Inclined conductor device

Abstract

A conductor arrangement is for a collection of subterranean wells for recovering fluids from an underground structure. A frame is provided with several conductor guides, each forming an inlet opening for a conductor in an upper portion of the frame and an outlet opening for the conductor in a lower portion of the frame. The conductor is arranged to border a portion of a borehole towards a surrounding unconsolidated mass and has been passed through the conductor guide and down into the unconsolidated mass. The conductor guides are arranged in a mutually diverging manner in the direction from the inlet opening, and each conductor is extendable by a bend, the deflection angle of the bends providing mutually parallel center axes in coupling interfaces arranged in upper end portions of the bends.

Claims

1. A conductor arrangement for a collection of subterranean wells for recovering fluids from an underground structure, in which a frame is provided with several conductor guides, each forming an inlet opening for a conductor in an upper portion of the frame and an outlet opening for the conductor in a lower portion of the frame, and the conductor, which is arranged to border a portion of a borehole towards a surrounding unconsolidated mass has been passed through the conductor guide and down into the unconsolidated mass, and the conductor guides are arranged in a mutually diverging manner in the direction from the inlet opening, and each conductor is extendable by a bend, the deflection angles of the bends providing mutually approximately parallel center axes in coupling interfaces arranged in upper end portions of the bends, wherein the conductor guide is sectioned, an upper guide element forming the inlet opening and being releasably arranged in a cut-out in the upper portion of the frame, and the upper portion of the frame being formed as a grid, the grid openings forming cut-outs which are each arranged to receive a releasable upper guide element.

2. The conductor arrangement in accordance with claim 1, wherein the conductor guides are rectilinear.

3. The conductor arrangement in accordance with claim 1, wherein the axial direction of each conductor guide diverges by 1-3 relative to the center axes of adjacent conductor guides.

4. The conductor arrangement in accordance with claim 1, wherein the cross section of the bend is identical to the cross section of the conductor.

5. The conductor arrangement in accordance with claim 1, wherein the bend is formed by an induction bending of a tubular body.

6. The conductor arrangement in accordance with claim 1, wherein the conductor and the bend are joined in a fluid-tight manner by a connecting coupling.

7. The conductor arrangement in accordance with claim 1, wherein the bend is held fixed in the upper portion of the frame by a fixing element arranged in a cut-out in the upper portion of the frame.

8. The conductor arrangement in accordance with claim 7, wherein the fixing element for holding a bend fixed is arranged in the same cut-out as the upper guide element for a corresponding conductor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In what follows, an example of a preferred embodiment is described, which is visualized in the accompanying drawings, in which:

(2) FIG. 1 shows a principle drawing of a frame placed on a seabed, in which some conductor guides are shown, several conductors having been driven down into an underlying unconsolidated mass, and two of the conductors having been extended by bends for connection to parallel risers;

(3) FIG. 2 shows a section on a larger scale of the frame with a conductor passed down through a conductor guide and connected to a bend by means of a connecting coupling;

(4) FIG. 3 shows an axial section on a larger scale through a joint between a conductor and a bend;

(5) FIG. 4 shows an alternative embodiment of the frame, in which upper and lower portions of the frame form a grid with cut-outs for receiving guide elements, and a conductor is being driven down into the unconsolidated mass;

(6) FIG. 5 shows the conductor after an upper guide element has been removed and the upper portion of the conductor is being driven down towards a lower guide element;

(7) FIG. 6 shows a phase in the connection of conductors and bends in the frame according to FIG. 4, in a side view; and

(8) FIG. 7 shows a conductor arrangement prepared in the frame according to FIG. 4.

DETAILED DESCRIPTION OF THE DRAWINGS

(9) A frame 1 which is arranged to rest stably on a sea floor 61 is provided with several conductor guides 13 extending through the frame 1 from an upper portion 11 to a lower portion 12, an upper guide mouth 131 being arranged in the upper frame portion 11 and a lower guide portion 132 forming a lower end of the conductor guide 13. The conductor guides 13 are rigidly attached to the frame 1, diverging relative to each other in the direction from the upper guide mouths 131 by an angle of 1-3. In the exemplary embodiment shown in FIG. 1, the conductor guides 13 are sloping more and more the longer their distances from the centre of the frame 1, but it lies within the scope of the invention for the sloping to be arranged in a different manner. The internal diameter of the conductor guide 13 corresponds to the external diameter of a corresponding conductor 2 which is to be passed through the conductor guide 13 with a prescribed clearance in accordance with dimensional tolerances for the conductor 2 and conductor guide 13 and in accordance with the directional precision prescribed by the operator for the collection of boreholes. A person skilled in the art will have knowledge about acceptable tolerances.

