EP3246513A1

EP3246513A1 - Downhole system having lateral sections

Info

Publication number: EP3246513A1
Application number: EP16169973.1A
Authority: EP
Inventors: Christian Krüger
Original assignee: Welltec AS
Current assignee: Welltec AS
Priority date: 2016-05-17
Filing date: 2016-05-17
Publication date: 2017-11-22

Abstract

Downhole system (100) for completing a well (1) having a borehole (2) and a top (3). The downhole system comprises a well tubular metal structure (4) arranged in the borehole, having a longitudinal axis; and a lateral section (6) comprising a tubular part (7) mounted as part of the well tubular metal structure, the tubular part having a first part section (8) having a first outer diameter (OD1), and a second part section (9) having a second outer diameter (OD2), the second outer diameter being larger than the first outer diameter and the second part section comprising an angled through-bore (10) extending downwards, away from the top, wherein a lateral tubular assembly (11) extends at least partly through the through-bore and downwards, away from the top and forms a lateral from the tubular part. Furthermore, the invention relates to completion method for completing a well comprising the downhole system.

Description

Field of the invention

The present invention relates to a downhole system for completing a well having a borehole and a top and to a completion method for completing a well comprising the downhole system.

Background art

When making laterals, the laterals are drilled from within the well tubular metal structure or main casing and out through the casing wall, and then the lateral tubular assembly is inserted into the though-bore in the casing wall and further into the lateral. However, the lateral tubular assembly decreases the inner diameter of the casing, which makes the flow of production fluid in the casing less efficient. However, increasing the inner diameter of the casing at the lateral would weaken the casing too much, and there is therefore a need for another solution for making a lateral junction without reducing the flow of production fluid in the casing.

Summary of the invention

It is an object of the present invention to wholly or partly overcome the above disadvantages and drawbacks of the prior art. More specifically, it is an object to provide an improved downhole system form making lateral junctions without reducing the flow of production fluid in the casing.
The above objects, together with numerous other objects, advantages and features, which will become evident from the below description, are accomplished by a solution in accordance with the present invention by a downhole system for completing a well having a borehole and a top, comprising:

a well tubular metal structure arranged in the borehole, having a longitudinal axis, and
a lateral section comprising a tubular part mounted as part of the well tubular metal structure, the tubular part having a first part section having a first outer diameter, and a second part section having a second outer diameter, the second outer diameter being larger than the first outer diameter and the second part section comprising an angled through-bore extending downwards away from the top,

In an embodiment, the lateral tubular assembly may have a flange.
The flange may be an annular flange.
Furthermore, the lateral tubular assembly may comprise a pipe section extending from the flange in through the through-bore.
Also, a sealing element may be arranged between the flange and the tubular part.
Moreover, the second part section may have a recess and the through-bore may extend from the recess to an outer face of the second part section.
In addition, the recess may be configured to receive the flange of the lateral tubular assembly.
Further, the second part section may have the recess when submerged into the well or the recess may be made after the second part section has been submerged into the well.
Additionally, the recess may be made in situ downhole.
Also, the recess may be made by milling or from acid.
In an embodiment, the second part section may have a first area comprising the recess and the through-bore, and a second area without the recess and the through-bore, and the first area may have an inner diameter larger than an inner diameter of the second area.
Furthermore, the first area may partly be made of a first material different from a second material of the second area.
In addition, the first material may be removable by acid, whereas the second material may not be.
Moreover, the first material may be easier to machine than the second material.
Also, the first area may have a wall thickness which is equal to or larger than a wall thickness of the first part section.
Further, the second area may have an inclining outer face.
Additionally, the recess may be circumferential and extend along the inner diameter of the tubular part.
Furthermore, the first area may have an extension along the longitudinal axis, the extension being at least twice the extension of the flange along the longitudinal axis.
The downhole system described above may further comprise at least one annular barrier, the annular barrier comprising:

a tubular metal part for mounting as part of the well tubular metal structure, the tubular metal part having a first expansion opening and an outer face,
an expandable metal sleeve surrounding the tubular metal part and having an inner face facing the tubular metal part and an outer face facing a wall of the borehole, each end of the expandable metal sleeve being connected with the tubular metal part, and
an annular space between the inner face of the expandable metal sleeve and the tubular metal part, the expandable metal sleeve being configured to expand by allowing pressurised fluid to enter into the annular space through the first expansion opening.

