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Title:
A METHOD FOR ALIGNING A TOOL FACE OF A MULTI BEND DRILLING APPARATUS AND AN ADAPTABLE DIRECTIONAL MULTI BEND DRILLING APPARATUS
Document Type and Number:
WIPO Patent Application WO/2021/038274
Kind Code:
A1
Abstract:
A method for aligning a tool face of a multi bend drilling apparatus and an adaptable directional multi bend drilling apparatus The present invention provides an apparatus and a method that allows building short and ultra- short curves, passing through small casings and surface equipment, minimize issues with the friction. These problems are solved in the present invention by providing an efficient method for aligning a tool face of a multi bend drilling apparatus and providing an adaptable directional multi bend drilling apparatus. Therefore, in the present invention the limitation of having identical bend angles is not there. Furthermore, the present invention provides a drilling tool (such as a mud motor, Vane motor, drilling turbine or any hydraulic motor that will be powered by the drilling fluid) to build a short and ultra-short curve that cannot be done using a conventional single or double power section tool with minimum risk and less stresses on the internal parts of the tool.

Inventors:
DIAB HADI ALI (LB)
Application Number:
IB2019/057181
Publication Date:
March 04, 2021
Filing Date:
August 27, 2019
Export Citation:
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Assignee:
TURBOTEK LTD (AE)
International Classes:
E21B7/04; E21B7/08
Foreign References:
US5248004A1993-09-28
US5343966A1994-09-06
US20100065143A12010-03-18
US20110140411A12011-06-16
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Claims:
Claims:

1. A method for aligning a tool face of a multi bend drilling apparatus for a selective adjustment, the method comprising: connecting a first tubular member and a second tubular member to form an adjustable bend, the first tubular member having a primary axis and a connection means protruding from the first tubular member having a secondary axis such that the primary axis of the first tubular and the secondary axis of the first tubular member define an axes plane, the second tubular member having a primary axis and a connection means having a secondary axis of the first tubular member such that the secondary axis of the first tubular member and the secondary axis of the secondary tubular member are collinear for each adjustable bend, and the plane containing the primary axis of the first tubular member and the primary axis of the second tubular member defines a tool face plane of each adjustable bend; defining a circular path for a first adjustable bend comprising determining the center of the circular path and locating a point such that it traverses to form the circular path wherein the center of the circular path is determined by the intersection between the secondary axis of the first adjustable bend and a plane perpendicular to the first adjustable bend and the point is located in a plane perpendicular to the secondary axis of the first tubular member and the secondary axis of the second tubular member by intersection between the primary axis of first tubular member and the perpendicular plane; selecting a tool face position on the circular path for the first adjustable bend; and aligning a plurality of adjustable bends for a selected tool face position in an end to end relation wherein the second tubular member of each adjustable bend is connected with the first tubular member of a succeeding adjustable bend such that the primary axis of the second tubular member of each adjustable bend is coincident with the primary axis of the first tubular member of each succeeding adjustable bend, and the primary axis of the second tubular member of each adjacent adjustable bend move to define a circular path for the adjacent adjustable bend such that for a selected tool face position on the circular path for the first adjustable bend, two positions where tool faces of the succeeding adjustable bends are aligned is when on the circular path the primary axis of the second tubular member of each succeeding adjustable bend is coincident with a plane containing the primary axis of the first tubular member of the first adjustable bend and the primary axis of the second tubular member of the first adjustable bend.

2. The method as claimed in claim 1, wherein there are at least two adjustable bends.

3. The method as claimed in claim 1, wherein the circular path for each adjustable bend is located in a plane perpendicular to the secondary axis of the first tubular member and the secondary axis of the second tubular member of each adjustable bend and is defined by an intersection between the primary axis of the first tubular member of the bend and a plane perpendicular to the secondary axis of the first tubular member and the secondary axis of the second tubular member of the bend.

4. The method as claimed in claim 1, wherein each adjacent adjustable bend can be set to any one of zero angle position or a bent angle position when the tool faces of all the adjustable bends are aligned.

5. The method as claimed in claim 1, wherein for the selected tool face position a common tool face for the multi bend drilling apparatus is determined by an intersection of the tool face plane and the circular path of each adjustable bend.

6. The method as claimed in claim 1, wherein the circular path for each adjacent adjustable bend is located in a plane perpendicular to the secondary axis of the first and the second tubular members of the adjacent adjustable bend.

7. The method as claimed in claim 1, wherein an offset angle between the primary axis of the first tubular member and the primary axis of second tubular member of each adjustable bend is a bent angle for the adjustable bend.

