RU2260117C1 - Method for reducing influence of mechanical impurities on downhole equipment operation - Google Patents

Abstract

FIELD: oil production equipment, particularly to reduce mechanical impurity effect.

SUBSTANCE: method involves providing downhole equipment with electric centrifugal pump; installing composite acoustic noise transducer composed of quarter-wave resonators under submersed electric centrifugal pump; converting low-frequency noise of submersed electric centrifugal pump into ultrasound; forming ultrasonic stationary waves in annular space between casing pipe and composite acoustic noise transducer; creating ultrasound in annular gap between casing pipe and composite acoustic noise transducer under stationary waves action upon mechanical impurity particle coagulation and depositing mechanical impurity particles on well bottom.

EFFECT: increased efficiency of wells provided with electric centrifugal pumps during extraction of liquid with high suspension particle concentration.

5 dwg, 1 ex

Description

The invention relates to the oil industry, in particular to methods for controlling mechanical impurities during the operation of submersible electric centrifugal pumps.

Known methods for protecting downhole pumping equipment, based on the separation of sand from the liquid before it enters the pump at the pump inlet, for example, sand anchors [1].

The disadvantage is that sand anchors are blocked by mechanical impurities, i.e. operation of wells in conditions of intensive removal of mechanical impurities (especially when forcing production) leads to premature failure of pumping equipment.

The closest way to the technical essence of reducing the influence of particles of mechanical impurities (fractions of the solid phase of the well production) on the operation of downhole equipment is the well-known phenomenon - acoustic coagulation in a fluid; - if this phenomenon is applied to oil production technology, in particular to combat mechanical impurities during the operation of submersible electric centrifugal pumps [2].

The disadvantage of this method (in the case of using modern methods of exciting ultrasound in pipes) is the difficulty of using ultrasonic vibrations, for example, when using the magnetostrictive method (or other methods), electricity, a cable and an ultrasonic frequency generator are required.

The objective of the invention is to ensure efficient operation of wells equipped with submersible electric centrifugal pumps in the production of liquids with a high concentration of suspended particles.

The technical result - reducing the influence of mechanical impurity on the operation of downhole equipment - is achieved by the fact that a method of reducing the influence of mechanical impurity on the operation of downhole equipment equipped with a submersible electric centrifugal pump, which includes the following operations: a) - installation of a composite acoustic noise converter from quarter-wave resonators under a submersible electric centrifugal pump ; b) - the conversion of low-frequency noise submersible electric centrifugal pump into ultrasound; c) - the formation in the annular space between the casing string and the composite acoustic noise converter from quarter-wave resonators of ultrasonic standing waves; d) - the creation by the action of standing waves of ultrasound in the annular space between the casing and the composite acoustic noise converter from quarter-wave resonators on the process of coagulation of particles of mechanical impurity, followed by their deposition on the bottom of the well.

Comparative analysis with the prototype shows that in the claimed method of reducing the influence of mechanical impurities on the operation of downhole equipment, ultrasonic vibrations are used that are converted from the low-frequency noise of the mud pump. The emitter of ultrasonic vibrations is a composite acoustic noise converter from quarter-wave resonators, which is located under a submersible electric centrifugal pump.

Thus, the present invention meets the criterion of a composite acoustic noise converter of quarter-wave resonators placed under a submersible electric centrifugal pump with the creation of standing waves, coagulation of particles of mechanical impurities and their deposition on the bottom of the well.

Thus, the present invention meets the criterion of "Novelty."

Comparison of the claimed solution with other technical solutions shows that acoustic coagulation of solid particles in a liquid is known [2]. However, it is not known that ultrasound can be created using a well.

Thus, the present invention meets the criterion of "Inventive step".

The main provisions of the physical nature of the method.

Reducing the effect of particles of mechanical impurities on the operation of downhole equipment.

