RU2544200C2 - Method and device for generating wave field at injector bottomhole with automatic tuning of generation resonant mode - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: group of inventions is related to the oil producing industry and intended for the improvement of oil recovery of productive formations. The method for generating a wave field at an injector bottomhole with the automatic tuning of a generation resonant mode lies in the generation of pressure fluctuations in a fluid flow pumped to a productive formation through tubing strings by its pumping through the flow-excited Helmholtz resonator (FEHR). At that the respective flow rate and the FEHR volume is maintained at the cross-section of a feed nozzle. Moreover the respective flow rate at the cross-section of the feed nozzle and the FEHR volume is maintained due to the movement of its downstream rare bottom, thus increasing the FEHR volume at a reduced flow rate and reduced FEHR volume at an increased flow rate. The device used to this end consists of FEHR installed inside the tubing string; it represents a hollow cylindrical chamber with flat bottoms. In the front chamber of the bottom the feed nozzle is mounted and a discharge outlet with sharp edges is made at the rare bottom. At that the rare bottom is made movable and inside the tubing string behind FEHR there is a fixed hydraulic cylinder with a spring-supported piston connected by a rod to the movable rare bottom. At that the cavity inside the hydraulic cylinder in front of the piston is connected downstream to the inner volume of the tubing string while the cavity behind the piston is communicated to the annular space.

EFFECT: improved efficiency to maintain the stable high intensity of the wave field at the bottomhole.

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Description

The invention relates to the oil industry and is intended to increase the mobility of reservoir fluids.

There is a method of generating a wave field at the bottom of an injection well (see patent No. 2399746), in which pressure fluctuations are formed in the fluid flow pumped into the reservoir through tubing, pumping the fluid through the jet resonator.

Drops of oil and water - fluids filling the capillaries of a productive oil reservoir, have low mobility due to a number of reasons. Their movement along the formation to the production well is accelerated by drilling around several injection wells, through which various technical fluids are pumped into the reservoir under high pressure. It has long been noted by oil industry workers that pumping technical fluids into the formation with shocks promotes a better exit of fluids through the producing well. To generate pressure fluctuations in the flow of the injected fluid, a special device is used - a jet resonator that converts the kinetic energy of the flow into vibrational energy.

Liquid is supplied through injection wells to the reservoir: water, air, steam, chemicals. Tubing (tubing) is inserted into the wells, and a jet resonator is mounted at the lower end of the tubing. The fluid supplied to the reservoir is pumped through the jet resonator, which excites pressure fluctuations in the flow. These pressure fluctuations propagate in all directions in the form of acoustic waves, forming a wave field at the bottom of the well (see patent No. 212109).

Also known is a method of generating pressure fluctuations in the flow of a flowing fluid, implemented in a jet resonator (see patent No. 2077960) by pumping fluid through a jet resonator with a nozzle and an outlet with sharp edges, the volume of which is consistent with the speed of the jet at the exit of the supply nozzle.

The fluid injected into the well is fed to the inlet of the feed nozzle and a jet is formed, directed towards the sharp edge of the outlet. At the same time, local pressure perturbations are formed in the region adjacent to the sharp edge of the region, called the tone of the hole, the amplitude of which is small. If the speed of the jet is selected in such a way that the frequency of the tone of the hole coincides with the natural frequency of the chamber of the jet resonator, then resonance occurs, and the amplitude of the tone of the hole increases many times.

The disadvantage of this method is the low gain of the ring resonator.

A known method of generating pressure fluctuations in the flow of a flowing fluid, implemented in a Helmholtz jet resonator (see Morel Th article. Experimental study of a Helmholtz oscillator controlled by a jet. Translation of the VTsP No. B-56251 from J. Fluid Engineering, 1979, 101, IX, No. 3 , 383-390), in which pressure fluctuations are formed in the fluid stream pumped into the reservoir through tubing by pumping it through a Helmholtz jet resonator (SRH), and at the same time, the flow rate at the cut section is maintained in accordance nozzle and volume (AWG).

Since the nozzle passage area is constant, the jet velocity at the nozzle exit is determined by the pressure drop across the device and is determined by the flow rate of the pumped liquid. More fluid flow - more and jet velocity and vice versa. When changing the speed of the jet flowing on the sharp edges of the outlet, the tone frequency of the hole also changes, despite the fact that the resonator is tuned to a certain frequency. When the hole tone frequency deviates from the resonator natural vibration frequency, the generation amplitude decreases.

