RU2430235C1 - Spring centraliser - Google Patents

Abstract

FIELD: oil and gas production. ^ SUBSTANCE: spring centraliser consists of case with end parts in form of rings and centralising ribs with holes for connection by means of fasts. Also, the fasts are made in form of tubes with internal thread and flared ends. ^ EFFECT: raised reliability and efficiency of spring centraliser implementation. ^ 12 cl, 7 dwg

Description

The invention relates to the oil and gas industry, and in particular to the field of construction of oil and gas wells, and can be used to center the sleeve and sleeveless casing of oil and gas wells of any type.

Known elastic centralizer of collapsible design, made with the possibility of assembly directly at the well and comprising two rings with retainers in the form of screws and elastic ribs in the form of arched planks, connected on the outer surface of these rings by fasteners, which are rivets of one-sided riveting or pins (see US patent No. 5097905, CL EV 17/10, publ. 24.03.1992).

The centralizer is complex in design, it is applicable mainly to sleeveless casing pipes, it has low reliability and centering efficiency of the casing, especially in bent sections of the well. The operation of the centralizer does not exclude the possibility of its parts getting into the well due to the external unreliable fastening of the arcuate slats on the rings, which limits its scope.

Known elastic centralizer collapsible design made with the possibility of Assembly directly at the well and comprising two rings having threaded holes and slots, and elastic ribs in the form of arcuate slats, the ends of which are built into the slots and connected on the outer surface of these rings with threaded fasteners, which are made with the possibility of installing rings in the threaded holes and interacting with conventional tools (hex wrench, wrench), and the threaded fasteners are elastic casing centralizer on the casing (see international application WO 2008134333, CL E21B 17/10, publ. November 6, 2008).

The main disadvantage of collapsible centralizers is the possibility of centralizer parts falling into the well, i.e. low degree of application safety. Even with the careful assembly of centralizers at the place of operation, their breakdowns are not avoided. In this case, the possibility of their parts getting into the well due to the external fastening of the arcuate slats on the rings is not excluded. It is dangerous to use such centralizers in horizontal and deviated wells in order to avoid the formation of landings (jamming) of the column during descent, which increases the cost and complicates the work of well construction.

The closest in purpose, design and used elements is a spring centralizer, comprising a housing with ring end parts and centering ribs, while the rings and centering ribs have holes for connecting them with fasteners (see US patent No. 4545436, cl. ЕВВ 17/10, publ. 08.10.1985).

The centralizer is complicated. Rings consist of segments, the assembly of which involves several types of holes, U-shaped elements, cutouts in the segments. In addition, the inevitable assembly of the centralizer at the place of operation, depending on the handling and accuracy of the user, does not exclude the corresponding danger of involuntary (accidental) loss of parts.

Thus, these well-known centralizers are not universal, do not provide safety of use, speed and ease of handling, ease and low complexity of installation on the casing.

The present invention is the creation of a new design of the centralizer, devoid of the above disadvantages.

The technical result of the invention is to create a universal reliable centralizer for sleeve and sleeveless casing strings of the well, providing safe use, installation speed, ease of handling, lightness and low complexity of installation on the casing string.

The technical result is achieved in that in a spring centralizer, comprising a housing with end parts in the form of rings and centering ribs made with holes for connecting fasteners, the fasteners are made in the form of tubes with internal thread and flared ends, at least the lower ring and lower the ends of the centering ribs are made with corresponding holes for accommodating these tubes.

Preferably, the rings, centering ribs, and fasteners are flush mounted.

It is advisable to connect the rings with the centering ribs on the inner surface of the rings.

The centering ribs are preferably made in the form of elastic arcuate planks.

The holes in at least the lower ring and the corresponding ends of the centering ribs are expediently made with a taper for the flared ends of the tubes.

Preferably, the fastening element is in the form of a hollow rivet.

It is advisable to have centralizer clamps on the casing in the form of a hollow core with an external thread for interacting with the threads of the fastener and the cutting edge on the end face for abutment in the casing, said end face having an external bevel at an angle from 25-35 degrees to the axis of the core.

Preferably, in the retainer, the end face for abutment in the casing is made with a conical recess, the larger diameter of which is made by the cutting edge, and the specified end is made with a bevel at an angle of 45-65 degrees to form a conical recess.

