DK2518263T3 - Downhole cleaning system - Google Patents

Description

Description - a wireline cleaning tool having a longitudinal direc tion and comprising:

Field of the invention a rotatable nozzle head having a plurality of noz- [0001] The present invention relates to a downhole zles, cleaning system for cleaning an element inside a casing - a tool housing having an inlet being in fluid com- in a wellbore comprising well fluid having a wellbore pres- munication with the nozzles for letting well fluid sure, comprising the casing, a wireline cleaning tool hav- into the tool, ing a longitudinal direction and comprising a rotatable - a flow hindering element arranged on an outside nozzle head having a plurality of nozzles, a tool housing of the housing dividing the too! into a first and a having an inlet being in fluid communication with the noz- second tool part and dividing the casing into a zles for letting well fluid into the tool, a flow hindering first and a second casing part, and element arranged on an outside of the housing, dividing - a rotatable shaft connecting the nozzle head the tool into a first and a second tool part and dividing with the housing, the casing into a first and a second casing part and a rotatable shaft connecting the nozzle head with the hous- wherein the system further comprises a pumping device ing, wherein the system further comprises a pumping de- for pressurising the well fluid in the first part of casing to vice for pressurising the well fluid in the first part of casing a pressure substantially above the wellbore pressure and to a pressure substantially above the wellbore pressure above a pressure in the second part of the casing so that and above a pressure in the second part of the casing well fluid is pumped in through the inlet and out through so that well fluid is pumped in through the inlet and out the nozzles. through the nozzles. Furthermore, the invention relates [0006] Also the downhole cleaning system according to a wireline cleaning tool and to a cleaning method. to the invention may comprise a control device to control the rotation of the shaft and the nozzle head.

Background art [0007] In one embodiment, the control device may be an electrical motor for rotating the shaft, [0002] During oil production, the completion needs to [0008] In another embodiment, the control means may be optimised in order to produce as much oil as possible. comprise a gear, a motor brake or a centrifugal brake.

Therefore, it is necessary that some valves are open and [0009] Furthermore, the nozzle head may comprise a others closed. However, such valves may get stuck due hydraulic control unit for controlling which nozzles are to precipitation scale and other particles accumulated on open and which nozzles are closed. the valve so that the valve is stuck. Thus, it is sometimes [0010] In addition, the nozzle head may comprise a necessary for the valves to be cleaned before being able hydraulic control unit for controlling a supply of fluid to to operate them. each nozzle.

[0003] Known cleaning tools, e.g. disclosed in US [0011] In one embodiment, the shaft is hollow for sup- 2010/032154, require the presence of coiled tubing on plying the well fluid to the nozzle head. the rig or vessel In order to clean a valve in a casing within [0012] In another embodiment, the flow hindering ele- a wellbore, However, such coiled tubing is not always ment is a packer, an inflatable unit, a rubber element or situated on the rig or vessel and therefore needs to be an elastomeric element transported to the rig or vessel. [0013] The downhole cleaning system according to the invention may further comprise a stroker being a device Summary of the invention providing a stroking reprocicating movement of the noz zle head in relation to the longitudinal direction of the tool, [0004] It is an object of the present invention to wholly or a piston interacting with a piston housing in which a or partly overcome the above disadvantages and draw- spring device is arranged for providing a reprocicating backs of the prior art. More specifically, it is an object to movement of the nozzle head in relation to the longitu- provide a downhole cleaning system which is more sim- dinal direction of the tool. pie and easier to submerge into a wellbore without using [0014] In one embodiment, the tool may comprise an-drill pipes or coiled tubing. choring units.

[0005] The above objects, togetherwith numerous oth- [0015] In another embodiment a filter may be arranged er objects, advantages, and features, which will become upstream of the inlet or inside the inlet. evident from the below description, are accomplished by [0016] Furthermore, the downhole cleaning system a solution in accordance with the present invention by a may comprise a downhole driving unit driving the tool downhole cleaning system for cleaning an element inside and itself in the casing. a casing in a wellbore comprising well fluid having a well- [0017] Also, the downhole cleaning system may corn- bore pressure, comprising: prise a measuring device measuring a rotational speed of the nozzle head. the casing, [0018] Additionally, the downhole cleaning system may comprise a control unit to control the measuring de- Detailed description of the invention vice from surface.

