GB2339814A

GB2339814A - Apparatus and method for cleaning well risers

Info

Publication number: GB2339814A
Application number: GB9913406A
Authority: GB
Inventors: Mark Carmichael; Paul David Howlett
Original assignee: Specialised Petroleum Services Ltd
Current assignee: Schlumberger UK Holdings Ltd
Priority date: 1998-06-09
Filing date: 1999-06-09
Publication date: 2000-02-09
Anticipated expiration: 2019-06-09
Also published as: GB9913406D0; GB2339814B; GB9812306D0

Description

-. 1 2339814 I APPARATUS AND METHOD FOR CLEANING WELL RISERS 2 3 This

invention relates to apparatus for circulating fluid.4 and in particular, apparatus for circulating fluid in a 5 well riser, and to a method of cleaning same using the 6 apparatus. 7 8 A number of forms of cleaning equipment or apparatus are 9 known for cleaning out the inside of a well casing or 10 liner to wash away any debris or other contaminants. 11 However, apparatus and method suitable for cleaning well 12 risers above the seabed are less common and generally 13 unsatisfactory. This, in part, is because of the 14 relatively large internal diameter of typical risers, 15 rendering most known equipment impractical for this 16 purpose. 17 18 one type of clean-up apparatus is known as a circulating 19 tool. This apparatus relies on the use of high flow 20 rates to create turbulence to aid the cleaning out 21 process. 22 2 1 In our earlier British Patent Number 2,272,923 there is 2 described a multifunction circulating tool. The tool has 3 an axial through passage between an inlet and a first 4 outlet, the inlet and the first outlet being adapted for connection in a drill string supported from the surface, 6 a second outlet extending generally transversely of the 7 apparatus, wherein the apparatus includes an obturating 8 member movable between a first position closing the 9 second outlet and a second position permitting fluid flow through the second outlet; and in which the apparatus is 11 associated with a shoulder engageable with a shoulder 12 portion in the borehole.

13 14 Typically, said formation in the borehole is defined by the tope edge of a liner within the borehole and the 16 shoulder is connected to the obturating member. However, 17 the application of the top edge of the liner as the 18 formation is not entirely or always suitable when it is 19 desired to flush or clean the well riser.

21 An object of the present invention therefore is to 22 provide a method for using this known circulating tool to 23 clean well risers.

24 According to the present invention there is provided a 26 method of cleaning a well riser, the method comprising 27 suspending in a drill pipe from surface a circulating 28 tool in the well riser, and causing the circulating tool 29 to axially collapse so as to open one or more radial outlets in the tool and allow cleaning fluid to be 31 expelled out of the tool and impact on the inside of the 32 well riser.

33 3 I Typically the well riser is provided with blow out 2 pointers incorporating drill pipe rams and the 3 circulating tool is caused to axially collapse by closing 4 the drill pipe rams around the drill pipe below the circulating tool and slacking off sufficient drill pipe 6 weight to hang the pipe and collapse the tool.

7 8 Alternatively, the tool may be provided with a shoulder 9 which co-operates with a formation in the well riser to allow for the slacking off of sufficient drill pipe 11 weight to hang the pipe and collapse the tool.

12 13 The method may further include passing the cleaning fl-,;id 14 down the drill string to an inlet of the apparatus and thence via a first outlet communicating with the drill 16 string below the circulating tool before setting down the 17 weight of the drill string.

18 19 The method may be employed after drilling or milling is complete and include pulling the drill pipe upward and 21 out of a well bore until the tool is above the drill pipe 22 rams.

23 24 According to a second aspect of the present invention there is provided a circulating tool for cleaning well 26 risers, the tool comprising a generally axial body having 27 an axial through passage between an inlet and a first 28 outlet, the inlet and the first outlet being adapted for 29 connection in a drill string supported from the surface, a second outlet extending generally transversely of the 31 tool, wherein the tool further includes an obturating 32 member movable between a first position closing the 33 second outlet and a second position permitting fluid flow 34 through the second outlet.

4 2 The drill string may be provided with a shoulder for co3 operating with a formation in the well bore or riser. The 4 shoulder may be provided as part of the circulating tool. 5 6 Preferably, the second outlet comprises a number of 7 apertures in a body member which communicate with the 8 inlet and typically, the apertures may be distributed 9 circumferentially around the outer surface of the body 10 member.

