RU2733238C1 - Bracket for well conductor suspension in cellar - Google Patents

Abstract

FIELD: oil and gas industry.SUBSTANCE: invention relates to oil and gas industry, in particular, to equipment for suspension of well conductor for cementing in case of cellar pit, and can be used in construction of directional wells. Bracket for the conductor of the well conductor in the cellar pit is a housing with a central hole, wherein the housing is made of two adjacent symmetrical parts A and B. Each symmetrical part consists of lower 1 and upper plate 2, which by welding are interconnected by axial 3 and intermediate ribs rigidity 4, the latter converge to central hole generatrix 6. Axial stiffeners 3 are located in the plane of connection of parts A and B and have lugs 5, in which tightening pins 7 with nuts are installed. Coaxial holes for pins 12 are located on edges of upper 1 and lower 2 plates and are equipped with pipe inserts 16.EFFECT: creation of reliable device for suspension of well conductor in cellar pit, which provides reduction of time for construction of directional wells.5 cl, 8 dwg

Description

The invention relates to the oil and gas industry, in particular to equipment for hanging a conductor of a well for cementing in the case of using a back-hole, and can be used in the construction of directional wells.

Known unloading pipe, installed on a pipe string, containing a pipe on which the unloading sleeve is screwed, the latter is made with a ledge in the inner cavity, on which a suspended centralizer with a ledge on the outer surface and cementing holes is fixed (utility model patent RU No. 193562, publ. 05.112019).

The closest technical solution adopted for the prototype is the wellhead equipment, which contains sequentially placed column head, bottom flange, body with side outlets, upper flange, coil, tee, while devices for suspension of technological strings are installed in the upper and lower flanges, and the side outlets of the body and the tee are connected with locking and measuring devices. The device for suspending the process column is made in the form of a sub connected through a coupling with the process column. O-rings are installed between the column head, bottom flange, body, top flange, coil and tee. The known device has a housing with a central hole, in the housing there are coaxial holes for pins (patent for a useful model RU No. 141765, publ. 10.06.2014).

Despite the many known solutions for suspending wellhead equipment, none of them can be effectively used to suspend a surface conductor in a borehole during the construction of directional wells. This significantly increases the construction time of directional wells, because requires additional downhole operations and increased waiting time for cement to set to release the derrick or rig lifting device.

The technical objective of the claimed invention is to create a reliable device for suspending a wellbore conductor in a borehole, which reduces the construction time of directional wells by reducing operations and providing the possibility of releasing the lifting device of the derrick and / or drilling rig to move it until the end of cementing.

The technical problem is achieved by the fact that the bracket for suspending the conductor of the well in the borehole, made in the form of a body with a central hole for the coupling for the conductor, in the body there are coaxial holes for the pins, characterized in that the body is made of two adjacent symmetrical parts that are detachably connected to each other. with the other, each symmetrical part consists of a lower and an upper plate, which are permanently connected to each other by axial and intermediate stiffeners, the axial stiffeners are located in the plane of the detachable connection of symmetrical parts to each other and have lugs for installing fasteners, and intermediate stiffeners are made converging to the generatrix of the central hole, and the coaxial holes for the pins are located at the edges of the upper and lower plates of the symmetrical parts.

In addition, the coaxial holes for the studs are equipped with pipe inserts.

Fasteners that provide a detachable connection of symmetrical parts with each other are preferably tie rods.

Comparison of the proposed technical solution with the prototype shows that it differs in the following features:

- the body is made of two symmetrical parts, which are detachably connected to each other;

- each part consists of a bottom and top plate;

- plates are permanently connected to each other by axial and intermediate stiffeners;

- intermediate stiffeners converge to the generatrix of the central hole;

- axial stiffeners, located in the plane of the detachable connection of symmetrical parts, have lugs for installing fasteners;

- coaxial holes for pins are located at the edges of the upper and lower plates.

Therefore, we can assume that the proposed technical solution meets the criterion of "novelty".

