RU2140519C1 - Device for acoustic stimulation of oil-gas formation - Google Patents

Abstract

FIELD: oil and gas producing industry; applicable in elimination of hydrate-resin-paraffin deposits in wells, increase of productivity of entire formation and also permeability of formation after drilling and repair. SUBSTANCE: device has surface control unit connected by means of cable with downhole instrument including generator, acoustic radiator and transducer. Downhole instrument is made in form of two parts interconnected by cable. Located in upper part of instrument is generator, and in lower part, transducer communicating with environment. At least one acoustic generator has, at least, one reflector coaxial to generator. Reflector has conical surface with angle at the top equalling 90 deg and facing the radiator. Distance from and face of radiator to reflector surface is selected to provide for formation of standing wave in well pipe. EFFECT: higher efficiency of stimulation on well bottom-hole formation zone and on the entire formation due to extended region of exposure to acoustic radiation. 5 cl, 3 dwg

Description

 The invention relates to the oil and gas industry and can be used to eliminate hydro-resin-paraffin deposits in wells, increase well productivity and return of the entire formation.

 Known "Device for well restoration", RF patent N 2066365, E 21 B 37/00, publ. 09/10/96, bull. N 25, which contains a striker and an elastic emitter. As a drummer, a pulsed hydropneumatic actuator is used. The emitter converts pulsed loads into molecular wave vibrations.

 The disadvantage of this device is a powerful impact on the tubing in a small enclosed space, which causes plastic deformation in the pipes and can even lead to their destruction. Efficiency is achieved due to the additional use along with molecular-wave vibrations of mechanical and chemical effects on the well. Known adopted for the prototype "Device for acoustic impact on the bottomhole zone of productive formations", RF patent N 2066970, E 21 B 43/25, publ. 01/20/95, bull. N 2, comprising a ground unit connected via a cable to a downhole tool, in which a generator and an acoustic emitter are filled with transformer oil.

 This device propagates an acoustic wave only in the axial direction, does not provide an impact on the entire bed, and, in addition, filling the emitter with oil causes a loss in acoustic power, considering this, it can be concluded that the device is not working efficiently.

 The proposed device solves the problem of increasing the effectiveness of the impact on the well, bottomhole zone and the entire bed by extending the area of acoustic impact, in addition, the device is simple in design, easy to operate and high performance.

The problem with the achievement of the technical result is solved due to the fact that the device for acoustic impact on the oil and gas reservoir contains a ground control unit connected via a cable to a downhole tool, consisting of a generator, an acoustic emitter and a sensor, and the downhole tool is made in the form of two parts connected by a cable , in the upper part there is a generator, and in the lower part communicating with the environment - a sensor and at least one acoustic emitter, which is equipped with at least one, are installed coaxial with the acoustic wave reflector having a conical surface facing the apex to the emitter with an apex angle of 90 degrees, and the distance between the end surface of the emitter and the apex of the conical surface of the acoustic wave reflector — a is selected from the conditions of formation of a standing wave in the medium by the formula :
a = nλ / 2-b,
where n = 1,2,3 ...;
λ is the wavelength
b is the inner radius of the borehole pipe.

The lower part of the downhole tool ends with an acoustic concentrator, the tip of which can be made with a disk-shaped belt designed for mechanical cleaning of the walls from deposits;
the lower part of the downhole tool ends with an echo sounder;
the lower part of the downhole tool communicates with the environment through rectangular windows made in the wall of the body in the areas where acoustic wave reflectors are located.

 The device is illustrated by drawings.

In FIG. 1 shows a block diagram of a device;
In FIG. 2 shows a general view of the device.

 In FIG. 3 shows a section along aa.

 The device consists (Fig. 1) of ground equipment 1 connected by a cable 2 to a downhole tool 3, which is divided into two parts 4 and 5 connected by a cable 6, a generator 7 is located in the upper part 4 (Fig. 2), and in the lower 5 - sensor and acoustic emitters. The lower part 5 of the downhole tool contains acoustic wave emitters made in the form of piezoceramic emitters (piezoelectric emitters) 8, 9, 10, acoustic waves reflectors 11 coaxially mounted on both sides of the piezoelectric emitters 8 and 9, having a conical surface with an apex angle of 90 degrees. facing the apex to the piezo emitters. The piezoceramic emitter 10 is mounted by means of a stud 12 together with a conical tip 13, forming an acoustic concentrator, to increase the amplitude of vibration. In the upper section of the borehole unit part 5, an acoustic vibration sensor 14 is located. FIG. 3 shows the location of the rectangular windows in the body of part 5 of the downhole tool, which contribute to reducing radiation power losses.

The distance - a (Fig. 2) is selected from the condition of the formation of a standing wave in the space between the piezo-emitter 9, the reflector 11 and the wall of the downhole pipe 15 according to the formula:
a = nλ / 2-b,
where n = 1,2,3 ...;
λ is the traveling wavelength;
b is the inner radius of the borehole pipe.

The length of the traveling wave is determined by the formula:
λ = vT or λ = v / ν,
where T is the period of oscillation,
v is the propagation velocity of an acoustic wave, depending on the properties of the medium of its density, elasticity, etc., it is determined experimentally or from available reference data,
ν is the oscillation frequency.

 For example, when the frequency of the generator supplying the piezoelectric emitters is 20-30 kHz, the propagation velocity of the acoustic wave is v = 1800 m / s and the inner radius of the pipe is b = 0.05 m, the distance a = 0.04-0.01 m at n = 2.