8. The method as claimed in claim 7, wherein the bent angle for each adjustable bend is identical.

9. The method as claimed in claim 7, wherein the bent angle for each adjustable bend is different.

10. The method as claimed in claim 7, wherein the bent angle for at least any two adjustable bends is identical.

11. The method as claimed claim 7, wherein the bent angle for at least one of the adjustable bend is set to zero degree.

12. The method as claimed in claim 1, wherein an offset angle between the primary axis and the secondary axis of the first tubular member and an offset angle between the primary axis and the secondary axis of the second tubular member are different.

13. The method as claimed in claim 1, wherein an offset angle between the primary axis and the secondary axis of the first tubular member and the offset angle between the primary axis and the secondary axis of the second tubular member are identical.

14. The method as claimed in claim 1, wherein the axes plane of the second tubular member of each adjustable bend and the axes plane of the first tubular member of the adjacent adjustable bend are set at random positions.

15. The method as claimed in claim 1, wherein the intersection of the tool face plane with the circumference of each tubular member at the selected position defines a radial position.

16. The method as claimed in claim 15, wherein in a selected radial position, the total bent angle is the sum of the bent angle for each bend.

17. The method as claimed in claim 15, wherein the resulting angle at a radial position at each bend is determined by the equation: A =ASIN (SIN (2* a )*COS (90- (Ap+ B)) where A is the resulting bent angle for the adjustable bend, a is the offset angle between the primary axis and secondary axis of the first tubular member and the second tubular member of the selected bend, Ap is the angle between the axes plane for the first tubular member of the first bend and the axes plane of the first tubular member of the selected bend, and b is the radial position of the common tool face relative to “Axes plane” of first element of first bend.

18. The method as claimed in claim 1, wherein the first tubular member and the second tubular member are connected in a sliding fit relation.

19. The method as claimed in claim 1, wherein the first tubular member contains external thread means and the second tubular member contains internal thread means.

20. The method as claimed in claim 7, wherein the total bent angle is located in a plan containing the primary axis of first member and the primary axis of second member of each bend.

21. An adaptable directional drilling apparatus comprising: at least two adjustable bends arranged in an end to end relation, each bend including: i) a first tubular member with a primary axis and a connection means protruding from said first tubular member defining a secondary axis, the secondary axis of the first tubular member disposed at a predetermined offset angle with respect to the primary axis of the first tubular member, and ii) a second tubular member with a primary axis and a connection means defining a secondary axis, said secondary axis of said second tubular member is disposed at a predetermined offset angle with respect to said primary axis of the second tubular member, wherein the internal connection means of the second tubular member is adapted receive the connection means protruding from the first tubular member such that the secondary axis of the first tubular member and the secondary axis of the second tubular member are collinear allowing rotation of the second tubular member relative to the first tubular member altering the position of the primary axis of first tubular member relative to the primary axis of second tubular member such that the plane containing the primary axis of first tubular member and the primary axis of second tubular member defines the tool face plane of each bend, wherein plurality of bends are aligned at a common tool face of the multi bend drilling apparatus, thereby providing variation of bit offset and bit- to-bend distance.

22. The apparatus as claimed in claim 21, wherein the common tool face of the multi bend drilling apparatus is the intersection of the tool face plane and a circular path of each bend.

23. The apparatus as claimed in claim 21, wherein a circular path for each bend is defined by determining the center of the circular path and locating a point such that it traverses to form the circular path, wherein the center of the circular path is determined by the intersection between the secondary axis of the first adjustable bend and a plane perpendicular to the first adjustable bend and the point is located in a plane perpendicular to the secondary axis of the first tubular member and the secondary axis of the second tubular member by intersection between the primary axis of first tubular member and the perpendicular plane.

24. The apparatus as claimed in claim 21, wherein each adjacent bend can be set to any one of zero angle position or a bent angle position when the tool faces of all the bends are aligned.

25. The apparatus as claimed in claim 21, wherein an offset angle between the primary axis of the first tubular member and the primary axis of second tubular member of each bend is the bent angle for that bend.

26. The apparatus as claimed in claim 25, wherein the bent angle for each bend is identical.

27. The apparatus as claimed in claim 25, wherein the bent angle for each bend is different.

28. The apparatus as claimed in claim 25, wherein the bent angle for at least any two bends is identical.

29. The apparatus as claimed in claim 25, wherein the bent angle for at least one of the bend is set to zero degree.

30. The apparatus as claimed in claim 21, wherein an offset angle between the primary axis and the secondary axis of first tubular member and an offset angle between the primary axis and the secondary axis of second tubular member are different.

31. The apparatus as claimed in claim 21, wherein an offset angle between the primary axis and the secondary axis of first tubular member and the offset angle between the primary axis and the secondary axis of second tubular member are identical.

32. The apparatus as claimed in claim 22, wherein the intersection of tool face plane with the circumference of each tubular member at the selected position defines a radial position.

33. The apparatus as claimed in claim 25, wherein the total bent angle is the sum of the bent angle for each bend in a selected radial position.

