WO2017091142A1

WO2017091142A1 - Apparatus, system and method for recovering and/or installing conductor casing

Info

Publication number: WO2017091142A1
Application number: PCT/SG2015/050471
Authority: WO
Inventors: Robert James DAVIDSON
Original assignee: Ezra Holdings Limited
Priority date: 2015-11-25
Filing date: 2015-11-25
Publication date: 2017-06-01

Abstract

Embodiments of the invention provide an apparatus, system and method for recovering and/or installing conductor casing. The apparatus or frame comprises: a base; and a mast having a bottom end pivotally mounted to the base and hydraulically actuable to move between a vertical position and a horizontal position, the mast having a clamp and a tension table for releasably securing a conductor casing segment in tension, wherein the mast is configured to lay down a conductor casing segment by pivotally lowering the mast from the vertical position to the horizontal position or erect the conductor casing segment by pivotally raising the mast from the horizontal position to the vertical position.

Description

APPARATUS, SYSTEM AND METHOD FOR RECOVERING AND/OR

INSTALLING CONDUCTOR CASING

Field of Invention

The invention relates to a rig-less apparatus, system and method for conducting plugging and abandonment operations of wells by recovering, cutting, laying down of conductor casing from an oil or gas well. The apparatus may be deployed for installing conductor casing during well commissioning.

Background

Well plugging and abandonment project for decommissioning of well is normally planned years ahead before the well runs dry. The plugging and abandonment operations typically involve the placement of cement plugs within the conductor casing and on the surface thereof, and subsequent removal of the cemented conductor casing from the well.

The height of removal varies from field to field. In the Gulf of Mexico, the Department of the Interior Bureau of Ocean Energy Management, Regulation, and Enforcement ("BOEMRE") mandates that all platform components including conductor casings must be removed to at least 15 feet below the ocean floor or to a depth approved by the regional supervisor based upon the type of structure or ocean-bottom conditions.

In an existing method, a conductor casing removal system works in conjunction with a gantry crane which is positioned on top of the removal system. This gantry crane arrangement restricts the length of conductor casing that can be safely removed as a length of conductor casing to be cut cannot exceed the tonnage that can be safely lifted by the gantry crane, and cannot exceed the height of the gantry crane. In view of the aforesaid weight and height restrictions and other issues, it would be highly desirable to provide an improved apparatus, system and method for conducting plugging and abandonment operations.

Summary

According to one embodiment of the invention, a frame for recovering and/or installing conductor casing is provided. The frame comprises:

a base; and

a mast having a bottom end pivotally mounted to the base and hydraulically actuable to move between a vertical positon and a horizontal position, the mast having a clamp and a tension table for releasably securing a conductor casing segment in tension, wherein the mast is configured to lay down a conductor casing segment by pivotally lowering the mast from the vertical position to the horizontal position.

In certain embodiments, the mast is further configured to erect the conductor casing segment by pivotally raising the mast from the horizontal position to the vertical position.

In certain embodiments, the mast and the base are telescopically extendable.

In certain embodiments, the clamp and the tension table are foldable.

According to one embodiment of the invention, a system is provided which comprises:

a frame for recovering and/or installing conductor casing, the frame comprising:

a base; and

a mast having a bottom end pivotally mounted to the base and hydraulically actuable to move between a vertical positon and a horizontal position, the mast having a clamp and a tension table for releasably securing a conductor casing segment in tension, wherein the mast is configured to lay down the conductor casing segment by pivotally lowering the mast from the vertical position to the horizontal position; and a lifting crane configured to transfer the conductor casing segment to or from the mast.

According to one embodiment of the invention, a method of recovering conductor casing during well decommissioning is provided. The method comprises:

providing a frame having a mast disposed in a vertical position;

lifting a conductor casing from a well;

securing in tension a first portion of the conductor casing to the mast; while the first portion of the conductor casing is secured in tension, cutting the conductor casing at a position below the first portion of the conductor casing;

while the cut conductor casing segment is secured to the mast, laying down the cut conductor casing segment from the vertical position to a horizontal position by lowering the mast pivotally about a bottom end of the mast; and

offloading the cut conductor casing segment from the mast.

In certain embodiments, the step of securing in tension a first portion of the conductor casing to the mast includes securing the first portion of the conductor by a clamp and a tension table provided at the mast. In certain embodiments, the step of offloading the cut first portion of the conductor casing from the mast includes releasing the clamp and the tension table, and transferring the cut conductor casing segment by a lifting crane.

