Mud filter

Abstract

A downhole mud filter (100) comprising a tubular member (1) connectable to the drill string used to prevent debris-laden fluid from entering sensitive BHA tools and components further downhole relative to the mud filter. A tubular member having a sub assembly consisting of a bristle rings (6) and/or rupture (7) to intentionally create a restriction and divert debris-laden fluid around a cylindrical mesh (2) and/or screen surrounded by permanent magnets (3). The openings (9) on the mesh and/or screen allow fluid to pass through while preventing particulates or debris from entering and retaining such debris on the outside of the screen and/or mesh. Magnets (3) arranged around the outer diameter of the screen and/or mesh (2) and along its length captures and retains smaller ferrous debris which the screen and/or mesh cannot filter.

Claims

1. A wellbore tool usable to capture and retain debris from drilling fluid entering a drill string (300) and prevent debris-laden fluid from entering sensitive BHA components, comprising: a tubular body with selectively connectable threaded connections to the drill string (300) and/or workstring and housing a sub-assembly (600), comprising; a steel tubular screen and/or mesh (2) with an outer diameter smaller than an inside diameter of the tubular body supported within a bore of the tubular body by a dart support member (13) and a tapered conical support member, allowing for an annular collection gap surrounded by a set of magnetic bars (15), a bristle ring (6) or a set of bristle rings mounted in a bore of the steel tubular screen and/or mesh (2) used independently or in conjunction with a rupture disc, (7) which prevents fluid from entering a bore of the wellbore tool and diverts it around towards the annular collection gap between the inside diameter of the tubular body and outer diameter of the steel tubular screen and/or mesh (2), and wherein the rupture disc (7) can be burst by a change in pressure or by applying a load against a membrane of the rupture disc.

2. The wellbore tool as claimed in claim 1, wherein the bore of the wellbore tool is further configured to direct away drilling fluid in the drill string (300) from the bore of the wellbore tool and into the annular collection gap between the steel tubular screen and/or mesh (2) and the bore of the tubular body.

3. The wellbore tool as claimed in claim 1, wherein the steel tubular screen and/or mesh is further configured to retained large debris in the annular collection gap and not allow the large debris in the drilling fluid to pass through the steel tubular screen and/or mesh.

4. The wellbore tool as claimed in claim 1, wherein the set of magnetic bars are further configured to capture any metallic or ferrous debris.

5. The wellbore tool as claimed in claim 1, wherein the steel tubular screen and/or mesh (2) has a plurality of openings (9) in the form of holes (9a) or longitudinally extended slots (9b) or a combination of both.

6. The wellbore tool as claimed in claim 1, wherein the steel tubular screen and/or mesh is further configured to allow drilling fluid to pass through and into the bore of the wellbore tool free from debris.

7. The wellbore tool as claimed in claim 1, wherein the bristle ring (6) or sets of bristle rings and/or rupture disc (7) are configured to divert the fluid away from the bore of the wellbore tool and into the annular collection gap.

8. The wellbore tool as claimed in claim 1, wherein the rupture disc (7) is configured to burst by either a change in pressure or by applying a load against the membrane of the rupture disc.

9. The wellbore tool as claimed in claim 1, wherein the pressure can be changed by varying a thickness of the membrane of the rupture disc.

10. The wellbore tool as claimed in claim 1, wherein individual bristles of the bristle ring (6) are made from a resilient material which is able to withstand high flow rates and debris tolerant to divert the fluid flow, prevent debris from entering the bore of the wellbore tool and, if required, protect the rupture disc (7).

11. The wellbore tool as claimed in claim 10, wherein material of the individual bristles is a polymer or steel.

12. The wellbore tool as claimed in claim 1, further comprising a wireline tool, and wherein the bore of the wellbore tool is configured to be large enough to allow the wireline tool to be passed through.

13. The wellbore tool as claimed in claim 1, wherein the set of magnetic bars (15) are permanent magnets (3) with high strength and temperature resistance.

14. The wellbore tool as claimed in claim 1, wherein the set of magnetic bars are further configured to be arranged equi-spaced radially around the steel tubular screen and/or mesh (2) to maximize flow and minimize pressure drop across the wellbore tool.

