RU2357067C1 - Method of well head pressurising and facility for implementation of this method - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention refers to equipment for well head pressurising and can be implemented at geophysical survey in horizontal wells with excess pressure at well head by means of geo-physical instruments connected to flow string of small diametre and lowered into well on geo-physical cable together with flow string. When instruments and pipes pass through the well head, pressurising is performed by means of a tube preventer and pipe pressurising facilities. When the geo-physical cable passes through the well head, well head pressurising is performed by means of a cable preventer and attached lubricator. Transition from pressurising with one elements of equipment to pressurising with other elements of equipment is carried out using a special three-coupling branch, arranging it so, that closed die-heads of the pipe preventer are located between two lower couplings of the branch, while the upper coupling is located above an upper flange of pipe pressurising facilities.

EFFECT: expanding functionality at performing survey of horizontal wells and increasing reliability of well head pressurising in process of survey.

5 cl, 3 dwg

Description

The invention relates to equipment for sealing a wellhead and can be used in geophysical surveys in horizontal wells with overpressure at the wellhead.

A well-known lubricator designed to provide descent and lifting of downhole tools on a cable or wire without depressurization of the wellhead ("Technical Instructions for conducting geophysical research and work on cable devices in oil and gas wells", RD 153-39.0-072-01, MERF, M., 2001, p.231-233) installed on the buffer valve of the fountain valves of existing wells. The main elements of the lubricator are an adapter for connecting to the buffer gate valve, a lock chamber for accommodating the device, consisting of sectional pipes screwed together and equipped with a pressure relief valve, and a cable sealing device (cable sealant), which is a combination of seals that insulate the lubricator cavity from the surrounding area. In addition, the lubricator may include a cable preventer for emergency shut-off of the well with a cable, having the shape of a cylinder with a pair of cylindrical dies with mechanical seals placed in it to seal the well cavity from the lubricator, a trap for indicating the device’s entry into the lubricator when lifting and preventing the device from falling into the well .

The descent of the device into the well through the lubricator is as follows. At the wellhead, closed by a buffer valve, a cable preventer is installed. A lubricator with a lock chamber and a cable with a cable lug previously passed through it is raised above the wellhead and a geophysical instrument is connected to the cable lug. The attached device is pulled into the lock chamber. The lubricator with the device in the lock chamber is mounted on the cable preventer and the pressure in the well and the lock chamber is equalized using the buffer valve and the pressure equalization device (bypass valve) of the cable preventer. The cable preventer and the buffer valve are opened and the device is lowered into the well. When lifting, the device is pulled into the lock chamber, close the buffer valve, close the cable preventer, release the pressure in the lock chamber, dismantle the lubricator. The cable preventer is also closed during repair of the lubricator and during prolonged shutdowns.

When lowering several devices connected by flexible connections, for example, cable segments, the devices are sequentially placed in a lubricator (RF patent No. 2041349 "Device for lowering devices into a high-pressure well", IPC Е21В 47/01, date of publication 09.08.1995, ), while sealing the borehole from the lock chamber is done using a cable preventer, when the flexible connection is located opposite the dies of the cable preventer.

The disadvantage of this method and device is the impossibility of their use during the descent, ascent on the cable of long geophysical instruments that do not fit in the lock chamber, assemblies consisting of several geophysical instruments connected by hard connectors, assemblies consisting of geophysical instruments and pipes, in particular pump compressor pipes (tubing), as well as devices whose diameter exceeds the size of the internal channel of the lock chamber or cable preventer.

The well-known layout of the equipment for sealing the wellhead (Handbook "Development and repair of oil and gas wells under pressure", Moscow, publ. "Nedra", 1982, S. 46-51), used by the company "Baker" for lowering and raising the pipe string . The arrangement includes a tube preventer with blind dies installed in the sequence from bottom to top, an emergency preventer with tube dies, and lower and upper working preventers, between which there is a riser forming a lock chamber. The lateral branches of the upper working preventer are in communication with the borehole and the pressure relief valves. In the upper part of the layout, the pipe sealant body is coaxially mounted.

