RU2283951C1 - Electrohydraulic impulse device (variants) - Google Patents

Abstract

FIELD: oil production, particularly methods for stimulating production, namely current pulse generators for electrohydraulic impact shaping devices used in different industries.

SUBSTANCE: device comprises electric accumulator, triggering means and discharge chamber provided with electrodes. Discharge chamber interior is isolated from ambient space so that one wall thereof is opened in hydraulic medium to be treated. At least one electrode is arranged near wall opposite to opened wall. The second electrode is spaced short distance from the first one or discharge chamber wall or hydraulic medium are used as the second electrode. Vertical inner dimension of discharge chamber is selected to prevent direct contact between electrode and hydraulic medium to be treated. Inner discharge chamber volume is small enough to provide cumulative effect of electrodischarge pulse.

EFFECT: improves efficiency of oil-bearing formation treatment due to increased energy generated between discharge device electrodes, decreased environment parameters influence on discharge mode along with simplified electrohydraulic impulse devices usage.

4 cl, 12 dwg, 1 tbl

Description

The invention relates to a pulse technique, in particular to current pulse generators for electro-hydraulic installations, and can be used in the field of oil production as a device for electro-hydraulic impact molding in various industries.

A known method of producing high and ultrahigh pressures [1], in which the pressure is produced as a result of a pulsed electric discharge inside the volume of any conductive or non-conductive liquid located in an open or closed vessel, and also inside the jet of this liquid so that the pressure increases with increasing power, and the steepness of the pulse front. In order to increase the resulting pressure, or to expand the pressure zone, the discharges can be carried out on several arresters supplied from separate circuits.

It is also known a device for producing ultra-high hydraulic pressures [2], made in the form of a cylindrical hydraulic chamber, divided into compartments or without them, communicating at one end with a pipeline supplying liquid, and the other with a receiver, with spark gaps located in it, located at the length of the camera at a certain distance from each other or in each compartment of the camera. Between the compartments installed check valves.

In another embodiment, the compartments may be separated by partitions with openings. The compartments are given the shape of a parabola entering one another (in cross section). In order to implement a given sequential scrolling around the discharges of the entire series of spark gaps, a tumbler or incendiary device is used.

There is also known a method of producing high and ultrahigh pressures to create electro-hydraulic shocks, as well as a device for its implementation [3], which consists in the fact that high and ultrahigh pressures in a liquid are obtained by evaporation of a pulsed discharge of conductive elements in the form of a wire, tape or sponges closing electrodes. The conductive elements are bent along a contour corresponding to a given, or give them the shape of a conical or spherical spiral.

The disadvantages of the described methods and devices include the design complexity and low reliability due to the presence of evaporating conductive elements. Conductive elements must be fed into the zone continuously and synchronized, which complicates both the method and the device.

The closest technical solution, selected as a prototype, is a downhole generator [4], based on the principle of electro-hydraulic effect and designed to treat an oil reservoir in order to increase oil recovery, which is a steel pipe with a streamlined tip. The generator contains a cable lug with an energy storage device, made in the form of a transformer-rectifier unit with pulsed high-voltage capacitors, a controlled arrester with an ignition unit, mounted on the chassis and placed in a hermetic steel casing. A discharge chamber with two electrodes is attached to the lower end of the casing. The output of electrical energy to the generator is carried out through the cable lug, which is an intermediate link when suspending the EGE generator in the well on the cable.

The disadvantages of the known device are as follows.

The electrodes of the discharge device are located directly in the processed medium, which in the bottomhole zone and in the oil reservoir can be industrial water with a degree of mineralization of up to 1.24, clay solutions, oils with varying degrees of gas contamination and suspension of the substances mentioned.

Such a medium is characterized either by increased electrical conductivity (reducing the breakdown voltage of the discharge gap), or, on the contrary, complicated conditions for creating a breakdown due to its electrical insulating properties, as well as due to increased ambient pressures reaching tens of atmospheres (see Paschen curve - Fig. one).

