0048] In the following are described examples of preferred embodiments illustrated in the accompanying drawings, wherein:
[0049] FIG. 1 shows a drilling system according to present disclosure in a first position of use;
[0050] FIG. 2 shows a drilling system according to the present disclosure provided on a vessel;
[0051] FIG. 3 shows a drilling system according to the present disclosure provided on a jack-up rig;
[0052] FIGS. 4-5 shows a drilling system according to the present disclosure in a second and third position of use, respectively;
[0053] FIGS. 6-7 shows details of a reel as included a drilling system according to the present disclosure;
[0054] FIG. 8 shows a detail of a coilable drill string on a reel;
[0055] FIGS. 9-12 shows a process of bending a coilable drill string over a sheave with a movable lid for connecting a coilable drill string to a stick-up at the well centre;
[0056] FIG. 13 shows details of one embodiment a connection joint between a coilable drill string and the stick-up at the well centre;
[0057] FIGS. 14-15 shows the process of spooling the coilable drill string into the well through the well centre;
[0058] FIG. 16 shows an alternative embodiment of a deflection means with a fixed lid;
[0059] FIG. 17 shows a deflection means with integrated cooling and lubrication means; and
[0060] FIG. 18 shows schematically process of cooling drilling mud.
DETAILED DESCRIPTION OF THE DISCLOSED EXEMPLARY EMBODIMENTS
[0061] In the following the reference numeral 1 will indicate a drilling system according to the present disclosure, whereas the reference numeral 10 indicates a drilling rig comprising such a drilling system. Identical reference numerals will indicate identical or similar features in the drawings. The figures are drawn simplified and schematically and various features therein are not necessarily drawn to scale.
[0062] FIG. 1 shows a first embodiment of a drilling system 1 according to the present invention as provided as part of a drilling rig 10. A coilable drill string 2 is stored on first reel 4 and extends from the first reel 4 and over a deflection means 6, here shown in the form of a quarter circular sheave, and into a not shown well through a well centre 8. In the shown position of use, the sheave 6 is placed next to the well centre 8. When the sheave 6 is not in use, as will be indicated in FIGS. 4 and 5, the sheave 6 is skid away from the well centre 8. The sheave 6 is placed on a base 14 that can skid away from and towards the well centre 8 on rails 12 in order to place the sheave 6 near the well centre 8 when needed to deflect the coilable drill string 2 from a horizontal direction and to a vertical direction through the well centre 8. The first reel 4 is placed on a base 16 adapted to skid towards and away from the horizontal part of the firing line through the well centre 8 on rails 18, i.e. perpendicularly to the skidding direction of the sheave 6. In the shown embodiment, the first reel base 16 and the sheave base 14 are movable by means of not shown push/pull hydraulic actuators. In the shown embodiment, the drilling system 1 further comprises a second reel 20 placed on a second base 22 adapted to skid towards and away from the firing line on rails 24 parallel to the rails 18 on which the first reel base 16 is placed. Having more than one reel may be beneficial for being able to switch between a coilable drill string 2 with a first configuration to a coilable drill string 2′ of a second configuration or to be able to switch between a coilable drill string and another coilable string, such as a lifting string. It should be noted that the defection means 6, shown schematically as a quarter of a circular sheave, may in certain embodiments utilize the inner, concave part of the sheave 6 as opposed to the outer, convex part in order to control the bending of the coilable drill pipe. In the shown embodiment the first reel 4, as well as the sheave 6, are provided with a radius of approximately 6.5 metres, corresponding to the minimum bending radius of the coilable drill string 2, which is provided in a composite material. In FIG. 1, the coilable drill string 2 is driven into the well through the well centre 8 by actively rotating the first reel 4 by means of a not shown drive means in the form of hydraulic motor rotating the reel via a worm gear transmission 26 as indicated in FIG. 7. A top drive 28 suspended from a derrick 30 is idle during the tripping operation, but will be engaged after the target tripping depth has been reached, as will be explained in the following.
[0063] FIGS. 2 and 3 show two possible uses of drilling systems 1 according to the present disclosure as used in a drilling rig 10 placed on a drillship 32 and a jack-up platform 34 respectively. The drilling system 1 on the jack-up platform 34 only comprises one reel 4, whereas the drilling system 1 on the drillship comprises first and second reels 4, 20 similarly to the embodiment shown in FIG. 1.
[0064] Once the target depth has been reached in the well, the coilable drill string 2, if any remains on the first reel 4, needs to be disconnected from the part of the coilable drill string 2 that has been run into the well as will been shown in the following figures. In one embodiment the full length of the coilable drill string 2 is run into the well, while in another embodiment a joint of the coilable drill string 2 is broken up in order to separate the part of the coilable drill string 2 run into the well from the coilable drill string 2 on the first reel 4, as will be explained in the following. In both embodiments a stick-up 36 remains at the well centre 8, as shown in FIG. 4.
[0065] FIG. 5 shows and embodiment of the drilling system 1 according to the first aspect of the disclosure, wherein the top drive 28 has connected to the stick-up 36, corresponding to a second end 44 of the coilable drill string 2, via a drill stand 38. The sheave 6 has been skid away from the well centre 8 and drilling may commence by rotating the drill string 2 by means of the top drive 28.