34. The apparatus as claimed in claim 21, wherein the first tubular member contains external thread means and the second tubular member contains internal thread means.

35. The apparatus as claimed in claim 32, wherein the alignment of radial position in two adjacent members is secured by a ring having selected thickness disposed between adjacent elements.

Description:
A method for aligning a tool face of a multi bend drilling apparatus and an adaptable directional multi bend drilling apparatus

Field of the Invention

[ 1 ] The present invention relates to a method for aligning a tool face of a multi bend drilling apparatus and an adaptable directional multi bend drilling apparatus and more particularly relates to the method for aligning a tool face of a multi bend drilling apparatus and an adaptable directional multi bend drilling apparatus for improving directional/deflection performance of a drilling steerable motor and a method to adjust the deflection rate on site without the need of sending the tool back to the workshop.

Background of the Invention

[2] The oil and gas industry increasingly relies on directional drilling to develop petroleum reserves in environmentally sensitive areas or in restricted surface areas, using multilateral, horizontal, and extended reach wells.

[3] The industry has witnessed a steady increase in the use of horizontal drilling in the past decade to enhance well productivity. As the popularity of horizontal drilling has grown, the operators have developed a better understanding of how and where horizontal wells should be utilized and which technology is best for a given application. Initiating a lateral from an existing wellbore is often much more cost effective than drilling a new well down to the kick off point. Therefore, the use of Short and Ultra-Short Radius Drilling and Completion technology to reactivate and rejuvenate existing fields is being widely used.

[4] The short-radius technique offers many economical and technical benefits such as enabling kick-off point to be at a depth very near, or in numerous cases, inside the objective hydrocarbon zone itself. Accordingly, it enables the landing of the well bore at a distance very near to original well bore in case of re-entry drilling from an existing well. This allows drilling within the same zone using one casing only and may be a great benefit when a depleted sand is located below a pressurized shale. Production can be maximized where lease lines limit displacement and collision risks in a congested area can be simplified. [5] Presently, two different methods are used for directionally drilling a well: rotary steering and drilling with a downhole motor system. The motor system is designed with a downhole motor and a bent housing. There are several variant types of bent housing subs, such as fixed-angle types and adjustable types, and most steerable system runs are with bent-housing motors (single or double-bend).

[6] Most horizontal wells are currently drilled with a conventional mud motor or turbine drilling system equipped with a single or double bend Housing. These tools are well suited for drilling medium and long radius curves, but short-radius and ultra-short-radius wells are more difficult and risky. But considering the advantage of drilling a short radius curve, drilling operators are looking for a system that can deliver High Dogleg Severity (DLS) - which means that higher bend angles are required. For example, in some locations typical slim-hole wells are drilled in 3-5/8” hole size and the maximum DLS requirements are around 30°/100 ft, maximum. Presently, the requirements for drilling with an average DLS of 50°/100 ft have also come up.

[7] US 3,586,116 discloses a single bend system is where there is provided only one bending point in the tool that allows the motor to build angle and control well trajectory. The use of a single bend is acceptable for low DLS requirements but is physically restrictive above a certain bend angle. The disadvantage of the single bent system is the limitation of bend angle due to high stress on the internal flexible shaft, especially for drilling tools operating at high RPM such as a drilling turbine. In addition, such a system has a limitation to pass through small casings and create friction or drag on the well bore due to the single point contact and causes difficulty when sliding using a high bend angle. The maximum bend angle on such systems is typically 2°. Moreover, to make adjustments and to modify the deflection angle, the tool must be sent to the workshop. This increases the time, effort and cost costs extensively. Furthermore, these tools are not at all suited for drilling short-radius and ultra-short-radius wells.

[8] The double bent housing was thereafter introduced to the market as a non-adjustable (fixed) bent housing in the 1990’s and has proven to offer better directional performance helping to achieve better build-up rate (BUR) compared to single bent housing.

[9] WO 2018/158627 discloses an adjustable bent housing consisting of a first adjustable bend, a second adjustable bend, and a middle housing that has a fixed member. The limitation with kind of system is that the bend angle between the first adjustable bend and the middle housing must be identical to the bend angle between the second adjustable bend and the middle housing to achieve tool face alignment. Therefore, this system still does not address the multiple challenges of: a) Building short and ultra-short curves due to bend angle limitation (current maximum double-bend angle is limited to 3.0 degrees), b) Passing through small casings and surface equipment, and c) Minimize issues with friction or drag - as the middle of the double-bent sub will be sitting on the well bore.

[10] Additionally, the design of the existing adjustable bent systems limits the DLS potential. For keeping the tool face of both adjustable bends aligned, the middle housing has a fixed member with identical bend angles at both ends which limits the DLS capability of the tool, as the tool can achieve much higher DLS by keeping the lower bent angle (i.e. closest to the bit) higher than the upper bent angle.