As a result, the following operational disadvantages of the downhole generator arise.

With a high conductivity of the medium in the well (brine), the device enters the short circuit mode or "leakage" of the discharge energy and, accordingly, becomes inefficient by reducing the amount of energy actually spent on creating a pressure pulse. Moreover, while in the nominal discharge mode of the accumulated energy, the duration of the leading edge of the current pulse is explosive with a duration of 15-50 μs, then in the "leak" mode, the duration of the leading edge of the current increases to 500-1500 μs or more. In this case, the creation of an explosive pulsed regime of the release of electrical energy and a pressure pulse is impossible.

Pre-breakdown energy losses in the "leak" mode reach values up to 13%. Compensation of losses leads to an increase in overall dimensions due to an increase in the dimensions and mass of the electric energy storage device.

For example, the design of one of the options for the practical implementation of the downhole generator using the electric discharge effect was a device with a diameter of 250 mm and a height of 3500 mm with a stored energy of not more than 18 J. Operation of a device with such a small amount of energy and increased dimensions is ineffective, restricts the processing of casing with reduced diameters, with a variable configuration of slopes along the section of the reservoir, makes it difficult to move such a generator from well to well.

In addition, due to an increase in breakdown stresses when reaching depths in the well of up to 2000 meters or more and due to an increase in the electric strength of the oil medium, it is necessary to reduce the discharge gap to ensure guaranteed breakdown, which reduces the energy actually released between the electrodes of the discharge device by reducing the voltage drop in the discharge gap and, accordingly, the efficiency of the formation treatment.

The use of generators based on an electric discharge into a liquid below depths of 2000 meters is problematic due to the failure of the discharge device due to high breakdown voltage of the discharge gap, for example, up to 20 kV and higher in accordance with the Paschen curve.

The interconnection and mutual influence of generator and well parameters, such as pressure, spark gap, medium conductivity, energy loss, leads to instability of energy release in a wide range of stored energies, to the need for pre-launch analysis and preparation of generators for each use, taking into account the characteristics of a particular well. This greatly complicates the operation of such generators, the selection of optimal parameters and the prediction of the results and the effectiveness of the impact on the reservoir.

The problem solved by the claimed invention is to increase the energy released between the electrodes of the discharge device, which will entail an increase in the impact on the oil reservoir by simultaneously reducing the influence of environmental parameters on the nature of the discharge while simplifying the design of electro-hydraulic pulse devices.

This goal is achieved by the fact that in an electro-hydraulic pulse device containing an electric energy storage device, a trigger device and a discharge chamber with electrodes, the internal cavity of the discharge chamber is isolated from the environment in such a way that one of the walls of the discharge cavity is open to the surrounding hydraulic medium being processed, at least one electrode is placed against the wall opposite the open one; the second electrode is either the second electrode located next to the first one or the wall of the discharge chamber, or about the hydraulic medium, while the vertical internal size of the discharge cavity is set in such a way that the first electrode does not come into direct contact with the processed hydraulic medium, and the internal volume of the discharge cavity is selected sufficiently small, providing a cumulative effect of the electric discharge pulse. A discharge cavity is placed in the hydraulic fluid being processed with a vertically open part of the wall down, like an overturned glass, in which a gas-air bubble always forms.

The principle of operation and design features of an electro-hydraulic pulse device are as follows.

Figure 1 shows the Paschen curve of the dependence of the breakdown voltage of the discharge gap on the ambient pressure (at d = const), figure 2 shows a block diagram of the inventive electro-hydraulic pulse device, figure 3 - three design options for the arrester, figure 4 , 5, 6, 7 - oscillograms of the process of propagation of a pressure pulse.

The inventive electro-hydraulic pulsed device (see figure 2) consists of an electric energy storage device 1, the input of which is connected to a power source 2, the output - to a trigger device 3, which is connected to a spark gap 4, made in the form of a discharge cavity in which the electrodes 5 are located , 6, forming a spark gap.