The invention can be implemented using known technological processes, therefore, it meets the criterion of "industrial applicability".

Drilling and casing the interval under the direction is carried out to prevent losses of drilling fluid and washout of the wellhead during drilling under the surface. Direction is the traditional solution for wellhead stability. However, according to the requirements of regulatory documents, it is allowed to drill wells for existing projects without taking into account directions. Modern technology can significantly increase the running speed of drilling the interval under the surface, and, consequently, reduce the risk of wellhead washout. In the claimed technical solution, drilling and fixing operations are excluded from the well construction cycle, which significantly reduces the time for well construction. To this end, the applicant has proposed the claimed bracket design, which can be used when using a back-hole when cementing a surface conductor.

The claimed device is illustrated by the following drawings and figures.

Figure 1 shows the installed claimed device assembled without tie rods and without tube inserts.

FIG. 2 shows one symmetrical part of the device - general view from the left in isometric.

FIG. 3 shows one symmetrical part of the device - a general view on the right.

FIG. 4 shows one symmetrical section of the device without the top plate.

FIG. 5 shows the position of the claimed device relative to the conductor and I-beams (main view).

FIG. 6 shows the position of the claimed device relative to the conductor and I-beams (section in isometric view).

FIG. 7 shows a bottom view of the installed bracket (isometric).

FIG. 8 shows the results of calculating the von Mises stress of the structure with the inventive bracket.

The claimed device is a housing with a central hole, and the housing is made of two adjacent symmetrical parts A and B (Figs, 1,2,3,4). Each part consists of a lower 1 and an upper plate 2, which are welded together by axial 3 and intermediate stiffeners 4, the latter converging to the generatrix 6 of the central hole. Axial stiffening ribs 3, located in the plane of connection of parts A and B, have lugs 5, into which tie rods 7 with nuts are installed. Coaxial holes for pins 12 are located at the edges of the upper 1 and lower 2 plates and are equipped with pipe inserts 16.

Work on the installation of the bracket for suspending the well conductor is carried out in the following order (Fig. 5.6): using the auxiliary winch of the drilling rig (not shown in the figure), the metal base 8 is laid on the dump of the well pad 9. On the metal base 8, support I-beams are placed 10 and 11 with pre-installed bracket. For this, the symmetrical parts A and B of the bracket are suspended on I-beams 10, 11 with the help of fastening plates 13 and pins 12 with the possibility of free movement along them. After deepening the interval for the conductor and lowering the conductor, under the clutch 14 of the conductor 15, symmetrical parts A and B of the bracket are inserted from both sides, which are pulled together by tie rods 7 through the lugs 5. Then all the pins 12 are evenly tightened with nuts. I-beams 10,11 are centered and fixed on the metal base 8, all stud connections are finally pulled. Thus, the conductor 15 is slowly, with the control of subsidence, unloaded onto the I-beams 10,11, then the conductor is cemented in the usual mode. At the end of the cementing process, the casing head and BOP are installed, and further work on the well construction is continued.

Dismantling of the suspension device is carried out at the OZTs of the production string, or when moving to the next well. Stud connections are loosened, the bracket is removed from the jig. Further, with the help of an auxiliary winch, the I-beams and the metal base are dismantled, the whole structure is moved to the next well.

Tests of the bracket showed that the arrangement of axial 3 and intermediate 4 stiffeners in the bracket ensures the strength of the bracket and maintains its geometry (no bending of the plates was detected). Additionally, the unchanged geometry of the bracket body is provided by pipe inserts 16.

The initial data for the strength calculation were the already indicated values: the length of the casing of the casing string - 1300 m; the specific weight of the casing string of the surface conductor - 47.2 kg / m; calculated axial load Fw - 615.0 kN.

The calculation of threaded connections showed that the minimum allowable number of pins 12 for hanging the bracket was 8 pcs. М32х2, Strength class of studs not less than 5.8, strength class of nuts not less than 4.6.