[11] Therefore, the problem to be solved is to provide building short and ultra-short curves, passing through small casings and surface equipment, minimize issues with the friction, and to eliminate the limitation wherein the offset angle between the first tubular member and the central tubular member must be identical to the offset angle between the second tubular member and the central tubular member to achieve the tool face alignment.

[12] These problems are solved by the present invention by providing an efficient method for aligning a tool face of a multi bend drilling apparatus and providing an adaptable directional multi bend drilling apparatus. Therefore, in the present invention the limitation of having identical bend angles is not there. Furthermore, the present invention provides a drilling tool (such as a mud motor, Vane motor, drilling turbine or any hydraulic motor that will be powered by the drilling fluid) to build a short and ultra-short curve that cannot be done using a conventional single or double power section tool with minimum risk and less stresses on the internal parts of the tool. Summary of the Invention

[13] According to an embodiment of the invention, a method for aligning a tool face of a multi bend drilling apparatus for a selective adjustment, the method comprising: connecting a first tubular member and a second tubular member to form an adjustable bend, the first tubular member having a primary axis and a connection means protruding from the first tubular member having a secondary axis such that the primary axis of the first tubular and the secondary axis of the first tubular member define an axes plane, the second tubular member having a primary axis and a connection means having a secondary axis such that the secondary axis of the first tubular member and the secondary axis of the secondary tubular member are collinear for each adjustable bend, and the plane containing the primary axis of the first tubular member and the primary axis of the second tubular member defines a tool face plane of each adjustable bend defining a circular path for a first adjustable bend comprising determining the center of the circular path and locating a point such that it traverses to form the circular path wherein the center of the circular path is determined by the intersection between the secondary axis of the first adjustable bend and a plane perpendicular to the first adjustable bend and the point is located in a plane perpendicular to the secondary axis of the first tubular member and the secondary axis of the second tubular member by intersection between the primary axis of first tubular member and the perpendicular plane; selecting a tool face position on the circular path for the first adjustable bend; and aligning a plurality of adjustable bends for a selected tool face position in an end to end relation wherein the second tubular member of each adjustable bend is connected with the first tubular member of a succeeding adjustable bend such that the primary axis of the second tubular member of each adjustable bend is coincident with the primary axis of the first tubular member of each succeeding adjustable bend, and the primary axis of the second tubular member of each adjacent adjustable bend move to define a circular path for the adjacent adjustable bend such that for a selected tool face position on the circular path for the first adjustable bend, two positions where tool faces of the succeeding adjustable bends are aligned is when on the circular path the primary axis of the second tubular member of each succeeding adjustable bend is coincident with a plane containing the primary axis of the first tubular member of the first adjustable bend and the primary axis of the second tubular member of the first adjustable bend.

[14] According to an embodiment of the invention, there are at least two adjustable bends. [15] According to an embodiment of the invention, a center of the circular path for each adjustable bend is defined by an intersection between the secondary axis of the adjustable bend and a plane perpendicular to the adjustable bend.

[16] According to an embodiment of the invention, wherein the circular path for each adjustable bend is located in a plane perpendicular to the secondary axis of the first tubular member and the secondary axis of the second tubular member of each adjustable bend and is defined by an intersection between the primary axis of the first tubular member of the bend and a plane perpendicular to the secondary axis of the first tubular member and the secondary axis of the second tubular member of the bend.

[17] According to an embodiment of the invention, each adjacent adjustable bend can be set to any one of zero angle position or a bent angle position when the tool faces of all the adjustable bends are aligned.

[18] According to an embodiment of the invention, the selected tool face position a common tool face for the multi bend drilling apparatus is determined by an intersection of the tool face plane and the circular path of each adjustable bend.

[19] According to an embodiment of the invention, the circular path for each adjacent adjustable bend is located in a plane perpendicular to the secondary axis of the first and the second tubular members of the adjacent adjustable bend.

[20] According to an embodiment of the invention, an offset angle between the primary axis of the first tubular member and the primary axis of second tubular member of each adjustable bend is a bent angle for the adjustable bend.

[21] According to an embodiment of the invention, the bent angle for each adjustable bend is identical.

[22] According to an embodiment of the invention, the bent angle for each adjustable bend is different.

[23] According to an embodiment of the invention, the bent angle for at least any two adjustable bends is identical. [24] According to an embodiment of the invention, the bent angle for at least one of the adjustable bend is set to zero degree.

[25] According to an embodiment of the invention, an offset angle between the primary axis and the secondary axis of the first tubular member and an offset angle between the primary axis and the secondary axis of the second tubular member are different.