(10) The frame 1 is placed on the sea floor 61 over an unconsolidated mass 6. To a person skilled in the art, it will be obvious to provide the frame 1 with means (not shown) providing for the frame 1 to lie stably and in a prescribed orientation, for example horizontally. The design of the frame 1 may depend on the nature of the seabed, for example when it comes to evenness, gradient of slope and firmness.

(11) A conductor 2 which is to be arranged in the unconsolidated mass 6 in a manner known per se in order to border an upper portion of a borehole (not shown) towards the unconsolidated mass 6 is passed through a conductor guide 13 which thereby provides for the conductor 2 to be placed in the unconsolidated mass in a prescribed direction relative to other conductors 2. The conductor 2 is positioned by driving or rotating in a rectilinear movement, for example.

(12) The upper end 21 of the conductor 2 projects above the frame 1. A bend 3 with a deflection angle corresponding to the slope of the conductor 2 is connected to the conductor 2 by means of a connecting coupling 4. In an upper end portion 31, the bend 3 is provided with a coupling interface 32 (see FIG. 2) for connection to a riser 5. The coupling interface 32 may be a prior-art wellhead with blow-out preventers and so on. The bends 3 of the different conductors 2 have a deflection angle which provides for the centre axis CR in the coupling interface 32 for each bend 3 to have approximately the same direction. Thereby, all the risers 5 will be approximately parallel.

(13) The bend 3 exhibits a circular cross section in its entire length. This is achieved by induction-bending for example.

(14) Here, the conductor 2 and the bend 3 are shown joined by means of the connecting coupling 4. This is shown only as an example of joining, the essential thing being that there are no substantial, internal cross-sectional restrictions in the joint. In the embodiment shown, according to FIG. 3, the connecting coupling 4 is provided with several internal grooves 41, and portions of the walls of the conductor 2 and the bend 3 have been squeezed into the grooves 41, for example by rolling.

(15) Reference is now made to FIGS. 4-7 which show an alternative embodiment of the conductor arrangement. The frame 1 is formed as a truss-work structure in which, in the upper and lower frame portions 11, 12, several cut-outs 14 have been formed, shown here as openings in crossbarred upper and lower frame portions 11, 12.

(16) The cut-outs 14 are arranged to receive sectioned conductor guides 13, more specifically upper guide elements 13a arranged in the upper frame portion 11 and corresponding lower guide elements 13b arranged in the lower frame portion 12. The guide elements 13a, 13b are provided with abutment portions 133 that abut supportingly against the side edges of the cut-outs 14. The guide elements 13a, 13b and the cutouts 14 are arranged in such a way that the centre axis through pipe lead-throughs 134 in guide elements 13a, 13b belonging together in a pair exhibits a prescribed angle of slope. A conductor 2 is lowered through a set of guide elements 13a, 13b and driven down into the unconsolidated masses 6 by means of a driving device known per se, for example a hammer arrangement 8. To achieve a sufficient spreading of the wells (not shown) that are to be established, it is obvious to let the axial direction of each conductor guide 13 diverge relative to the centre axes of adjacent conductor guides 13, typically by 1-3.

(17) Reference is now made to FIG. 5 in particular. The upper guide element 13a has been removed, and the upper end 21 of the conductor 2 is driven down towards the lower guide element 13b, the cut-outs 14 of the upper frame portion 11 being arranged in such a way that the hammer arrangement 8 may pass in between the cutouts 14 of the upper frame portion 11.

(18) In this embodiment of the frame 1 and the conductor guide 13, the bend 3 and the conductor 2 can be connected inside the frame 1. The corresponding cut-out 14 of the upper frame portion 11 forms an abutment for a fixing element 13c which at least gives the bend 3 lateral support. The bend 3 may be rigidly connected to the upper frame portion 11 via the fixing element 13c. Beyond the advantage of the bend 3 being given lateral support, this embodiment has the advantage of the conductor arrangement exhibiting a moderate building height substantially determined by the length of the bends 3.

(19) With a conductor arrangement according to the invention, diverging conductors 2 may be set with a great degree of precision without the use of complicated technology to guide the conductor 2 in the desired direction, for example by the conductor 2 being provided with an asymmetrical conductor shoe that gives the conductor 2 a deflection as it is driven down into the unconsolidated mass 6.