GB2350632A

GB2350632A - Magnetic well cleaning apparatus

Info

Publication number: GB2350632A
Application number: GB0012913A
Authority: GB
Inventors: Mark Carmichael; Paul David Howlett
Original assignee: Specialised Petroleum Services Ltd
Current assignee: Schlumberger UK Holdings Ltd
Priority date: 1999-05-29
Filing date: 2000-05-30
Publication date: 2000-12-06
Anticipated expiration: 2020-05-30
Also published as: US6655462B1; GB9912666D0; GB0012913D0; GB2350632B

Abstract

The apparatus can collect loose debris, particularly ferrous debris, and has a body 2 with upper 3 and lower 4 stabiliser sleeves. The body 2 has a one or more integral magnets or magnetic areas 5. In one embodiment the magnets are located in a first and second row on a split sleeve 6 and are covered by a protective stainless steel sleeve 7. The apparatus may alternatively comprise magnetic scraper blades or a magnetic sub. The magnets are selectively activated. There is also described a method of trapping or retaining debris in a well bore.

Description

1 2350632 I MAGNETIC WELL CLEANING APPARATUS 2 3 This invention relates to

well cleaning equipment and 4 more specifically, apparatus and method for cleaning out 5 the inside of a liner or casing in an oil or gas well. 6 7 It is common practice after drilling a borehole for the 8 purpose of oil extraction, to line the borehole with a 9 well casing and a liner. After installation of the 10 liner, it is generally necessary to clean out the inside 11 thereof in order to wash away any debris or other 12 contaminants. 13 14 Various types of cleaning apparatus are known and 15 available. One such type of cleaning apparatus is 16 generically referred to as a casing scraper. This type 17 of tool typically incorporates steel casing scraper 18 blades that scrape the inside of the casing or tubing in 19 the well. Scraper blades are particularly suitable for 20 removing relatively large particles or debris from the 21 surface of the casing or liner. A considerable amount of 22 debris found within the well bore and on the surface of 23 the casing or liner comprises of rust particles and/or 2 1 metal chips or scrapings originating from equipment used 2 in the well and the casing or liner itself. 3 4 Usually, the scraper blades are biased in an outward or 5 radial direction by springs which are designed to 6 maintain the blades in firm contact with the casing wall 7 or other tubing in the well. In the present invention, 8 it is recognised that while this is desirable for the 9 purposes of cleaning the casing and removing debris 10 therefrom, there are other times when the pressure of the 11 casing blades against the tubing or casing is 12 disadvantageous. For example, when a casing scraper is 13 removed from the well, the outwardly biased scraper 14 blades can dislodge further debris causing same to become 15 loose in the circulation fluid and negate the effect of 16 the cleaning work that has already been performed. 17 18 Similar difficulties can be encountered with other types 19 of well clean-up tools, including brushes, circulation 20 tools and the like. 21 22 An object of the present invention is to obviate or at 23 least mitigate the disadvantage described above and, more 24 particularly, the disadvantage of debris having been 25 removed from the casing wall or liner becoming loose in 26 the circulation fluid, thereby remaining in the well. 27 28 In our co-pending British Patent Application Number 29 9806274.8, there is described apparatus for catching such 30 debris and this is one proposed method and apparatus for 31 dealing with the aforementioned problem. The present 32 invention provides an alternative solution in the form of 3 1 apparatus and method for collecting loose debris and 2 particles in a well casing or liner. The present 3 invention also provides apparatus which can remove 4 ferrous materials suspended in viscous fluid within a 5 well. 6 7 According to the present invention, there is provided 8 apparatus for collecting loose debris or particles in a 9 well casing or liner, the apparatus comprising a body 10 having or supporting one or more magnets. 11 12 The apparatus may be a casing scraper having scraper 13 blades, wherein the scraper blades are magnetic. 14 15 The apparatus may alternatively be a catcher for catching 16 loose debris particularly during the extraction of the 17 catcher from the well. 18 19 The body is preferably adapted for attachment to a work 20 string. 21 22 Typically, the magnets are permanent magnets. 23 24 The apparatus may comprise a magnetic sub. 25 26 In a preferred embodiment the apparatus is comprised of 27 an upper and lower stabiliser wherein a magnetic sub is 28 located between the stabilisers. 29 30 The apparatus may also comprise a protective sleeve, 31 positioned over the magnets which preferably can rotate 4 1 relative to the upper and lower stabilisers. Typically 2 the protective sleeve is made of stainless steel.

3 4 The apparatus may be changeable between an inactivated mode wherein the magnetic field which attracts loose

6 debris or particles is off, and an activated mode where 7 the magnetic field is on.

8 9 In one embodiment the apparatus comprises a split sleeve having a first and second row of magnets.

11 12 Preferably the magnets are selectively activated or 13) deactivated by virtue of moving one of the first or 14 second row of magnets relative to the other of the first or second row of magnets.