[26] According to an embodiment of the invention, an offset angle between the primary axis and the secondary axis of the first tubular member and the offset angle between the primary axis and the secondary axis of the second tubular member are identical.

[27] According to an embodiment of the invention, the axes plane of the second tubular member of each adjustable bend and the axes plane of the first tubular member of the adjacent adjustable bend are set at random positions.

[28] According to an embodiment of the invention, the intersection of the tool face plane with the circumference of each tubular member at the selected position defines a radial position.

[29] According to an embodiment of the invention in a selected radial position the total bent angle is the sum of the bent angle for each bend. .

[30] According to an embodiment of the invention the resulting angle at a radial position at each bend is determined by the equation: A =ASIN (SIN (2* a )*COS (90- (Ap+ B)) where A is the resulting bent angle for the adjustable bend, a is the offset angle between the primary axis and secondary axis of the first tubular member and the second tubular member of the selected bend , Ap is the angle between the axes plane for the first tubular member of the first bend and the axes plane of the first tubular member of selected bend, and B is the radial position of the common tool face relative to “Axes plane” of first element of first bend.

[31] According to an embodiment of the invention the first tubular member and the second tubular member are connected in a sliding fit relation. [32] According to an embodiment of the invention, the first tubular member contains external thread means and the second tubular member contains internal thread means.

[33] According to an embodiment of the invention, total bent angle is located in a plan containing the primary axis of first member and the primary axis of second member of each bend.

[34] According to an embodiment of the invention, an adaptable directional drilling apparatus comprising: at least two adjustable bends arranged in an end to end relation, each bend including: i) a first tubular member with a primary axis and a connection means protruding from said first tubular member defining a secondary axis, the secondary axis of the first tubular member disposed at a predetermined offset angle with respect to the primary axis of the first tubular member, and ii) a second tubular member with a primary axis and a connection means defining a secondary axis, said secondary axis of said second tubular member is disposed at a predetermined offset angle with respect to said primary axis of the second tubular member, wherein the internal connection means of the second tubular member is adapted to receive the connection means protruding from the first tubular member such that the secondary axis of the first tubular member and the secondary axis of the second tubular member are collinear allowing rotation of the second tubular member relative to the first tubular member altering the position of the primary axis of first tubular member relative to the primary axis of second tubular member such that the plane containing the primary axis of first tubular member and the primary axis of second tubular member defines the tool face plane of each bend, wherein plurality of bends are aligned at a common tool face of the multi bend drilling apparatus, thereby providing variation of bit offset and bit-to-bend distance.

[35] According to an embodiment of the invention the common tool face of the multi bend drilling apparatus is the intersection of the tool face plane and a circular path of each bend.

[36] According to an embodiment of the invention a circular path for each bend is defined by determining the center of the circular path and locating a point such that it traverses to form the circular path, wherein the center of the circular path is determined by the intersection between the secondary axis of the first adjustable bend and a plane perpendicular to the first adjustable bend and the point is located in a plane perpendicular to the secondary axis of the first tubular member and the secondary axis of the second tubular member by intersection between the primary axis of first tubular member and the perpendicular plane.

[37] According to an embodiment of the invention, each adjacent bend can be set to any one of zero angle position or a bent angle position when the tool faces of all the bends are aligned.

[38] According to an embodiment of the invention, an offset angle between the primary axis of the first tubular member and the primary axis of second tubular member of each bend is the bent angle for that bend.

[39] According to an embodiment of the invention, the bent angle for each bend is identical.

[40] According to an embodiment of the invention, the bent angle for each bend is different.

[41] According to an embodiment of the invention, wherein the bent angle for at least any two bends is identical.

[42] According to an embodiment of the invention, the bent angle for at least one of the bend is set to zero degree.

[43] According to an embodiment of the invention, an offset angle between the primary axis and the secondary axis of first tubular member and an offset angle between the primary axis and the secondary axis of second tubular member are different.

[44] According to an embodiment of the invention, an offset angle between the primary axis and the secondary axis of first tubular member and the offset angle between the primary axis and the secondary axis of second tubular member are identical. [45] According to an embodiment of the invention, the intersection of tool face plane with the circumference of each tubular member at the selected position defines a radial position.

[46] According to an embodiment of the invention, the total bent angle is the sum of the bent angle for each bend in a selected radial position. [47] According to an embodiment of the invention, the first tubular member contains external thread means and the second tubular member contains internal thread means.

[48] According to an embodiment of the invention, the alignment of radial position in two adjacent member is secured by a ring having selected thickness disposed between adjacent elements.

Brief description of Drawings

[49] Fig. la represents an embodiment of the present invention depicting side view of the first tubular member and the second tubular member of the adjustable bend.

[50] Fig. lb represents an embodiment of the present invention depicting side view of the first tubular member and the second tubular member of the adjustable bend at zero offset angle.