1. The presence of constant low-frequency noise in the well.

2. The source of low-frequency noise is the operation of a submersible electric centrifugal pump.

3. Converting the low-frequency noise of a submersible centrifugal pump into ultrasound.

4. The conversion of low-frequency noise in the well is carried out by a composite acoustic noise converter from quarter-wave resonators placed under a submersible electric centrifugal pump.

5. The formation of ultrasonic standing waves in the space between the casing and the composite acoustic noise converter from quarter-wave resonators.

6. Using the phenomenon of the physical process of acoustic coagulation of particles of mechanical impurities (fractions of the solid phase of the borehole production) by a standing wave, followed by the deposition of particles on the bottom of the well.

We show the possibility of using acoustic coagulation of particles of mechanical impurity in well production by ultrasonic standing waves, followed by their deposition on the bottom of the well.

1. Waves and vibrational velocity.

The wave equation describing the elastic perturbation has the form / 2 /.

A particular solution to equation (1) is

where a is the displacement of a particle of the medium relative to the resting position; A is the amplitude of the bias; Ω is the angular frequency; t is time.

Expression (2) describes a plane harmonic wave of frequency f = ω / 2π propagating in the positive direction of the x axis.

Differentiating (2) with respect to t, we obtain for the particle velocity of the medium - the so-called vibrational velocity

Therefore, the amplitude of the vibrational velocity

The value of U determines the maximum speed with which particles move in the process of oscillation.

According to expression (4), the particle velocity fluctuates between this quantity and zero.

2. The interference of waves. Standing waves.

Phenomena associated with the simultaneous existence of several oscillations at some point in the medium are called interference.

Interference phenomena play an important role in the emission of sound.

A particularly important role is played by interference in the propagation of two identical waves in opposite directions. Oscillations propagating in the positive and negative directions along the x axis can be written as

Applying the addition theorem, we obtain for the resulting standing wave the expression

from which it directly follows that at the points Cos (2πх / λ) vanishes, the displacement a is identically equal to zero; this occurs when x is an odd number λ / 4. In the middle between these points are the points at which Cos (2πх / λ) is maximal in absolute value; here, the amplitude of the displacement in the standing wave is twice the amplitude in the initial traveling waves.

We find the expression for the vibrational velocity in a standing wave, differentiating the expression

Thus, the nodes and antinodes of the vibrational velocity are located at the same points as the nodes and antinodes of the bias.

3. Pressure in a standing wave.

We now turn to the question of the distribution of pressure in a standing wave. In a wave propagating in the direction of the x-axis forces, the pressure p is proportional to the change in displacement along x, i.e. value da / dx. Differentiating expression (7) with respect to x, we obtain

Thus, in a standing wave and sound pressure contains nodes and antinodes; however, the location of the pressure nodes coincides with the position of the displacement antinodes and vice versa. The pressure amplitude in the antinodes is twice the amplitude in the initial traveling waves [2].

4. Acoustic coagulation.

It has long been known that under the influence of sound vibrations between particles oscillating in a sound field, attractive and repulsive forces can arise. For spherical particles, this process was experimentally and theoretically investigated by Koenig [3] in connection with the work of Bjerkness [4]. Partially, the appearance of dust figures in Kundt tubes is based on this phenomenon.

Brandt and Freund [5] and Brand and Gideman [6] showed that under the action of ultrasonic waves in aerosols, coagulation and sedimentation of particles instantly occur.

Brandt and Freund studied the details of the process of settling particles by microphotography under illumination using the dark field method.

Based on these experiments, Brandt and Gideman distinguish two stages of coagulation. First, the particles take part in the oscillatory process and follow the motion of the fluid between the antinodes and the vibration nodes. Moreover, as a result of collisions and under the action of forces of mutual attraction, they stick together and increase in size. In the second stage, the increased particles no longer follow sound vibrations, but make random motions, and as a result of new mutual collisions and collisions with smaller particles, their sizes continue to increase, and then precipitate.

5. Coagulation of particles of a mechanical impurity in a standing wave.

Let an impurity particle with a radius R and density ρ be located in a fluid with a dynamic viscosity η oscillating with amplitude U _W and frequency f.

