RU2663770C1 - Impacting bottom area method - Google Patents

Abstract

FIELD: mining.SUBSTANCE: invention relates to means for generating seismic energy, for example, elastic vibrations in oil reservoirs, in particular to impact devices on the bottomhole well zone and oil saturated beds during hydrocarbon production. Method of impact on the bottomhole zone is that electrodes are installed in the interelectrode space. Then, a high-voltage pulse is applied to the electrodes, forming an electric arc between them and, thus, breakdown of the interelectrode gap and obtaining a plasma channel between the electrodes to form electrical discharges in the liquid medium of the well. In this case, the interelectrode space is ionized. Breakdown of the interelectrode space is made by high voltage pulses, repeated by signals of piezoelectric sensors. And the breakdown energy of the interelectrode gap is used to restore the ionized layer destroyed by the discharge. In this case, the pulses are fed in time with the oscillatory process that occurs in the well.EFFECT: increased well flow rate at the production stage, providing the fastest and least labor-intensive output of the product to the maximum production and improved reliability of the system.3 cl, 4 dwg

Description

The invention relates to means for generating seismic energy, for example, elastic vibrations in oil-bearing formations, in particular to means for impacting the bottom-hole zone of wells and oil-saturated formations during hydrocarbon production.

The prior art method of impact on the bottom-hole zone of a well by creating depressive-repressive pressure pulses in a hydraulic medium (RU RU 2248591 (13) C2, 05.20.2005).

A disadvantage of the known technical solution is the complexity of execution and the limited possibilities of using the known method.

As a prototype, the known method of impact on the bottom-hole zone is selected, which consists in the fact that in the bottom-hole zone in the well cavity, electrodes are installed, separated by a gap and equipped with a metal wire that closes the electrodes, a device for supplying this wire to the electrodes and a voltage pulse generation system, providing thereby heating the wire, its explosion and the formation of a plasma channel between the electrodes, followed by the formation of a shock wave that propagates inside the well, electrodes, (RU 2373386 C1, November 20, 2009).

A disadvantage of the known technical solution is that it has limited ability to create the necessary dynamic mode, which reduces production debit. In addition, the wire and its filing system in the gap are unreliable elements in the device that implements this method.

The objective of the invention is to increase the flow rate from the well at the production stage, which provides a quick and with minimal labor output of the product at maximum performance and increasing the reliability of the system.

The technical result is to form resonant vibrations in the elements of the system “well - bottomhole zone - formations”, which ensure the release of pore channels of the bottomhole zone and perforation holes from clogging substances and create the necessary dynamic mode of inducing a wave pattern in the formations to increase flow rate over the entire power formation; improvement of the filtration properties of the bottomhole zone.

The specified technical result is achieved due to the fact that a high voltage pulse is applied to the interelectrode space into which the electrodes are installed, and an electric arc is generated between them and, thus, breaks the interelectrode gap and produces a plasma channel between the electrodes with the formation of electric discharges , in the liquid medium of the well, according to the invention, the interelectrode space is ionized, and the breakdown of the interelectrode space is carried out, repeating, according to the signals odatchikov, high voltage pulses.

The specified technical result is also achieved due to the fact that the energy of electric discharges is used to restore the ionized layer destroyed by the discharge.

The specified technical result is also achieved due to the fact that the frequency of the destruction pulses is randomly changed within certain limits in the system.

The specified technical result is also achieved due to the fact that the system uses a microprocessor that controls the process of supplying high-voltage pulses by the signals of the piezoelectric sensors.

The specified technical result is also achieved due to the fact that the supply of pulses is performed in time with the oscillatory process that occurs in the well.

The specified technical result can be achieved due to the fact that high-voltage pulses are supplied depending on the results obtained from previous pulses.

The specified technical result can be achieved due to the fact that the pulses are supplied in series of several inclusions of the high voltage source.

The ionization of the interelectrode space makes it possible to get rid of the wire mechanism, which increases the reliability of the system, and the breakdown of the interelectrode space by repeated high voltage pulses from the piezoelectric sensors provides a higher result in increasing the flow rate from the well.

Using the energy of the explosion to restore the ionized layer destroyed by the discharge allows repeatedly repeating the process of breakdown of the interelectrode space.

An arbitrary change within certain limits of the frequency of the destruction pulses gives the operator the opportunity to influence the operation of the system.

The use of a microprocessor in the system, triggered by the signals of the piezoelectric sensor, simplifies the work of the operator.