The disadvantage of this method is the narrow working range of the jet velocity.

The Helmholtz inkjet resonator is known which is closest in technical essence and taken as a prototype (see Experimental Study of a Jet-Driven Helmholtz Oscillator, J. Fluids Eng., September 1979, Volume 101, Issue 3, p.383, doi: 10.1115 / 1.3448983 , Translation of the VTsP No. B-56251 from J. Fluid Engineering, 1979, 101, IX, No. 3, 383-390), which is a hollow body of revolution, including: a shell secured between two bottoms; an inlet nozzle installed in the front, in the direction of flow, bottom; and an outlet channel coaxial with the nozzle with sharp edges, organized in the opposite, outlet bottom.

The Helmholtz ink resonator (SRH) is two flat parallel bottoms, between which the shell is clamped. Usually the shell is cylindrical, but there are square shells. At the same time, a round inlet nozzle is arranged in the inlet flat bottom, which can protrude into the chamber, and in the opposite, flat bottom outlet, a round outlet channel with sharp edges is organized. The output channel is a sharp-edged bushing installed in the bottom of the generator, or just a hole. The sleeve may also protrude into the chamber. The nozzle and the outlet channel are coaxial with respect to each other and are located on the axis of the cylindrical shell.

Local pressure disturbances are formed in the jet resonator in the region of the sharp edge of the outlet. The liquid column enclosed in the resonator is responsible for the conversion of the frequency spectrum of the acoustic wave propagating in it, with amplification of the harmonic corresponding to the natural frequency of the column. But without reflection of the incident waves, the operation of the resonator will cease. From this it follows that the amplification of waves in the cylinder occurs only in the direction along the flow, between end parallel bottoms. When propagating in the transverse direction, when reflected from a cylindrical shell, the waves scatter.

The liquid jet formed in the supply nozzle, when flowing out of the resonator, touches the sharp edges of the outlet opening with its periphery. In this case, local pressure disturbances are generated, propagating in all directions in the form of an acoustic wave. This is the so-called hole tone. The amplitude of local pressure perturbations is small, but if their frequency coincides with the frequency of the resonator’s own vibrations, then resonance occurs, and the amplitude increases by orders of magnitude.

The natural frequency of a cylindrical resonator is determined by the distance between the bottoms and to a lesser extent depends on its diameter. If the distance between the bottoms L is constant, then the jet velocity must be strictly defined, otherwise resonance is impossible. It should also be noted that the gain band of acoustic resonators is much wider than, for example, in piezoceramics, which, at the same time, has a significantly higher gain. From this it follows that there is a certain range of the flow velocity, determined by the quality factor of the resonator, within which resonance occurs. The greatest amplification of the amplitude of the hole tone occurs at the frequency of the natural oscillations of the resonator, but when the jet velocity deviates by an acceptable value, the oscillation amplitude still increases, however, with a lower gain.

The disadvantage of the Helmholtz inkjet resonator (AWG), taken as a prototype, is the inability to adjust the frequency of its own oscillations and adjust the resonance mode when changing the pressure drop across the device.

The technical result is achieved due to the fact that in the method of generating a wave field at the bottom of the injection well with automatic tuning of the resonant generation mode, in which pressure fluctuations are generated in the fluid flow pumped into the reservoir through tubing (tubing), through Helmholtz jet generator (SRG), and while maintaining in accordance with the speed of the jet at the cut of the feed nozzle and the volume of the SRG, maintain in accordance with the speed of the jet at the cut of the feed nozzle and the volume of the AWG due to the movement of its rear, in the direction of the flow, bottom, providing an increase in the volume of the AWG with a decrease in the speed of the jet and a decrease in the volume of the AWG with an increase in the speed of the jet.

In a device consisting of a Helmholtz jet resonator (SRG) installed inside a tubing (tubing) and consisting of a hollow cylindrical chamber with flat bottoms, in the front bottom of which there is a power nozzle, and in the rear bottom there is an outlet with sharp edges, the rear bottom is movable, and inside the tubing, behind the AWG, the hydraulic cylinder is fixedly mounted with a spring-loaded piston connected by a rod to the moving rear bottom, and the cavity inside the hydraulic cylinder in front of the piston, in the direction Otok is connected with the interior of the tubing and the cavity behind the piston communicates with the annular space.

The proposed method allows to maintain a stably high intensity of the wave field at the bottom of the injection well by matching the operating parameters and design dimensions of the jet resonator, while generating pressure fluctuations in the flowing fluid, and ensuring maximum gain.