In an embodiment, the downhole system may further comprise a flow section.
The flow section may be an inflow section or a frac port.
In addition, the downhole system may further comprise a lateral tubular metal structure in connection with the lateral tubular assembly.
Moreover, the lateral tubular metal structure may comprise at least one annular barrier.
Furthermore, the lateral tubular assembly may have a lateral axis.
Also, an angle may be defined between the longitudinal axis and the lateral axis.
In addition, the angle may be larger than 100 degrees, preferably larger than 120 degrees.
The present invention furthermore relates to a completion method for completing a well comprising the downhole system according to any of the preceding claims, the method comprising the steps of:

providing the well tubular metal structure in the borehole,
providing the angled through-bore in the second part section, and
inserting the lateral tubular assembly in the angled through-bore.

In an embodiment, the completion method may further comprise the step of providing a recess in the second part section around the through-bore.
Furthermore, the step of providing the recess may be performed by machining or aciding.
Finally, the completion method may further comprise the step of arranging a flange of the lateral tubular assembly in the recess.

Brief description of the drawings

The invention and its many advantages will be described in more detail below with reference to the accompanying schematic drawings, which for the purpose of illustration show some non-limiting embodiments and in which

Fig. 1 shows a partly cross-sectional view of a downhole system,
Fig. 2 shows a cross-sectional view of a lateral section,
Fig. 3 shows a cross-sectional view of another lateral section having a circumferential recess,
Fig. 4 shows a cross-sectional view of yet another lateral section having a longer extension than the lateral tubular assembly,
Fig. 5A shows a cross-sectional view of another downhole system in which no recess is provided in the lateral section,
Fig. 5B shows a cross-sectional view of the downhole system of Fig. 5A in which recesses and through-bores are made,
Fig. 5C shows a cross-sectional view of the downhole system of Fig. 5B in which lateral tubular assemblies are provided in the through-bores, and
Fig. 5D shows a cross-sectional view of the downhole system of Fig. 5C in which lateral well tubular metal structures are provided in the laterals.

All the figures are highly schematic and not necessarily to scale, and they show only those parts which are necessary in order to elucidate the invention, other parts being omitted or merely suggested.

