WO2003006787A1

WO2003006787A1 - Liner brushing and conditioning tool

Info

Publication number: WO2003006787A1
Application number: PCT/GB2002/002926
Authority: WO
Inventors: Gholam Hossein Rastegar
Original assignee: Weatherford/Lamb, Inc.
Priority date: 2001-07-07
Filing date: 2002-06-25
Publication date: 2003-01-23
Also published as: GB0116645D0

Abstract

An apparatus that combines mechanical scouring with hydraulic jetting action to brush and condition the internal surface of tubular structures such as well liner or casing. A liner brushing and conditioning tool comprises a mandrel (3) with male and female threaded ends (1,2) for connection to a work string, at least one brush sleeve (11) and at least two centralising sleeves (9) mounted directly onto the mandrel (3) and kept separated by means of spacer rings (10), means to allow relative rotation between the sleeves (9) and mandrel (3), and means to prevent relative rotation between the spacer rings (10) and mandrel (3).

Description

LINER BRUSHING AND CONDITIONING TOOL

The present invention relates to apparatus for brushing and conditioning the internal surface of a tubular structure.

According to the present invention there is provided a liner brushing and conditioning tool comprising: a mandrel with male and female threaded ends for connection to a work string; at least one brush sleeve and at least two centralising sleeves mounted directly onto the mandrel and kept separated by means of spacer rings; means to allow relative rotation between the sleeves and mandrel; and means to prevent relative rotation between the spacer rings and mandrel.

The present invention is applicable in particular to the oil and gas industry, particularly though not necessarily for cleaning and conditioning production liners.

Embodiments of the invention introduce a robust, failsafe mechanical device onto the work string so as to provide mechanical scouring of scale and debris from the inner surface of the tubular.

Embodiments of the present invention differ from conventional arrangements of sleeve over mandrel designs in so far as they allow for removal of the sleeves without the need for dismantling of the mandrel or sleeve, or heat expansion of the sleeve. Preferably, the sleeves and spacer rings are prevented from axial movement relative to the mandrel by means of two stops on the mandrel. The first stop is either integral with the mandrel body in the form of an upset on the mandrel, or is a removable stop secured on the mandrel body by means of three or more retaining devices. The second stop is removable from the mandrel body to facilitate removal of the sleeves and the spacer rings from the mandrel body.

The present invention, once assembled onto the work string, is run inside the tubular, e.g. a casing or liner. The outside diameter of the brush sleeves are designed to be sufficiently greater than the inside diameter of the tubing such that the action of tripping in and out of the tubing, whether in rotary or sliding mode, will result in the mechanical scouring of the inner surface of the tubular. While tripping in and out of the tubular, fluid may be pumped through the bore of the work string to assist with the conveyance of loosened up scale and debris to the surface.

It is desirable to be able to introduce a combined mechanical scouring action and hydraulic jetting action to provide a more efficient liner conditioning method. It is also desirable to introduce a device capable of the multiple activation of jetting action.

Preferably, the mandrel body, stops, sleeves, spacer rings and the retaining devices are made of steel, but sleeves may also be made from high temperature/high impacl/wear resistant ceramics, polymers or metals other than steel. For a better understanding of the present invention and in order to show how the same may be carried into effect reference will now be made, by way of example, to the accompanying drawings in which:

Figure 1 shows a side view of a mandrel body; Figure 2 shows a side view of a mandrel body with sectional views of sleeves, Spacer

Rings, Jetting Ports and retaining systems;

Figure 3 shows a cross sectional view of the mandrel of Figure 1 taken on the lines AA;

Figure 4 shows side and plan views of brush sleeves;

Figure 5 shows side and plan views of a centralising sleeve illustrating a centralising sleeve and an integral blade;

Figure 6 shows side and plan views of a retainer ring;

Figure 7 shows side and plan views of a spacer ring;

Figure 8 shows side and plan views of a ball catcher / plunger; and

Figure 9 shows side and plan views of a ball catcher / diverter chamber.

Prior to running and setting completion equipment and/or packers etc, the internal wall of a well casing or liner must be thoroughly cleaned, and it must be free from any cement, scale, debris or other contaminants. In practice, running of a conventional casing scraper alone is not sufficient to clear the liner wall of all deposits and scale; generally speaking some sort of brush tool is used to achieve a clean and smooth surface required for proper setting and sealing of the completion equipment.

Figure 1 illustrates two apparatus types for running into a well casing or liner, each of which consists of a single piece construction mandrel 3 with a male end 1 and a female end 2, a mandrel body upper neck 4, and a threaded bores 7. As is illustrated in Figure 2, one or more single piece construction brush sleeves 11 and at least two single piece construction centralising sleeves 9 may be mounted directly onto the mandrels 3 and are kept apart from each other by means of single piece construction space ring 10. The sleeves and spacer rings are prevented from axial movement relative to the mandrels 3 by means upper stops 5 or 8 (the upper stop upper 8 in the Type-1 apparatus is lengthened to allow for incorporation of a drop-ball activated mechanism and jetting ports which are integral with the mandrel 3, as described below), and single piece construction lower retaining rings 12 which are removable and are secured onto the mandrels 3 by means of three or more threaded locking devices.

With reference to Figure 4, each brush sleeve 11 comprises a number of angularly positioned and equally spaced integral blades 24 configured to provide 360° coverage of casing internal surface when axially displaced relative to the tubular structure. The blades 24 are separated by fluid channels to allow for free circulation of mud. Outer surfaces of these blades 24 are dressed with metallic or synthetic brush elements 25. With reference to Figure 5, the centralising sleeve 9 is similar to brush sleeve 11 in construction with the exception that it has a larger finished blade 26 outside diameter and that the blades 26 are not dressed with brush elements. The retainer ring 12 and the spacer ring 10 are illustrated in Figures 6 and 7 respectively.