 Figure 1 presents a diagram of a jet resonator with automatic tuning and hydraulic drive.

Figure 2 presents the amplitude-frequency characteristic of the acoustic resonator.

The invention consists in the following.

In the domestic technical literature, this combined device is called by the name of its part, which attracts the attention of the author more. A jet generator or a jet resonator. Although, if we talk about the resonator, then the resonator is, after all, acoustic, and not at all jet. The same mistake was made in the translation of the article by T. Morel, from which the prototype was taken. In foreign technical literature, this device is called an oscillator, but in Russian the concept of an oscillator is more often used in electronics.

It should not be forgotten that it is not the resonator body that resonates, but the column of liquid enclosed inside, although the body, of course, also sounds, but its frequency of natural vibrations is usually much lower. The resonator is passive, it only responds, i.e. enhances the pressure fluctuations created by some other device, because the column of liquid enclosed in it is almost motionless. The generator is active, it itself creates pressure fluctuations, since it contains a high-speed jet with a kinetic energy reserve.

Usually the overall dimensions of the AWG are unchanged. The resonator maximizes the tone of the hole at a strictly defined flow rate, measured at the nozzle exit. However, an increase in the flow rate of the liquid leads to an increase in the speed of the jet, and the frequency of the tone of the hole also increases, and with a decrease in the speed of the jet it decreases.

To match the speed of the jet with the volume of the resonator, it is proposed to move the bottom of the resonator to change the frequency of the natural oscillations of the resonator in accordance with the change in the speed of the jet: with an increase in the speed of the jet, the distance between the bottoms should be reduced, and with a decrease in the speed of the jet, increase. With increasing jet velocity, the tone frequency of the hole increases, and to ensure maximum amplification, the resonator’s own oscillation frequency should also be increased (see FIG. 2), for which the characteristic size of the resonator should be reduced. And vice versa: when the jet velocity decreases, the tone frequency of the hole also decreases, and the frequency of the natural oscillations of the resonator should be reduced, i.e. increase the characteristic size of the resonator.

For automatic tuning of the resonator in the tubing behind the resonator (in the direction of flow), a hydraulic cylinder is installed with a piston connected by a rod to the rear bottom of the resonator. The piston divides the hydraulic cylinder into two chambers, the rear communicates with the annulus, and the front is connected to the internal volume of the tubing.

With a calculated fluid flow rate and pressure drop across the resonator, the piston occupies a position in the middle of the cylinder. With increasing pressure in the tubing behind the resonator, the pressure drop across the resonator decreases, and the jet velocity also decreases. An increase in pressure in the tubing behind the resonator will increase the pressure in the front chamber of the hydraulic cylinder in front of the piston and cause the piston to move toward lower pressure and pull the bottom of the resonator. The increase in pressure in the tubing behind the resonator moves the piston of the hydraulic cylinder and the rear bottom of the resonator to increase the distance between the bottoms. This leads to an increase in the frequency of natural oscillations of the resonator and adjusts the resonance at the tone frequency of the hole.

You can install hydraulic cylinders on both sides of the AWG. With increasing pressure in front of the AWG and jet velocity, the piston of the front hydraulic cylinder must move the front bottom upstream to reduce the volume of the AWG and increase the frequency of natural vibrations, and with decreasing pressure in front of the AWG, move the front bottom against the flow to increase the volume of the AWG and reduce the frequency of natural oscillations. The rear hydraulic cylinder must also extend the bottoms while decreasing the pressure drop across the device and shift the bottoms as the differential increases. The installation of hydraulic cylinders on both sides of the AWG will automatically monitor all possible combinations of pressure changes in the tubing before and behind the AWG.

A device designed to excite a wave field at the bottom of an injection well includes an AWG and a hydraulic drive located inside the tubing. SRG is a hollow chamber, consisting of a cylindrical shell 1 (see figure 1) with flat bottoms at both ends. In the front (in the direction of flow) bottom 2, a nozzle 3 is installed, which is a sleeve with rounded edges at the inlet. In the rear bottom 4, a hole 5 is made with sharp input edges. Behind the AWG, a hydraulic cylinder 7 is installed with a piston, which is connected by a rod 6 with a bracket on the outside of the rear bottom of the AWG. The rear bottom itself is also a piston in shape due to the presence of a long cylindrical wall, the so-called “Skirts” designed to prevent the bottom from skewing when moving it. The movable bottom is centered in the cylindrical shell of the resonator with the help of a “skirt” with an o-ring. If both bottoms are movable, then they both represent the same piston mounted on the rod.