16 17 According to a second aspect of the present invention, 18 there is a method of trapping or retaining debris or 19 particles in a well casing or liner, the method comprising the steps of:

21 a) running a magnetic tool or sub in the liner or casing 22 with the magnets inactivated; 23 b) activating the magnetic tool to create a magnetic 24 force to attract and retain said debris or particles; and; 26 c) removing the magnetic tool or sub from the well in 27 order to remove the debris or particles.

28 29 Preferably, the magnetic tool is located below a well clean-up tool in a work string. The well clean-up tool 31 may be a casing scraper, brushing tool or the like.

32 1 Alternatively, the well cleanup tool may comprise a 2 magnetised portion or area, suitably below the cleaning 3 members located on the same tool. The cleaning members 4 may, for example, be casing scrapers, brushes or the 5 like. 6 7 Various embodiments of the invention will now be 8 described by way of example only with reference to the 9 accompanying figures, in which: 10 11 Figure 1 shows a magnetic well cleaning apparatus, 12 Figure 2 illustrates a magnet activation mechanism, 13 Figure 3 shows a casing scraper incorporating a 14 magnetic portion; and Figures 4 and 5 show a work string including a 16 magnetic sub.

17 18 Referring firstly to Figure 1, one embodiment of a 19 magnetic cleaning tool is generally depicted at 1 and is comprised of a body 2 having an upper 3 and lower 4 21 stabiliser sleeve which can be mounted on a work string 22 (not shown). The stabiliser sleeves 3 and 4 are 23 typically non-rotating spiral.stabilisers. The main tool 24 body 2 rotates through and relative to the stabiliser sleeves 3 and 4 and thus prevents wear and damage of the 26 casing or liner which lines the well bore during pipe 27 rotation. A plurality of magnets 5 are integrally 28 located in the body 2. The magnets 5 are mounted on a 29 split sleeve 6 in a first inner 9 and second outer 10 row. A protective sleeve of stainless steel 7 is located 31 over the split sleeve 6, the protective sleeve 7 also 32 being free to rotate relative to the stabilisers 3 and 4.

6 1 Ferrous metal debris which is present in the well is 2 attracted to the magnets 5 and held onto the stainless 3 steel sleeve 7 until the tool 1 is retrieved from the 4 well. Stabiliser sleeves 3 and 4 prevent the captured 5 debris from being brushed or wiped off the tool 1 by the 6 movement of the work string. 7 8 Typically the tool 1 would be run into a well with other 9 conventional well clean-up tools (not shown) in an 10 inactive mode, that is without a magnetic field to 11 attract any ferrous debris which may be in the well. 12 After the cleaning process is complete, the magnets are 13 activated and the tool is removed or "tripped" from the 14 well. As the tool 1 is raised from the well, ferrous 15 debris and particles will be attracted to the magnets 5 16 and retained on stainless steel sleeve 7 until the tool 17 is retrieved. 18 19 Figure 2 illustrates the magnet activation means of the 20 apparatus. It can be seen that sleeve 8 has a split 21 configuration having two rows of magnets 9 and 10. When 22 the split sleeve 8 is in the configuration shown at (a) 23 the magnets 9 and 10 are aligned such that the magnetic 24 fields act in addition to attract any ferrous debris and 25 particles 11 which are present. It can be seen from (a) 26 that as a result, ferrous debris 11 will attach to the 27 stainless steel sleeve 7. To covert the magnets to the 28 inactivated mode as shown at (b), movement of, in this 29 case the lower half of the split sleeve 8, displaces the 30 magnets 9 in the lower row, so that the orientation of 31 the magnetic field is changed such that it does not 32 attract the ferrous debris 11.