According to Stokes’s law [2], the friction force acting on a particle

where Δυ is the velocity difference between particles of a mechanical impurity and a liquid.

According to formula (10), the velocity of liquid particles

The motion of a particle of a mechanical impurity is described by the differential equation

or

The general solution to this equation has the form [2]

The non-periodic term represents the transient. It can be neglected, since coagulation occurs after a time when the transition process no longer has any effect.

Thus, the vibration amplitude of a particle of a mechanical impurity is equal to

The degree of particle participation in the sound vibrations of the medium (the so-called drag coefficient) in the case of a standing sound wave is determined by the relation

The ratio of amplitudes X _MP / U _W will be the smaller, the larger the radius of the particle and the higher the frequency.

Thus, for the degree of participation of a particle of a mechanical impurity in fluid oscillations, the value R ² f is decisive.

If we take the value of X _MP / U _W = 0.8 beyond the border to which particles of mechanical impurity are still carried away by sound vibrations, then from the relation

we get

The value of Z determines the degree of participation of particles of mechanical impurity in the oscillations of the liquid.

Thus, relation (18) allows one to calculate the frequencies necessary to create standing waves in order to coagulate particles of a mechanical impurity in front of a submersible electric centrifugal pump, followed by their precipitation.

According to the above provisions of the physical essence, acoustic coagulation of particles of a mechanical impurity is achieved.

Figure 1 shows the technological layout of a composite acoustic noise converter from quarter-wave resonators under a submersible electric centrifugal pump; figure 2 shows a diagram of the location of ultrasonic standing waves in the annular space between the well (casing) and acoustic noise transducer; figure 3 shows a diagram of the distribution of pressure in an ultrasonic standing wave and the movement of particles of a mechanical impurity from the antinode to the node; figure 4 shows the distribution of the vibrational velocity in an ultrasonic standing wave and the beginning of coagulation of particles of mechanical impurity in the antinode of the vibrational velocity; figure 5 shows the deposition of particles of mechanical impurities from antinodes of vibrational velocity at the bottom of the well after the acoustic coagulation process.

Figure 1 shows: 1 - a well (casing), 2 - a tubing (on which a submersible electric centrifugal pump is suspended), 3 - a submersible electric centrifugal pump, 4 - a composite acoustic noise converter from quarter-wave resonators, 5 - low-frequency noise propagation (sound) in the space between the well (casing) and the acoustic noise converter from quarter-wave resonators; 6 - downhole products (fluid).

Figure 2 shows: 1 - a well (casing), 3 - a submersible electric centrifugal pump, 4 - a composite acoustic noise converter from quarter-wave resonators, 5 - propagation of low-frequency noise (sound) from a submersible electric centrifugal pump in the space between the well (casing) and an acoustic noise converter of quarter-wave resonators; 6 - well production (fluid), 7 - vibrational velocity in an ultrasonic standing wave, 8 - sound pressure in an ultrasonic standing wave.

Figure 3 shows: 1 - well (casing), 4 - composite acoustic noise converter from quarter-wave resonators; 6 - downhole products (fluid), 8 - sound pressure in an ultrasonic standing wave, 9 - particles of mechanical impurity, 10 - movement of particles of mechanical impurity to the pressure node in an ultrasonic standing wave.

Figure 4 shows: 1 - well (casing), 4 - composite acoustic noise converter from quarter-wave resonators; 6 - downhole production (fluid), 7 - vibrational velocity in an ultrasonic standing wave, 11 - the initial stage of coagulation of particles of mechanical impurity.

Figure 5 shows: 1 - well (casing), 4 - composite acoustic noise converter from quarter-wave resonators; 6 - well production (fluid), 12 - coarse suspended particles of mechanical impurity after the process of acoustic coagulation, 13 - direction of deposition of coarse particles of mechanical impurity on the bottom of the well after the coagulation process.

An example implementation of the method.