The layout works as follows. The blind dies of the pipe preventer block the wellhead during installation and dismantling. The design of the emergency preventer with pipe dies allows for a short time to put a pipe string on its dies and replace the elements of wellhead equipment above the preventer. The riser forms a lock chamber for bypassing the elements of the column, the diameters of which exceed the diameters of the pipes. Raising the pipe string is carried out with the open emergency, pipe and lower working preventer and the closed upper working preventer until the oversized element is located in the riser (lock chamber) or until the connecting sleeve of the raised pipes stops in the dies of the upper working preventer. Then the lower working preventer is closed, the pressure in the riser (lock chamber) is vented using a pressure relief valve on the discharge, the upper working preventer is opened and the pipe string is raised to the stop of the oversized element in the dies of the lower working preventer. Next, close the upper working preventer, close the pressure relief valve on the discharge, open the valve connecting the lock chamber to the well, while the pressure in the riser (lock chamber) rises and becomes equal to the annular one, open the lower working preventer and lift the column higher, repeating the described sequence of actions . The descent of the column is carried out in the reverse order.

The disadvantage of this arrangement of the equipment for sealing the wellhead is the impossibility of using it when lowering and raising equipment on a geophysical cable.

Closest to the proposed invention in terms of technical nature and the technical result achieved is a method of sealing a wellhead using a set of equipment for washing wells (TU 00221801.002-92), designed to lower pipes under pressure and seal the mouth during erosion of hydrate-paraffin plugs in tubing with non-aggressive media . The set of equipment includes a tube preventer installed coaxially from the bottom up, which serves to seal the mouth and hold the pipe string using dies, a pipe sealant with a set of sealing elements, an upper flange for mounting a slip-on coil on it, a slip-on coil serving to hold the tubing string due to friction between spring-loaded wedges and the pipe surface from possible upward movement due to borehole pressure, as well as a clamp structurally identical to the slip-type coil and used to transmitting pushing force (holding) of the sling to the column reentry tubes. The disadvantage of this set of equipment is the impossibility of its use when lowering the assembly of instruments and pipes on the geophysical cable into the well.

To deliver an assembly consisting of several geophysical instruments connected by hard connectors (in particular, one geophysical instrument) to a horizontal well, a small diameter tubing string (33 mm or 42 mm) is used to push the instruments into the horizontal section of the well. To carry out electrical communication with the devices, an electrical communication device (UOES) is used located between the tubing string and the assembly of devices, while the cable with the cable lug is passed through the inner channel of the tubing lowered into the well before docking with a special UOES connector. The tubing string with devices is mechanically connected to the cable using a special clamp.

The aim of the invention is to improve the method of sealing the wellhead during geophysical surveys using geophysical instruments connected to a small tubing string and lowered into the well on a cable along with the tubing string.

The technical result consists in expanding the technical capabilities when conducting geophysical studies of horizontal wells under pressure, as well as in improving the reliability of sealing the wellhead during these studies, in particular, when passing through the wellhead instruments, tubing string, cable, as well as during the transition between transmission through the wellhead of instruments and tubing and passing cable through the wellhead.

The specified technical result is achieved due to the fact that after the descent into the well with the help of a tackle system, a slip-type coil and a clamp through the block of preventers and sealants (BPG) of the required number of tubing with geophysical instruments, a special three-coupling pipe is attached to the upper part of the run-out tubing, and the descent rise assemblies at the moment when between the two lower, closely located to each other couplings of a special three-coupling pipe, there are sealing dies of the BPG pipe preventer, for dig them, thus sealing the wellhead and fixing the descent pipes from axial movement, install a lubricator block on the BPG with a preliminary passed and electrically connected to the instrument assembly and mechanically with the tubing string geophysical cable, equalize the pressure in the BPG and the lubricator block, and then continue the descent into the well of the assembly of geophysical instruments and tubing string on the geophysical cable.