In certain embodiments, the step of lifting the conductor casing includes elevating at least part of the conductor casing above a top end of the mast, and the cut conductor casing segment has a length which is longer than a height of the mast. In certain embodiments, the step of lowering the mast from the vertical position to a horizontal position is by hydraulic action.

According to one embodiment of the invention, a method of installing conductor casing during well commissioning is provided. The method comprises:

providing a frame having a mast disposed in a horizontal position;

securing in tension a conductor casing segment to the mast;

while the conductor casing segment is secured to the mast, erecting the conductor casing segment by raising the mast pivotally about a bottom end of the mast from the horizontal position to the vertical position;

joining the erected conductor casing segment to a lowered conductor casing; and

lowering the joined conductor casing segment into a well. In certain embodiments, the step of raising the mast from the horizontal position to a vertical position is by hydraulic action.

Brief Description of the Drawings

The invention will be described in detail with reference to the accompanying drawings, in which:

Figure 1A is an isometric view of a frame for recovering and/or installing conductor casing, which is in a working position;

Figure 1 B is a side view of Figure 1 A;

Figure 2A is an isometric view of a frame for recovering and/or installing conductor casing, which is in a non-working position;

Figure 2B is a side view of Figure 2A;

Figure 3 is a flow sequence of a well decommissioning operation including recovering, cutting and laying down conductor casing;

Figure 4 illustrates a conductor casing being lifted into the frame of Figure 1A; Figure 5 illustrates the conductor casing being secured to the mast of the frame of Figure 1A;

Figure 6 illustrates the conductor casing being cut at the frame of Figure 1A;

Figure 7 illustrates a cut conductor casing segment being supported by the frame of Figure 1A;

Figures 8A to 8C illustrate a cut conductor casing segment being laid down by the frame of Figure 1A;

Figures 9A to 9C illustrate a cut conductor casing segment being offloaded from the frame of Figure 1A; and Figure 10 illustrates a flow sequence of a well commissioning operation including erecting, joining and lowering conductor casing.

Detailed Description of Embodiments of the Invention

In the following description, numerous specific details are set forth in order to provide a thorough understanding of various illustrative embodiments of the invention. It will be understood, however, to one skilled in the art, that embodiments of the invention may be practiced without some or all of these specific details. It is understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the invention. In the drawings, like reference numerals refer to same or similar functionalities or features throughout the several views.

Reference is made to Figures 1A, 1 B, 2A and 2B illustrating a frame 100 for recovering and/or installing conductor casing according to one embodiment of the invention.

The frame 100 includes a base 110 which is extendable between a working position having larger base dimensions (see Figure 1A) and a non-working position having smaller base dimensions (see Figure 2A). The frame 100 further includes a mast 120 having a bottom end pivotally mounted to the base 110. The mast 120 is hydraulically actuable to move among a vertical position, a horizontal position and intermediate positions therebetween. A hydraulic actuator 112 coupling the mast 120 to the base 110 is provided to drive the pivoting movements. The mast 120 is extendable between a working position having larger height dimension and a non-working position having smaller height dimension. Particularly, a top section 122 of the mast 120 is telescopically extendable from a bottom section 124 of the mast 120. The mast 120 is provided with a clamp 130, e.g. hydraulic clamp, at the top section 122 of the mast 20. The mast 120 is further provided with a tension table 140 positioned at the bottom section 124 of the mast 120. In the working position where the mast 120 is extended, the clamp 130 and tension table 140 are spaced further from each other than in the non-working position where the mast 120 is retracted. The clamp 130 and/or tension table 140 may be foldable to provide a more compact arrangement. The clamp 130 and tension table 140 are configured to releasably secure a conductor casing 210 arranged therein.

Reference is made to Figure 3 which illustrates a method 300 for recovering conductor casing during well decommissioning. The method 300 of Figure 3 is further illustrated by Figures 4 to 7, 8A to 8C, 9A to 9C.

In block 301 of Figure 3, a frame 100 for recovering and/or installing conductor casing is arranged in a vertical position over a well to be decommissioned. To this purpose, the frame 100 is lifted into position over an open well slot hole and laid on a deck. Hydraulic power is supplied from an electrical or diesel power source to an operating console of the frame 100 and further to various hydraulic actuators operating various parts of the frame 100. The base 110 of the frame 100 is extended horizontally to an extended position. The clamp 130 is unfolded to an extended position. The tension table 140 section is unfolded and secured in the extended position with locking pins coupling the tension table 140 to the mast 120. The top section 122 of the mast 120 is extended, and secured in the extended position with locking pins coupling the top section 122 to the bottom section 124 of the mast 120. Thereafter, the mast 120 is raised to a vertical position as illustrated in Figure 1A. The mast 120 is secured in the vertical position with locking pins which couple the bottom end of the mast 120 to the base 110. In block 301 , a hydraulic cutter 150 may be lifted onto securing points on the frame 100 and suitably oriented.