It is advisable to carry out the latch with a recess on the other end under the tool for screwing it into the fastener.

Preferably, the latch is configured to extend beyond the inner surface of the lower ring of the centralizer to a distance of 0.2-3 mm while resting against the casing.

The thickness of the centralizer ring must satisfy the condition Hk = (0.7 ... 1.4) Sp, where Sp is the thickness of the centering ribs.

It is advisable in the centralizer to have a ratio of height to its width of not less than 2: 1.

When conducting patent research, no solutions were found that are identical to the claimed, and therefore, the proposed solution meets the criterion of "novelty." The invention does not follow explicitly from the known solutions, therefore, the proposed invention meets the criterion of "inventive step".

Figure 1 shows a spring centralizer for sleeve casing (in section).

Figure 2 depicts an enlarged fragment A of the centralizer in figure 1 (with a tube without thread).

Figure 3 presents a spring centralizer for sleeveless casing (in the context).

Figure 4 depicts an enlarged fragment B of the centralizer of figure 3 (with tubes having a thread).

Figure 5 shows the Centralizer retainer on the casing (in section).

Figure 6 shows the Centralizer retainer on the casing (left side view).

In Fig.7 shows the connection of the clamp with the thread of the tube in the centralizer of Fig.3.

Spring centralizers can be made in two versions:

- without fixation on the casing;

- with fixation on the casing using clamps or fixing screws.

The spring centralizer includes a housing with end parts in the form of lower and upper rings 1, 2 and centering ribs 3, made in the form of elastic arcuate planks of a given profile and section, the number of which can be from 4 to 16. In figures 1, 3 are presented centralizers six centering ribs 3. The lower and upper rings 1, 2 and centering ribs 3 have corresponding through holes for installing special hollow rivets - fasteners in the form of tubes 4 (figure 2) with flared ends and in the form of tubes 5 (figure 4) with a break with curved ends and internal thread 6. These holes are partially made with a taper at an angle of (a) 10-45 degrees in the lower and upper rings 1, 2 and in the lower and upper ends of the centering ribs 3 for the flared ends of the corresponding tubes 4, 5. The lower and the upper rings 1, 2 are connected to the centering ribs 3 on the inner surface of these rings 1, 2.

Spring centralizers (Fig. 1) can be effectively used without fixing on a casing equipped with couplings (not shown in Fig.), And fasteners in the form of tubes 4 are used in them.

In the spring centralizer (Fig. 3) for the sleeveless casing, the fasteners connecting the lower ring 1 to the lower ends of the centering ribs 3 are made in the form of tubes 5, and the fasteners connecting the upper ring 1 to the upper ends of the centering ribs 3 are made in the form tubes 4. At the same time, the centralizer is equipped with clamps 7 (for mounting it on the casing) in the form of a hollow core with an external thread 8 for interacting with the thread 6 of the fastener and the cutting edge 9 at the end to abut the casing. In the retainer 7, the end face for abutment in the casing pipe is made with a conical recess 10, the larger diameter of which is made by the cutting edge 9. To form the cutting edge, this end face has an external bevel at an angle (β) of 25-35 degrees to the axis of the shaft 6 and a bevel under angle (φ) 45-65 degrees for the formation of a conical recess 10. The latch 7 is made with a hole 11, in particular, a rectangular shape on its other end under the tool (in particular, a key) for screwing it into the tube 5 and has a length that allows exit of its end face with a cutting edge 9 beyond the inner surface of the lower ring 1 at a distance (L) from 0.2 to 3 mm to abut the casing. The latches 7 are made of material, including steel, whose hardness is greater than the hardness of the casing material. On centralizers for casing, depending on their diameter, three to six clamps are installed.

In this case, spring centralizers for couplingless casing strings are possible, in which the upper ends of the centering ribs 3 can be connected to the upper ring 2 by any known method, including welding (not shown in Fig.). For reliability of the centralizer case, the thickness of the centralizer rings must satisfy the condition Нк = (0.7 ... 1.4) Sср, where Sср is the thickness of the centering ribs. The ratio of the height of the centralizer to its width is at least 2: 1. Spring centralizers are designed for high-quality centering of the casing (from casing pipes with diameters from 73 to 508 mm) during cementing and are made of high-quality sheet steel. The casing is centered due to the specified spring properties of the centering ribs in the form of arched centralizer bars.