 The device provides insulation of all elements that meets the requirements of spark protection, as well as ensuring reliable operation in the presence of temperature fluctuations and aggressive environments.

 The device operates as follows.

 The downhole tool 3, which is completely mounted and connected to the ground equipment, is tested for operability, while the ground equipment 1 operates in the diagnostic mode and gives a message about the nature of the malfunction or confirms the possibility of operation. After that, it is lowered into the well and power is turned on. All piezoelectric emitters 8, 9 and 10 and the sensor 14 work simultaneously. The acoustic concentrator 13 vibrates, acting like a punch, and ensures the device moves down the well, destroys and simultaneously scrapes the paraffin layers from the tubing walls with a disk-shaped belt made on its surface (not shown in the drawing shown). The separation of the immersed device into two parts 4 and 5, connected by a flexible cable 6, allows this design to move along the curved sections of the tubing. The sensor 14 signals to the ground equipment 1 about the penetration of acoustic waves. Feedback through the sensors provides the correction of the optimal mode of exposure to the medium according to the intensity and time of acoustic radiation.

 Ground-based equipment 1 takes into account information from other sensors about environmental parameters, namely: temperature, pressure, oil or gas consumption, etc. (not shown in the drawing). The immersed device 3 can be equipped with a head echo sounder, which will control the distance from the device to the bottom of the well and will avoid an impact on the bottom. Vertical acoustic waves that emanate from piezoelectric emitters 8 and 9 are reflected “turned” by reflectors 11 by 90 degrees, turning into horizontally directed acoustic waves, and form additional radiation zones, thus increasing the area of acoustic impact. When transmitting and under the influence of energy from piezoelectric emitters 8 and 9 in the form of a “deployed” horizontally directed acoustic wave, the frequencies of the medium begin to oscillate, and the medium itself heats up. Since the wall of the tubing 15 is an obstacle to the propagation of the wave, then there is an overlap (interference) of the direct and reflected waves having the same frequency and amplitude. An acoustic wave passes the path a + b = nλ / 2, the length of which is a multiple of half the length of the acoustic wave, which is a condition for the formation of a standing wave. At certain points in time, the amplitudes of the direct and reflected waves add up. Between the antinodes of the particle velocities, deformation nodes appear, a standing wave is formed, doubling the displacement of the particles of the medium. Thus, a mechanical change in the state of the medium occurs, the hydro-resin-paraffin layer is destroyed and the yield of oil or gas is increased. The design of the device allows, due to the formation of a standing wave, to increase the rate of destruction of the paraffin layer, and therefore, to accelerate the processing of the well and make it highly efficient without increasing the generator power. An increase in the amplitude of acoustic radiation causes a cavitation phenomenon in the medium, which is accompanied by a sharp short-term increase in pressure, and contributes to intensive cleaning of the tubing walls.

 The path length a + b will be the same from any point on the end surface of the piezoelectric transducer, since the conical surface of the reflector has an inclination of 45 degrees to the axis of the device. The design of the device provides a mode of formation of a standing wave in areas with different diameters of the well pipes. In the tubing section, the standing wave mode is ensured by the path length a + b in the direction: piezoelectric transducer 8 - reflector 11 - inner wall of the tubing 15. After passing through the tubing section 5 by the device 5, a similar process occurs in the space bounded by the casing, and a similar effective acoustic effect is carried out by the second piezoelectric transducer 9, along the path a + b, selected from the calculation of the formation of a standing wave in the direction: piezoelectric transducer 9 — reflector 11 — inner wall of the casing (not shown).

 When they enter the perforation zone, both piezoelectric emitters 8 and 9 begin to operate in the traveling wave mode, which propagates in the horizontal direction and penetrates far into the reservoir through the perforation, affecting the entire bed, increasing the productivity of several wells at once. In this mode, the process is optimized by varying the frequency of the emitters.

 The proposed device has an effective effect not only on the well, eliminating the hydro-resin-paraffin layer, and the bottom-hole zone, stabilizing its filtration properties, but also on the entire oil and gas bearing formation, increasing its productivity by more than 20 - 40%. The device provides an increase in the effectiveness of the impact by expanding the area of propagation of acoustic waves and high-performance operation in automatic mode using modern software, it is reliable, maintainable and does not require stopping the well. The prototypes were tested at the wells of the Fedorovskoye field in Western Siberia.

Claims (5)

1. Device for acoustic impact on an oil and gas bearing formation, comprising a ground control unit connected via a cable to a downhole tool, consisting of a generator, an acoustic emitter and a sensor, characterized in that the downhole tool is made in the form of two parts connected by a cable, in the upper part a generator, and in the lower one communicating with the environment, a sensor and at least one acoustic emitter, which is equipped with at least one reflector of acoustic waves having a conical surface b, the vertex facing the emitter, with an apex angle of 90 degrees, and the distance between the end surface of the emitter and the vertex of the conical surface of the acoustic wave reflector - and choose from the conditions of formation of a standing wave in the medium according to the formula
a = nλ / 2-b,
where n = 1,2,3 ...;
λ is the wavelength;
b is the inner radius of the borehole pipe.  2. The device according to p. 1, characterized in that the lower part of the downhole tool ends in an acoustic concentrator.  3. The device according to claim 2, characterized in that the tip of the acoustic concentrator is made with a disk-shaped belt for mechanical cleaning of deposits from the pipe walls.  4. The device according to p. 1, characterized in that the lower part of the downhole tool ends with an echo sounder.  5. The device according to claim 1, characterized in that the lower part of the device communicates with the environment through rectangular windows made in the wall of the housing in the areas where acoustic wave reflectors are located.

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