In block 302, a conductor casing 210 is lifted into the frame 100 (see Figure 4) and a first portion of the conductor casing 210 is secured in tension to the mast 120 by a clamp 130 and a tension table 140 (see Figure 5). To this purpose, the conductor casing 210 is jacked up from a wellhead casing jack (not shown) through the hole in the deck, through open frame slips of the tension table 140 until the leading end of the conductor casing 210 extends above the top of the mast 120. For example, the conductor casing 210 may extend about ten feet above the top of the mast 120, which will subsequently result in about thirty-five feet of cut conductor casing segment length. The conductor casing 210 is securely engaged by both stationary and travelling slips in the wellhead casing jack, and the slips are then closed. The slips are raised by applying hydraulic pressure to four pancake jacks of the tension table 140 to support the weight of the anticipated cut conductor casing segment 220. The tension table 140 is set at a suitable pressure level which is variable and depends on the weight in the slips.

In block 303, the conductor casing 210 is cut at a position below the first portion of the conductor casing 210 (see Figure 6). To this purpose, a hydraulic casing cutter 150 is arranged around the conductor casing 210 and secured thereto with a cutter clamp. Thereafter, the hydraulic cutter 150 cuts the conductor casing 210.

In block 304, the cut is completed, the cutter clamp is released and the cut conductor casing segment 220 is held in tension in the vertical position (see Figure 7). In block 305, the cut conductor casing segment 220, still secured in tension to the mast 120, is laid down from the vertical position to a horizontal position by lowering the mast 120 pivotally about a bottom end of the mast 120. Prior to the lowering the mast 120, locking pins which have been inserted earlier to secure the mast 120 (in block 302) are removed. Figures 8A to 8C shows the cut conductor casing segment 220 being lowered from the vertical position to an intermediate position and further to a horizontal position respectively.

In block 306, the cut conductor casing segment 220 is offloaded from the mast 120 while the mast 120 is in the horizontal position. Figure 9A shows a cut conductor casing segment 220 supported by the mast 120 in the horizontal position; the clamp 130 and hydraulic slips of the tension table 140 are released to facilitate removal of the cut segment 220. Figure 9B shows at least one suitable sling 910 wrapped around the cut segment 220. A lifting crane (not shown) manipulates the sling 910 to remove the cut segment 220 from the clamp 130 and slips of the tension table 140. Figure 9C shows the cut segment 220 being transferred from the mast 120. The cut segment 220 may be landed at a suitable area of the deck or loaded directly onto a supply boat or other suitable locations.

Thereafter, the mast 120 may be erected from the horizontal position to the vertical position by raising the mast 120 pivotally about a bottom end of the mast 120 and thereafter the mast 120 is secured with locking pins. The sequence as substantially described in blocks 302 to 306 may then be repeated to continue with removal, cutting and offloading of the remaining conductor casing in the well.

After laying down the last cut segment 220, the frame 100 and wellhead jack are rigged down to a non-working position. Particularly, the mast 120 is raised slightly from the horizontal position and thereafter locking pins securing the mast 120 in the extended position are removed. The top section 122 of the mast 120 is retracted into the lower section 124 of the mast 120 and thereafter the locking pins are re-inserted to secure the mast 120 in the retracted position. The mast 120 is lowered fully to the horizontal position. The power supply to the frame 100 is terminated. Any excess pressure in the hydraulic system is released and the hydraulic hoses are disconnected. The base 110 is retracted to a non-working position (see Figure 2A).

In another embodiment of the invention, the above sequence for recovering conductor casing during well decommissioning is modified or reversed for installing conductor casing 210 during well commissioning. Reference is made to Figure 10 which illustrates a method 1000 for installing conductor casing 210 in a well.

In block 1001 , the frame 100 for recovering and/or installing conductor casing is arranged over a well and disposed in the horizontal position.

In block 1002, a conductor casing segment 220 is transferred by a lifting crane onto the mast 120 of the frame 100. Particularly, the clamp 130 and tension table 140 are released to receive the conductor casing segment 220 therein. The clamp 130 and tension table 140 are then locked to secure the conductor casing segment 220 to the mast 120.

