System for sealing an annular space in a wellbore

FIELD OF THE INVENTION

The present invention relates to a method for installing an annular seal for a tubular member intended for use inside a well. When producing hydrocarbon fluids from a well, it is usually required to use a seal for the annular gap between the production pump compressor string extending inside the well and the surrounding casing or liner, or between the well wall and the casing or liner. Various types of packers are used to provide this compaction function. Conventional packers are typically pre-installed on sections of the tubular element, often called bushings, which should be included in the tubular element. Thus, when assembling the tubular element, it is required to install the tubular sections, on which the packers are pre-installed, in selected places on the tubular element, in accordance with the depth of the well on which these packers must be permanently installed. However, it turned out that the number of packers required and the depth at which they should be installed may not be known before assembling and installing the tubular element inside the well. After assembling the tubular element (or part thereof), the flexibility decreases when installing packers at the required depths in the well. In addition, pre-installed packers are usually required to be assembled on appropriate tubular sleeves in a specialized workshop, at a distance from the well. Such remote assembly can further reduce flexibility when using packers on tubular elements during assembly at the well site, taking into account the required costs of logistics.

SUMMARY OF THE INVENTION

The present invention is directed to an improved method of providing an annular seal for a tubular element for use in a well, which method overcomes the disadvantages of prior art packers and provides better flexibility when installing packers inside the well during assembly of the tubular element.

In accordance with the invention, a method for installing an annular sealant on a tubular element for use inside a well is provided, comprising:

a) providing at least one flexible sealing layer in place of the well, each sealing layer having a pair of opposing longitudinal edges moved relative to each other between an open position in which said sealing layer can be radially mounted on the tubular element and the closed position, in wherein the sealing layer extends essentially around the tubular element, the sealing layer being made of material, subject to swelling on contact with a selected fluid;

b) partial immersion of the tubular element into the well;

c) radial installation of the sealing layer in its open position on a portion of the tubular element extending above the well;

ά) transfer of the sealing layer to its closed position; and

e) further immersion of the tubular element with the sealing layer installed on it inside the well until the sealing layer is located at a selected location inside the well.

Using the method in accordance with the invention, it is ensured that during the assembly and immersion of the tubular element inside the well, the sealing layer can be installed on an already assembled section of the tubular element. Thus, increased flexibility in choosing locations within the borehole of the tubular element, where the sealing layer (s) can be installed on the tubular element. In addition, when using the method in accordance with the invention, the assembly of the tubular element from the tubular connectors becomes independent of the presence of pre-installed packers in place of the well. Logistics problems are also eliminated due to the need for distance assembly of packers on respective tubular bushings.

Preferably, step a) comprises providing a plurality of said sealing layers in place of the well, and step c) includes radially installing the sealing layers on the tubular member at mutually spaced apart locations along the tubular member.

Preferably, each sealing layer is made of a material that is subject to swelling upon contact with hydrocarbon fluids or water, for example, water from an underground formation.

To increase the area of ​​contact with the selected fluid, preferably, the sealing layer comprises a plurality of annular recesses on the outer surface of the sealing layer.

In the case where the sealing layer must be installed in the annular gap between the borehole wall and the casing or the liner, it is preferable that the sealing layer be made as long as possible to prevent fluid from passing around from the rocky soil of the formation opposite the sealing layer. In practical use, it is thus preferred that the length of the sealing layer corresponds essentially to the length of the section of the tubular element (i.e. tubular connector), on which the sealing layer is installed, minus the length of the corresponding connectors of the tubular connector. To ensure ease of handling and installation of the seal on the rig floor, it is preferable that the seal layer be formed from

- 1 008563 multiple sections of the sealing layers located next to each other. Such sections typically have a length of 0.5-2.0 m, for example about 1 m.