The device for sealing the wellhead during the descent and rise of the assembly of geophysical instruments and the tubing string into the well contains a block of preventers and sealants (BPG), a slip coil, a clamp with a plate, a lubricator block, a special three-sleeve pipe, a high pressure sleeve, valves for bleeding and pressure equalization pressure gauges.

Figure 1-3 presents a device for implementing the proposed method of sealing the wellhead.

In Fig.1 shows BPG at the time of being in its inner through channel of a three-coupling pipe.

Figure 2 shows the device in a configuration that implements a method of sealing the wellhead during the passage through it of instruments and tubing string.

Figure 3 shows the device in a configuration that implements a method of sealing a wellhead while passing through it a cable.

The block of preventers and sealants (FIG. 1) includes a bottom flange 1 installed sequentially from bottom to top, a pipe preventer 2 with sealing dies 3, a bypass valve 4, a valve 5 and a pressure gauge 6 (FIG. 2), a cable preventer 7 having a bypass valve, pipe sealants 8 and 9 and extension pipe 10 with valve 11 and pressure gauge 12, upper flange 13.

Figure 1 also shows a three-coupling pipe 14 in a position in which the lower couplings 15 and 16 are located so that between them are the dies 3 of the pipe preventer 2, and the upper coupling 17 is located above the flange 13. The three-coupling pipe 14 is used to implement the inventive method when the transition from sealing the mouth when passing through it instruments and pipes to sealing the mouth when passing through it a cable, and in the reverse transition.

To implement the method of sealing the wellhead when passing through the mouth of geophysical instruments and tubing, a slotted coil 18 is attached to the flange 13 of the device (Fig. 2), and a clamp 19 with a plate 20 is put on the tubing or device to be lowered, by means of which the pushing force is transmitted to them ( when lifting - holding force) from slings (not shown).

To implement the method of sealing the wellhead while passing a geophysical cable through it, a lubricator unit is connected to the flange 13 of the device (Fig. 3), which includes coaxially assembled cable gland 21, airlock 22, a transition pipe 23 with an attached high pressure sleeve 24, a valve 25 and a manometer 26. The high-pressure sleeve 24 is connected to the valve 5 by the other end and, when the valve 5 is opened, provides pressure equalization in the cavity over the dies 3 of the pipe preventer 2 and in the cavity of the lock chamber 22. Valve 25 serves to relieve pressure in the lock chamber 22.

The inventive method of sealing the wellhead during descent into the well on the cable assembly of geophysical instruments connected to the tubing string using the inventive device is implemented as follows:

- at the wellhead, closed with a valve, mount BPG;

- to the upper flange 13 of the BPG attach a slips coil 18;

- on the bottom of the tubing lowered into the well, a clamp 19 is fixed and an assembly of geophysical instruments is connected to it through the AEC;

- raise the assembled elements above the wellhead and lower the instruments into the well to the valve, while passing through a slip-coil and BPG;

- bring into operation a slips coil 18, a clamp 19 and other equipment for the forced lowering and lifting of pipes;

- open the central valve, switching to sealing the mouth of the pipe sealers 8 and 9, and make a descent using a slip coil, a clamp and other equipment for the forced descent of pipes, as well as a tackle system, while making the necessary extension of the tubing pipes;

- after the descent of the necessary number of tubing, the special three-sleeve pipe 14 is connected to the last one, and the process pipe 27 is connected to it and the descent is stopped at the moment when the dies 3 of the pipe preventer are between the two lower couplings 15 and 16 of the pipe 14, and the upper coupling of this pipe will be above the upper flange of 13 BPG;

- close the sealing dies 3 of the pipe preventer 2, sealing the well and fixing the pipe from unauthorized movement;

- disconnect the slip-coil coil 18 from the BPG, fix it together with the clamp 19 on the process pipe 27, disconnect the process pipe from the assembly;

- lower the cable with the cable lug, previously passed through the lubricator block, into the pipe string before docking with the AEC;

- attach the tubing string located in the well to the geophysical cable using a cable clamp;