In block 1003, the mast 120, together with the conductor casing segment 220, is erected from the horizontal position to a vertical position by raising the mast 120 pivotally about a bottom end of the mast 120.

In block 1004, the conductor casing segment 220, which is in a vertical position, is joined, such as by welding, to an installed or lowered conductor casing which has been positioned in the well.

In block 1005, the joined conductor casing segment 220 is installed or lowered into the well.

The sequence as substantially described in blocks 1001 to 1005 may then be repeated until a desired length of conductor casing is installed or lowered into the well slot. In view of the above, a system comprises the above-described frame 100 for recovering and/or installing conductor casing, and a lifting crane configured to transfer the conductor casing segment 220 to or from the mast 120 of the frame 100.

Embodiments of the invention are particularly advantageous at least as follows:

(1) An existing method for removal of conductor casings requires cranes to lift the cut conductor casing segment vertically, thereafter angle the cut segment against a groove for traction and having the crane to lower the cut segment to the ground at a 45-degree angle. The invention requires a lower load rating crane as the invention does not require the cut segment to be lowered from vertical to horizontal position by a crane. The invention requires the crane only to transfer a horizontally-arranged cut segment and therefore a lower load rating crane with slings is needed. This provides a safer and more efficient operation.

(2) In an existing method, a conductor casing removal system works in conjunction with a gantry crane which is positioned on top of the removal system. This gantry crane arrangement restricts the length of conductor casing that can be safely removed as a length of conductor casing to be cut cannot exceed the tonnage that can be safely lifted by the gantry crane and cannot exceed the height of the gantry crane. The invention provides a frame which allows cutting of a conductor segment having a longer dimension than the height of the mast.

(3) The frame of the invention is multi-functional as it can be deployed to remove, cut and lay down conductor casing during well decommissioning, as well as to install conductor casing in a well during well commissioning. (4) The frame of the invention is comprised of parts which are extended and/or unfolded in the working position and retracted and/or folded in non-working position. This provides a more compact footprint which reduces storage requirements.

It is to be understood that the embodiments and features described above should be considered exemplary and not restrictive. For example, the above- described embodiments may be used in combination with each other. Many other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the invention. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. Furthermore, certain terminology has been used for the purposes of descriptive clarity, and not to limit the disclosed embodiments of the invention.

Claims

1. A frame for recovering and/or installing conductor casing, the frame comprising: a base; and

2. The frame of claim 1 , wherein the mast is further configured to erect the conductor casing segment by pivotally raising the mast from the horizontal position to the vertical position.

3. The frame of claim 2, wherein the mast and the base are telescopically extendable.

4. The frame of claim 3, wherein the clamp and the tension table are foldable.

5. A system comprising:

a base; and

6. The system of claim 5, wherein the frame is further configured to erect the conductor casing segment by pivotally raising the mast from the horizontal position to the vertical position

7. The system of claim 6, wherein the mast and the base are telescopically extendable.

8. The system of claim 7, wherein the clamp and the tension table are foldable.

9. A method of recovering conductor casing during well decommissioning, the method comprising:

providing a frame having a mast disposed in a vertical position;

lifting a conductor casing from a well;

securing in tension a first portion of the conductor casing to the mast;

while the first portion of the conductor casing is secured in tension, cutting the conductor casing at a position below the first portion of the conductor casing;

offloading the cut conductor casing segment from the mast.

10. The method of claim 9, wherein securing in tension a first portion of the conductor casing to the mast includes securing the first portion of the conductor by a clamp and a tension table provided at the mast.

11. The method of claim 10, wherein offloading the cut first portion of the conductor casing from the mast includes releasing the clamp and the tension table, and transferring the cut conductor casing segment by a lifting crane.

12. The method of claim 11 , wherein lifting the conductor casing includes elevating at least part of the conductor casing above a top end of the mast, and wherein the cut conductor casing segment having a length which is longer than a height of the mast.

13. The method of claim 9, wherein lowering the mast from the vertical position to a horizontal position is by hydraulic action.

14. A method of installing conductor casing during well commissioning, the method comprising:

providing a frame having a mast disposed in a horizontal position;

securing in tension a conductor casing segment to the mast;

joining the erected conductor casing segment to a lowered conductor casing; and

lowering the joined conductor casing segment into a well.

15. The method of claim 14, wherein raising the mast from the horizontal position to a vertical position is by hydraulic action.