Brief Description of the Drawings

The invention will be described in more detail below by way of example, with reference to the accompanying drawings, in which in FIG. 1 schematically shows a well in which an embodiment of a pipeline and a sealing layer are used, used in the method in accordance with the invention;

in FIG. 2A is a schematic sectional view of the pipeline of FIG. one;

in FIG. 2B schematically shows a sealing layer prior to installation on a pipeline;

in FIG. 3 is a schematic longitudinal sectional view of a sealing layer mounted on a pipeline;

in FIG. 4 schematically shows a longitudinal section through a sealing layer mounted on a pipeline; and in FIG. 5 schematically shows part A of FIG. four.

In the drawings, like reference numerals refer to like components.

DETAILED DESCRIPTION OF THE INVENTION

In FIG. 1 shows a well 1 formed in an underground formation 2 for producing hydrocarbon fluid, well 1 has a substantially vertical upper section 1a and a substantially horizontal lower section 1b extending into zone 3 of the underground formation from which the hydrocarbon fluid is produced. Zone 3 of the underground formation has cracks, resulting in a risk of water from other formation zones (not shown) penetrating the lower section 1b of the well through cracks in zone 3 of the formation. The upper section 1 a of the well contains a casing 4 cemented into the well using a cement layer 5, and the wellhead 6 is located in the upper part of the well 1 on the surface 7. The production casing 7 extends from the lower end part of the casing 4, essentially horizontally section 1b of the well. The production tubing 9 provides fluid communication between the wellhead 6 and the production casing 7, while the production tubing 9 is suitably sealed relative to the production casing using a packer 10.

Production casing 7 contains many inflow control devices made in the form of inflow control valves 12, 13, 14, 15 located at certain intervals along the length of the casing 7. Each inflow control valve 12, 13, 14, 15 is electrically connected to the surface control center 16 through a set of control lines 18 extending along the outer surface of the production casing 7 and the inner surface of the casing 4, which makes it possible to open or close each valve 12, 13 , 14, 15 flow control from the control center 16.

Many sealing layers 20, 22, 24, 26 are located in the annular space 28 between the production casing 7 and the wall of the well section 1 b, in which the sealing layers 20, 22, 24, 26 and the inflow control valves 12, 13, 14, 15 are located alternating along production casing 7. Each sealing layer 20, 22, 24, 26 includes a material that is subject to swelling upon contact with water from the aquifer of the underground formation 2, which material is preferably an GBNA elastomer (ΗΝΒΚ, hydrogenated nitrile butadiene rubber).

In FIG. 2A and 2B show a cross-sectional view of the production casing 7 and the sealing layer 20 before installing the sealing layer on the production casing 7. The set of control lines 18 is enclosed inside the lid member 30, which is fixed to the outer surface of the production casing 7 using appropriate fastening means (not shown). The sealing layer 20 has a longitudinal section 31, forming a pair of opposite longitudinal edges 32, 34, which allow the sealing layer 20 to be installed between the open position (as shown in Fig. 2), in which these edges 32, 34 are spaced from each other, which allows radially install the sealing layer 20 in the direction of arrow 35 on the production casing 7, and the closed position (as shown in FIG. 3), in which these edges 32, 34 are located next to each other, which allows using the sealing layer 20, essentially, to cover the operational casing 7. In addition, the sealing layer 20 contains a pair of holes 36, 38 located through equal longitudinal intervals along the sealing layer 20. The holes 36, 38 of each pair are formed on the respective longitudinal edges 32, 34 so that it is possible to pass a bolt (hereinafter referred to as) through the aligned holes 36, 38 to secure the sealing layer 20 to the production casing 7. The sealing layer 20 contains a longitudinal recess 40 formed on its inner surface for installing inside it a set of control lines 18 and a cover element 30.

In FIG. 3 shows the production casing 7 and the sealing layer 20 after radially installing the sealing layer 20 on the production casing 7 so that it surrounds the production casing 7. The sealing layer 20 is clamped to the pipe with

- 2 008563 multiple nodes 42 bolt / nut, and each node 42 bolt / nut is passed through the corresponding pair of holes 36, 38.