Behind the jet resonator, a hydraulic cylinder with a piston and two windows is fixedly installed inside the tubing. The piston divides the internal volume of the hydraulic cylinder into two parts: the part closest to the SRG of the internal volume of the hydraulic cylinder is connected A to the internal volume of the tubing, and the part farthest from the jet resonator of the internal volume of the hydraulic cylinder is connected to the annulus. If two hydraulic cylinders are installed in the tubing on both sides of the jet resonator to move both resonator bottoms, then the logic remains the same - when the pressure drop across the nozzle increases, the bottoms get closer, and when the pressure drop decreases, the bottoms move apart.

The AWG works with automatic tuning as follows. The fluid is supplied under a certain pressure through the tubing to the bottom of the well, where the AWG is installed in the pipe. The fluid enters the AWG through the power nozzle and flows out of it through the outlet in the rear bottom. In this case, a jet is formed at a certain speed, which then touches the sharp edge of the hole with its periphery, and, as a result, local small-amplitude pressure perturbations are formed in the edge region, which propagate around in the form of an acoustic wave of a certain frequency.

Since the frequency of the acoustic wave propagating in the resonator corresponds to the frequency of the natural oscillations of the liquid column enclosed inside the resonator, the amplitude of the pressure fluctuations in the liquid flow increases many times. Further, the fluid through the perforation in the tubing is fed into the reservoir and causes vibrations to vibrate in the pore space.

With an increase in the backpressure behind the SRH, the pressure drop across the device will decrease, which will lead to a decrease in the jet velocity and a decrease in the frequency of the hole tone. At the same time, an increase in pressure inside the tubing behind the AWG will cause the piston of the rear hydraulic cylinder to move further from the AWG and drag the rear bottom of the AWG along with it, which will lead to an increase in the volume of the resonator and, accordingly, a decrease in the frequency of its own vibrations. The AWG will again work in harmonized mode with a maximum gain.

When the backpressure for the AWG decreases, the opposite will happen: the jet speed will increase, the tone frequency of the hole will also increase, but the decrease in pressure behind the AWG will cause the piston of the hydraulic cylinder to move towards the resonator and bring the rear bottom to the front. This will lead to an increase in the frequency of natural oscillations of the liquid column in the resonator and adjust its operation with a maximum gain at a higher frequency.

Claims (4)

1. A method of generating a wave field at the bottom of an injection well with automatic adjustment of the resonant generation mode, in which pressure fluctuations are generated in the fluid stream pumped into the reservoir through tubing (tubing) by pumping it through a Helmholtz jet resonator (SRG), and while maintaining in accordance with the speed of the jet at the exit of the feed nozzle and the volume of the AWG, characterized in that support in accordance with the speed of the jet at the exit of the nozzle and the volume of the AWG by moving I rear it, in the direction of flow, the bottom, providing an increase in the volume of the AWG with a decrease in the speed of the jet and a decrease in the volume of the AWG with an increase in the speed of the jet. 2. The method according to claim 1, characterized in that they maintain in accordance with the speed of the jet at the cut of the supply nozzle and the volume of the AWG due to the movement of both of its bottoms. 3. The device for implementing the method according to claim 1, consisting of a Helmholtz jet resonator (SRG) installed inside a tubing (tubing) and representing a hollow cylindrical chamber with flat bottoms, in the front bottom of which a power nozzle is placed, and in the rear the bottom has an outlet with sharp edges, characterized in that the rear bottom is movable, and inside the tubing, behind the AWG, the hydraulic cylinder is fixedly mounted with a spring-loaded piston connected by a rod to the movable rear bottom, and inside the hydraulic cylinder in front of the piston, in the downstream direction, it is connected to the internal volume of the tubing, and the cavity behind the piston is in communication with the annulus. 4. The device according to claim 3, characterized in that both bottoms are movable, and inside the tubing, both in front of and behind the AWG, it is mounted motionlessly along one hydraulic cylinder with a spring-loaded piston, the piston of the front hydraulic cylinder being connected in the flow direction rod with its movable front wall, and the piston of the rear hydraulic cylinder is connected by a rod to its movable rear wall, while the front cavity inside the front hydraulic cylinder is connected to the internal volume of the tubing, and the cavity behind the piston is in communication with the annulus, and at the rear the hydraulic cylinder is still the same - the front cavity is connected to the internal volume of the tubing, and the cavity behind the piston is in communication with the annulus.

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