STABILIZING SYSTEM FOR DEEP DRILLING

Abstract

The present invention relates to a stabilizing system (100, 200, 300) adapted to be used in a drilling system, wherein the transversal diameter of the stabilizing system (100, 200, 300) increases when drilling forces are applied onto the stabilizing system (100, 200, 300). The invention further comprises a corresponding method for drilling a hole.

Claims

1. A stabilizing system adapted to be used in a deep drilling system, wherein the transversal diameter of the stabilizing system increases when drilling forces are applied onto the stabilizing system.

2. The stabilizing system according to claim 1, wherein the stabilizing system is contracted along its longitudinal axis when an external load is applied in longitudinal direction onto the stabilizing system, and wherein the transversal diameter of the stabilizing system increases when the stabilizing system is contracted.

3. The stabilizing system according to claim 1, the system comprising: a hollow housing; at least one spacer supported in an opening in the housing, such that it can protrude through said opening and is movable relative to the housing between a retracted and an expanded position, wherein the extend of protrusion increases when the spacer is moved to the expanded position, and a column arranged inside the hollow housing, being adapted to transfer drilling forces applied onto the stabilizing system, wherein the column is movable relative to the housing between a drilling position and a pulling position; wherein the column moves to the drilling position when drilling forces are applied onto the stabilizing system, and wherein the spacer is moved to the expanded position by the column moving to the drilling position.

4. The stabilizing system according to claim 3, wherein the column is movable along a longitudinal axis of the housing between the drilling position and the pulling position, and wherein the column moves to the drilling position when an external load is applied in longitudinal direction onto the stabilizing system.

5. The stabilizing system according to claim 3, further comprising a restoring means adapted to apply a reset force to urge the spacer back to the retracted position, in particular wherein the restoring means comprises at least one helical spring arranged perpendicular to the longitudinal direction of the hollow housing, further in particular wherein the helical spring is arranged in-between the spacer and the housing.

6. The stabilizing system according to claim 3, wherein the column comprises a thin section with a first diameter and a thick section with a second diameter, wherein the second diameter is greater than the first diameter, and wherein the spacer comprises a recess adapted to receive said thick section when the column is in the pulling position, and wherein the thick section is adapted to urge the spacer into the expanded position when the column is moved to the drilling position.

7. The stabilizing system according to claim 3, wherein the column comprises a Kelly section and wherein the hollow housing comprises a corresponding Kelly bushing in which the Kelly section of the column is supported such that torques are transferred between the column and the hollow housing, and wherein the Kelly section is movable relative to the Kelly bushing along the longitudinal axis of the housing.

8. The stabilizing system according to claim 3, wherein the spacer comprises a hole or valve extending from an interior side of the spacer to an exterior side of the spacer, in particular wherein the hole or valve extends from an edge of the recess provided on the interior side of the spacer.

9. The stabilizing system according to claim 3, wherein the stabilizing system further comprises a first and a second drill pipe linkage, wherein the first drill pipe linkage is adapted to be connected to a drill bit via at least one preceding dill pipe, and wherein the second drill pipe linkage is adapted to be connected to a drilling motor via at least one succeeding drill pipe, and wherein the first and second drill pipe linkages are provided on opposing longitudinal ends of the stabilizing system.

10. The stabilizing system according to claim 3, wherein the maximal movement of one spacer relative to the housing is in the range of 5-50 mm, preferably in the range of 10-30 mm, more preferably in the range of 10-20 mm, and most preferred in the range of 10-15 mm.

11. The stabilizing system according to claim 3, further comprising at least one blade being fixed to the hollow housing such that it extends from an outer surface of said housing.

12. The stabilizing system according to claim 3, wherein the stabilizing system comprises at least one set of three spacers provided equally positioned around the hollow housing, whereby each one of the spacers is supported in one opening.

13. The stabilizing system according to claim 3, wherein the hollow housing has an abutting face adapted to transfer drilling forces acting in longitudinal direction onto the stabilizing system to a respective counter abutting stop provided on the column when the column is in the drilling position.

14. A drilling system comprising a stabilizing system according to claim 1 and further comprising a drill bit and drill pipes.

15. A method for drilling a hole utilizing a drilling system, comprising a stabilizing system, said stabilizing system comprising a hollow housing, at least one spacer being movable relative to the housing between a retracted and an expanded position, and a column arranged inside the hollow housing and being movable relative to the housing between a drilling position and a pulling position, the method comprising the following steps: a. applying a positive force onto the stabilizing system in longitudinal direction causing the column to move to the drilling position and causing the overall longitudinal length of the stabilizing system to shorten such that the at least one spacer is moved to the expanded position, and b. applying a negative force on the stabilizing system in longitudinal direction causing the column to move to the pulling position and causing the overall longitudinal length of the stabilizing system to elongate such that the at least one spacer is moved to the retracted position.

