DK2821586T3

DK2821586T3 - Well complete ring of storage well

Info

Publication number: DK2821586T3
Application number: DK14170623.4T
Authority: DK
Original assignee: Rwe Deutschland Ag
Priority date: 2013-07-04
Filing date: 2014-05-30
Publication date: 2016-12-12
Also published as: ES2604126T3; EP2821586A3; EP2821586A2; PT2821586T; PL2821586T3; DE102013011156A1; EP2821586B1

Description

Borehole completion of a storage bore

The invention relates to borehole completion of a storage bore of a compressed-air cavern, comprising a standing pipe string, an anchor pipe string, a lining pipe string of a first material, and a conveying pipe string extending into the compressed-air cavern.

Such borehole completions are known in the prior art, in particular for oil and gas conveying bores in various designs (see US 3,796,044). WO 01/71157 A1 discloses a submarine borehole completion for an oil or gas conveying bore. The borehole completion described there corresponds essentially to a usual borehole completion of so-called production bores. These usually comprise a standing pipe string, an anchor pipe string and a production pipe string. Depending on the final depth of the bore, the latter may comprise a plurality of Intermediate pipe strings and a production pipe string which comprises a lining pipe string (liner) and a conveying pipe string or standing pipe string (tubing).

The usual diameter of conveying pipes in production bores is between 6 5/8 and 9 5/8 inches.

Similar borehole rounds and completions are used as the sole conveyance from salt caverns or for cavern bores for the purpose of injection and withdrawal of fuel gas. EP 1 515 128 A1 discloses a method and an arrangement for testing the impermeability of cavern bores.

In particular, caverns in salt deposits are also used as compressed-air reservoirs. Air is compressed into caverns, wherein in analogy to pumped-storage power stations during low-load times of the power network, the compressed air is withdrawn at peak load times. Efficiencies of about 70% may be achieved with such compressed-air storage caverns.

The injection and withdrawal of the compressed air may, for example, be effected via correspondingly formed bores as the connecting element between day-to-day facilities and the salt cavern.

Unlike the Injection and withdrawal of natural gas in salt caverns, it is necessary to handle higher volumetric flows when operating compressed-air storage caverns. Moreover, there are increased friction pressure losses and higher pressure-swing stress of the casing as a result of the conveyance of larger volume flows.

Finally, the borehole installations may be exposed to increased corrosion because the moist compressed air is reiatively corrosive unlike fuel gas.

The invention is based on the object of providing borehole completion of a storage bore of a compressed-air cavern, with which it is, in particular, possible to promote high compressed-air volume flows and which is suitable for increased pressure-swing stress and for conveying a corrosive medium.

The object of the invention is achieved by borehole completion of a storage bore of a compressed-air cavern, comprising a standing pipe string, an anchor pipe string, a lining pipe string of a first material, and a conveying pipe string extending into the compressed-air cavern, wherein the borehole completion according to the invention is characterized by the fact that the conveying pipe string comprises, as lining pipe shoe at its leading end in the storage bore, at least one lining pipe shoe, in each case a lining pipe section or a lining pipe shoe made from a second corrosion-resistant material, which is different from the first material, wherein the lining pipe shoe is connected to the lining pipe string via an insulating pipe sleeve of a third material, wherein the third material is different from the first and second materials.

The term “lining pipe string” is used herein for the term “liner” that is commonly used in technical jargon. The term "conveying pipe string" is used herein for the term “standing pipe siring” or “tubing” that are commonly used in technical jargon. When the term "casing" is mentioned in the following text, this term refers to the individual pipe runs or pipe strings which form the permanent cemented borehole inventory.

The so-called lining pipe or liner usually forms the last production pipe string, which is cemented in the borehole.

In particular the last cemented lining pipe string needs to fulfill special requirements with respect to collapse and internal pressure resistance, as well as corrosion resistance.

According to the Invention, therefore, it is provided that the lining pipe string with a lining pipe shoe is made of a corrosion-resistant material, which is different from the first material of the other lining pipe shoe.

In the context of the present application, at least one pipe portion or pipe section or pipe shoe, is designated as forming the leading end of the relevant pipe string.

It is particularly appropriate and advantageous if the lining pipe shoe of the borehole completion according to the invention consists of a corrosion-resistant stainless steel.

For example, an unalloyed steel may be provided as the first material.