7 2 Turning now to Figure 3 an alternative embodiment of a 3 magnetic tool 12 is designed as a casing scraper and 4 includes scraper blades 13 that are biased in an outward 5 or radial direction by biasing means such as springs (not 6 shown). In use, the blades 13 are maintained in contact 7 with a casing wall 14 in a downhole well or environment. 8 9 The blades 13 are made of steel that has been pre10 magnetised during manufacture. The scraper blades 1 11 therefore act as permanent magnets suitable for 12 collecting and trapping debris susceptible to magnetic 13 attraction. 14 15 In use, debris is held most typically to the upper edge 16 13a of the magnetic scraper blades and, to a lesser 17 extent, to the lower edge 13b thereof. 18 19 In an alternative embodiment, permanent magnets may be 20 incorporated as separate elements in otherwise non21 magnetic scraper blades. 22 23 In Figure 4, a work string generally depicted at 15 is 24 illustrated which includes a well clean-up tool in the 25 form of a brush tool 16. Below the brush tool 16 is a 26 separate sub 17 provided with an enlarged outside 27 diameter having close contact with the casing wall 18. 28 Grooves 19 are provided near the outer circumference of 29 the sub 17 to enhance bypass area. 30 31 The sub 17 comprises largely of a permanent magnet 32 adapted to attract and retain debris or particles 8 1 susceptible to magnetic attraction. In a preferred 2 embodiment shown in Figure 5 the magnetic sub 19 is 3 rotatable through an upper 20 and lower 21 spiral 4 stabiliser which are mounted on a work string 22. 5 6 The clean-up tool 16 is appropriately positioned above 7 the sub 17 so that any particles or debris dislodged by 8 the bristles 16 are likely to fall.into the small annular 9 area between the casing wall 18 and the outer 10 circumference of the sub 17, whereat they are attracted 11 to the walls of the sub 17 and retained in contact 12 therewith. 13 14 In the situation where the work string is being extracted 15 from the well bore, the sub 17, being placed below the 16 clean-up tool 16, will follow the clean-up tool out of 17 the well and thus move into the position at which the 18 clean-up tool had been immediately prior, thereby 19 improving the efficiency of collecting metallic particles 20 and other debris suitable for magnetic attraction. 21 22 Notably, that any cleanup or other function tool could 23 replace the brush tool 16 depicted in Figure 4 without 24 departing from the invention. 25 26 In a preferable embodiment, there may be provided a 27 magnetic sub, similar to that depicted in Figure 4, but 28 also designed to catch and retain other particles or 29 debris which are not susceptible to magnetic attraction. 30 31 Thus, it may be seen that the present invention relates 32 to the collection and retention of debris and other 9 1 particles partially or wholly by magnetic means. The 2 invention provides a welcome improvement to collecting 3 debris that has been dislodged by the cleaning action of 4 known well clean-up tools. This accords with the desire 5 not only to clean casing and other tubing in a well, but 6 also clean the interior of the well itself. The 7 apparatus can be run in conjunction with other wellbore 8 clean-up tools to collect ferrous metal debris during 9 clean-up and remove it from the well. 10 11 While the invention finds an obvious application in well 12 used for the production of oil or gas, it may also have 13 alternative utility in the cleaning of pipelines or othe 14 tubing. 15 16 Further modifications and improvements may be 17 incorporated without departing from the scope of the 18 invention herein intended.

1 Cla s 2 3 l. Apparatus for collecting loose debris or particles in a 4 wellbore, the apparatus comprising a body having or supporting one or more magnets.

6

Claims

7
2. Apparatus as claimed in Claim 1 wherein the apparatus

8 is a casing scraper having scraper blades, wherein the 9 scraper blades are magnetic.

11
3. Apparatus as claimed in Claim 1 wherein the apparatus 12 is a catcher for catching loose debris particularly 13 during the extraction of the catcher from the well.

14
4. Apparatus as claimed in Claim 1 wherein the apparatus 16 comprises a magnetic sub.

17 18
5. Apparatus as claimed in Claim 4 wherein the magnetic 19 sub is located between an upper and lower stabiliser.

21
6. Apparatus as claimed in any one of the preceding Claims 22 being changeable between an inactivated mode where the 23 magnetic field which attracts loose debris is off and 24 an activated mode where the magnetic field is on.

26
7. Apparatus as claimed in Claim 6 having a split sleeve 27 comprising a first and second row of magnets.

28 29
8. Apparatus as claimed in Claim 6-7 wherein the magnets are selectively activated and deactivated by virtue of 31 moving one of the first or second row of magnets 1 relative to the other of the first or second row of 2 magnets.

3 4
9. Apparatus as claimed in Claims 4-8 having a protective sleeve positioned over the magnets.

6 7
10. Apparatus as claimed in Claim 9 wherein the 8 protective sleeve is rotatably positioned 9 between the upper and lower stabiliser.

11
11. Apparatus as claimed in Claims 9-10 wherein the 12 protective sleeve is made of stainless steel.

13 14
12. Apparatus as claimed in any one of the preceding Claims adapted for attachment to a work string.

16 17
13. Apparatus as claimed in any one of the preceding 18 Claims wherein the magnets are permanent magnets.

19
14. Apparatus as claimed in any one of the preceding Claims 21 wherein the magnetic tool is located below a separate 22 well clean-up tool on a work string.

23 24
15. Apparatus as claimed in Claim 14 wherein the well clean-up tool is a casing scraper.

26 27
16. Apparatus as claimed in Claim 14 wherein the well clean 28 up tool is a brushing tool.

29 12 1
17. Apparatus as claimed in any one of the preceding Claims 2 having integral cleaning members on the body of the 3 tool, above the magnetised section of the tool.

4
18. Apparatus as claimed in Claim 17 wherein the cleaning 6 members are casing scrapers.

7 8
19. Apparatus as claimed in Claim 17 wherein the cleaning 9 members are brushes.

11
20. A method of trapping or retaining debris or particles 12 in a well casing or liner, the method comprising the 13 steps of:

14 a) running a magnetic tool or sub in the liner or 16 casing with the magnets inactivated; 17 b) activating the magnetic tool to create a 18 magnetic force to attract and retain said 19 debris or particles; and; c) removing the magnetic tool or sub from the 21 well in order to remove the debris or 22 particles.

23 24