12 Preferably, the first outlet is closed when the second 13 outlet is open. 14 15 Typically, the cross-sectional area of the first outlet 16 is greater than the cross-sectional area of the second 17 outlet. 18 19 Preferably, the second outlet is designed to communicate 20 with the apertures in the sleeve irrespective of the 21 circumferential orientation of the sleeve with respect to 22 the second outlet. This could be designed by providing a 23 circumferentially extending groove on the inside of the 24 obturating member which aligns with the second outlet 25 when the second outlet is open. 26 27 Preferably, the second outlet is associated with one or 28 more nozzles adapted to increase the velocity of expelled 29 cleaning fluid from the second outlet. The nozzles may 30 be adapted to increase the effective outer diameter of 31 the second outlets.

32 33 An example embodiment and method within the scope of the 34 invention will now be described in order to better 1 portray the invention and with reference to the 2 accompanying drawings, in which:

3 4 Figure 1 is a schematic illustration of a drill pipe 5 hung off drill pipe rams in a well riser; and 6 7 Figure 2 shows, also as a partial cross-sectional 8 view, the tool of Figure 1 in a collapsed state; 9 Referring firstly to Figure 1, there is depicted an off- 11 shore oil rig 51 located above a well riser 52 and a 12 wellbore 53. Inserted in the well riser 52 and wellbore 13 53, is a drill string 54 having a drilling tool 55 14 located at its extremity. A casing string 56 is located also in the wellbore.

16 17 The well riser 52 is provided with blow out pointers 57.

18 Associated with the blow out pointers 57 are drill pipe 19 rams 58 which provide an opening and closing function around the drill string 54.

21 22 Within the drill string 54, is provided a multi-function 23 circulating tool 40. The tool is formed largely of an 24 upper and lower part wherein the two parts may collapse and open in an axial direction relative to each other.

26 When the tool 40 is in its axially extended or open 27 state, fluid may circulate axially down the drill pipe 28 including through the tool. Conversely, when the tool 10 29 is in a collapsed state, an axial outlet therein closes and a second and radial outlet opens such that 31 circulating or cleaning fluid passes in a generally 32 radial or transverse direction toward the well tubing.

33 6 1 In order to use the multi-function circulating tool 40 to 2 jet cleaning fluid on the well riser 52 during a drilling 3 or wellbore clean-up operation, the following method may 4 be employed.

6 The drill string 54 comprising drilling equipment is run 7 in the hole. Depending on the depth of the bore which 8 has been lined with casings and the length of the well 9 riser, the multi-function circulating tool 40 is positioned to be at or above the blow out pointers 57 11 when the bottom of the drill string 54 is inside the 12 casing shoe.

13 14 After drilling or milling is complete or it is otherwise desired to jet the well riser 52, the drill string is 16 pulled upwardly or retracted at the hole until the muIti- 17 function circulating tool 40 is above the drill pipe rams 18 58 inside the blow out pointers 57. At this point, the 19 drill bit 55 is inside the casing shoe.

21 The drill pipe rams 57 may then be closed around the 22 drill pipe 54 below the multi-function circulating tool 23 40. The weight of the drill pipe is then slackened off 24 such that the drill pipe is hung off the rams 8.

Additional weight may be slackened off such that a shear 26 ring or shear pin or similar means within the multi- 27 function circulating tool may be sheared or overcome to 28 cause the tool 40 to collapse. The collapse of the tool 29 40 brings about the opening of the second or radial outlets in the tool 40 and accordingly radial or 31 transverse circulation of fluid onto the inside walls of 32 the well riser 52 may commence.

33 7 1 After jetting and circulating is complete, pumping of 2 circulation fluid may cease and the drill pipe may be 3 picked up to close the second outlet of the multi- 4 function circulation tool 40. Before opening the rams 58, the well should be monitored. The weight of the 6 drill string 54 may then be picked up and the ram 58 and 7 blow out pointers 57 may be opened.

8 9 Thereafter, the drill string 54 may be run back in the hole and further drilling or other operation may be 11 undertaken, if desirable.

12 13 It will be appreciated by persons skilled in the art that 14 the function of the string in which the tool 40 is located is not an essential element of the present 16 invention. For example, the string could be used for 17 drilling, milling or for performing a wellbore clean-up 18 or well riser operation.

19 Turning now to Figure 2, there is depicted a circulation 21 tool comprising a body member 1 defining an internal 22 fluid flow path in the form of an axial bore 9.