- in place of the slip-type coil, the lubricator block is hermetically installed on the upper BPG flange 13;

- connect the high pressure sleeve 24 of the lubricator unit to the valve 5 of the tube preventer, open the valve 5, connecting the cavity of the lock chamber of the lubricator unit with the cavity above the rams of the tube preventer;

- partially open the tube preventer 2 so that the pressure balancing valve 4 is activated;

- after equalizing the pressure, the dies 3 of the pipe preventer are pushed apart, completely freeing the pipes from engagement, and the valve 5 is closed;

- continue further descent into the well of the tubing string with attached devices on the cable.

The method of sealing the wellhead when lifting the assembly of geophysical instruments attached to the tubing string from the well using the inventive device is implemented as follows:

- the movement of the instrument suspension and tubing string on the cable is stopped at the moment when the upper coupling 14 of the three-coupling pipe 13 is above the flange 10, and between the couplings 15 and 16 there are dies 3 of the pipe preventer;

- close the pipe preventer 2, open the valves 5, 25 and 11 sequentially, venting all the cavities above the rams of the pipe preventer, then close the valves 5, 25 and 11 and disconnect the high pressure sleeve 24 from valve 5;

- disconnect the lubricator from the flange 10;

- disconnect the cable from the tubing and electrical power station, remove it from the pipes;

- raise the technological tubing 26 above the wellhead with a slips coil 17 and a clamp 18 fixed to it and attach to a three-coupling pipe 13;

- attach to the flange 10 a slips coil 17, bring it into working condition, bring the clamp 18 and the rest of the equipment for the forced lowering-raising of the pipes;

- open the pipe preventer 2, moving on to sealing the mouth of the pipe sealants 8 and 9;

- carry out the lifting of the tubing string and assembly of devices using the tackle system and equipment for the forced lowering and lifting of pipes;

- stop the rise when the bottom of the device is above the central valve;

- close the central valve;

- release the pressure between the pipe sealants and in the cavity of the pipe preventer using valves 5 and 11;

- remove the bottom tubing and device from the well;

- dismantle BPG.

Downhole geophysical instruments and geophysical instrument assemblies may have dimensions that do not allow the use of the sequence of actions described above. In the event that the assembly length of the devices, including the AEC, exceeds the size for their placement in the cavity between the central gate valve and the BPG, and there may also be unsealed sections in the form of windows in which the sensors, centralizers and joints of the assembly elements are located, this method has the following implementation features:

- at the beginning of the descent process and at the end of the lifting process, the role of the tubing during sealing and retention is performed by the device body;

- in the process of pushing the devices, when the unsealed section approaches the upper pipe seal 9, stop the descent and release the pressure between the pipe sealants using valve 11;

- after venting, close valve 11 and continue to descent into the well;

- in the process of lifting devices, when approaching the unsealed section to the upper pipe seal 9, when the unsealed section is completely located between the pipe sealants 8 and 9, stop the descent and release the pressure between the pipe sealants using valve 11;

- after venting, close valve 11 and continue to rise. The distance between the pipe seals 8 and 9, which determines the length of the extension pipe 10, is chosen so that it is slightly greater than the length of any unsealed section of the assembly and less than the distance between adjacent unsealed sections.

If in the assembly of geophysical instruments there is a device that can be placed between the central gate valve and the BPG, but cannot be passed through the BPG due to the large diameter, this method has the following implementation features:

- if the large-diameter device is the only one in the assembly, then before installing the BPG, the lower tubing string is passed through the internal channel of the BPG, fix it with dies of the tube preventer, connect the geophysical device to the lower pipe through the electrical power unit, and then raise the assembled elements above the mouth, lower the geophysical device into well and connect BPG to the mouth; when lifting, after closing the central valve, the pressure is vented using valves 5 and 11, the lower tubing is fixed with the tube preventer dies, the BPG is disconnected from the mouth, the BPG is lifted from the lower tubing and the device above the wellhead and laid on the bridges, the device is disconnected from the tubing, the tubing is removed from the BPG ;

- if it is necessary to place other assembly devices above the large-diameter device, then the next assembly device plays the role of the lower tubing, while the electrical resistivity unit is connected between the upper geophysical device and the lower tubing.

