RU2700425C2 - Device for pressure testing of pipe string in well - Google Patents

Abstract

FIELD: oil, gas and coke-chemical industries.

SUBSTANCE: invention relates to oil and gas industry and is intended for pressure testing and detection of place of flow of pipe string in well, for example, tubing string lowered into production string. Device for pressure testing of the pipe string in the well includes a shut-off element equipped with a lifting cable and mating surface in the pipe string. Rope in bottom part is equipped with float with central through hole with possibility of relative movement along rope, in which below float fixed stop is installed with possibility of interaction with lower end of float. Float is equipped with instruments and is connected to the shut-off element by means of at least one breaking thread. Length of rope section between shutoff element and float is more than thread length.

EFFECT: technical result is reduction of labour input and duration of pipe string pressure testing with simultaneous detection of non-tight places of pipe string.

1 cl, 6 dwg

Description

The invention relates to the field of oil and gas production, namely to crimping a tubing string (tubing) lowered into a well.

A well-known installation for researching wells, containing a drum winch with a drive, a wire and a bypass roller (see book: Bukhalenko E.I., Vershkova V.V., Dzhafarov Sh.T. and other Oilfield equipment. Reference. - M. : Nedra, 1990, S. 286-291).

The disadvantage of this device is only the descent and lifting of the tool on the wire.

A known technological complex for geophysical research using a flexible element, including a lubricator with a bypass roller, a cover with a central through hole provided with a sealing element, a flexible element thrown through the bypass roller and passed through the through hole (see Pat. RF No. 2491422, MKP E21B 47/01, ЕВВ 23/14, publ. 08/27/2013, bull. No. 24).

Equipping the lubricator cap with a sealing element allows sealing the tubing string and performing work in the presence of pressure in the well.

A device for crimping a pipe string comprising a sleeve with a saddle connected to the bottom of the column, a locking member responsive to the saddle, a lifting device having the ability to connect with the locking member (see Pat. RF No. 2312204, MKP E21B 34/06, E21B 17 / 00, published on December 10, 2007, Bulletin No. 34).

The disadvantages of the known device is the significant complexity and duration of the lifting of the shut-off body after crimping, as well as the inability to determine leaking pipe places.

A device for crimping a pipe string containing a locking member provided with a lifting rope, a seating surface in the lower part of the string made in response to the locking member (see Utility Model of the Russian Federation No. 29090, MKP ЕВВ 33/12, publ. 04/27/2003, bull. No. 12), which is taken as a prototype.

The technical task of the invention is to reduce the complexity and duration of crimping the pipe string with the simultaneous determination of leaks in the pipe string.

The solution to the technical problem is achieved by the fact that in the device for crimping the pipe string in the well, containing a shutoff member provided with a lifting rope and reciprocating the seating surface in the pipe string, according to the technical solution, the rope in the lower part is provided with a float with a central through hole with the possibility of relative movement along the rope, in which a fixed stop is installed below the float with the possibility of interaction with the lower end of the float, while the float is equipped with devices and is connected to by means of at least one discontinuous thread, wherein the length of the portion of the rope between the locking member and the float is greater than the length of the thread.

The design of the device for checking the tightness of the tubing string in the well is illustrated in the drawing.

In FIG. 1 shows a general diagram of a device without a float;

In FIG. 2 - site seal rope (wire) at the wellhead;

In FIG. 3 - design of a prefabricated locking body;

In FIG. 4 is a General view of the locking body with a float;

In FIG. 5 - embodiment of the locking element;

In FIG. 6 - embodiment of the locking body streamlined shape with a conical supporting sealing surface;

A device for checking the tightness (crimping) of a pipe string 1 (Fig. 1), for example, a tubing string (tubing), contains, for example, a compression sleeve 2 connected by a threaded connection (not shown in Fig.) To the bottom of the pipe string 1 equipped with a saddle 3, for example, with a conical supporting-sealing surface 4. The device is equipped with a locking body 5, made, for example, with a spherical supporting-sealing surface, freely lowered and raised on a flexible element 6, for example, on a rope or wire along the channel of columns s of pipes 1. Lifting rope 6 is passed, for example, through a central through hole (not shown in FIG.) of cover 7 (FIG. 2) of the wellhead. The cover 7 is provided with a sealing element 8 and a pressure nut 9. Next, the rope 6 goes around the bypass pulley 10 and is connected, for example, to the drum 11 of the lifting winch 12.

