RU2379463C1 - Centraliser for additional casing string centralising inside main casing string and its manufacture method - Google Patents

Abstract

FIELD: oil-and-gas industry.

SUBSTANCE: centraliser for additional casing string cementation inside of a main casing string, includes cylindrical case with blades, fixed with fixers on its surface and equipped with top and bottom cants. The cylindrical case executed as a pipe of the additional casing string, and fixers as a top and a bottom rings with conical external surfaces, interacting with blades cants and stiffly fixed on the pipe. The centraliser manufacturing method includes the cylindrical case with blades manufacture, and its installation between sleeves as a part of the additional casing string, at that the cylindrical case made as a pipe of the additional casing string, and install blades with the top and bottom cants on the pipe surface, clamping blades cants from the top and the bottom with the fixer rings conical surfaces, which are stiffly fixed on the cylindrical case surface, after that fix it between the additional casing string pipes. The centralizer for additional casing string centralising inside of a main casing string and its manufacture method allows decrease metal consumption, because the pipe of the additional casing string used as the cylindrical case, and centralizers crosscut profile area decrease allows to use them as a part non-sleeved additional casing string , keeping well pas through diametre at a large.

EFFECT: centraliser's blades dislocation on the pipe itself increase between blades channels throughput capacity, which allows to decrease pumping in cement flow resistance and increase cementation quality.

2 cl, 2 dwg

Description

The invention relates to the oil industry, and in particular to centering non-weldable devices for centering an additional casing string of pipes, including clutchless pipes, lowered into the main casing string.

The well-known "Centralizer" (see US patent No. 6435275, IPC ЕВВ 17/10, publ. 08/20/2002), comprising a cylindrical body made of polyamide with inclined ribs made of polyamide fixed on its surface, with an inner diameter of the cylindrical body larger than the outer diameter centered casing, with the diameter of the forming ribs smaller than the inner diameter of the centered casing.

The disadvantages of this centralizer are:

firstly, the centralizer ribs are located at large angles with respect to the generatrix of the cylindrical body, which complicates the passage of fluid along the casing;

secondly, the direction of inclination of the ribs is not oriented relative to the direction of rotation of the pipes when making up the additional casing string, which can cause a turning moment when mounting the casing string.

The closest in technical essence and the achieved result is "Centralizer for centering an additional casing string inside the main casing string" (see patent RU No. 2263760, IPC 7 ЕВВ 17/10, publ. Bull. No. 31 dated 10.11.2005), including cylindrical a polyamide casing with at least 4 ribs, channels between the ribs, with an inner diameter of the cylindrical body larger than the outer diameter of the centered casing string, with a diameter forming ribs smaller than the inner diameter of the centered string, while the ribs are located us angle of 10-20 ° with respect to the cylinder body, and the direction of inclination of ribs is adapted to the deviation of fluid flow in fluid flow channels at the bottom upwards in the pipe direction of rotation when screwing the secondary casing.

A method of manufacturing centralizers consists in manufacturing a cylindrical body with inclined ribs fixed to the body along the inner plane.

The disadvantages of this centralizer and method of its manufacture are:

firstly, high material consumption, since the cylindrical body and ribs are made of polyamide;

secondly, a large cross-sectional area of the centralizer, which significantly narrows the borehole cross section after descent of an additional small-diameter string into the worn main casing;

thirdly, a small capacity of intercostal canals, which increases the flow resistance of the injected cement and impairs the quality of cementing.

The objective of the invention is to reduce the consumption of materials and reduce the cross-sectional area of the centralizers, which will allow them to be used as a part of a sleeveless additional pipe string while maintaining a larger bore of the additional pipe string in the well, as well as an increase in the throughput of intercostal channels, which will reduce the flow resistance of the injected cement and will improve the quality of cementing.

The problem is solved by a centralizer to center the additional casing inside the main casing, including a cylindrical body with ribs fixed on its surface with clamps and equipped with upper and lower bevels.

What is new is that the cylindrical body is made in the form of an additional casing string pipe, and the latches are made in the form of upper and lower rings with conical inner surfaces interacting with the bevels of the ribs and rigidly fixed to the pipe.

This problem is also solved by the method of manufacturing a centralizer, including the manufacture of a cylindrical body with ribs and installing it between the couplings as part of an additional casing.

What is new is that the cylindrical body is made in the form of an additional casing string pipe, and the ribs with upper and lower bevels are installed on the pipe surface, pressing the bevels of the ribs from above and below with the conical surfaces of the retainer rings, which are rigidly fixed to the surface of the cylindrical body, after which they are fixed with couplings between the pipes of the additional casing string.

The essence of the proposed method is as follows.

During the operation of the wells, its casing is worn out (3-4 violations along the entire length of the casing), for example, due to corrosion or poor-quality cementing during the construction of the well. In this connection, the need arises to restore the well’s working capacity, therefore an additional smaller casing string is lowered into the main casing from the bottom to the mouth, which covers all intervals of casing failure. After that, the additional casing is cemented in the well, and the size of the additional casing, lowered inside the worn casing, is selected with the maximum possible preservation of the borehole cross section. The proposed design of the centralizer can be used both as a part of an additional sleeve casing string of pipes, and in a sleeveless one.