Cable preventer 7 is closed when repairing an installed lubricator unit. Pipe and cable preventers are also closed during interruptions in work and in dangerous situations. Venting and pressure equalization with the help of valves is carried out only at descent stops - lifting of geophysical instruments and pipes. After bleeding and pressure equalization operations, the valves are closed. Pressure monitoring is carried out using pressure gauges.

The proposed method of sealing the wellhead and a device for its implementation uses OJSC Permneftegeofizika to conduct geophysical and hydrodynamic studies on a geophysical cable in production and horizontal wells drilled by fields of LLC LUKOIL-PERM. The equipment was manufactured at a working pressure of 35 MPa using a tubing string with a diameter of 33 mm.

Claims (5)

1. The method of sealing the wellhead during the descent, ascent into it on the geophysical suspension cable, consisting of a string of tubing and tubing assembly of geophysical instruments connected to the tubing string, comprising installing a block of preventers and sealants (BPG) at the wellhead the structure of which includes a pipe preventer, a pipe sealant and an upper flange, the use of a slip-type coil and a clamp for pushing during lowering and holding the tubing string while lifting, pressure equalization in the cavities installed equipment using bypass valves and gates, characterized in that, in order to make the transition from sealing the wellhead during the descent-lifting of the tubing string with the assembly of geophysical instruments to sealing the mouth of the well when passing through it a geophysical cable to which the tubing string is connected, and also for the implementation of the reverse transition, a special three-coupling pipe is connected to the upper pipe of the descent-raised tubing string, and it is placed at the described transitions so that between the two knowing it with the lower, closely located couplings, there are tubes of the tube preventer, and the upper coupling of the nozzle is located above the upper BPG flange, while with the tubes of the tube preventer closed when lowering it is installed (when lifting it is removed) on the upper BPG flange instead of the slip-type coil, the lubricator is preliminarily passed through it and through the internal channel of the tubing string, as well as already connected to the geophysical instrument assembly and tubing string by a geophysical cable, in order to seal the wellhead during repair Onto the lubricator, the BPG includes a cable preventer. 2. The method according to claim 1, characterized in that, in order to seal the mouth when passing through it an assembly of geophysical instruments having unsealed sections, the BPG includes an additional pipe sealant and an extension pipe connecting two pipe sealants, while the distance between the pipe sealants are chosen so that it is not less than the length of any of the unsealed sections of the assembly, and no more than the distance between any adjacent unsealed sections. 3. The method according to claim 1, characterized in that, in order to seal the wellhead during the descent, ascent into the well of a geophysical instrument having a diameter larger than the inner diameter of the through passage channel of the BPG and a length less than the distance from the BPG to the central valve , before installing the BPG at the wellhead, the bottom pipe of the tubing string is passed through the internal channel of the BPG, fix it with rams of the pipe preventer, attach a geophysical device to it, raise the assembled elements above the wellhead, lower the device into the well and attach unite the block of preventers and sealants to the wellhead. 4. The wellhead sealing device, including a block of preventers and sealants (BPG), which includes a pipe preventer, a pipe sealant and an upper flange, a slip coil, a clamp, bypass valves, valves and manometers, characterized in that the device further comprises a cable preventer as a part of BPG, a special three-coupling pipe connected to the last of the descent-lift pipes of the tubing string, and a lubricator containing at least one cable sealant, a lock chamber and a transition pipe k with attached thereto a high-pressure hose. 5. The device according to claim 4, characterized in that, in order to seal the wellhead while passing through it the assembly of geophysical instruments having unsealed sections, the BPG contains at least two pipe sealants and an extension pipe between them, the length of which is not less than the length of any of the unsealed sections of the assembly of geophysical instruments, and no more than the distance between any adjacent unsealed sections.

Images