The locking body 5 with a spherical supporting sealing surface includes, for example, a ball 13 (Fig. 3) connected to a shank 14, for example, by means of a threaded connection (not shown in Fig.), A rope clamping device 6, including at least two crackers 15 made in the form of truncated cones and installed with the possibility of a limited conical guide (not shown in FIG.) of the axial displacement shank 14, an emphasis 16, made, for example, in the form of a pressure nut.

The device is also equipped with a pump 17 and a pressure gauge 18 installed at the pump outlet.

The pipe string 1 is lowered into production string 19.

To detect leaks, the device is equipped with a float 20 (Fig. 4), made, for example, of light plastic, with a central through hole 21 through which a rope or wire 6 is passed.

The float 6 is mounted on the rope 6 with the possibility of free movement along it, and is connected to the locking body 5 by at least one breaking thread or wire 22. In the lower part, the rope 6, below the float 20, is equipped with a stop 23 fixed with respect to the rope 6 interaction with the bottom end of the float 20. In this case, the length of the section 24 of the rope 6 between the locking member 5 and the float 20 is greater than the length of the tensile thread 22. The breaking force of the thread 22 is much less than the breaking strength of the rope 6, and significantly exceeds the lifting force of the float 20. Pop the bench is equipped with a device 25, for example, an echo sounder, for recording and / or transmitting a signal about the presence of leaks and the depth of immersion of the float 20.

The locking body 5 (Fig. 5) can be performed as a single part.

The locking body 5 (Fig. 6) can be made with a conical supporting-sealing surface, and the supporting-sealing surface 4 of the saddle 3 can be made in the form of a torus. The length of the locking member 5 is greater than the inner diameter of the pipe string 1, for example, by at least 30%.

Pressure testing and leak detection of a tubing string lowered into the well is carried out as follows.

After flushing the well, a locking member 5 connected to the lower end of the cable 6 is lowered into the inside of the pipe string 1 (Figs. 1 and 4). The cable 6 is preliminarily passed through the central hole in the cover 7 (Fig. 2), the sealing element 8 and the pressure nut 9 .

Rigid fastening of the rope 6 to the locking body 5 is carried out by means of clamping crackers 15 (Fig. 3) and emphasis 16.

Under the action of gravity, the locking member 5, and the float 20 connected to it, overcoming the drag and pressure drop caused by the movement of fluid through the gap between the surfaces of the ball 13 of the locking member 5, the float 20 and the pipe string 1, are lowered. Reaching

bottom of the column, the locking member 5 with a spherical surface is seated on the supporting-sealing surface 4 of the seat 3. The duration of lowering the locking member 5 to the seat 3 depends on the difference in the diameters of the pipe string 1 and the locking member 5, its mass, and also the density and viscosity of the liquid.

Taking into account the resistance flowing through the gap between the locking member 5 and the pipe string 1, as well as the drag, the lowering speed of the locking member can be determined by the formula

The lowering speed of the locking element on the tubing (excluding the lifting force acting on the float) is determined by the formula

where ρ, ρж - respectively, the density of the material of the locking device and the liquid;

m is the mass of the locking device;

g = 10 m / s - acceleration of gravity;

C is the drag coefficient;

F is the largest cross-sectional area of the locking member;

F, Fш - the passage area of the pipe string and the gap between the locking device and the pipe wall;

ξ is the coefficient of local resistance in the gap (sudden narrowing and expansion).

With an inner tubing diameter of 50 mm, a maximum diameter of the closure 44 mm, the mass of the closure m = 1.1 kg, C = 0.2, ξ = 1, ρ = 7.85 g / cm3, ρzh = 1 g / cm3, speed lowering of the locking member is V = 0.9 m / s.

With the length of the pipe string 1 N = 1000 m, the duration of free lowering of the shut-off member 5 will be t = H / V = 1000 / 0.9 = 1111 s = 18.5 min.