Detailed description of the invention

Fig. 1 shows a downhole system 100 for completing a well 1 having a borehole 2 and a top 3 at which top a well head or blowout preventer may be arranged. The downhole system 100 comprises a well tubular metal structure 4 arranged in the borehole 2 with a longitudinal axis 5 along the borehole. The downhole system 100 further comprises a lateral section 6 comprising a tubular part 7 mounted as part of the well tubular metal structure 4. The tubular part 7 has a first part section 8 having a first outer diameter OD₁ and a second part section 9 having a second outer diameter OD₂ being larger than the first outer diameter. The second part section 9 comprises an angled through-bore 10 extending downwards, away from the top 3. The downhole system 100 further comprises a lateral tubular assembly 11 extending at least partly through the through-bore 10 and downwards, away from the top 3 and forming a lateral 12 from the tubular part 7.
By increasing the outer diameter of the lateral section, room can be made for receiving the lateral tubular assembly 11 without reducing the inner diameter of the well tubular metal structure 4, and thus, the flow of production fluid is not reduced when making a lateral junction between the main casing being the well tubular metal structure and a lateral. Furthermore, the moment of resistance and/or the bending moment are/is not decreased in the lateral section and therefore do/does not weaken the lateral section 6 in relation to the remaining part of the well tubular metal structure 4.
The lateral tubular assembly 11 has a flange 14 for abutment with a recess 16 in the second part section 9, and the through-bore 10 extends from the recess to an outer face 17 of the second part section. The recess 16 is a circumferential groove and extends along an inner diameter ID_t of the tubular part 7.
In Fig. 2, the flange 14 is an annular flange and is received in the recess 16 which is only comprised in part of the tubular part 7 and is thus not circumferential. The lateral tubular assembly 11 has a pipe section 32 having a lateral axis 44 and extending from the flange 14 in an angle β from the longitudinal axis 5, and thereby forming the lateral 12. The angle β is thus defined between the longitudinal axis 5 and the lateral axis 44 and is larger than 10 degrees, preferably larger than 120 degrees, and preferably larger than 150 degrees. The lateral tubular assembly 11 has two sealing elements 15 arranged between the flange 14 and the tubular part 7 and around the pipe section 32 in a circumferential groove 33. The tubular part 7 of the lateral section 6 is mounted as part of the well tubular metal structure 4 by means of threads 34. The second part section 9 has a first area 18 comprising the recess 16 and the through-bore 10 and a second area 19 without the recess and the through-bore. The first area 18 has an inner diameter ID_R which is larger than an inner diameter ID_2A of the second area 19, and the inner diameter of the tubular part 7 is opposite the lateral tubular assembly 11 equal to or larger than the inner diameter ID_2A of the second area 19. Hence, the lateral tubular assembly 11 is arranged flush with the tubular part 7 so that the inner diameter of the tubular part is equal to the inner diameter of the well tubular metal structure 4, and the well tubular metal structure is thus a mono bore. The lateral tubular assembly 11 is held in place by a projection 35A which, when the flange 14 is pressed against the recess 16, is pressed into the tubular part 7 or forms a welded connection between the flange and the recess. The flange 14 is pressed against the recess 16 by means of a tool inserted into the well tubular metal structure 4, and a cone forces the flange radially outwards.
In Fig. 3, the recess 16 is a circumferential recess, and the first area 18 has a wall thickness t1 which is equal to or larger than a wall thickness t2 of the first part section 8. The second area 19 has an inclining outer face 35, making it easy to run the lateral section 6 into the borehole as the inclined outer face slides along any projections of the wall of the borehole.
The second part section 9 has a recess 16 in Fig. 4 which is made after the second part section has been submerged into the well. The first area 18 is partly made of a first material 36 different from a second material 37 of the second area 19. The recess 16 is made in situ downhole, e.g. by machining, such as milling, or by acid. When using acid, the first material 36 is an acid-dissolvable material, such as aluminium. When machining the first material 36, the material may be a material which is easier to machine than the second material 37. In Fig. 4, the recess 16 is present in the second part section 9 when submerged into the well. The first area 18 has an extension along the longitudinal axis 5 which is at least twice the length, i.e. extension, of the flange 14 along the longitudinal axis so that the position of the lateral 12 can be determined later and the lateral can positioned in the right level compared to the production zone. The lateral tubular assembly comprises a second part 38 abutting the flange 14 along the circumference of the recess 16 and forming the remaining part of the circumference and thereby fixates the flange in the predetermined position and presses the flange against the recess. The second part may be substituted by a second lateral tubular assembly arranged opposite the first lateral tubular assembly in the same recess, as shown in Fig. 5C.
As can be seen in Fig. 1, the downhole system 100 further comprises two annular barriers 20. Each annular barrier 20 comprises a tubular metal part 21 for mounting as part of the well tubular metal structure 4, and the tubular metal part has a first expansion opening 22 and an outer face 23. The annular barriers 20 further comprise an expandable metal sleeve 24 surrounding the tubular metal part 21 and having an inner face 25 facing the tubular metal part and an outer face 26 facing a wall 27 of the borehole 2. Each end 28 of the expandable metal sleeve 24 is connected with the tubular metal part 21, thereby defining an annular space 29 between the inner face of the expandable metal sleeve and the tubular metal part. The expandable metal sleeve 24 is configured to expand by allowing pressurised fluid to enter into the annular space 29 through the first expansion opening 22. The lateral section 6 is arranged between the two annular barriers 20. An annular barrier may also be arranged between an intermediate casing 41 and the well tubular metal structure 4, thereby sealing off a first annulus 42.
The recess in the lateral section 6 may be formed after the well tubular metal structure 4 comprising the lateral tubular assembly has been submerged into the borehole 2 so that the lateral section does not comprise a recess when submerged, as shown in Fig. 5A. In this way, the laterals 12 can be made at a later stage, as shown in the 5B, e.g. by machining or drilling the recess 16 and drilling the through-bore 10 from the recess to the outer face of the tubular part 7 in an angle to the longitudinal axis. The drilling process is continued to make the laterals 12. Then, each lateral tubular assembly 11 is arranged in a recess 16 so that the flange 14 is received in the recess 16, as shown in Fig. 5C, and the pipe section 32 extends into the lateral 12. Subsequently, a lateral tubular metal structure 31 is run into each lateral 12 and arranged in connection with the lateral tubular assembly 11 of that lateral, as shown in Fig. 5D. Each lateral tubular metal structure 31 comprises two annular barriers 20 in order to isolate a production zone 101. The lateral tubular metal structure 31 comprises a flow section 43, e.g. an inflow section, through which production fluid can flow into the lateral tubular metal structure or a frac port out through which pressurised fluid may flow to provide fractures in the formation of the production zone.
After submerging the well tubular metal structure into the borehole 2, the well tubular metal structure 4 is pressurised and the annular barriers 20 are expanded substantially simultaneously.
By fluid or well fluid is meant any kind of fluid that may be present in oil or gas wells downhole, such as natural gas, oil, oil mud, crude oil, water, etc. By gas is meant any kind of gas composition present in a well, completion, or open hole, and by oil is meant any kind of oil composition, such as crude oil, an oil- containing fluid, etc. Gas, oil, and water fluids may thus all comprise other elements or substances than gas, oil, and/or water, respectively.
By a casing, well tubular metal structure or lateral tubular metal structure is meant any kind of pipe, tubing, tubular, liner, string etc. used downhole in relation to oil or natural gas production.
In the event that the tool is not submergible all the way into the casing, a downhole tractor can be used to push the tool all the way into position in the well. The downhole tractor may have projectable arms having wheels, wherein the wheels contact the inner surface of the casing for propelling the tractor and the tool forward in the casing. A downhole tractor is any kind of driving tool capable of pushing or pulling tools in a well downhole, such as a Well Tractor®.
Although the invention has been described in the above in connection with preferred embodiments of the invention, it will be evident for a person skilled in the art that several modifications are conceivable without departing from the invention as defined by the following claims.

