Liner setting tool

Abstract

There is a provided a liner setting tool for running liner or casing into a well bore which comprises an elongate body for attachment to the casing or liner, but which allows for movement of the liner setting tool relative to the liner or casing. The elongate body has radial outlets which may be closed or open in alternative states, whereby these radial outlets may be used for circulating fluid in order to clean the well bore.

Description

[0001] The present invention relates to a liner setting tool as may be typically used to introduce liner or casing into a well bore.

[0002] It is conventional practice to drill a well bore in sections, where a drill shoe mounted on the end of a drill string is run to a predetermined depth and then removed or "tripped". Structural casing is then introduced and cemented in place in the newly formed section in order to stabilise the bore to prevent collapse of unstable sections and prevent contamination of the oil or gas reservoir. Further sections of the bore can then be drilled and cased off by further casing or liner, the latter being typically used near the production area of the bore.

[0003] In order to set liner, the drill shoe used to bore the well is tripped from the well and the structural liner is lowered into the bore on a work string through the previously drilled and cased section of well. Conventionally the liner is mounted on a hanger which is adapted to temporarily hold the liner in place prior to cementing. The liner can then be cemented in place by pumping cement slurry to the bottom of the bore from where it is displaced into the annular gap between the outer wall of the lining and the external wall of the bore. The work string and hanger can then be removed from the bore after the cement has set the liner in place.

[0004] During the boring procedure, fluid is continuously passed through the section of well being bored to lubricate the drill and wash out the bore by bringing drill cuttings to the surface. However it is also advantageous to pass fluid through the bore after the liner has been cemented in place, to eliminate any foreign matter such as scale or burrs which may remain within the well and well wall, This prevents any subsequent contamination of the oil or gas reservoir.

[0005] It is uncommon for the cement which passes into the annulus to set entirely and evenly. In particular, fluid may leak into the annular area during the cementing procedure and weaken sections of the cement. As a result it is common for the cement to have cracks or gaps within it which can harbour foreign material.

[0006] To prevent contamination of the oil or gas reservoir it is therefore advantageous to wash out the entire area around the liner and work string, including the annular area which is cemented. This is difficult, however, as conventional liner setting tools are configured to only allow fluid flow in axial direction, as the standard method for cementing the annular space between the liner and bore wall is achieved by pumping cement axially to the bottom of the section of well from where it is displaced into the annulus. As a result, after the cement sets, flow is restricted in the axial direction by the cement itself. It would therefore be a distinct advantage to provide a liner setting tool which allows liner or casing to be run into a well bore and cemented in place in the conventional manner, but which also allows the flow of a cleaning fluid in a radial direction after the cement has been set.

[0007] It is an object of the present invention to provide a liner setting tool for running liner or casing into a pre formed well bore.

[0008] It is a further object of the present invention to provide a liner setting tool which facilitates both cementing to set the liner or casing in place and fluid by pass to allow cleaning of the bore.

[0009] It is a yet further object of the present invention to provide a liner setting tool which in a first configuration allows cement to flow in an axial direction to the bottom of the section of well bore, and in a second configuration allows fluid by pass in a radial direction into the annulus between the liner or casing and the bore wall.

[0010] It is a further object of the present invention to provide a liner setting tool with superior mounting means for attachment to liner.

[0011] According to a first aspect of the present invention there is provided a liner setting tool for running liner or casing into a well bore wherein said liner setting tool is comprised of an elongate body with a number of integral radial outlets and is adapted for attachment to said casing or liner and wherein the liner setting tool is moveable between a first and second position relative to the liner or casing, wherein the radial outlets are closed when the liner setting tool is in a first position relative to the liner or casing and open when the liner setting tool is in a second position relative to the liner or casing.

[0012] Preferably the radial outlets of the liner setting tool are ports.

[0013] Preferably the liner has flow ports corresponding to the ports of the liner setting tool.

[0014] Preferably movement of the liner setting tool relative to the liner or casing is provided by rotation of the liner setting tool relative to the liner or casing.

[0015] Preferably when the liner setting tool is in a first position the radial outlets are closed by virtue of the liner or casing.