The supply of pulses to the beat with an oscillatory process occurring in the well contributes to the deep penetration of the seismic-acoustic wave into the formation and the creation of resonance processes in the formation that increase the debit of the product.

The supply of high voltage pulses, depending on the results obtained from previous pulses, allows you to optimize the production process of the product.

The supply of pulses in series of several inclusions of a high-voltage source contributes to an increase in the productivity of the destruction of clogging substances and to the flow of fluid into the production well increasing the injectivity of the formation.

The list of drawings:

FIG. 1 Emitter of an electrohydropulse discharge source with ionizing electrodes installed in it.

FIG. 2 Control circuit for the supply of high voltage pulses.

FIG. 3 Schematic diagram of the ionizer.

FIG. 4 Microprocessor control system.

A device for impact on the bottomhole zone according to the proposed method is as follows. The source of elastic vibrations consists of a downhole tool (not shown in Fig.), Lowered into the well on a wireline cable. In the downhole tool there is a discharge device and energy storage device, a device for supplying power pulses and an ionizer power device. In addition, a seismic sensor (not shown in FIG.) Is inserted into the borehole wall. The discharge device is adjacent to the downhole tool and mounted in the form of a tubular body 1 with an external diameter smaller than the internal diameter of the well, and is installed in the hydraulic medium in the well cavity. The discharge device comprises an external electrode 2 and a movable internal electrode 3, located towards each other (Fig. 1). In turn, the inner electrode 3 rests on the outside of the fixed plug 4. In other words, the fixed plug 4 is an integral part of the movable electrode 3. The inner side of the plug is a support for the flange 5 of the tubular body 1. Inside the tubular body 1 includes a pipe 6, which the spacer ring 7 is rigidly fixed inside the tubular body 1. The tubular body 1 contains extensive windows (not shown in Fig.). These windows are located in the area of the interelectrode space at the level of electrodes 2 and 3 and are necessary for the free passage of the blast wave from the interelectrode space into the bottom hole. In turn, the plug 4 is provided with an inner ring 8 connected to the outer ring by four ribs (not shown in FIG.) Radially diverging from the inner ring 8 to the outer one. Thus, windows are also formed in the plug that allow free passage of the blast wave from the electrodes 2 and 3. An intermediate movable tube 9 is inserted inside the pipe 6. A compression spring 10 is installed around the tube 9 between the flange 5 and the inner end of the tube 9. One compression spring abuts against the inner surface of the flange 5, and the other side abuts against the edge of the intermediate tube 7. In turn, the inner tube 6, with one of its edges, enters the intermediate tube 7, which is rigidly behind replen inside the tubular body 1. The upper part of the tube 7 is provided with a cap 11. made in the form of a flat cylinder with four ribs (not shown in Fig.), radially diverging from the center of the cap 11 and converging on the outer ring of the cap 11. In the central part of the cap 11 its axis, the round rod 12 is firmly mounted. The rod 12 passes through the gland (not shown in FIG.) along the axis inward of a separate closed cylindrical body 13 of smaller diameter than the tubular body 1. A pin 14 is firmly fixed to the rod 12. In the walls of the cylindrical rpusa 13 on pins 15 mounted piezo elements 16 and 17. The distance between facing each other peelementami 16 and 17 is equal to the gap between the electrodes 2 and 3. The pins 15 have some flexibility, but the inner part of the cylindrical body 13 is filled with dielectric fluid. On the inner walls of the pipe 1 between the electrodes 2 and 3 there is an ionizer consisting of ionizing electrodes 18 and 19. The electrodes 18 and 19 are mounted on opposite sides in parallel planes on the dielectric plates, respectively 20 and 21. The distance between the tips of the ionizing electrodes is selected from the conditions of creation stable corona discharge in local areas located between two opposite ionizing tips and with the maximum possible ion productivity.

To ensure normal operation, the circuit must be provided with a high voltage source applied to the electrodes 2 and 3, with a charger with energy storage of FIG. 2. The charger consists of a high-voltage transformer 22, a rectifier 23, a limiting resistance 24, an energy storage device 25, a discharge device in the form of a spark gap 26 with a start electrode 27 and a pulse shaping unit 28. A boost transformer 29 and a relay 30 are used to start the spark gap 26 the cores of cable 31, and the Rogowski belt 32. The latter is designed to record current in the discharge circuit of storage capacitors, which is simultaneously used as an electric signal shaper for counter working pulses. The use of the Rogowski belt also allows you to control the current amplitude of the discharge circuit and, accordingly, the overall performance of the device.