[0019] In one embodiment, the nozzle head may com- [0024] Fig. 1 shows a downhole cleaning system 1 for prise a check valve. cleaning an element 2, such as a gas lift valve, a sleeve [0020] The present invention also relates to a wireline or a side pocket mandrel, in a casing 3 in a wellbore 4 cleaning tool arranged in a casing downhole and having comprising well fluid 5 having a well fluid pressure F’w. a longitudinal direction, comprising: The downhole cleaning system 1 comprises the casing 3 and a wireline cleaning tool 10. The wireline cleaning a rotatable nozzle head having a plurality of nozzles, tool 10 has a longitudinal direction 11, and comprises in a tool housing having an inlet being in fluid commu- the end furthest away from the surface a rotatable nozzle nication with the nozzles for letting well fluid into the head 12 having a plurality of nozzles 13 for cleaning the tool and out through the nozzles, gas lift valve by jetting high pressurised well fluid towards a flow hindering element arranged on an outside of the valve. the housing, dividing the tool into a first and a second [0025] By having a wireline cleaning tool 10, the clean- tool part and dividing the casing into a first and a ing operation can be performed anywhere in the well, second casing part, also in the more horizontal parts of the well. No landing a rotatable shaft connecting the nozzle head with the nipple is required in order to perform a cleaning operation, housing, The system is easy to use, and the cleaning tool is easily retrieved from the well by pulling in the wireline. wherein the shaft may be a hollow shaft for supplying the [0026] The wireline cleaning tool 10 has a tool housing nozzles with well fluid. 14 having an inlet 15 for letting well fluid into the too! 10, [0021] Finally, the invention relates to a cleaning meth- and the inlet 15 Is inside the tool in fluid communication od comprising the steps of entering a wireline cleaning with the nozzles 13. The well fluid travels in through the tool of the system according to the invention into a casing, inlet and out through the nozzle head, illustrated with activating the pumping device and pressurising the first arrows. The wireline cleaning tool 10 is submerged into casing part, turning the nozzle head and cleaning a cas- the casing 3 in the well, and a flow hindering element 16 ing element by letting wei! fluid in through the inlet in the arranged on an outside 17 of the housing 14 is set or pressurised first casing part and out through nozzles in inflated so that it divides the casing 3 in a first 20 and a the second casing part. second casing part 21. This enables that the well fluid in the first casing part 21 can be pressurised from the top Brief description of the drawings of the well by a pumping device 23 and the fluid is forced into the inlets 15 and out through the nozzles in order to [0022] The invention and its many advantages will be clean the casing or elements therein. Thus, the second described in further detail below' with reference to the part of the casing 21 has a substantially lower well fluid accompanying schematic drawings, which for the pur- pressure so that the high pressurised well fluid in the first pose of illustration show some non-limiting embodiments part 20 can be ejected as jets in the weil fluid in the second and in which part of the casing. In this way, the casing is used as the coiled tubing or drill pipe in order to provide the nozzles Fig. 1 shows a downhole cleaning system inacasing, with high pressurised fluid; however, the fluid jetted from the nozzles is not a special cleaning fluid but merely the Fig. 2 shows a partly cross-sectional view along the well fluid surrounding the tool. Thus, the environmentsur- longitudinal direction of the downhole cleaning sys- rounding the gas lift valve to be cleaned is not interfered, tern seen from the side, [0027] As shown in Fig. 1, the wireline cleaning tool 10 is connected with a wireline 41. The tool comprises an Fig. 3 shows a partly cross-sectional view of another electronic section 30, a motor 31, a pump 32 and an embodiment of the system, anchoring device 33 in a first tool part 18 above the flow hindering element 16. In a second tool part 19 below the and flow hindering element 16, the nozzie head 12 is ar ranged.