23 24 Slidably mounted within the throughbore 9 is an obturating member 7. The obturating member 7 is also 26 provided with an axial flow path 10 therethrough which 27 co-ordinates with the body member 1 to provide a 28 generally axial circulation path for fluid between the 29 inlet 11 and a first outlet 13.

31 The body 1 is provided with a plurality of 32 circumferentially spaced radial ports 2 which provide a 33 second outlet for circulating fluid. However, when the 34 tool 40 is in the state shown in Figure 2 hereto, the 8 1 second outlet 2 is open and the only possible flow path 2 through the tool is from the inlet 11 and out the second 3 outlet 2.

4 The obturating member 7 is provided with a shoulder 8 6 suitable for landing on a formation in the well riser.

7 For example, the shoulder 8 may be suitably sized to land 8 on the top end of a blow out pointer.

9 A shear ring 6 provides a connecting means between the 11 body 1 and the obturating member 7. When the shear ring 12 6 is intact, the tool is held in a first or expanded 13 position with the obturating member 7 obturating the 14 second outlet 2.

16 one or more collets 5 may also be provided in respective 17 seats in the obturating member 7; the collets 5 engaging 18 respective cavities in the body 1.

19 It should be noted that the tool is suitable for 21 attachment in a drill string; there being a female 22 connector provided near the inlet 11 and a male connector 23 provided in the vicinity of the first outlet 13.

24 Further modifications and improvements may be 26 incorporated without departing from the scope of the 27 invention herein intended.

Claims

9 1 CLAIMS 2 3 1. A method of cleaning a well riser, the method

4 comprising suspending in a drill pipe from surface a 5 circulating tool in the well riser, and causing the 6 circulating tool to axially collapse so as to open 7 one or more radial outlets in the tool and allow 8 cleaning fluid to be expelled out of the tool and 9 impact on the inside of the well riser. 10 11
2. A method as claimed in Claim 1 wherein the well 12 riser is provided with blow out pointers 13 incorporating drill pipe rams and the circulating 14 tool is caused to axially collapse by closing the 15 drill pipe rams around the drill pipe below the 16 circulating tool and slacking off sufficient drill 17 pipe weight to hang the pipe and collapse the tool. 18 19
3. A method as claimed in Claim 1 or Claim 2 wherein the tool is provided with a shoulder which co21 operates with a formation in the well riser to allow 22 for the slacking off of sufficient drill pipe weight 23 to hang the pipe and collapse the tool. 24
4. A method as claimed in any one of the preceding 26 Claims wherein the method further includes passing 27 the cleaning fluid down the drill string to an inlet 28 of the apparatus and thence via a first outlet 29 communicating with the drill string below the 30 circulating tool before setting down the weight of 31 the drill string. 32 33
5. A method as claimed in any one of the preceding 34 Claims employed after drilling or milling is I complete and including pulling the drill pipe upward 2 and out of a well bore until the tool is above the 3 drill pipe rams.

4
6. A circulating tool for cleaning well risers, the 6 tool comprising a generally axial body having an 7 axial through passage between an inlet and a first 8 outlet, the inlet and the first outlet being adapted 9 for connection in a drill string supported from the surface, a second outlet extending generally 11 transversely of the tool, wherein the tool further 12 includes an obturating member movable between a 13 first position closing the second outlet and a 14 second position permitting fluid flow through the second outlet.

16 17
7. A circulating tool as claimed in Claim 6 wherein the 18 drill string is provided with a shoulder for co- 19 operating with a formation in the well bore or riser.

21 22
8. A circulating tool as claimed in Claim 7 wherein the 23 shoulder is provided as part of the circulating 24 tool.

26
9. A circulating tool as claimed in any one of Claims 6 27 to 8 wherein the second outlet comprises a number of 28 apertures in a body member which communicate with 29 the inlet and the apertures are distributed circumferentially around the outer surface of the 31 body member.

32 1
10. A circulating tool as claimed in any one of Claims 6 2 to 9 wherein the first outlet is closed when the 3 second outlet is open.

4
11. A circulating tool as claimed in any one of Claims 6 6 to 10 wherein the second outlet is associated with 7 one or more nozzles adapted to increase the velocity 8 of expelled cleaning fluid from the second outlet.

9
12. A circulating tool as claimed in Claim 11 wherein 11 the nozzles are adapted to increase the effective 12 outer diameter of the second outlets.

13