RU2752905C1 - Method for connection and disconnection of pipe by laser beam welding - Google Patents

Abstract

FIELD: working of plastics.

SUBSTANCE: invention relates to the mining industry and can find an application in connecting plastic pipes applied during construction of boreholes used for petroleum, gas production by chemical leaching. The method includes lowering pipes into a borehole and connecting with laser beam welding when the laser beam is located in the pipe joint area and rotated around the welded or cut pipes, and lifting the pipes and disconnecting with a laser beam in a single revolution around the connection point. PVC pipes with reinforcing components, non-transparent or slightly transparent for laser emission, are used. An annular pad with the width of the laser beam made of PVC transparent to the laser beam is inserted in the area of the pipe joint over said joint. An annular cover plate is inserted in the pipe joint with a threaded flared connection into the flare and tightened by rotation on the last turn. In end-to-end connection, the annular cover plate is clamped between the pipe joints, followed by heating the annular pad until melting, the melt uniformity is visually monitored, the pipe is lowered, and the process is repeated with the next pipe. While the pipes are removed from the borehole, the pipe joint with welding is disconnected by a laser beam and the pipes are sequentially removed from the wellhead equipment.

EFFECT: reliability and strength of connection and the pipes themselves increases during work with aggressive liquids is increased.

1 cl, 3 dwg

Description

The invention relates to the mining industry and can be used to connect plastic pipes used in the construction of wells used for oil, gas and chemical leaching.

The known method of laser welding of pipes (patent RU No. 2704947, IPC V 23/348, publ. 10/31/2019, bull. No. 31) includes laser welding of metal pipes of large diameter, by creating an external working seam.

The disadvantage is the inability to use plastic pipes for welding.

There is a known method of developing an oil field (patent RU No. 2433254, IPC E21B 43/24, publ. In Bulletin No. 31 of 04/21/2010), lowering and fastening of casing pipes, lowering of production strings. When running into the well, the pipes are connected to each other by threaded connections. Disadvantages of the method: the pipes used are of high cost, and with alternating loads on the threaded pipe connections arising from temperature changes, the threaded connections lose their tightness. Inability to use for plastic pipes.

There is also known a method of drilling wells (patent RU No. 2147664, IPC E21B 7/00, 17/04, B23K 26/00, publ. In Bull. No. 11 dated 20.04.2000), including a serial connection of drill pipes when they are lowered into borehole by laser welding and sequential separation of them by laser cutting during lifting, and the laser head is aimed at the pipe joint to be welded and does not move, and the drill pipe makes one revolution around its own axis.

Disadvantages of the method: when drilling a well, the drilling rig is subjected to strong vibrations, and the drill string - to significant longitudinal and radial vibrations; this complicates the copying of the trajectory of the pipe joint to be welded by the laser beam and makes it impossible to weld without stopping the drilling. There are also no equipment and tools for laser cutting pipes. Inability to use for plastic pipes.

Known laser-arc module for orbital welding of non-rotating circular pipe joints (patent RU No. 2548842, IPC В23К 28/02, 26/30, 101/10, published in Bull. No. 11 dated 20.04.2015), containing a guide belt , a movable orbital carriage mounted on the guide belt with the ability to move along the guide belt. A joint tracking sensor, a wire feeder and a manipulator are installed on the carriage. A laser head, an arc welding torch, a video surveillance camera and a controller are installed on the transverse guide.

The disadvantage of the device is that the laser-arc module for each pipe joint to be welded must be adjusted individually. In a drilling rig, this takes a long time, increases the cost of well construction and reduces labor productivity. Inability to use for plastic pipes.

The method of connecting and disconnecting pipes for the extraction of bituminous oil and a device for laser welding and cutting during the implementation of the method (patent RU No. 2630327, IPC Е21В 43/24, publ. 07.09.2017, bull. No. 25) was selected as a prototype. pipes into a borehole with a laser-welded connection when the laser beam is located in the pipe joint zone and rotates around the pipes being welded or cut and pipes are lifted with a laser beam in one revolution around the joint, the welding or cutting laser beam is located in the pipe joint zone when rotating around the pipes being welded or pipes to be cut, the pipes are joined end to end, the pipe welding process is repeated until all pipes to be welded are lowered into the well, when the pipes are removed from the well, the first pipe from the edge is removed, rotatable at the cutting speed and removed from the wellhead equipment.

The disadvantage of this method is that the method is used for metal pipes, this increases the cost of well construction and there is an impossibility of using it for wells with corrosive liquids. Inability to use for plastic pipes.

Disclosure of the invention.

The technical objectives of the proposed invention are to increase labor productivity during well construction, reduce costs due to the use of cheaper PVC (polyvinyl chloride) pipes and increase the reliability of pipe strings when using chemical and corrosive well fluids.