The conductors of cable 31 are connected to terminals 33, 34 and 35, and the armor to terminal 36 of the connector.

As a circuit for the ionizer, a high voltage source is used, made on the basis of a multivibrator 37, built on transistors VT1 and VT2 (Fig. 3). The multivibrator frequency is changed using the tuning resistor 38 in the range from 30 to 60 kHz. From the multivibrator, the pulses are fed to a voltage converter 39, built on two transistors VT3, VT4, and a transformer 40. When the frequency changes, the output voltage at the converter output changes. If you reduce the frequency, the output voltage will increase. Next, a high voltage (of the order of 2.5 kV) from the secondary winding of the transformer 40 goes to the input of the multiplier assembled on capacitors 41 (C8-C13) and diodes 42 (VD5-VD10). Then the voltage is supplied directly to the tips 18 and 19. One terminal of the secondary winding of the transformer 40 is connected to the minus of the device. The distance between the electrodes is selected individually. To prevent the system from occurring between the electrodes 18, 19 and other structural elements of an excessively large potential difference, resistors are used. In order not to break through the secondary winding of the transformer 40, a spark gap 43 is provided in the system. The power supply circuit is built on reactive capacitance. It consists of a zener diode 44 (VD2), capacitors 45 (C1, C2), a diode bridge 46 (VD1) and a resistor 47. As a diode, KTs106G or KTs123 can be used. Voltage is supplied to the ionizer circuit from a single-phase transformer 48. The electrical circuits of FIG. 3 and FIG. 2 must be untied, i.e. do not contain common points. The ionizer can ionize the space between the electrodes, both in air and in a liquid medium by controlling the frequency of the pulses.

The control system contains a microprocessor 49 (Fig. 4), to which signals are supplied from a high-voltage voltage supply sensor to the electrodes 2, 3 connected to the Rogowski belt 32, piezoelectric sensors 16 and 17, and a seismic sensor 50 mounted in the borehole wall. The latter is intended to determine the direction of motion of the oscillatory process. The circuit also has a pulse counter (not shown in FIG.). The microprocessor 49 is equipped with a control unit 51, a control handle 52 and a switch 53. The control system with microprocessor 49 are located on the operator’s control panel. The control handle has several fixed positions with the designation of the number of pulses for switching on the high voltage source.

The method of impact on the bottom-hole zone is as follows. In the interelectrode space on the electrodes 18 and 19 (Fig. 1) from the electric circuit of the ionizer (Fig. 4), voltage is supplied from a source of high pulse voltage, due to which the interelectrode space is filled with ions of nitrogen, oxygen and ions of other elements present in the well space between electrodes.

To start the process, you must press the switch control circuit on the handle 52 of the microprocessor 49 (Fig. 4). Then, the signal along the wire 35 of the wireline cable 31 is supplied with an electrical signal to the relay coils R, the contacts of which switch correspondingly, the conductors 33, 34, 35, 36 coming from the cable: 31. After that, a start signal is sent to the input of the trigger pulse generating unit through conductor 33 28. It rises using a transformer 29. After the spark gap 27 is triggered, a high voltage pulse is supplied to the electrodes 2, 3, which is fed into the energy storage 25. When a high voltage pulse is applied to the electrodes 2 and 3, an electric current arises between them Skye arc, the ionization electrode due to the air to create an electric arc requires a much lower voltage. A breakdown of the interelectrode gap occurs, and the appearance of a plasma channel between the electrodes 2 and 3 with the formation of an electric discharge in the liquid medium of the well. The shock wave propagates inside the well. At the same time, the energy of the explosion exerts pressure on the flange 5, which causes the inner pipe 6 to move (Fig. 1). The power spring 12 is compressed. The volume of interelectrode space increases. Due to the influx of liquid medium and the continued operation of the ionizer, destroyed during electrical breakdown, the ionized medium is restored. Using the spring 12, the reverse movement of the inner pipe 6 occurs. The compression process of the spring 12 and its reverse movement last several microseconds. During this time, a new charge of capacitors 25 occurs (Fig. 2). and the concentration of ions in the interelectrode space increases.