In FIG. 4 and 5 show a sealing layer 20 and a production casing 7 in longitudinal section. Production casing 7 is assembled from a plurality of tubular connectors 44 having a standard length of approximately 10 m (30 ft), in which each sealing layer 20, 22, 24, 26 extends substantially along the entire length of the corresponding tubular connector 44 on which sealing layer 20. Each such connector 44 comprises corresponding connecting portions 48 at its opposite ends for connecting various connectors 44. The outer surface of the annular sealing layer 20 comprises a plurality of annular recesses 46 located at an equal distance from each other along the length of the sealing layer 20.

For normal operation, the production casing 7 is assembled from the corresponding tubular connectors 44 and from the corresponding short sections of the tubular element (called bushings; not shown), which include the corresponding control valves 12, 13, 14, 15. Assembly takes place at the site of the drilling of the well as the production casing 7 is lowered into the well 1. A set of control lines 18, together with the cap element 30, is supplied to the production casing 7 and firmly connected to it, simultaneously with the production casing 7 being immersed inside the well 1. Each sealing layer 20, 22, 24, 26 is then radially fixed to the production casing 7 in its required places so that inside the recess 40 is installed element 30 of the cover (and, therefore, the control line 18). The sealing layer 20 is then transferred to its closed position, in which it surrounds the tubular connector 44, and fixed to the tubular connector 20 by securing the bolt / nut assemblies 42, continuing through the corresponding pair of holes 36, 38. Other sealing layers 22, 24, 26 are assembled on the corresponding tubular connectors 44 in a similar manner. Production casing 7 is installed inside the well 1 in such a way that the sealing layers 20, 22, 24, 26 and the inflow control valves 12, 13, 14, 15 are located in zone 3 of the underground formation containing hydrocarbon fluids.

After well 1 is appropriately completed, hydrocarbon fluid flows through zone 3 of subterranean formation 3 into well section 1a, and from there through inflow control valves 12, 13, 14, 15 enter the production casing 7 and the production tubing 9. When water from the formation enters the annular space between the production casing 7 and the well wall, one or more sealing layers 20, 22, 24, 26 that come into contact with water from the formation swells until further swelling is stopped well wall. Annular recesses 46 increase the contact area of ​​the sealing layers with the formation water, thereby enhancing the swelling of the sealing layers. After the swollen sealing layers 20, 22, 24, 26 are sandwiched between the production casing 7 and the well wall, further penetration of water from the formation through the annular space will be stopped. To determine the position of the flow of water, a test is performed by successively opening and / or closing the flow control valves 12, 13, 14, 15 while measuring the flow of water from the formation. The place of inflow is determined by the observed decrease (or elimination) of water inflow from the formation as a result of the closure of one or more specific inflow control valves 12, 13, 14, 15. After determining the place of water inflow, one or more of the inflow control valves 12, 13, 14, 15 at the inflow site is closed, thus eliminating the inflow of water from the formation into the production casing string 7.

The swelling of each of the sealing layers 20, 22, 24, 26 also provides adequate sealing of the sealing layer relative to the production casing 7 and the corresponding element 30 of the cover, which prevents the penetration of fluids between the sealing layer and production casing, or elements 30 of the cover.

Instead of swelling the sealing layer as a result of contact with water from the subterranean formation, such swelling can be initiated by bringing the sealing layer into contact with the wellbore fluid based on water injected into the well.

In addition, the sealing layer may be made of a material subject to swelling due to contact with a hydrocarbon fluid, such as crude oil or diesel fuel. In such an embodiment, swelling of the sealant layer may be induced by contact with a hydrocarbon fluid from the well or by contact with a hydrocarbon fluid pumped into the well.

In addition, a hybrid system may be used that includes sections of the sealing layer that are subject to swelling due to contact with the hydrocarbon fluid, and sections of the sealing layer that are subject to swelling due to contact with water from the subterranean formation.

Instead of swelling the seal layer as a result of contact with water or oil from the subterranean formation, swelling of the seal layer can be initiated by pumping a selected fluid, such as diesel, into the well. Such a procedure has the advantage of

- 3 008563 standing in the prevention of premature swelling during immersion of the tubular element in the well.