[0016] Preferably when the liner casing tool is in a second position the radial outlets are open by virtue of them communicating with the ports in the liner or casing.

[0017] Preferably the integral ports of the liner setting tool are associated with seal rings which restrict the flow of fluid between the tool and the liner.

[0018] Most preferably said seal rings are made from a relatively hard wearing but flexible material such as rubber although any other suitable material may be used.

[0019] Preferably the elongate body of the liner setting tool is cylindrical and hollow.

[0020] Preferably the liner setting tool is attached to the liner by thread which is threadably engaged to the liner or casing.

[0021] Preferably the liner setting tool has a first upper end comprising attachment means for attaching the tool to a work string.

[0022] Preferably the liner setting tool has a second lower end formation which co-operates with a seat formed in the casing or liner so as to restrict the axial movement of the liner setting tool relative to the liner or casing.

[0023] According to a second aspect of the present invention there is provided a liner setting tool wherein said liner setting tool is attached to the liner by threaded connections.

[0024] Preferably the threaded connections are loosened by rotation of the liner setting tool in an anti-clockwise or left-hand direction.

[0025] According to a third aspect of the present invention there is provided a method for lining a well bore, comprising the steps of:

[0026] a) running the liner on a work string attached to the liner setting tool;

[0027] b) cementing the liner in place by introducing cement slurry axially into the bore, through the tool, to the bottom of the section of bore, from where the cement can flow into the annular space between the external surface of the liner and the bore well wall;

[0028] c) lifting the liner setting tool relative to the liner by rotating the tool until the integral ports of the liner setting tool are aligned with the by pass port of the liner, and;

[0029] d) passing fluid through the bore, which flows in an radial direction, through the newly aligned integral ports of the liner setting tool and flow ports of the liner, to clean the well bore.

[0030] Preferably the liner setting tool is lifted relative to the liner by rotating the tool in an anti-clockwise direction.

[0031] An example embodiment of the invention will now be illustrated with reference to the following Figures in which;

[0032] FIG. 1 illustrates a liner setting tool in accordance with the present invention, and;

[0033] FIG. 2 shows the liner setting tool of FIG. 1 attached to liner, being introduced into a pre formed well.

[0034] Referring firstly to FIG. 1, a liner setting tool, generally depicted at 1, is comprised of a cylindrical body 2 with a first upper end with connection means 3 for mounting the liner setting tool 1 on a work string (not shown) and a second lower end with a seat conformation 4. The liner setting tool 1 further comprises threaded connections 5 for connecting liner (not shown) to the tool 1. The cylindrical body 2 also has a plurality of radial outlets or integral ports 6 and corresponding seal rings 7, and an axial outlet 8.

[0035] FIG. 2 shows the liner setting tool of FIG. 1, generally depicted at 1, as it is advanced through a preformed section of well bore, which is generally depicted at 9, and has already been lined with casing 10. The liner setting tool 1, is attached to liner 11, by the threaded connections 4. The tool 1 and liner 4 have a smaller diameter than the well and can therefore be passed through the preformed bore 9.

[0036] The tool 1 is advanced through the pre formed bore 9 on a work string (not shown) to the section of drilled bore it is intended to line. Upon reaching this section cement is pumped into the well bore 9 from the surface. In a first configuration (Position A), the axial outlet 8 of the liner setting tool 1 allows the cement to pass down the bore 9 and continue flowing in an axial direction towards the bottom of the section of the well 9. The cement passes to the bottom of the well bore 9 and is displaced into the annular space between the external surface of the liner 11 and the wall of the well bore 9. In this first configuration (Position A) the integral ports 6 of the cylindrical body 2 are closed by virtue of the liner 11 which obstructs the port 6 and therefore prevents the flow of fluid in a radial direction.