Description

4. DESCRIPTION OF PREFERRED EMBODIMENTS

[0033] In the following the invention is described exemplarily with reference to the enclosed figures:

[0034] FIGS. 1-3 illustrate schematically a drilling system in different configurations.

[0035] FIG. 4 illustrates a preferred embodiment of a stabilizing system according to the present invention.

[0036] FIG. 5 is a cross-sectional view of the stabilizing system of FIG. 3.

[0037] FIG. 6 illustrates the stabilizing system of FIG. 4 in another configuration.

[0038] FIG. 7 is a cross-section view of the stabilizing system of FIG. 6.

[0039] FIG. 8 illustrates a cross-section of another stabilizing system according to a preferred embodiment of the present invention.

[0040] FIG. 9 illustrates another preferred embodiment of a stabilizing system according to the present invention.

[0041] FIGS. 10 and 11 illustrate two respective cross-sections of the stabilizing system of FIG. 9.

[0042] FIG. 4 illustrates a stabilizing system 100 according to the present invention, which is adapted to be connected to drill pipes at each end thereof via respective drill pipe linkages. FIG. 5 shows a cross-sectional view of the arrangement of FIG. 4.

[0043] The stabilizing system 100 of FIGS. 4 and 5 comprises a hollow housing 110, in which a column 130 is linearly movably arranged. The stabilizing system 100 further comprises three spacers 120 which are positioned in respective openings 112 provided on the housing 110. As can it can be seen, the openings 112 and spacers 120 are positioned equally around the hollow housing no at the same length of the stabilizing system 100, thereby providing optimal centering of the stabilizer 100 within a bore hole. The spacers 120 are connected to the housing 110 via helical springs 140, which apply a force to urge the spacers 120 to protrude less through the openings 112 of the housing 110. The helical springs 140 are arranged in-between the spacers 120 and the housing 110. Preferably they are arranged in separately serviceable pockets such that the springs 140 and the spacers 120 can be easily unmounted and removed from the housing 110. Accordingly, if any spacer becomes worn or eroded, the operator can change one or all of the spacers instead of replacing the whole stabilizer. Further, due to the versatility of the stabilizing system, different sizes of spacers can be utilized within the same hollow housing. Thus the stabilizing system 100, 200, 300 can be used for different bore hole 5 diameters.

[0044] The column 130 further comprises a Kelly section 132 which is supported in a corresponding Kelly bushing in of the hollow housing 110. Accordingly, when applying torques onto the hollow housing 110 of the stabilizing system 100, the torques are transferred via the Kelly bushing in and Kelly section 132 to the column 130. Thus any rotational forces of the drill string are transmitted to drill bit via the stabilizing system 100, 200, 300. Further on, the Kelly section 132 of the column 130 is moveable relative to the Kelly bushing 111 along the longitudinal axis of the housing 110, i.e. along the drilling direction. Thus, the overall length of the stabilizing system 100 can be varied in order to utilize the longitudinal drilling forces for increasing the transversal diameter of the stabilizing system 100. The Kelly bushing 111 of the hollow housing 110 is arranged such that the column 130 can only be moved between two positions, which are denoted to as pulling position and drilling position herein. The column 130 presented in FIGS. 4 and 5 is in the pulling position. The Kelly bushing 111 features two end stops, preventing a full retraction of the column 130 from the housing 110. Preferably, the Kelly section 132 of the column has a length of 305 mm (1 foot).

[0045] The column 130 further comprises a thick section 131, which is arranged corresponding to respective recesses 121 of the spacers 120. The helical springs 140 urge the spacers 120 inwards the hollow housing 110 until the thick section 131 and/or the thin sections flanking the thick section 131 of the column 130 contact the spacers 120. Accordingly, the spacers 120 are in the fully retracted position in the configuration as illustrated in FIGS. 4 and 5.

[0046] FIGS. 6 and 7 correspond to the illustrations of FIG. 4 and 5, but with the spacers 120 being in the fully expanded position. As can be seen, in particular from FIG. 7, the Kelly section 132 of the column 130 is positioned at the opposite end stop of the Kelly bushing 111 compared to the configuration illustrated in FIG. 5. Thus, the column 130 is now in the drilling position and the overall length of the stabilizing system 100 is shorter compared to a configuration with the column 130 being in the pulling position. Due to this repositioning of column 130, the thick section 131 of the column 130 now urges the spacers 120 into the expanded position, i.e. to protrude to the outside further from the openings 112 provided on the housing 110. The helical springs 140 are thus in a more compressed state.

[0047] As can further be seen, an abutting face 113 of the housing no is now in contact with a counter abutting stop 123 provided on the column 130. Thus, longitudinal drilling forces, i.e. forces acting in drilling direction, are fully transferred between the hollow housing 110 and the column 130 due to the contact between the abutting face 113 and the counter abutting stop 123. In addition, torques or torsional forces are transferred via the cooperation of Kelly section 132 and Kelly bushing 111. Accordingly, and also due to the symmetric setup of the stabilizing system 100, the drilling forces are efficiently transferred along the stabilizing system 100, while it stabilizes the drill string.