The use of a sleeveless additional pipe casing instead of a sleeve additional pipe casing can significantly save the borehole cross section. For example, if a sleeve pipe with a maximum diameter of 102 mm, equipped with centralizers with subsequent cementing, can be lowered into a worn 146 mm pipe casing, then an additional 120 mm sleeveless additional pipe pipe with subsequent cementing can be lowered into the same worn 146 mm pipe casing, followed by cementing. since in a sleeveless pipe string as a whole, the outer diameter of the string is smaller than in a conventional additional pipe casing due to the absence of couplings in its composition.

Figure 1 shows the proposed centralizer for centering an additional casing string inside the main casing string.

Figure 2 shows the proposed centralizer for centering the additional casing inside the main casing in cross section AA.

The centralizer for centering the additional casing string inside the main casing string (not shown) includes a cylindrical body 1 (see FIG. 1) made in the form of a pipe of the additional casing string (for example, a sleeveless 120 mm additional pipe string running inside 146 mm of the worn main casing columns), with ribs 2 (for example, made of steel or cast iron, aluminum), fixators fixed on its surface (for example, made of steel or cast iron, aluminum), made in the form of upper 3 'and lower 3' 'rings with conical inner surfaces 4 'and 4' ', while the ribs 2 are equipped with upper 5' and lower 5 '' bevels. The latches made in the form of the upper 3 'and lower 3' 'rings and interacting with the upper 5' and lower 5 '' bevels of the ribs 2, respectively, are rigidly fixed to the pipe 1 (for example, by welding, soldering or adhesive).

A method of manufacturing a centralizer consists in the fact that, depending on the length of the additional pipe string being lowered inside the worn casing and on the well curvature (selected for each well individually), several pipes are selected on the pipe base (for example, every fourth pipe from the pipes being lowered into the well, if there is a length of one pipe of 10 meters, with an average length of a collarless additional casing string of 2000 meters, 50 pipes are selected) from the composition of the additional casing string acting as a cylindrical Pusa 1.

On the selected pipes (see FIGS. 1 and 2) an additional casing string, which is a cylindrical body 1, is installed (threaded onto the cylindrical body 1 from one or two sides, as shown in FIG. 1), latches made in the form of upper 3 'and lower 3 '' rings, and the rings can be made (for example, of steel or cast iron, aluminum). Further, in the calculated quantity, which are made in advance, ribs 2 are prepared for installation (for example, from steel, cast iron or aluminum).

Then on the outer surface of the cylindrical body 1, parallel to the generatrix (see figure 1), place at least four ribs 2 (at an angle of 90 ° between the ribs 2). Further, the ribs 2 with the upper 5 'and lower 5' 'bevels located on the surface of the pipe 1 are pressed from above and below by clamps made in the form of rings 3' and 3 '', and the bevels 5 'and 5' 'of the ribs 2 and conical surfaces 4 'and 4' 'rings 3' and 3 '', respectively, interact with each other.

Then the rings 3 'and 3' 'are rigidly fixed (for example, by welding, soldering or adhesive) to the surface of the cylindrical body 1. The number of ribs equal to four is optimal in terms of the quality of centering and the presence of channels 6 between the ribs 2 for the passage of fluid, including cement mortar.

Next, the selected pipes (see Fig. 1) with centralizers installed along with the rest of the pipes are delivered to the well (not shown), where the couplings are fixed between the pipes of the additional casing and lowered into the well inside the worn casing (not shown) according to the plan work followed by cementing.

The proposed centralizer for centering an additional casing string inside the main casing and the method of its manufacture reduces material consumption, since the pipe of the additional casing string is used as a cylindrical body, and a decrease in the cross-sectional area of the centralizers will make it possible to use them as part of a sleeveless additional casing string while maintaining a larger diameter borehole cross section.

Placing the centralizer ribs directly on the pipe body increases the throughput of the intercostal channels, which will reduce the flow resistance of the injected cement and improve the quality of cementing.

Claims (2)

1. A centralizer for centering an additional casing string inside the main casing string, including a cylindrical body with ribs fixed on its surface with clamps and equipped with upper and lower bevels, characterized in that the cylindrical body is made in the form of a pipe of an additional casing string, and the clamps are made in the form upper and lower rings with conical inner surfaces interacting with the bevels of the ribs and rigidly fixed to the pipe. 2. A method of manufacturing a centralizer, including the manufacture of a cylindrical body with ribs and installing it between the couplings as part of an additional casing string, characterized in that the cylindrical body is made in the form of a pipe of an additional casing string, and the ribs with upper and lower bevels are installed on the surface of the pipe, pressing from above and below the bevels of the ribs with the conical surfaces of the retainer rings, which are rigidly fixed to the surface of the cylindrical body, after which the couplings are fixed between the pipes Yelnia casing.

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