[0037] After the cement has set within the annular space, the liner setting tool 1 is lifted by a predetermined distance relative to the liner 11. This is achieved by rotating the tool 1 relative to the liner 11 in an anti-clockwise, or left-hand direction. This loosens the threaded connections 4 which attach the liner setting tool 1 to the liner 11, thereby allowing the tool 1 to move relative to the liner 11. The thread 4 which attaches the liner setting tool 1 to the liner 11 is double start thread which allows the operator to rotate the liner setting tool 1 relative to the liner 11 to a second configuration where the integral ports 6 of the cylindrical body 2 are aligned with corresponding by pass ports 12 on the liner 11 (Position B). Therefore in this second configuration the integral ports 6 of the cylindrical body 2 are open and cleaning fluid can be passed through the well bore 9. The fluid can pass in a radial direction, through the integral ports 6 of the cylindrical body 2, and the by pass ports 12 on the liner 11, into the annular space. Accordingly the fluid can be passed over the entire area around the liner 11 and the work string (not shown) in order to wash out the bore 9.

[0038] Once the procedure is complete, the second `start` of the double start thread 4 can be initiated by setting down weight or applying tension, thereby allowing further rotation of the tool 1 relative to the liner 11 in an anti clockwise direction, in order to remove the tool 1 from the liner 11 and subsequently from the well bore 9.

[0039] The present invention is described for use in setting liner such as that typically used near the production area of the bore, but could readily be adapted to be suitable for use with any structural casing.

[0040] The advantage of the present invention is that in one configuration the liner setting tool allows cement to be passed axially into a well bore to allow the liner or casing to be cemented in place as is conventional, and in another configuration allows fluid to be passed from the liner setting tool, in a radial direction to allow the well bore to be washed out.

[0041] Furthermore the use of threaded connections as means for attaching the liner setting tool to the liner or casing provides greater control over the positioning and release of the liner.

[0042] Further modifications and improvements may be incorporated without departing from the scope of the invention herein intended.

Claims

1. A liner setting tool for running liner or casing into a well bore wherein said liner setting tool is comprised of an elongate body with a number of integral radial outlets and is adapted for attachment to said casing or liner and wherein the liner setting tool is moveable between a first and second position relative to the liner or casing, wherein the radial outlets are closed when the liner setting tool is in a first position relative to the liner or casing and open when the liner setting tool is in a second position relative to the liner or casing.

2. A liner setting tool as claimed in claim 1, wherein the casing or liner has flow ports corresponding to the outlets of the liner setting tool.

3. A liner setting tool as claimed in claim 1, wherein movement of the liner setting tool between the first and second position is provided by rotation of the liner setting tool relative to the liner or casing.

4. A liner setting tool as claimed in claim 1, wherein when the liner setting tool is in the first position the radial outlets are closed by virtue of the liner or casing.

5. A liner setting tool as claimed in claim 2, wherein when the liner setting tool is in a second position the radial outlets are open by virtue of them communicating with the ports in the liner or casing.

6. A liner setting tool as claimed in claim 1, wherein the radial outlets are associated with seal rings which restrict the flow of fluid between the tool and the liner.

7. A liner setting tool as claimed in claim 6, wherein the seal rings are made from a relatively hard wearing but flexible material, such as rubber.

8. A liner setting tool as claimed in claim 1, being adapted to threadably engage with the liner or casing.

9. A liner setting tool as claimed in claim 1, comprising a first upper end having attachment means for attaching the tool to a work string.

10. A liner setting tool as claimed in claim 1, having a lower end formation which co-operates with a seat formed in the casing or liner so as to restrict the axial movement of the liner setting tool relative to the liner or casing.

11. A liner setting tool attachable to an associated casing or liner by threaded connections.

12. A liner setting tool as claimed in claim 11, wherein the threaded connections may be loosened by rotation of the liner setting tool in an anti-clockwise or left-hand direction.

13. A method for lining a well bore, comprising the steps of: a) running the liner on a work string attached to the liner setting tool; b) cementing the liner in place by introducing cement slurry axially into the bore, through the tool, to the bottom of the section of bore, from where the cement can flow into the annular space between the external surface of the liner and the bore well wall; c) lifting the liner setting tool relative to the liner by rotating the tool until the integral ports of the liner setting tool are aligned with the by pass port of the liner, and; d) passing fluid through the bore, which flows in an radial direction, through the newly aligned integral ports of the liner setting tool and flow ports of the liner, to clean the well bore.