Relative rotation between the spacer rings 10 and mandrels 3 may be prevented by incorporation of keys on the outer surface of the mandrel and corresponding grooves on the inner surface of the spacer rings. The retainer ring 12 slides over the mandrel body lower neck and is pushed up until each access port 27 line up with its corresponding threaded bore 7. The retainer ring 12 is then secured onto the mandrel body 3 by means of threaded retaining bolts. A locking clip is then fitted into a locking clip recess 28 on each circular access port 27 as shown in Figure 6, this being a secondary safety measure to prevent the threaded locking bolts from accidental unwinding and becoming dislodged. In this configuration, the brush sleeves 11 are free to rotate about the mandrel, relative to the spacer rings 10.

When the sleeves are mounted on a mandrel body, and secured in position by the retaining device, the outside diameter of the centraliser sleeve is sufficiently greater than the outside diameter of the mandrel body to keep the tool central with respect to the inside of the tubular structure. The finished outside diameter of the dense brash elements on the brush sleeve is larger than the internal diameter of the liner or casing. However, the brush elements are sufficiently flexible to allow the brush sleeve to fit inside the liner or casing and exert sufficient force against the internal surface of the tubular structure to affect cleaning and conditioning of the tubular structure. The centraliser sleeve will prevent the over flexing of the brush elements and subsequent damage in highly deviated and horizontal wells.

In the apparatus of Type - 1, the upper stop 8 incorporates one or more jetting ports 6 and an internal chamber that accommodates a drop-ball activated mechanism, see Figures 3 and 8. The drop-ball activated mechanism comprises a ball catcher / plunger 17, a ball seat recess 30, shear / squeeze ring 18, ball 19, spring 20 and a ball catcher / diverter chamber 21. Once activated, the drop-ball activated mechanism is designed to divert the flow of mud from the mandrel bore 13 to the jetting port 6 on application of a pre-determined hydraulic pressure. The drop-ball activated mechanism also incorporates a shear or squeeze mechanism to allow the closure of the jetting port 6 on application of a predetermined hydraulic pressure and to redirect the fluid flow through the mandrel bore 13. The drop ball mechanism is held within the casing or liner by a clip 15 which engages a recess 14 in the inner surface of the mandrel, and is sealed thereto by sealing rings 16 located in respective grooves 29.

Referring to Figure 3, to activate the jetting action a rubber or other flexible elastomer coated steel ball 19 is dropped inside the work string bore and the ball pumped down by fluid until it is lodged on top of the ball seat 18. Hydraulic pressure built up behind the seat will force the ball catcher / plunger 1 downward depressing the coil spring 20,. Increasing the hydraulic pressure to a pre-determined amount will drive the ball catcher / plunger 17 far enough to expose the jetting port 6, at which point the hydraulic flow from the workstring bore is diverted through the jetting port 6 causing the water jetting action against the casing / liner inner wall. To stop the jetting action, the fluid pump pressure is gradually increased to a pre-determined level to squeeze the ball 19 through the bore of the ball seat 18, at which point the coil spring 20 will force the ball catcher / plunger upward to its original position sealing off the jetting port 6. The fluid pressure will force the ball down inside the ball catcher /diverter chamber 21 into contact with a seal formed in a sealing groove 23b formed in a ball seat 23. Fluid flow is diverted through one or more diverter ports 22 down through the workstring bore, see Figure 9. This process may be repeated as many times as required without the need to pull out the string as the length of the ball catcher / diverter chamber can be designed to match the number of balls that are required to be dropped to activate the jetting action. It will be appreciated by the person of skill in the art that various modifications may be made to the above described embodiment without departing from the scope of the present invention.

Claims

1. A liner brushing and conditioning tool comprising: a mandrel with male and female threaded ends for connection to a work string; at least one brash sleeve and at least two centralising sleeves mounted directly onto the mandrel and kept separated by means of spacer rings; means to allow relative rotation between the sleeves and mandrel; and means to prevent relative rotation between the spacer rings and mandrel.

2. A liner brushing and conditioning tool as claimed in claim 1, wherein the centralising and brash sleeves are of single-piece construction.

3. A liner brushing and conditioning tool as claimed in claim 1 or 2, wherein the mandrel and spacer rings are of single-piece construction.

4. A liner brushing and conditioning tool as claimed in any one of the preceding claims, wherein the said centralising and brash sleeves are of high temperature / high impact / wear resistant alumina ceramic, polymer or metallic material.

5. A liner brushing and conditioning tool as claimed any one of the preceding claims and comprising: a ball-drop activated mechanism, one or more jetting ports, a fully contained and replaceable ball catcher / diverter mechanism, shear / squeeze mechanism which allows for multiple activation of the jetting action.

6. A liner brushing and conditioning tool as claimed in any one of the preceding claims, wherein the centralising and brush sleeves and spacer rings are restricted from moving in a vertical direction by a stop ring having primary and secondary locking devices.

7. A liner brushing and conditioning tool according to claim 1, wherein the mandrel comprises a substantially cylindrical wall defining a central fluid flow passage which in use is in communication with a flow passage of said work string, and one or more jetting ports extending through the cylindrical wall above said brash and centralising sleeves, the tool comprising means located within said mandrel for enabling a flow of fluid to be diverted from said central fluid flow passage to the exterior of said mandrel and vice versa.

8. A liner brushing and conditioning tool according to claim 7, wherein said means for enabling a flow of fluid to be diverted from said central fluid flow passage to the exterior of said mandrel comprises a ball-drop activated valve mechanism.