Technical problems are solved by the described method, including lowering pipes into a well with a laser-welded joint when the laser beam is located in the pipe joint zone and rotates around the pipes being welded or cut and the pipes are lifted with a laser beam disconnected in one revolution around the joint.

What is new is that PVC pipes (polyvinyl chloride) are used with amplifying components that are opaque or weakly transparent for laser radiation, in the pipe joint area, over which an annular gasket is inserted with the width of a PVC laser beam, transparent for the laser beam, while the pipe joint is a socket joint, an annular gasket is inserted into the socket and tightened by rotation at the last turn, and when connected to a joint, the annular gasket is clamped between the pipe joints, after which the annular gasket is heated until melting, visually control the uniformity of the melt, lower the pipe and repeat the process with the next pipe, and when removing pipes from the well, the pipe joint with welding is disconnected with a laser beam and sequentially removed from the wellhead equipment.

The technical result consists in increasing labor productivity during well construction, reducing costs due to the use of cheaper PVC (polyvinyl chloride) pipes and increasing the reliability of the pipe strings when using chemical and corrosive well fluids.

Implementation of the invention.

The inventive method is illustrated with the help of Figures 1, 2, 3, which show (Fig. 1) connections of PVC pipes, threaded coupling (a) and non-coupling (b) (socket) (1) and (Fig. 2) butt joint.

An external pipe thread is cut at both ends of the pipe coupling 1, and the corresponding internal thread in the coupling 2 (Fig. 1, a). In the second case, an upset 3 is made at one end of the pipe and an internal pipe thread is cut in it (Fig. 1, b). The weak point of the casing, both in terms of tensile strength and tightness, is the threaded pipe connection. Sealing of threads in light operating conditions is ensured by sealing lubricants, for example, "Sealant" grease. For harsh operating conditions and especially for gas wells and wells under liquid pressure, this is not enough. Therefore, it is necessary to use laser welding (2, 3).

High quality, reproducibility and total absence of solvents - joining plastic parts using a laser has many advantages and replaces classical methods such as bonding, ultrasonic or vibration welding in various industries. In addition, when joining parts with a laser, the weld seam can be adapted to any new workpiece geometry. Welding seams are of consistently high quality. In this case, the obtained seams have a strength that corresponds to the strength of the base material. There are usually four types of laser welding of synthetic materials: contour, quasi-synchronous, synchronous and stencil welding. Typically, when welding plastics, laser power up to 300 watts is used.

Butt welding (Fig. 2) is a well-known technological process, which is carried out by pressing against each other two oppositely directed end surfaces of two parts to be joined, and these adjoining ends of the parts are heated to a softening or melting temperature so that their contact under pressure makes it possible to obtain immediately welded seam of satisfactory quality.

With rare exceptions, only polymeric materials of the same chemical composition can weld well together. In addition, the materials should have a similar melt flow rate (MFR). In practice, this means that when the surfaces to be welded are heated, the molten material of both parts should have approximately the same fluidity. The color of polymeric materials, as a rule, is determined by the introduction of an insignificant amount (in percentage) of a chemically neutral pigment.

PVC-U (2) casing pipe is quite common due to its high strength and high resistance to chemicals. Welding methods of connecting pipes in a casing have a positive effect on strengthening the strength and tightness of the structure. Plastic pipe can be made of polyvinyl chloride (PVC), low pressure polyethylene (HDPE) and polypropylene (PP). Plastic takes side loads well and is corrosion resistant.

Polyvinyl chloride (PVC) belongs to thermoplastic synthetic materials. Depending on the polymerization conditions, products of various degrees of polymerization with different physicochemical properties are formed. PVC-based materials are produced in two types:

- using a plasticizer (plasticized PVC);

- without the use of a plasticizer (not plasticized PVC-U). PVC is a polymer, 56% of the weight of which is chlorine. When using special additives, the material becomes well processed and usable. With the help of additives, a wide range of characteristics can be obtained and adapted to the intended application. There are two grades of PVC material. Soft PVC obtained by adding plasticizers (such as phthalates). Rigid PVC, the so-called unplasticized PVC-U, is used in the production of pipelines. PVC-U is an amorphous thermoplastic. The characteristics of PVC-U cast elements are highly dependent on the composition of the composite, but also on the technology. Unpainted PVCVC undergoes destruction (decomposition) under the influence of ultraviolet radiation, therefore it is painted with opaque paints.

When laser welding (3, 4) of synthetic materials, two types of thermoplastic synthetic materials are connected by the transmission method: the laser beam passes through the transparent part and heats the absorbing one. Absorbent plastic melts the transparent area of the joint. For sufficient heat transfer, the parts to be joined must be pressed against each other using a suitable fixing device. In this case, the gap should be as small as 150 µm as possible.