[51] Fig. lc represents an embodiment of the present invention depicting side view of the first tubular member and second tubular member of the adjustable bend at an offset angle.

[52] Fig. lc represents an embodiment of the present invention depicting the rotation of the first tubular member about its axis and the rotation of the second tubular member about its axis.

[53] Fig. 2 represents an embodiment of the present invention depicting the first tubular member and the second tubular member arranged in the position of maximum bend angle.

[54] Fig. 3 represents an embodiment of the present invention depicting the connection between plurality of adjustable bends.

[55] Fig. 4 represents an embodiment of the present invention depicting the tool face plane.

[56] Fig. 5 represents an embodiment of the present invention depicting tool face alignment at a random position of the three axis plane of the drilling apparatus with three bends. [57] Fig. 6 represents an embodiment of the present invention depicting the intersection of the circular paths to locate a common tool face for the multiple bends of the drilling apparatus.

[58] Fig. 7 represents an embodiment of the present invention depicting determination of resulting bent at each angle mark position angle for a single bend of the drilling apparatus.

[59] Fig. 8 represents an embodiment of the present invention depicting determination of resulting bent at each angle mark position angle for a multi bend drilling apparatus.

[60] Fig. 9 represents an embodiment of the present invention depicting the multi bend drilling apparatus in operation to achieve the maximum resulting bend angle.

Detailed description of the Invention

[61] The embodiments of the present invention can be understood by reading following detailed description of some the embodiments with reference to the accompanying drawings.

[62] In an embodiment of the present invention, a multi bend drilling apparatus and a method for aligning a tool face of the multi bend drilling apparatus for a selective adjustment is disclosed. The main challenge in using a multi bend drilling apparatus is the tool face alignment, as it is critical to keep the tool face of all the bends in the same selected plane. Pre determining the bend alignment patterns avoids possible internal conditions in the tool that could result in operational issues such as high lateral shaft vibrations or internal damage from bending stresses. The above challenge does not exist in the simple, single bend system since the solitary bending point does not need alignment with any other part of the tool assembly. In the present invention, the angle that is set at each bend can be different and do not have to be set in the same plane. The resultant net angle of the bends is determined by calculations and the radial point on the tool circumference is identified which is used for steering the tool. Thus, in the present invention the limitation of having identical bend angles is not there.

[63] As shown in Fig. 1(a) each adjustable bend comprises a first tubular member 1 and a second tubular member 2. The first tubular member 1 has connection means la with an axis 3 which makes an offset angle "a" with the primary axis 4 of the first tubular member. The connection means of the first tubular member 1 has an external threaded means and the second tubular member 2 has an internal thread means (Pin or box). The second tubular member 2 has primary axis 6 which makes an offset angle "a" with its secondary axis 5. The axis 3 and 4 make a plane ‘axes plane APla’, and the axis 5 and 6 make a plane which is called ‘axes Plane APlbk

[64] As shown in Fig. 1(b), the first tubular member 1 and the second tubular member 2 are in the reference position where the axis 3 and 5 are in alignment with each other. In this position the two central axis 4 and 6 are collinear and the first tubular member 1 and the second tubular member 2 are parallel.

[65] As shown in Fig. 1 (c), the rotation of the first tubular member 1 about its axis 3 and the rotation of the second tubular member 2 about its axis 5 in the opposite direction form identical angle B, in each positions the axis 4 of the first tubular member 1 makes with the axis

6 of second tubular member 2 an angle between 0 and 2a in the plane TF1 “Tool Face of the apparatus” (which is coincident with axis 4 and makes an angle B with the APla).

[66] As shown in Fig. 2, the first tubular member 1 and the second tubular member 2 are in the position of max bent angle “BA1 = 2a”. This is obtained for a radial displacement B of 180 degrees, or for a 90 degree displacement of the first tubular member 1 about its axis 3 and a 90 degree displacement of the second tubular member 2 about its axis 5 in the opposite direction. Between two positions where the first tubular member 1 and the second tubular member 2 are parallel shown is Fig. lb and the maximum bent angle position shown is Fig. lc. The rotation of the first tubular member 1 about its axis 3 and the rotation of the second tubular member 2 about its axis 5 in the opposite direction for an identical angle B, resulting the movement of axis 6 on a circular path of center 8 (coincident with the axis 3 and 5) and diameter 7-9 where