Fig, 4 shows another embodiment of the downhole [0028] In Fig. 2, the tool 10 is shown having a rotatable cleaning system in a casing. shaft 22 connecting the nozzle head 12 with the housing 14. The rotation of the shaft is controlled by a control [0023] All the figures are highly schematic and not nec- device 24 in the form of an electrical motor having a gear, essarlly to scale, and they show only those parts which a motor brake or a centrifugal brake 25. The shaft 22 is are necessary in order to elucidate the invention, other hollow and in fluid communication with the inlet 15 for parts being omitted or merely suggested. supplying well fluid to the nozzles 13 of the nozzle head 12. The shaft 22 is connected with the motor control device 24, which controls the rotation of the nozzle head 12 while fluid is jetted out through the nozzles 13, If the 2, the filter 36 or screen surrounds the part of the tool 10 nozzle head was not controlled, the well fluid jet stream having the inlet 15. The tool 10 comprises several inlets 43 ejected from the nozzles would loose its effect as fluid all in fluid communication with the hollow shaft. The hol- ejected through the nozzles would then force the nozzle low shaft may be internally sectionised having an internal head to rotate too fast, resulting in the jet stream being frame structure to strengthen the shaft, spread along an inner circumference of the casing and [0034] As shown in Fig. 4, the downhole cleaning sys- not ejected as a straight line in the radially direction of tern 1 may further comprise a downhole driving unit 37 the casing. driving the tool 10 and itself forward in the casing 3. The [0029] The flow hindering element 16 is shown as a driving unit 37 has wheels on arms and can be used as rubber element being squeezed in the longitudinal direc- the anchoring device in order to set the packer. The tion 11 of the tool between two rings 42 forcing the rubber downhole cleaning system 1 may also comprise a meas- element radially outwards to seal against the casing at a uring device 38 measuring a rotational speed of the noz- pressure of 3,000-5,000 PSI. Theflow hindering element zle head 12. As shown in Fig. 4, the measuring device could also be a packer, an inflatable unitor an elastomeric 38 may be arranged in the motor control device 24 around element. The flow hindering element does not necessar- the shaft 22 so that the nozzle head is controlled to rotate ily have to seal against the inner wall of the casing in at a speed lower than 30 RPM, preferably lower than 25 order to be able to create a pressure difference between RPM and more preferably lower than 20 RPM. The con- the first and upper part of the casing and the second and trol device 24 may be controlled from above surface by lower part of the casing. means of a control unit 39 shown in Fig. 4.

[0030] The tool 10 is anchored up inside the casing 3 [0035] Before and after the cleaning operation, a iog- by means of anchoring units 35 so that the nozzle head ging unit of the cleaning too! can investigate the casing 12 is arranged outside a target area to be cleaned. The to see which part or element of the casing needs to be flow hindering element 16 is then inflated or set, and the cleaned and if the part or element to be cleaned is proppumping device 23 pressurising the well fluid in the first erly cleaned. and top part of the casing 20 is activated. High pressu- [0036] The nozzle head 12 may further comprise a rised fluid is subsequently jetted as a jet stream out check valve 40 in an end opposite the end connected through the nozzles 13 of the nozzle head 12 as the noz- with the shaft 22. zle head turns in a controlled manner so that the jet [0037] The tool 10 may comprise a chamber with a streams do not loose too much jetting power. cleaning fluid which is mixed with the well fluid before [0031] The nozzle head comprises a hydraulic control being jetted out through the nozzles 13. unit for controlling which of the nozzles that jet fluid to [0038] By fluid or well fluid is meant any kind of fluid clean a valve or the like element. The hydraulic control which may be present in oil or gas wells downhole, such unit controls the openings and closings of the nozzles as natural gas, oil, oil mud, crude oil, water, etc. By gas and/or the supply of fluid to each nozzle. As can be seen is meant any kind of gas composition present in a well, in Fig. 1, only two of the nozzles jet fluid into the casing completion, or open hole, and by oil is meant any kind of in order to clean an element, such as a valve. In Fig. 2, oil composition, such as crude oil, an oil-containing fluid, only one nozzle jets fluid. If a high fluid velocity is needed etc. Gas, oil, and water fluids may thus all comprise other in order to clean an object, the hydraulic control unit only elements or substances than gas, oil, and/or water, re- lets one nozzle jet at a time. However, if a high volume spectively. of fluid is needed, the hydraulic control unit lets several [0039] By high pressurised fluid is meant fluid flowing nozzles jet. Furthermore, the hydraulic control unit has at a volume flow rate of at least 250 L/min, preferably at means to control in which angles along the circumference least 300 L/min and even more preferably 350 L/min. of the nozzle head the nozzles are tojet so that their jet [0040] By a casing is meant any kind of pipe, tubing, hits against the element to be cleaned. tubular, liner, string etc. used downhole in relation to oil [0032] In order to reach a larger target area, the too! or natural gas production. may have means for moving the nozzle head in a repro- [0041] In the event that the system is not submerged cicating movement. In Fig. 2, a piston 26 interacting with all the way into the casing, a downhole tractor can be a piston housing 27 in which a spring device 28 is ar- used to push the system all the way into position in the ranged provides a reprocicating movement of the nozzle well. Adownhole tractor is any kind ofdrivingtoo! capable head 12 in relation to the longitudinal direction 11 1 of of pushing or pulling tools in a well downhole, such as a the tool 10. In Fig. 3, the tool 10 comprises a stroker 29 Well Tractor®). being a device providing a stroking reprocicating move- [0042] Although the invention has been described in ment of the nozzle head 12 in relation to the longitudinal the above in connection with preferred embodiments of direction 11 of the too! 10. The reprocicating movement the invention, it will be evident for a person skilled in the of the nozzle head 12 is illustrated by a double arrow in art that several modifications are conceivable.