Since many weldable thermoplastic plastics absorb only a small fraction of the laser radiation from solid-state lasers, additional materials (additives) such as carbon black are added. This enables the melting and welding of these thermoplastics using laser radiation. The welding force is provided by pressing the workpiece against the contour clamping mask or special glass.

Ytterbium fiber lasers emitting wavelengths of 1064-1070 nm have already been used to weld transparent and dark colored polymer combinations or where special additives have been included to improve absorption in one or both of the polymers for welding. The 2μm wavelength fiber laser is directly absorbed by many polymers, making it possible to efficiently weld plastic / clear plastic combinations and other color combinations. Clamping requirements for assembly to be welded are relaxed due to the more uniform heating achieved on both sides of the weld. Welding with a thulium fiber laser is usually carried out using a laser beam, with optics designed for an output power of 2 μm CW (usually in the range from 50 to 200 W) (3, 4).

To achieve a strong connection, PVC pipes with reinforcing components are used in accordance with (7) TU 2248-002-51758796-2008 (introduction of stabilizers - lead carbonate salts, calcium stearate) opaque or slightly transparent for laser radiation, therefore, an annular a gasket made of a material transparent to radiation (usually PVC without additives - Wikipedia - "Polyvinyl chloride (PVC, polyvinyl chloride, vinyl, vestolite, hostalite, vinnol, corvik, sicron, geon, nippon, sumilite, lukovil, helvik, norvik, etc. - colorless, transparent plastic, vinyl chloride thermoplastic polymer "). When exposed to laser radiation, a heated layer is formed on the contact surface of the annular gasket transparent for laser radiation and the pipe surface of an opaque material, which melts the surrounding material and fuses it (3, 4, 5). Transparent PVC is characterized light transmittance up to 88% The technical implementation is illustrated in Fig. 2, 3.

In fig. 2 shows a diagram of the location of a transparent gasket when welding pipes into a joint 5. When joining into a joint, an annular gasket 4 is clamped between the joints of pipes 5, after which the annular gasket 4 is heated, which ensures the passage of a laser beam to an opaque surface 5 for heating and melting.

Figure 3 shows the welding of threaded pipe joints 1 with a sleeve connection 6 and a sleeveless connection into the socket 7. In the area of the pipe sleeve connection 1-6, an annular gasket 4 is inserted with the width of a PVC laser beam, transparent for the laser beam. With a sleeveless threaded socket connection 7 into the pipe joint 1, the ring gasket 4 is inserted into the socket 7 and tightened by rotation on the last turn, heats up and melts, ensuring surface welding.

Welding and hardening of the ends of threaded joints with laser radiation provides additional strength and sealing for critical sections of wells. The reverse cutting process is provided by evaporation and destruction of the weld section with an O-ring that is transparent to laser radiation, allowing the pipe sections to be reused.

Welding of threaded connections provides additional strength and sealing of connections, the ability to use existing stockpiles of pipes and the possibility of repairing existing wells.

The proposed method is of great national economic importance, will reduce the cost of drilling and increase the productivity of the existing well stock (6).

It becomes possible to quickly repair the emergency fleet with the restoration of the debit of the product.

Literature.

1. Catalog of threaded connections, www.tmk-group.com.

2. VST magazine, No. 2, 2017, A.A. Romanov. Use of PVC-U casing.

3. ANALYTICAL PORTAL OF THE CHEMICAL INDUSTRY, Laser welding of plastics, Gordon Graff, http://www.omnexus.com

4. IPG Photonics Corporation handout, www.ipgphotonics.com.

5. WELDING OF PLASTIC (OR PLASTIC, POLYMER) PRODUCTS, ADR-Technology company, www.adr-t.ru.

6. Sinev SV Models of the drilling process // Oil and Gas Business. 2009. No. 2.

7.TU 2248-002-51758796-2008.

Claims (1)

A method of connecting and disconnecting pipes by laser welding, including lowering pipes into a well with a laser welding connection with the location of the laser beam in the pipe joint area and rotating around the pipes being welded or cut and lifting the pipes with a laser beam disconnecting in one revolution around the connection, characterized in that PVC pipes are used with reinforcing components, opaque or slightly transparent for laser radiation, in the area of the pipe joint, over which an O-ring is inserted with the width of a PVC laser beam, transparent to the laser beam, while the pipe joint is inserted into the bell is tightened by rotation at the last turn, and when butt-joint, the ring gasket is clamped between the pipe joints, after which the ring gasket is heated to melting, visually monitors the uniformity of the melt, the pipe is lowered and the process is repeated with the next pipe, and when the pipes are removed from the well, they are disconnected by a laser beam, the pipe joint is welded and sequentially removed from the wellhead equipment.

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