15. The wellbore tool as claimed in claim 1, wherein a quantity of the set of magnetic bars (15) is configured to be changed and/or is selected depending on an amount of ferrous required to be captured.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments of the present invention will now be described, by way of example only and not in any limitative sense, with reference to the accompanying drawings, in which:

(2) FIG. 1 is a schematic sectional view of the mud filter connected to elongate members at the upper and lower end of the tool and located inside the wellbore.

(3) FIG. 2 is an exploded schematic view of the sub-assembly housed within the tubular body.

(4) FIG. 3 is a schematic sectional view of the dart support member with the rupture disc and bristle ring assembled.

(5) FIG. 4 is a schematic view of the rupture disc.

(6) FIG. 5 is a schematic view of the bristle ring.

DETAILED DESCRIPTION OF THE DRAWINGS

(7) FIG. 1 is a schematic sectional view of the mud filter assembly 100, in accordance with an embodiment of an aspect of the present invention. The mud filter 100 is shown in a wellbore 200 and connected to a drill string with elongate members above 400 and below 500 the mud filter assembly 100. The debris-laden drilling fluid 700 is present in the upper bore of the drill string 300 prior to entering the mud filter 100. When the drilling fluid passes through the mud filter assembly 100, the drilling mud 800 below the drill string is free from debris.

(8) The mugs filter 100 comprises a meta tubular body 1 and houses the cylindrical screen/mesh 2, magnets 3, shovel support member 4, centralizer support member 5, bristle ring 6 and rupture disc 7. As is common in the relevant industry, the tubular body 1 has threads on either end of the body. This allows the tubular body 1 to be selectively connectable to an elongate string (for example., a work string or drill string) and lowered downhole into a wellbore.

(9) FIG. 2 shows a schematic view of the sub-assembly 600 housed within the tubular body 1. The screen/mesh 2 comprises a metal tubular in which a number of openings 9 have been cut These openings 9 can be but not limited to holes 9a and/or longitudinally-extending slots 9b or a combination of both. The arrangement may be sized as desired depending on the particular application to allow fluid flow through the screen/mesh 2 while filtering and retaining solids and debris within the annulus (described below). The screen/mash 2 can be constructed from a number of materials such as stainless steel, carbon steel or Inconel. Optionally, the screen/mesh 2 can be surface coated or treated to be able to withstand harsh chemicals as well as flow cutting associated with high flow rates, it is preferred that both ends of the screen/mesh 2 is threaded 10. In embodiment, the thread is a male external thread.

(10) At the lower end of the sub-assembly 600, a conical funnel support member 11 is selectively connectable to the screen/mesh 2. In this embodiment, the conical funnel 11 comprises of a female internal thread and engages with the male external thread 10 of the screen/mesh 2. The conical funnel 11 has an internal bore 12 sized the same as the internal bore of the screen/mesh 2. The profile of the conical funnel 11 has an outer diameter slightly undersized from the bore of the tubular body. The funnel-like profile provides a scooping action when the sub-assembly 600 is removed from the tubular body when servicing. Additionally, the outer diameter provides support and centralizes the sub-assembly within the tubular body.

(11) At the upper end of the sub-assembly 600, a dart support member 13 is selectively connectable to the screen/mesh 2 by mating threads 10. Similar to the conical funnel 11, the outer diameter is slightly undersized from the bore of the tubular body to provide support and centralizes the screen/mesh 2. The minor diameter is sized the same as the outer diameter of the screen/mesh 2. The tapered transition between the differing diameters is supported by ribs 14. Areas between the ribs 14 provider a flow path for the fluid to pass through. The internal profile of the centralization dart is tapered and narrows down to the internal diameter.

(12) The magnet assembly 700 consists of lengths of magnetic bars 15 supported at either end by support rings 16. The assembly is preferably made from stainless steel or a steel alloy that has good mechanical properties and can withstand temperature and chemical resistance. The bore of the support rings 16 is sized larger than the outer diameter of the screen/mesh 2. The outer edges of the support rings 16 are tapered to encourage the fluid to flow around the rings 16 and into the annulus between the tubular body and outer edge of the screen/mesh 2. The magnetic bars 15 are mounted equi-spaced around the circumference of the support rings 16. The magnetic bars 15 can be welded onto the support rings 16 or by any other permanent means. Optionally, the number of magnetic bars can be changed depending on the amount of debris to be recovered and is selected on the amount of debris to be recovered, respectively. Optionally, the number of magnetic bars will not create a significant pressure drop across the tool.