First operation. A composite acoustic noise converter of quarter-wave resonators 4 (for example, [7]) (Fig. 1) is embedded under a submersible electric centrifugal pump 3 (Fig. 1).

The second operation. The composite acoustic noise converter from the quarter-wave resonators 4 (Fig. 1) is lowered together with the submersible electric centrifugal pump 3 on the tubing 2 (Fig. 1) into the wells (casing) 1 (Fig. 1).

The third operation. Include submersible electric centrifugal pump 3 (figure 1).

The fourth operation. Create a low-frequency spectrum of noise (sound) 5 submersible electric centrifugal pump 3 in the well (casing) 1 (figure 1).

Fifth operation. Create a composite acoustic noise transducer from quarter-wave resonators 4 from low-frequency noise (sound) 5 generated by a submersible electric centrifugal pump 3, (Fig.2) ultrasonic standing waves (with vibrational velocity 7 and sound pressure 8) over a section length equal to the length of the composite acoustic transducer noise from the quarter-wave resonators 4 (figure 2).

Sixth operation. Particles of mechanical impurity 9 (FIG. 3) are created in the annular gap between the casing (casing) 1 (FIG. 3) and the acoustic noise transducer from quarter-wave resonators 4 (FIG. 3) for their enlargement to the sound pressure node of the standing wave ( according to the expression (9)

Seventh operation. The particles of the mechanical impurity 11 (Fig. 4) are coarsened into a clot 12 (Fig. 5) at the antinode of a standing wave with vibrational velocity (according to expression (8))

The eighth operation. Precipitate 13 (FIG. 5) of coagulated particles 9 (FIG. 3) in a clot 12 (FIG. 5) of a mechanical impurity from antinodes of the vibrational velocity 11 (FIG. 4) of a standing wave under its own weight on the bottom of the well.

Field tests were carried out at well No. 668 of a cluster 684 of the Samotlor field. The content of solids in the extracted products decreased 3.4 times.

Field tests were conducted at well No. 668 of well 684 of Workshop No. 7 of the Samotlor field, the content of solids in the mined products decreased 3.4 times.

Sourse of information

1. Handbook of oil production / Ed. I.M. Muraviev. - M.: Gostoptekhizdat, 1959.V.2. - S.238-241.

2. Bergman L. Ultrasound and its application in science and technology. IL - M .: IL, 1957. - S.23-25, 489-491, 495-497 [PROTOTYPE].

3. König W., Hydrodynamisch-akustische Untersuchungen, Ann. d. Phys. (3), 42, 353, 549 (1891).

4. Bjerknes C.A. Remarques historiques sur la theori du mouvement d'un ou de plusieurs corps, de formes constantes ou variables, dans un fluide incompfessible; sur les forces apparentes, qui en resultent et sur les experiences qui s'y rattachent, Compt. Rent., 84, 1222, 1309, 1375, 1446, 1493 (1867).

5. Brandt., Über das Verhalten von Schwebstofen in schwingen Gasen bei Schall - und Ultraschallfrequenzen, Kolloid / Zs., 76, 272 (1936).

6. Brandt O., Hiedenmann E., Über das Verhalten von Aerosolen im akustischen Feld, Kolloid. Zs., 75, 129 (1936).

7. Patent RU 2109134, cl. E 21 V 43/25.

Claims (1)

A method of reducing the influence of mechanical impurity on the operation of downhole equipment equipped with a submersible electric centrifugal pump, which includes the following operations: a) installing a composite acoustic noise converter from quarter-wave resonators under a submersible electric centrifugal pump; b) the conversion of low-frequency noise submersible electric centrifugal pump into ultrasound; c) the formation in the annular space between the casing and the composite acoustic noise converter from the quarter-wave resonators of the ultrasonic standing waves; e) the creation by the action of standing waves of ultrasound in the annular space between the casing and the composite acoustic noise converter from quarter-wave resonators on the process of coagulation of particles of mechanical impurity with their subsequent deposition on the bottom of the well.

Images