The discharge is recorded by the level of the signal from the Rogowski belt 32 installed in the current circuit of the storage capacitors. The system is ready for re-action. Continuation of the operation is possible in automatic mode, according to the signals of the sensors 16, 17 and 50 of the control system (Fig. 4) or at the command of the operator. The sensor 50 detects the beginning of the wave in a certain direction, consistent with the start of a new movement. This signal is amplified and turns on the discharge device. In this case, the microprocessor determines the time of the complete cycle of movement of the electrode 3 according to the results of calculating the time of movement of the pin 19 during its movement from the piezoelectric sensor 16 to the sensor 17 and vice versa. If the movement time of the pin 19 exceeds the half-wave time of the seismic sensor, then the time for repeated switching on increases according to the readings of the microprocessor.

The operator can influence the reservoir depending on the results of previous pulses, which allows to increase well productivity.

The supply of pulses to the beat with the oscillatory process occurring in the well, allows to further increase the productivity of the destruction of the clogging substances, to receive an influx of fluid into the producing well to increase the injectivity of the formation.

Based on the results of exposure to the well, the operator can arbitrarily change the frequency of fracture pulses within certain limits.

The impact on the reservoir, depending on the results of previous pulses, can increase well productivity.

Modeling of nonlinear processes occurring in the reservoir allows us to consider the reservoir as a set of oscillatory systems (nonlinear oscillator in a nonequilibrium elastic medium), which can be influenced by external forced oscillations. The most important feature of a nonequilibrium medium is that even a small disturbing force can lead to a disproportionately large effect (trigger effect). It is important that the exposure is periodic.

As you know, the expansion of the plasma channel and its subsequent “collapse” on a periodic basis exerts alternating loads on the bottom-hole zone of the formation and the formation as a whole. As a result of repeated periodic repetition of cycles “repression - depression”, shock hydraulic waves ”of pressure propagate along the skeleton of the formation and its porous medium and change the capacitive and filtration properties of the rocks. Under their influence, the perforation intervals are cleaned of sediments, mud particles of the rock and mud residues, its filtrate, as well as salts and asphalt-resin-paraffin formations deposited in the porous medium. Repeated pressure pulses reveal natural reservoir cracks and contribute to the formation of new cracks.

Thus, the oil reservoir can be considered as an open dissipative nonlinear system, free of self-organization and containing a huge source of unknown and therefore unclaimed energy, which during operation is inextricably nonlinearly connected to production and injection wells.

Based on the foregoing, the developers of the method of influencing the bottom-hole zone came to the following conclusion: in order to excite such a complex system at resonant frequencies, it is necessary to have a broadband controlled borehole source of periodic elastic oscillations (pump generator). Such a source of initiated periodic oscillations will inevitably lead to self-organization of the system, i.e., to ordering of oscillations in the formation, which will be manifested in the appearance of one or more (in the case of a multilayer system) quasiharmonics, and consequently, the appearance of resonance phenomena.

Practice shows that in order to obtain additional fluid inflow into the production well or to increase the injectivity of the injection well formation, it is necessary to initiate a series of elastic periodic pulses along the entire perforation operating interval, the pressure of which would exceed the plugging coefficient, and the propagation velocity of these pulses would increase the piezoelectric conductivity coefficient.

A feature of the proposed downhole plasma-pulse technology is the influence not only on the bottomhole zone, but also on the formation as a whole due to the deep penetration of the seismic-acoustic wave into the formation and the creation of resonance processes in the formation.

The range of the plasma-pulsed action on the formation under certain geological conditions can be up to 1500-1800 m. Therefore, wells located on the treated formation often perceive this effect. Due to the cleaning of the pores of the reservoir, the formation of new cracks, and the better washability of the oil, the mobility of the reservoir fluid increases, the water cut decreases, and the production rate of the processed and reactive wells increases.

Claims (3)

1. The method of impact on the bottom-hole zone, namely, that electrodes are installed in the interelectrode space, then a high voltage pulse is applied to the electrodes, forming an electric arc between them and, thus, breaking the interelectrode gap and obtaining a plasma channel between the electrodes to form electrical discharges in the liquid medium of the well, characterized in that the interelectrode space is ionized, and the breakdown of the interelectrode space is performed by repeating the signal piezoelectric high voltage pulses, the breakdown energy of the interelectrode gap is used for restoring the destroyed ionized discharge layer and pulsing is performed in time with an oscillatory process occurring in the well. 2 .. The impact method according to claim 1, characterized in that a microprocessor that controls the process is used to obtain repetitive pulse signals from the piezoelectric sensors. 3. The impact method according to claim 1, characterized in that the pulses are supplied in series of several inclusions of the high voltage source.

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