Claims

A downhole system (100) for completing a well (1) having a borehole (2) and a top (3), comprising:
- a well tubular metal structure (4) arranged in the borehole, having a longitudinal axis (5), and

- a lateral section (6) comprising a tubular part (7) mounted as part of the well tubular metal structure, the tubular part having a first part section (8) having a first outer diameter (OD₁), and a second part section (9) having a second outer diameter (OD₂), the second outer diameter being larger than the first outer diameter and the second part section comprising an angled through-bore (10) extending downwards, away from the top,
wherein a lateral tubular assembly (11) extends at least partly through the through-bore and downwards, away from the top and forms a lateral (12) from the tubular part.
A downhole system according to claim 1, wherein the lateral tubular assembly has a flange (14).
A downhole system according to claim 2, wherein a sealing element (15) is arranged between the flange and the tubular part.
A downhole system according to any of the preceding claims, wherein the second part section has a recess (16) and the through-bore extends from the recess to an outer face (17) of the second part section.
A downhole system according to claim 4, wherein the recess is configured to receive the flange of the lateral tubular assembly.
A downhole system according to claim 4, wherein the second part section has the recess when submerged into the well or the recess is made after the second part section has been submerged into the well.
A downhole system according to claim 4, wherein the second part section has a first area (18) comprising the recess and the through-bore, and a second area (19) without the recess and the through-bore, and the first area has an inner diameter (ID_R) larger than an inner diameter (ID_2A) of the second area.
A downhole system according to claim 7, wherein the first area has a wall thickness (t₁) which is equal to or larger than a wall thickness (t₂) of the first part section.
A downhole system according to any of the preceding claims, further comprising at least one annular barrier (20), the annular barrier comprising:
- a tubular metal part (21) for mounting as part of the well tubular metal structure, the tubular metal part having a first expansion opening (22) and an outer face (23),

- an expandable metal sleeve (24) surrounding the tubular metal part and having an inner face (25) facing the tubular metal part and an outer face (26) facing a wall (27) of the borehole, each end (28) of the expandable metal sleeve being connected with the tubular metal part, and

- an annular space (29) between the inner face of the expandable metal sleeve and the tubular metal part, the expandable metal sleeve being configured to expand by allowing pressurised fluid to enter into the annular space through the first expansion opening.
A downhole system according to any of the preceding claims, further comprising a lateral tubular metal structure (31) in connection with the lateral tubular assembly.
A downhole system according to claim 10, wherein the lateral tubular metal structure comprises at least one annular barrier (20).
A completion method for completing a well (2) comprising the downhole system (100) according to any of the preceding claims, the method comprising the steps of:
- providing the well tubular metal structure in the borehole,

- providing the angled through-bore in the second part section, and

- inserting the lateral tubular assembly in the angled through-bore.
A completion method according to claim 12, further comprising the step of providing a recess (16) in the second part section around the through-bore.
A completion method according to claim 13, wherein the step of providing the recess is performed by machining or aciding.
A completion method according to claim 13, further comprising the step of arranging a flange (14) of the lateral tubular assembly in the recess.