(13) The magnetic bars 15 consist of hollow section which houses rare earth magnetic discs. In the preferred embodiment, rectangular hollow section is used. It is preferred that the discs are arranged inside the hollow section alternating every magnet with a spacer. Optionally the spacer can be made from steel. Either end of the magnetic bars 15 are capped to encapsulate the magnetic discs. The strength of the magnet discs are to be strong enough to capture and hold the debris without being washed off by the velocity of the flawing fluid. The magnetic bars 15 are to be strong enough to magnetize the screen/mesh 2 to further increase the capture ability.

(14) Within the dart support member 13, is sized to house a rupture disc 7 and/or bristle rings 6. The internal shoulder 17 of the dart support member 13 and shoulder of the mesh/screen secures the rupture disc 7 and/or bristle rings 6 and prevents from movement while in operation. The two components can work together or independently to restrict the flow of drilling fluid or similar through the bore of the mud filter tool. This restriction encourages the majority of the drilling fluid to bypass the inner string bore and instead pass through the annular side of the screen/mesh allowing for maximum debris retention as well as ensuring that the majority of the drilling fluid has passed the magnets & is clean of any suspended metal/magnetic particles. If the rupture disc 7 and bristle ring 6 is used together, a spacer ring 22 is required to maintain the gap between the two components. This allows the bristles on the brush ring 6 enough adage to deflect without impeding the membrane of the rupture disc 7.

(15) The rupture disc 7 can be manufactured out of a number of materials. In the preferred embodiment, the rupture disc 7 is manufactured from hydrogenated acrylonitrile butadiene rubber (HNBR). The rubber membrane 18 is bonded to a metal ring 19. The membrane of the rupture disc designed to be non-fragmented when burst. This aids in preventing further debris from entering the drill string. The rupture disc 7 is primarily designed to be activated by a change in pressure however, applying a load against the membrane 18 will also burst the disc and provide a passage through the tool. The bore of the rupture disc 7 is sized the same as the bore of the screen/mesh as to create a constant flow area. Optionally the bonded HNBR on the metal ring can create a seal against the bore of the dart support member. This further helps prevent debris from entering the bore of the tool.

(16) The bristle ring 6 can be positioned in front of the rupture disc 7 to prevent damage b the flowing drilling fluid. In the preferred embodiment, the individual bristles 20 are made from steel/stainless steel or steel alloy. This provides the resilience as well as durability to withstand and capture debris present in the drilling fluid. Optionally, the individual bristles 20 can also be made from plastic or a compound of plastic. Optionally, the bristle ring 6 can be stacked together to provide the preferred resilience with more bristle strips providing a greater resilience. Optionally, the bristle ring 6 can be used independently of the rupture disc 7 to prevent fluid flow through the mud filter tool. Optionally, the brush strip 6 can be made by forming a metal ring 21, with the same diameter as the internal diameter of the dart support member, around individual bristles 20 wrapped around a steel wire wherein the length of individual bristle is twice as long as is the required length so to fully enclose the ring.

(17) Those of skill in the art will appreciate the above-described embodiments are merely exemplary of the present invention, and that various modifications and improvements may be made thereto without departing from the scope of the invention.

(18) While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

REFERENCE NUMERALS

(19) 1 metal tubular body

(20) 2 cylindrical screen/mesh

(21) 3 magnet

(22) 4 shovel support member

(23) 5 centralizer support member

(24) 6 bristle ring

(25) 7 rupture disc

(26) 9 opening

(27) 9a hole

(28) 9b longitudinally-extending slot

(29) 10 thread(ed)

(30) 11 conical funnel support member

(31) 12 internal bore

(32) 13 dart support member

(33) 14 rib

(34) 15 magnetic bar

(35) 16 support rind

(36) 17 internal shoulder

(37) 18 rubber membrane

(38) 19 metal ring

(39) 20 individual bristle

(40) 21 metal ring

(41) 22 spacer ring

(42) 100 mud filter assembly

(43) 200 wellbore

(44) 300 drill string

(45) 400 drill string with elongate members above the mud filter assembly

(46) 500 drill string with elongate members below the mud filter assembly

(47) 600 sub-assembly

(48) 700 debris-laden drilling fluid

(49) 800 drilling mud below the drill string