[0066] FIGS. 6 and 7 show further details of the first reel 4 on which the coilable drill string 2 is stored. The first reel 4 is rotatably stored on the base 16, and rotation is enabled by means of the worm drive 26, as mentioned above.
[0067] FIG. 8 shows a detail of one embodiment of a first reel 4, wherein the outer surface 40 of the reel is provided with recesses 41, only one of which is shown in the figure, for accommodating joints 42 between portions 21, 23 of the coilable drill string 2. This may be useful where the coilable drill string 2 comprises two or more portions and where the joint(s) have a larger diameter than the rest of the coilable drill string 2 as was discussed above.
[0068] FIGS. 9 to 12 show one embodiment of the process of driving a first end 46 of the coilable drill string 2 from the first reel 4, over the sheave 6 and down towards the stick-up 36 in the well centre 8, the stick-up 36 being a part of a not fully shown bottom-hole-assembly. In order to obtain the desired deflection of the coilable drill string 2, sheave 6 provided with a bending means 44, here in the form of a movable cover, for forcing the coilable drill string 2 to bend over the sheave 6 and towards the drill centre 8. The cover 44 is movable my means of hydraulic actuators 45 rotatably hinged to the sheave 6. In order to bring the first end 46 of the coilable drill string 2 from the first reel 4 (not shown in these figures) and onto the sheave 6, it may be necessary to support the first end 46 of the coilable drill string 2 with not shown support means, such as a not shown lifting wire from a crane, that typically will be available on a platform or drilling vessel. The support means may operate in combination with the drive means for rotating the first reel 4. After the coilable drill string 2 has been bent into position, as indicated in FIG. 11, an iron roughneck 48 approaches the well centre 8 and engages the joint between the first end 46 of the coilable drill string 2 and the stick-up 36 to make up the connection. After the make-up of the joint, the coilable drill sting 2 is ready to be tripped into the well by rotation of the first reel 4, similarly to tripping with traditional coil tubing, as described with reference to FIGS. 14-15 below.
[0069] FIG. 13 shows one embodiment of a sleeved tool joint 64, which may be used to connect the first end 46 of the coilable drill string 2 to the stick-up 36. The shown sleeved toil joint 64 does not require any rotation of the first end 46 of the coilable drill string 2 relative to the stick-up prior to making up our breaking out the joint, which may be done with an iron roughneck 48, as indicated in the figures, or by means of a casing tong.
[0070] FIGS. 14-15 show the process of spooling the coilable drill string 2 from the first reel 4 (not shown in these figures) and into the not shown well via the well centre 8. After having made up the joint between the first end 46 of the coilable drill string 2 and the stick-up 36 part of the bottom-hole-assembly, as shown in FIG. 12, the iron roughneck 48 retracts from the well centre as indicated in FIG. 14. In the shown embodiment of FIGS. 14 and 15, a lifting wire 50 is connected to the second end 44 of the coilable drill string 2, for securely guiding the last portion, including the second end 44, of the coilable drill string 2 towards the well centre 8.
[0071] FIGS. 16 show a different embodiment of a sheave 6, as used in a drilling system 1 according to the disclosure. Instead of the movable cover 46 shown in the previous figures, the sheave 6 is provided with a fixed cover 47 through which the coilable drill string 2 is forced in order to be bent against the inner concave portion of the fixed cover 47. In the shown embodiment, the sheave 6 is also provided with drive means in the form of a set of rollers 52 for actively driving the coilable drill string 2 through the space between the sheave 6 and the fixed cover 47. A support means, such as a not shown winch and lifting wire may be used to bring the first end 46 of the coilable drill string 2 into contact with the rollers 52. The rollers 52 may operate in combination with or instead of other drive means mentioned herein for driving the coilable drill string 2 into the well.
[0072] FIG. 17 shows an embodiment of a deflection means 6 provided with cooling means 54 for cooling the coilable drill string 2 in the deflection zone, which is typically an area where a lot of friction, and thereby also heating, may occur. An inlet 56 for a coolant is provided at an upper portion of the deflection means 6 whereas and outlet 58 for the same coolant is provided at a lower portion of the deflection means 6. The coolant may be circulated through deflection means 6, such as in the cover. The cooling system 54 may in addition or as an alternative be used to lubricate the coilable drill string 2.
[0073] In addition or as an alternative, cooling of the coilable drill string 2 may also be effectuated indirectly by cooling the drilling mud circulating therethrough during operation. FIG. 18 shows schematically one possible way of cooling the drilling mud, where the mud flows from a mud pump 56, through a mud manifold 58 and to a heat exchanger through which a cooling fluid is circulated in refrigeration circle 60. From the heat exchanger the mud flows through the top drive 28, though the coilable drill string 2, over the deflection means 6 and into the well. From the well it is circulated back up, in an not shown annulus between the outside of the coilable drill string 2 and a not shown casing, top-side to a mud treatment unit 62 from which treated mud is extracted by means of the mud pump 56, whereby circulation continues.
[0074] It should be noted that the above-mentioned exemplary embodiments illustrate rather than limit the claimed invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the invention as defined by the claims that are set out below. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb “comprise” and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article “a” or “an” preceding an element does not exclude the presence of a plurality of such elements.
[0075] The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.