The design of the arrester is shown in Fig. 3 and is made in the form of a housing 7, in which the central electrode 5 is fixed in the center of the discharge cavity, the role of the second electrode is performed by the housing 7 of the arrester 4, the electrode 6 is isolated by a layer 8, the arrester 4 is lowered into the hydraulic medium with the open wall down that the cavity of the discharge chamber is filled with a gas-air mixture.

The vertical internal size of the discharge cavity is set in such a way that the electrode 6 is constantly located in the medium of the gas-air mixture and does not come into direct contact with the processed hydraulic medium in the range of increased ambient pressure of the hydraulic medium in the well.

The internal volume of the discharge cavity is chosen small enough to provide the cumulative effect of the electric discharge pulse.

Structurally, the functional blocks of the EGIU (Fig. 2) are located in a single building, the shape and overall dimensions of which allow it to be lowered into an oil well.

The principle of operation of an electro-hydraulic pulse device is as follows.

The voltage from the power source to the electric energy storage device (for example, a large-capacity electric capacitor) is supplied through a wireline cable, on which the EGI is lowered into the well (not shown in the figures) and applied to the electrodes (to two separate electrodes, to the first electrode and the spark gap wall, or to the first electrode and hydraulic medium through the spark gap wall). When the voltage on the drive 1 reaches a value corresponding to the response of the trigger device 3, which may be, for example, a gas-filled spark gap, the latter automatically closes the drive on the electrodes of the spark gap 4. Between the electrodes located inside the discharge cavity, the electric energy corresponding to the energy stored in the drive size. When discharged in a gas-air medium, a cumulative effect occurs, which spreads in the hydraulic medium and then reaches the layers that are to be treated.

In addition, due to the sufficiently small internal volume of the discharge cavity, which provides the cumulative effect of the electric discharge pulse, if the surrounding hydraulic medium accidentally gets under the electrodes and its contact with the electrodes occurs, during the first electric discharge pulses due to the cumulative effect and the high temperature of the discharge plasma, the hydraulic medium will emit pulsed from discharge cavity and drainage of the electrodes or at least the first electrode.

Due to this, there are no “leakage" modes of discharge energy due to the increased conductivity of the medium in the spark gap between the electrodes or to an increase in the breakdown voltage of the spark gap due to the increased insulating properties of the medium.

Moreover, due to the choice of the magnitude of the discharge gap between the electrodes, sufficient for its breakdown, at high ambient pressures in the well, the formation of an electrohydropulse is guaranteed.

When the device is immersed to a greater depth of the hydraulic medium, it will press on the gas cavity inside the discharge chamber 4, compressing it. With increasing pressure inside the discharge chamber in the case of using the hydraulic medium as the second electrode, the breakdown voltage will increase, and the interelectrode gap will decrease, which also guarantees the operation of the device.

Table 1 shows the parameters of the pressure pulses measured on the casing wall, depending on the magnitude of the electrical energy of the drive and the design of the UGIU.

Table 1 Type of UGIV Storage Energy (J) Oscillogram No. (Fig. No.) Amplitude of the first impulse (at) Duration of the oscillatory process (ms) First Pulse Duration (ms) The number of pulses expressed by him per one discharge To: claimed 200 four 390 53 1,080 8 claimed one hundred 5 310 44,328 1,070 eleven claimed twenty 6 90 102,817 0.960 thirty prototype 200 7 83 128,818 0.810 24

Oscillograms of the pressure propagation process are oscillatory damped in nature:

- the number of registered pressure pulses of the hydraulic medium reaches 30 (Fig.6),

- the amplitude of the pressure pulses varies from the maximum values of 390 ati to 10 ati (figure 4),

- the duration of the oscillatory process of the hydraulic system is registered in the range from 44.328 to 128.818 ms (Fig.5-Fig.7),

- the duration of the first pulses is approximately the same: 0.81-1.08 ms (Fig.7, 2),

- in Fig. 7 (analogue), a “leak” mode is noted in the initial section,

- the probable cause of the increased duration of the oscillatory process of FIG. 7 is the “leak” mode.