7 is coincident with axis 6 at the max position of angle B of 180 degree and 9 is coincident with the axis 4 of the first tubular member 1. The tool face plane at each position PI, P2, P3, P4, P5 ... is the plane of the axis 4 and 6 at each position. Herein, the axis 6 will be variable along the circle perimeter as OP1, OP2, OP3, OP4, OP5...). [67] As shown in Fig. 3, three adjustable single bends have four tubular members 10, 11, 12 and 13. The tubular member 10 has a lower thread connection with a secondary axis 15 and main primary axis 14. The tubular member 11 has an upper thread connection with a secondary axis 16 and main primary axis 17. The axis plane “APla” is the plane containing the axis 14 and 15. The axis plane “APlb” is the plane containing the axis 16 and 17. The axis 14 and axis 15 have an offset angle “Al”. The axis 16 and axis 17 also have an offset angle “Al”. The tubular member 11 has a lower thread connection with a secondary axis 19 and main primary axis 18. The tubular member 12 has an upper thread connection with a secondary axis 20 and main primary axis 21. The axis plane “AP2a” is the plane containing the axis 18 and 19, the axis plane “AP2b” is the plane containing the axis 20 and 21. The axis 18 and axis 19 have an offset angle “A2”. The axis 20 and axis 21 also have an offset angle “A2”. The tubular member 12 has a lower thread connection with a secondary axis 23 and main primary axis 24. The tubular member 13 has an upper thread connection with a secondary axis 26 and main primary axis 25. The axis plane “AP3a” is the plane containing the axis 23 and 24. The axis plane “AP3b” is the plane containing the axis 25 and 26. The axis 23 and axis 24 have an offset angle “A3”. The axis 25 and the axis 26 also have an offset angle “A3”. The three adjustable bends can have three different angles “Al”, “A2” and “A3” and the axis planes “APla”, “APlb”, “AP2a”, “AP2b”, “AP3a” & “AP3b” can be at any position - as shown in the side views in sections A-A, B-B and C-C. The rotation of tubular member 11 about its thread axis 16 will make a resulting angle between the axis 14 and 17 of the tubular member 10 and the tubular member 11 changing from 0 degrees to 2*A1 degrees. The rotation of the tubular member 12 about its thread axis 20 will make a resulting angle between the axis 18 and 21 of the tubular member 11 and the tubular member 12 change from 0 to 2*A2 degrees. The rotation of the tubular member 13 about its thread axis 26 will make the resulting angle between the axis 24 and 25 of the tubular member 12 and the tubular member 13 change from 0 to 2*A3 degrees.

[68] The total resulting angle at selected tool face is the angle between the axis 14 and 25 which can change from “0” degrees to “2*A1+2*A2+2*A3” degrees (In the case where the three planes A-A, B-B and C-C are coincident). In the case where the three planes A-A, B-B and C-C are in 3 different planes, the resulting maximum angle will be less than “2*A1+2*A2+2*A3” degrees. Referring to Fig. 2, the tool face of each bend will follow a circular path with center 8 (coincident with the secondary axis of both elements) and diameter AB where A is coincident with the axis of the first tubular member 1 and B is coincident with the primary axis of the first tubular member 1 at the max bent position (b= 180 degrees).

[69] As shown in Fig 4, the axis plane API, AP2 and AP3 are in three different positions having a common axis 14. Each bend has a tool face circular path with a center coincident with its secondary axis and diameter A1B1, A2B2, A3B3 respectively where Al, A2 and A3 are coincident with Axis 14 and B1 coincident with Axis 17, B2 coincident with Axis 21 and B3 coincident with Axis 25. The intersection of the three circular paths is the area where a common tool face for the three adjustable bends is located, and which is the tool face of the drilling tool.

[70] As shown in Fig 5, at the intersection of the 3 circular paths a common tool face for the multiple bends is located, which is be the tool face of the drilling tool.

[71] As shown in Fig.6, an example of tool face alignment is given.

[72] 1 is the primary axis of first tubular member of the first adjustable bend. 2 is the secondary axis of the first tubular member of first adjustable bend which is coincident with the secondary axis of second tubular member of first adjustable bend. 3 is the primary axis of second tubular member of the adjustable bend. The angle Al is the resulting bent angle of the first adjustable bend in the tool face plane which is the plane of axis 1 and 3, and 4 is the circular path of tool face plane for the first bent.

[73] 5 is the primary axis of first tubular member of second adjustable bend. 6 is the secondary axis of first tubular member of the second tubular member which is coincident with the secondary axis of second tubular member of adjustable bend. 7 is the primary axis of second tubular member of the second adjustable bend. The angle A2 is the resulting bent angle of the second adjustable bend in the tool face plan which is the plane of axis 5 and 7, and 8 is the circular path of tool face plane for the second adjustable bend.

[74] 9 is the primary axis of first tubular member of the third adjustable bend. 10 is the secondary axis of first tubular member of third adjustable bend which is coincident with the secondary axis of second tubular member of the third adjustable bend. 11 is the primary axis of second tubular member of third adjustable bend. The angle A3 is the resulting bent angle of third bent system in the tool face plan which is the plane of axis 9 and 11, and 12 is the circular path of tool face plane for the third adjustable bend. The resulting Total bent angle is the total resulting angle is plane of Axes 1, 3, 5 ,7 ,9 and 11, and the total angle Value is A1+A2+A3.