It is particularly advantageous if the lining pipe section of the first material is coated internally with a synthetic resin, for example with a polymer.

Expediently, the annular space between the conveying pipe string and the lining pipe string is sealed off with respect to the compressed-air cavern above the lining pipe shoe so that only the lining pipe shoe is exposed to the compressed-air cavern.

In a particularly advantageous variant of the borehole completion according to the invention, it is provided that the pipe sleeve is designed as a double sleeve, each of which sleeve receives a threaded section of a pipe section.

As already mentioned above, the pipe sleeve consists of a third material, which is different from the first and second materials, so that contact corrosion between the lining pipe shoe and the rest of the lining pipe string is reliably avoided in this way.

The pipe sleeve may, for example, be designed as a double sleeve, each of which sleeve receives a threaded section of a pipe section.

In a particularly advantageous variant, it is provided that the pipe sleeve consists of a giass-fiber-reinforced polymer. The pipe sleeve may be so designed that it overlaps the pipe sections to be connected to each other in such a way that it is not subjected to any appreciable pressure-swing stresses.

The conveying pipe string may, for example, be sealed within the lining pipe string at the level of the sleeve or below the sleeve with a packer. A packer in the context of the present invention is to be understood as a ring-shaped shut-off element which may be hydraulically, pneumatically or mechanically locked. For example, a permanent casing packer may be provided as a packer. Casing packers of this type are also known in the prior art as so-called permanent packers or so-called retrievable packers.

In a further advantageous variant of the borehole completion according to the invention, It is provided that the end pipe of the conveying pipe string is inserted as an immersion pipe into the compressed-air cavern.

The conveying pipe may, for example, consist completely of a corrosion-resistant stainless steel.

In a preferred variant of the invention, the end pipe of the conveying pipe string extends into the cavern neck of the compressed-air cavern. The diameter of the conveying pipe string may be, for example, approximately 18 inches, which is relatively large compared to a standing pipe string of a petroleum production bore or natural gas production bore.

It is particularly advantageous if the annular space between the conveying pipe string and the lining pipe string is filled with a protective fluid above the seal to the compressed-air cavern. For example, a protective gas or a protective liquid may be provided as the protective fluid. Nitrogen may be considered as a protective gas, for example.

The invention is explained below with reference to an exemplary embodiment shown in the drawings.

Fig. 1 shows a schematic sectional view through a borehole completion according to the invention,

Fig. 2 shows an enlarged view of the completion shown in Fig, 1 in the region of a packer which seals the delivery pipe string, and

Fig. 3 shows an enlarged detail view of the detail 111 In Fig. 2.

Fig. 1 schematically shows a storage bore 1 of a compressed-air cavern 2. The compressed-air cavern 2 is designed as a cavern in a salt deposit, which serves for the injection and withdrawal of compressed-air. The injection and withdrawal of the compressed air is carried out via a conveying pipe string 3, which is suspended at the borehole head via a so-called tubing hanger spool. The tubing hanger spool is a steel fitting which is flanged to the borehole head in a known manner and at which the conveying pipe string 3 ends or is suspended.

The borehole head is not shown in the drawings for the sake of simplicity.

The borehole completion according to the invention comprises in a known manner, a standing pipe string 4, an anchor pipe string 5 and a lining pipe string 6.

The standing pipe string 4 is a rammed pipe string, which serves only to secure the upper sediment layers. The anchor pipe string 5 takes up the loads of the casing in a known manner.

The lining pipe string 6 is cemented in the storage bore 1.

The lining pipe string 6 is suspended in the so-called casing head, wherein intermediate pipe strings may also be connected upstream depending on the final depth of the storage bore 1 of the lining pipe string 6.

The cemented lining pipe string 6 serves primarily to stabilize the borehole and the hydraulic separation of the horizons bored by the storage bore 1. The conveying pipe string 3 is sealed within the lining pipe string 6 by means of a packer 7.

In the present case, the packer 7 is designed as a permanent packer with flexible seals. The annular space 8 above the packer 7 is filled with an annular space protection fluid, for example, an annular space protection liquid. This serves to maintain a constant pressure distribution in the annular space 8 for the protection of the casing and the cementing chamber 9. In addition, the annular space protection liquid serves to protect the inside of the lining pipe string 6 and the outside of the conveying pipe string 3. Finally, the annular space-protecting liquid acts in an insulating manner, in the sense that it allows a minimization of temperature fluctuations during the storage operation of the compressed-air cavern 2, A protective gas, for example nitrogen, may also be provided instead of an annular space protection liquid.