Table 1 presents comparative data in relation to the claimed device and prototype, depending on the value of the stored energy of the capacitor (item 1 of FIG. 1) from 20 to 200 J. The table is compiled on the basis of the analysis of the oscillograms of FIGS. 4, 5, 6 and 7. From of this table, the advantage of the claimed device is obvious: with an energy value of 20 Joules, its efficiency is 90 ati, while the efficiency of the prototype 83 ati is achieved only with an accumulated energy of 200 J.

The inventive device can be used:

1) to create an elastic effect on the formation in order to increase the production rate of oil and gas fields;

2) to increase the permeability of the near-wellbore zone of the formation, to clean the perforation holes and pores of the reservoirs from mechanical impurities and other contaminants, to develop fracture systems in the formation due to hardening of the annulus cementitious mortar;

3) for cleaning filters of artesian wells in order to increase the flow rate of water in combination with other devices;

4) to create installations for molding materials by, for example, stamping, crimping, expanding, compaction, recrystallization and the like processing of materials,

5) can be used in the construction and operation of oil, injection, water, exploratory wells, etc.

The advantages of the claimed device is:

- lack of pre-launch preparation of the installation due to the simplicity of the design;

- environmental cleanliness of technology;

- the productivity of well processing increases due to an unlimited number of hydraulic shocks per one dive into the well;

- reduced weight and size characteristics allow the operation of EGIU in well conditions with any configuration of slopes along the section of the formation and with any operational movements from well to well;

- Installation maintenance by no more than 2 specialists.

Information sources

1. A.S. USSR No. 105011, IPC 58 A, 1950.

2. A.S. USSR No. 119074, IPC B 30 V, 1950.

3. A.C. USSR No. 129945, IPC B 30 C, 1952.

4. L.F. Petryashin, G.N. Lysyanoy, V.V. Zheltoukhov. On studies of the efficiency of using electrical pulses to intensify oil production. Proceedings of the Institute IFING, issue 13, 1976, p. 92-93.

Claims (3)

1. Electro-hydraulic pulse device EGIU, containing an electric energy storage device, a trigger device-discharger with electrodes, characterized in that the electrodes are placed inside the discharge cavity, and its internal cavity is isolated from the environment so that one of the walls of the body of the discharge cavity is open to the surrounding the hydraulic medium being processed, at least one of the electrodes is placed near the opposite wall, while the vertical internal size of the discharge cavity is set so that the electrodes do not come into direct contact with the fluid being treated, and the internal volume of the discharge cavity is set to provide the cumulative effect of the electric discharge pulse. 2. Electro-hydraulic pulse device EGIU containing an electric energy storage device, a trigger device-discharger with electrodes, characterized in that the electrodes are placed inside the discharge cavity, and its internal cavity is isolated from the environment so that one of the walls of the body of the discharge cavity is open to the surrounding processed hydraulic medium, one of the electrodes is located at the wall opposite from the hydraulic medium, the second electrode is the spark gap wall, while the vertical internal size of the discharge the second cavity is set in such a way that the electrodes do not come into direct contact with the fluid being treated, and the internal volume of the discharge cavity is set to provide the cumulative effect of the electric discharge pulse. 3. Electro-hydraulic pulse device EGIU, containing an electric energy storage device, a trigger device-discharger with electrodes, characterized in that the electrodes are placed inside the discharge cavity, and its internal cavity is isolated from the environment so that one of the walls of the body of the discharge cavity is open to the surrounding processed hydraulic medium, one of the electrodes is placed at (on) the opposite wall, the second electrode is a hydraulic medium, and the vertical internal dimension of the discharge cavity is given by Thus, the electrodes do not come into direct contact with the process fluid, and the internal volume of the discharge cavity is set to provide the cumulative effect of the electric discharge pulse.

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