[75] As shown in Fig. 7 and Fig. 8 the Total Angle is calculated as follows:

Referring to Fig 7, for a Single bent housing the resulting bent angle at each angle mark position is calculated using the formula:

A1 =ASIN (SIN (2* a) * COS (90- b)

Where:

A1 is the angle between the primary axis 3 of first tubular member 1 and the primary axis 4 of second tubular member 2; b is the angular position of tool face plan where the bent angle is calculated; a is the offset angle (fixed) between the primary axis and the secondary axis of the first tubular member 1 and the second tubular member 2.

[76] For a multi bend adjustable system, since the planes of the axes for the 3 adjustable bends are not aligned in the same plane the resulting angle for each adjustable bend is different. The position of the common tool face for all adjustable bends is found using the method shown in Fig. 4 and Fig. 5, where the common tool face location is at the intersection area of the circular paths of the three adjustable bends. This common tool face position (noted ‘TF’) is the fixed position where the resulting angle between the primary axes of the first tubular member and the second tubular member of each bend system add up to the desired, total bend angle for the drilling tool.

[77] As shown in Fig. 8, for the first adjustable bend, the plane of axes 30 and 38 is the reference plane which is also the axis plane of the first adjustable bend. Axis 31 is perpendicular to axis 30, and 31 is the tool face position where the first tubular member and the second tubular member of the first adjustable bend are parallel (radial displacement b=90 degree is opposite direction for both elements). Axis 32 is the random position with an angle B1 between 0 and 90 degree, the plane of axis 32 and axis 38 is the tool face plane for the first bend. [78] For the second adjustable bend, the plane of axes 33 and 38 is the axis plane which makes an angle “AP2” with the reference plane. The axis 34 is perpendicular to axis 33, the axis 35 is the common tool face position, the angle B2 is the angle between the axis 34 and the axis 35.

[79] For the third adjustable bend, the plane of two axes 40 and 38 is the axis plane which makes an angle “AP3” with the reference plane. The axis 36 is perpendicular to axis 40, the axis 37 is the common tool face position, the angle B3 is the angle between the axis 36 and 37. Since the tool face axes 32, 35 and 37 of the three adjustable bends are in the same plane the total resulting bent angle is calculated as per following: a- A1 =ASIN (SIN (2* al )*COS (90- Bl) ,

Where:

Al is the resulting angle of first adjustable bend at the selected tool face position.

Bl is the angular potion of tool face axis from the axis 31 al is the offset angle (fixed) between the primary axis and the secondary axis of the first adjustable bend b- A2 =ASIN (SIN (2* a2 )*COS (90- (Ap2+ Bl)) ,

Where:

A2 is the resulting angle of second adjustable bend at the selected tool face position. a2 is the offset angle (fixed) between the primary axis and the secondary axis of second adjustable bend

Ap2 is the angular position of “axis plane” of second bend (from reference plane) c- A3 =ASIN (SIN (2* a3)*COS (90- (Ap3+ Bl)) ,

Where:

A3 is the resulting angle of third adjustable bend at the selected tool face position. a3 is the offset angle (fixed) between the primary axis and the secondary axis of the third adjustable bend. Ap3 is the angular position of “axis plane” of third adjustable bend (from reference plane)

[80] The total resulting angle at the TF position (Bl from axis 31, B2 from axis 34 and B3 from axis 36) is TA= Al+A2+A3= ASIN (SIN (2* al)*COS (90- Bl) + ASIN (SIN (2* a2 )*COS (90- (Ap2+ Bl)) + ASIN (SIN (2* a3 )*COS (90- (Ap3+ Bl)).

[81] Fig. 9 shows an adaptable directional drilling apparatus with adjustable bit-to-bend. As an advantage, with the present invention, the bit-to-bend-distance can be adjusted such that it will help to improve the build-up rate of the drilling tool. So, this adaptable directional drilling apparatus is a customizable apparatus that allows switching between single, double and triple bent housings and adjusting the bit-to-bend-distance in order to maximize the coverage of directional drilling applications required by drilling operators. As may be noted from Fig. 9, mechanism 2 (first adjustable bend), mechanism 3 (second adjustable bend) and mechanism 4 (third adjustable bend) can be adjusted in 7 different configurations in order to change the bit- to-bend-distance. Also, switching between single, double or triple-bends is simply done by setting one or two of the mechanisms to zero and set the remaining mechanism to the desired angle.

[82] The present invention is however not limited to the embodiments disclosed above and referred in Fig(s). 1 to 9, and other embodiments within the scope of the invention can be used for achieving the result of the present invention without limiting the scope of the invention.