In order to increase the lowering speed of the locking member 5, liquid can be supplied to the pipe string 1 by the pump 17 with a hermetically closed cover 7.

We determine the required volume of fluid to increase the pressure to P = 10 MPa in the tubing string with an inner diameter of d = 50 mm and a length of H = 1000 m

V = V0P / E = 1962xl0 / 2000 = 9.8 dm3,

where V0 = 0.785d2H = 0.785x0.502xl0000 = 1962 dm3 is the internal volume of the pipe string;

E = 2000 MPa is the modulus of elasticity of water.

When using the extracted shut-off element, the required volume of liquid for crimping during initial full filling with the liquid of the well does not exceed 10 dm3 per 1000 m of pipe with a diameter of 50 mm and with an increase in pressure to 10 MPa. Therefore, to test the pipe string, a low-capacity pump can be used, up to the hand pump, provided that the well is completely filled with liquid.

It should be said that in case of incomplete filling of the well, the fluid can be supplied without pressure, by free filling.

After the locking member 5 is seated on the saddle 3, the gap between the rope 6 and the hole in the cover 7 (FIG. 2) is sealed by pressing the sealing element 8 by nut 9. To increase the pressure in the cavity of the pipe string 1, pump 17 feeds liquid into the internal cavity of the column. The pressure is controlled by a pressure gauge 18.

After holding the pipe string 1 under pressure, and making sure the pipe string 1 is tight, the nut 7 is unscrewed with the possibility of the sealing element 8 moving away from the rope 6.

Using a winch 12, the rope 6 is wound on the drum 11.

In the presence of leaks, which is determined by the pressure drop in the pipe string, the stage of detecting leaks begins.

The winch 12 (Fig. 1) stretches the rope 6 until the stop 23 touches the float 20. Since the length of the section 24 of the rope 6 between the locking element 5 and the float 20 is greater than the length of the breaking thread (wires) 22, then the tension of the rope 6 is received by the threads 22. With a diameter of the locking element of 40-50 mm, already at a pressure of 2 MPa, the required breaking force of the locking element 5 from the seat 3 will be 2500-3900 N. Therefore, the total breaking force of the threads 22 can be selected within 150-200 N. The indicated force is much exceeds the lifting force of the float 20, not exceeding 10-30 N.

Further, the winch 12 rope 6 is stretched by a force exceeding the breaking force of the threads 22. After breaking the threads 22, the winch 12 stops, and the float with devices 25 under the action of the lifting force begins to rise up along the rope 6. The places of fluid leakage, accompanied by sound, are fixed by the devices 25. The float 20, rising to the very mouth of the well, fixes all available leak points.

Leaky places of the pipe string 1 can be determined based on the total duration of the rise of the float. Given the significant depth of the wells, the speed of the float rise can be assumed constant.

The lifting of the locking body 5 after crimping is carried out by a winch 12.

From the condition of limiting the load on the rope (wire), eliminating excessive pressure drop in the gap between the shutoff member 5 and the wall of the pipe string 1, the lifting speed of the shutoff member can be taken 4-5 m / s. Then the lifting time of the locking device will be 3-4 minutes.

The operation of the device with a locking member in FIG. 5 is similar to that described above. The execution of the locking body streamlined shape can significantly increase the speed of free lowering of the locking body 1 along the pipe string 1.

When performing the locking member 4 with a conical supporting sealing surface (Fig. 6), and the surface 4 of the saddle 3 is torus-shaped, the locking member 1 will be more deformed. The streamlined shape of the locking member 5 reduces the drag and local drag coefficients.

Thus, the proposed technical device allows for pressure testing of the tubing string quickly retrieved by the locking body with the simultaneous determination of leaks in the pipe string.

Claims (1)

A device for crimping a pipe string in a well, comprising a locking member provided with a lifting rope and reciprocating a seating surface in the pipe string, characterized in that the rope in the lower part is provided with a float with a central through hole with the possibility of relative movement along the rope, in which the float is installed below fixed emphasis with the possibility of interaction with the bottom end of the float, while the float is equipped with devices and connected to the locking body through at least one breaking thread, the length of the section of the rope between the locking body and the float is greater than the length of the thread.

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