In the described embodiment, the lining pipe string 6 has a diameter of 20 inches over about 95% of the total installation length. This consists of a non-ailoyed steel, which has a wall thickness of 16.13 mm and is provided with a plastic coating as corrosion protection on the inside.

As may be seen in particular in Fig. 3, the lining pipe string 8 comprises a lining pipe shoe 10, which may comprise one or more pipe sections made of an alloyed stainless steel. The lining pipe shoe also has an outer diameter of 20 inches and is connected to the lining pipe string 6 with an insulating sleeve 11. The insulating sleeve 11 is designed as a double sleeve with two sleeve ends and consists of a glass-fiber-reinforced plastic. This results in a galvanic separation between the lining pipe string 8 made of non-alloyed stainless steel and the lining pipe shoe 10 made of stainless steel.

The conveying pipe string 3 has an outer diameter of 16 inches over about 90% of its installation length and is made entirely of alloyed stainless steel.

As already mentioned above, the conveyor pipe string 3 is sealed by means of the permanent packer 7 against the lining pipe string 6, wherein the packer 7 is installed approximately at the level of the insulating sleeve 11 or below the insulating sleeve 11 so that only the lining pipe string 6 is exposed to the corrosive atmosphere of the compressed-air cavern 2.

As may be seen, in particular in Fig. 1 and 2, the conveying pipe string 3 is introduced relatively far into the cavern neck 12 so that the conveying pipe string 3 may be temporarily blocked there by means of a so-called retrievable bridge plug 13, for example. A “bridge plug” is generally understood to mean a plug-like borehole closure, which may be detached and released in the manner of a packer.

List of reference numerals 1 Storage bore 2 Compressed-air cavern 3 Conveyor pipe string 4 Standing pipe string 5 Anchor pipe string 6 Lining pipe string 7 Packer 8 Annular space 9 Cementing chamber 10 Lining pipe shoe 11 Insulating sleeve 12 Cavern neck 13 Bridge plug

Claims

LIQUID COVIPLETTING OF STORAGE WELL PATENT REQUIREMENTS

A well completion of a storage well (1) of a compressed air cavity (2) comprising a standing pipe string (4), an anchor pipe string (5), a casing string (6) of a first material, and a conveyor string (3) extending into the compressed air cavern (2), characterized in that the casing string (6) comprises, as the casing shoe (10) at its front end in the storage well (1), at least one casing section of a second corrosion-resistant material different from the first material, that the casing shoe (10) is connected to the casing string (6) via a pipe sleeve of a third material and that the third material is different from the first and second materials.

Well completion according to claim 1, characterized in that the casing shoe (10) consists of corrosion-resistant stainless steel and / or the first material is non-alloy steel.

Well completion according to one of claims 1 or 2, characterized in that the casing section of the first material is coated with an artificial resin, for example with a polymer.

Well completion according to one of claims 1 to 3, characterized in that the annulus (8) between the conveyor pipe string (3) and the casing string (6) above the casing shoe (10) is sealed against the compressed air cavern (2).

Well completion according to one of Claims 1 to 4, characterized in that the pipe sleeve is designed as a double sleeve which receives a respective thread section of a pipe section.

Well completion according to one of claims 1 to 5, characterized in that the pipe sleeve consists of a glass fiber reinforced polymer.

A well completion according to any one of claims 1 to 10. 6, characterized in that the conveyor string (3) is sealed within the casing string (6) with a packer (7) at the height of the sleeve or under the sleeve, preferably the packer (7) is provided as a permanent packer.

A well completion according to any one of claims 1 to 10. 7, characterized in that the conveyor tube string (6) is inserted into the compressed air cavern (2) as a diving tube.

Well completion according to one of claims 1 to 8, characterized in that the conveyor pipe string (3) consists entirely of corrosion-resistant stainless steel.

A well completion according to any one of claims 1 to 10. 9, characterized in that the annulus (8) between the conveyor pipe string (3) and the casing string (6) is filled with a protective fluid.

A well supplement according to claim 10, characterized in that the protective fluid provided is a protective gas or a protective liquid.

Well completion according to one of claims 1 to 11, characterized in that the conveyor tube string can be closed at its front end.