Fig. 3.

[0033] The wireline cleaning too! comprises a filter 36 arranged upstream of the inlet 15 or in the inlet, in Fig.

Claims (15)

A wireline cleaning tool (GB: "wireline cleaning tool") (10) located in a casing down a well and having a longitudinal direction (11), comprising the wireline cleaning tool: - a rotatable nozzle head (12) with a plurality of nozzles (13), - a tool housing (14) having an inlet (15) which is in fluid communication with the nozzles in order to allow well fluid to flow into the tool and out through the nozzles, - a flow blocking element ( 16) located on an outer side (17) of the housing which divides the tool into a first (18) and a second (19) tool part and divides the casing into a first (20) and a second (21) casing portion, and - a rotatable shaft (22) connecting the nozzle head to the housing, the shaft being a hollow shaft for supplying well fluid to the nozzles, characterized in that the wireline cleaning tool further comprises a control means (24) for controlling the rotation of the shaft and the nozzle head. A wireline cleaning tool according to claim 1, further comprising an electronic section (30), a motor (31), a pump (32) and anchoring device (33) in a first tool part (18) above the flow section. hindering element. 3. Downhole cleaning system (GB) (1) for cleaning an element (2) within a casing (3) of a wellbore (4) comprising well fluid (5) and having a wellbore pressure (Pw) said well cleaning system comprising: - the casing; and - a wireline cleaning tool (10) according to any one of claims 1 or 2, wherein the system further comprises a pumping means (23, 32) for pressurizing the well fluid in the first portion of the casing to a pressure substantially above the wellbore pressure and above a pressure in the second portion of the casing so that the well fluid is pumped in through the inlet and out through the nozzles. The well cleaning system of claim 3, wherein the control device is an electric motor for rotating the shaft. A well cleaning system according to claim 3 or 4, wherein the control means comprises a gear, a motor brake or a centrifugal brake (25). A well cleaning system according to any one of claims 3-5, wherein the shaft is hollow for supplying the well fluid to the nozzle head. The well-cleaning system of claim 6, wherein the flow-blocking element is a gasket, an inflatable unit, a rubber element or an elastomer element. A well cleaning system according to any one of claims 3-7, further comprising a cylinder tool (GB: "Stroker") (29), which is a device which provides a reciprocating stroke of the nozzle head relative to the nozzle head. longitudinal direction of the tool, or a piston (26) interacting with a piston housing (27), wherein a spring device (28) is arranged to provide reciprocating movement of the nozzle head relative to the longitudinal direction of the tool. A well cleaning system according to any one of claims 3-8, wherein the tool comprises anchoring units (35). A well cleaning system according to any one of claims 3-9, wherein a filter (36) is located upstream of the inlet or inside of the inlet. A well cleaning system according to any of claims 3-10, further comprising a well downhole driving unit (37) operating the tool and itself in the casing. A well cleaning system according to any of claims 3-11, further comprising a measuring device (38) for measuring a rotational speed of the nozzle head. A well cleaning system according to claim 12, further comprising a control unit (39) for controlling the measuring device from the surface. The well cleaning system of claim 13, wherein the nozzle head comprises a stop valve (40). A cleaning method comprising the following steps: - introducing a wireline cleaning tool of the system according to any one of claims 3-14 in a casing, - activating the pumping device and pressurizing the first casing part, - turning the nozzle head, - cleaning a casing element by allowing well fluid to flow through the inlet of the pressurized first casing portion and out through nozzles of the second casing portion.