With the given parameters, the values of the safety factors are: tensile k - 1.78; for thread cut k - 2.03; torsion k - 1.59; for the nut cut k - 1.54. The torque on the key to provide the force with lubrication Fw is 65.2 kgf * m.

Also, the calculation of tie-down studs was made with a transverse load Fw - 615.0 kN. The calculation showed that the minimum permissible number of tie rods 7 for connecting symmetrical parts of the bracket to each other was 4 pcs. М44х4.5, Strength class of tie rods 7 not less than 8.8, strength class of nuts not less than 4.6. With the given parameters, the safety factor for the bolt shear is k - 1.41.

To assess the strength and metal content of the structure, a finite element analysis of stresses was carried out using the Huber-Mises-Genki theory in the Inventor Professional software product. The results of the analysis of the structure with a special clamp are presented in Fig. 8

Based on the results of calculations with various boundary conditions, the following preliminary values were determined: with a span length of up to 2.5 m, the I-beam profile must be taken according to GOST 26020-83 at least 30SH1, with a span length of up to 3.5 m - 35SH1; thickness of plates 1, 2 brackets - 20mm.

As seen in FIG. 8 in the claimed bracket there are no areas of diffuse stress concentrations, only minor local stress concentrators are noted at the points of contact of individual elements (nuts, top plates and I-beams, metal base and I-beams).

As a result of patent information studies of the claimed set of signs, no signs were identified, while the claimed bracket avoids time-consuming work in the back-hole, and also makes it possible to move the drilling rig during the cementing of the conductor for drilling the next well, therefore the claimed technical solution meets the criterion "Inventive step".

The claimed design has been tested at LLC RN-Yuganskneftegaz (well No. 102VZ / K10 of the Imilorskoye field). Design of directional well 102VZ: a 245 mm casing was run to a depth of 610 m and cemented to the wellhead, a 146 mm production casing was run to a depth of 2070 m. The time spent on drilling and lowering of the casing was 28 hours. No complications were recorded during drilling under a surface conductor without direction.

The use of the inventive bracket allows you to place the supporting I-beams, on which the conductor is suspended, without immersion in the borehole. This eliminates the need to perform traditional and time-consuming operations in the borehole, further reducing the time of the technological cycle of well construction without direction. The design of the bracket allows you to release from the load only by loosening the tightening of the stud connections. These features will significantly reduce the time of assembly (dismantling) work. At the same time, the strength characteristics of the bracket ensure operation with the casing string of the surface casing with a length of 1300 m; specific gravity - 47.2 kg / m; calculated axial load F _w - 615.0 kN.

The proposed design allows you to abandon the direction and reduce the standard well construction period by 0.6 days, which leads to a decrease in costs in the amount of 649.8 thousand rubles per well (at a daily rate of 1038 thousand rubles for BU 3000 EUK). The expected increase in commercial speed for directional and horizontal wells is 470 and 115 m / stm. respectively.

Claims (5)

1. A bracket for suspending a well conductor in a borehole in the form of a body with a central hole for a conductor coupling, coaxial holes for pins are made in the body, characterized in that the body is made of two adjacent symmetrical parts, detachably connected to each other, each symmetrical part consists of a lower and an upper plate, which are permanently connected to each other by axial and intermediate stiffeners, the axial stiffeners are located in the plane of the detachable connection of symmetrical parts to each other and have lugs for installing fasteners, and the intermediate stiffeners are made converging to the generatrix of the central hole, moreover, the coaxial holes for the pins are located at the edges of the upper and lower plates of the symmetrical parts. 2. The bracket according to claim 1, characterized in that the coaxial holes are provided with pipe inserts. 3. The bracket according to claim 1, characterized in that the fastening elements for the lugs are tie rods. 4. The bracket according to claim 1, characterized in that at least two lugs are made at the edges of the axial stiffeners. 5. The bracket according to claim 1, characterized in that at least four coaxial holes for studs are made on each symmetrical part.

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