[0048] Preferably, the spacers according to the present invention have a dimension such that when in the expanded position, the outer diameter of the stabilizing system is 298 mm (11.75 inches). Further preferred, when the spacers are in the retracted position, the outer diameter of the stabilizing system is reduced by 25.4 mm (1 inch) to 273 mm (10.75 inches). Hence, the maximum retraction of each spacer is preferably 12.7 mm (0.5 inch). However, the skilled person understands that the spacers can have different dimensions, according to the used drill bit and respective diameter of the bore hole. Favorably, the maximal movement of the spacers between the expanded and retracted position is in the range of 5-50 mm, preferably in the range of 10-30 mm, more preferably in the range of 10-20 mm and most preferred in the range of 10-15 mm. Due to the inventive design, the spacers 120 can be replaced where necessary or appropriate.

[0049] The hollow housing 110 must not be a single integral element, but can be composed of several elements. Accordingly, by decomposing or dissembling the housing, it is possible to remove the column 130 from the stabilizing system 100 and to replace the spacers 120. Similarly, also the column 130 can be made from more than one piece, preferably from two pieces, for easier manufacturing and assembly. The column is hollow, such that a drilling fluid can be pumped through the column 130 and hence through the stabilizing system 110 as through the complete drilling string. Further on, the stabilizing system no can feature any number of spacers 120. In addition, the stabilizing system can in addition comprise also at least one rigid blade or fin which is fixed to the hollow housing no such that it extends from an outer surface thereof.

[0050] FIG. 8 illustrates another stabilizing system 200 according to the present invention. The illustrated stabilizing system 200 is similar to that of FIGS. 4 to 7, with the additional feature that the column 230 is made of two column parts 230a, 230b, and the spacers 220 comprise a hole or valve 222 which is extending from an interior side of the spacers 220 to an exterior side thereof. As can be seen, the valves 222 extend from an edge of the recesses 221 provided on the interior side of the spacers 220. Accordingly, when the column 230 is moved from the drilling position to the pulling position, and the thick section 231 of the column 230 enters the recesses 221 of the spacers 220, any mud or debris collected under the spacers 220, i.e. in the recesses 221, is pushed through the valve 222 in order to leave a clean and empty place. Hence, the illustrated preferred embodiment allows for a more reliable functionality of the inventive stabilizing system.

[0051] FIGS. 9, 10 and 11 illustrate another preferred embodiment, wherein the stabilizing system 300 features two sets of spacers 320 arranged at different lengths of the stabilizing system 300. Each set comprises three spacers 320 positioned equally around the stabilizing system 300. The spacers 320 of the second set are positioned such that they are aligned between the circumferential position of the spacers of the first set, but at a different length or longitudinal position along the stabilizing system 300. This configuration provides improved stabilizing function. Although balling might occur, the stabilizing system 300 featuring the inventive mechanism to alter the outer diameter thereof can efficiently loosen the mud cake or mud ball.

[0052] FIGS. 10 and 11 illustrate cross-sections of the stabilizing system 300 of FIG. 9. Similarly to the stabilizing systems 100 and 200 described above, the present stabilizing system 300 features a column 330 made of two column parts 330a and 330b, a hollow housing 310 composed of at least two parts, and several spacers 320. In order to interact with the spacers provided at two longitudinal positions along stabilizing system 300, the column 330 features several thick sections 331. In the illustrated embodiment, each spacer 320 is urged to the expanded position by two thick sections 331. This layout provides improved interaction between the column and the spacers.

[0053] When the column 330 is in the pulling position, and the spacers 320 are in the retracted position, the respective recesses 321 provided on the spacers 320 receive the respective one of the thick sections 331.

[0054] In another preferred embodiment, the spacers 320 provided at different longitudinal positions along the stabilizing system 300 are of different sizes, such that the respective outer diameter of the stabilizing system 300 with expanded spacers 320 is different at these longitudinal positions. For example, when drilling a bore hole with a diameter of 298 mm (11.75 inches), the spacers can be selected such that the outer diameter of the stabilizing system is 260 mm (10.25 inches), 267 mm (10.5 inches), or 273 mm (10.75 inches) when the spacers are in the expanded position.

[0055] The stabilizing system according to the present invention is configured such that the spacers 120, 220, 320 can easily be replaced by disassembling the housing 310, removing the column 320 therefrom and extracting the blades though the disassembled housing.

TABLE-US-00001 List of reference numbers:  1 drill string  2 blade  3 drill bit  4 earth  5 bore hole  6 cavity  7 mud cake 100, 200, 300 stabilizing system 110, 210, 310 hollow housing 111 Kelly bushing 112 opening 113 abutting face 120, 220, 320 spacer 121, 221, 321 recess 222 hole or valve 123 counter abutting face 130, 230, 330 column 131, 231, 331 thick section 132 Kelly section 140 helical spring