Spring centralizer (figure 1) without fixing on the casing works as follows. Before the descent into the well, it is put on the casing (not shown in FIG.). It has the possibility of axial movement from the coupling to the coupling and rotation around the column pipe, which contributes to better passability during descent into the well. It is lowered together with the pipe string into the well section where cementing is required. The design of the centralizer with an elongated streamlined shape and secret connection of all elements of its body allows for descent without landing, i.e. ensure high traffic, since the centralizer during descent moves as if sliding in the well.

Spring centralizers (figure 3) with fixation on the casing using the clamps work as follows. A spring centralizer is mounted on the casing in a predetermined location. Fasten the lower ring (shell) 1 spring centralizer. Insert a key, for example a tetrahedral key, into the corresponding square hole 11 of the retainer 7 and make several turns, screwing them into the holes of the tubes 5 until the sharp cutting edge 9 cuts into the casing material. Rearrange the key to the hole 11 of the next retainer 7. Thus, uniformly tighten all the retainers 7. Performing the retainer 7 hollow with a sharp cutting edge allows you to reliably fix the centralizer on the casing coupling. The upper ring (shell) 2 is not fixed.

The use of centralizers allows you to get a uniform gap between the casing and the walls of the well, which eliminates the possibility of cross-flow flows (complete insulation with cement stone without gaps), and, therefore, significantly extends the life of the well. It is possible to use the proposed centralizers in wells with a borehole curvature intensity of more than 5 degrees per 10 meters. In addition, the small width and profile of the centering ribs provide the most complete replacement of the drilling fluid with cement in the annulus along its entire length.

The proposed centralizer has a simple safe design, as well as high performance in wells of any type, including those with a curved profile, since high-quality centering eliminates the possibility of the pipes adhering to the walls of the wellbore. The centralizer installation time on the casing is not more than 1 minute. The centralizer has an optimal metal consumption, ensures the creation of a uniform cement ring around the casing.

Claims (12)

1. Spring centralizer, comprising a housing with end parts in the form of rings and centering ribs made with holes for connecting fasteners, characterized in that the fasteners are made in the form of tubes with internal thread and flared ends, at least the lower ring and lower the ends of the centering ribs are made with corresponding holes for accommodating these tubes. 2. The centralizer according to claim 1, characterized in that the rings, centering ribs and fasteners are made with the possibility of a secret connection. 3. The centralizer according to claim 2, characterized in that the rings are connected to the centering ribs on the inner surface of the rings. 4. The centralizer according to claim 1, characterized in that the centering ribs are made in the form of elastic arcuate planks. 5. The centralizer according to claim 1, characterized in that the holes in at least the lower ring and the corresponding ends of the centering ribs are made with a taper for the flared ends of the tubes. 6. The centralizer according to claim 1, characterized in that the fastener is a hollow rivet. 7. The centralizer according to claim 6, characterized in that it is provided with centralizer latches on the casing in the form of a hollow core with an external thread for interacting with the thread of the fastener and a cutting edge at the end for abutment in the casing, said end face having an external bevel under angle from 25-35 ° to the axis of the rod. 8. The centralizer according to claim 7, characterized in that in the retainer the end face for abutment in the casing is made with a conical recess, the larger diameter of which is made by a cutting edge, said end having an external bevel at an angle of 45-65 ° to form a conical recess. 9. The centralizer of claim 8, characterized in that the latch is made with a recess on the other end under the tool for screwing it into the fastener. 10. The centralizer of claim 8, characterized in that the latch is made with the possibility of going beyond the inner surface of the lower ring of the centralizer at a distance of 0.2-3 mm with an emphasis in the casing. 11. The centralizer according to claim 1, characterized in that the thickness of the centralizer ring must satisfy the condition Hk = (0.7 ... 1.4) Sp, where Sp is the thickness of the centering ribs. 12. The centralizer according to claim 1, characterized in that the ratio of its height to width is not less than 2: 1.

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