RU2248591C2 - Borehole source of elastic vibrations - Google Patents

Abstract

FIELD: petroleum extractive industry, methods for prospecting geophysics.

SUBSTANCE: the borehole source of elastic vibrations has a borehole tool with an ignition circuit, electrohydropulse discharger with two electrodes, device for feeding of metal wire to the operating interelectrode space. The feeding device has a drum for keeping of a stock of wire, wire pulling-through mechanism. The wire pulling-through mechanism is made in the form of two metal plates fastened with one ends on diametrically opposite sides of a rod. The plates are pressed by springs by opposite sharpened ends to the wire located on the guide platform and oriented at an angle to it providing for alternative engagement and motion in the direction of the interelectrode space at a reciprocating motion of the rod connected with the aid of an axle and linkage to the movable armature of the solenoid. The solenoid and the linkage connected to the solenoid armature are located on one side of the dielectric plate, and the drum for keeping of wire, two spring-loaded metal plates, guide platform for the wire and the rod are positioned on the other side of the dielectric plate. The rod and the linkage connected to the solenoid armature are connected by an axle passing through an opening in the dielectric plate. A relay is installed in the borehole tool. A Rogovsky belt is installed in the discharging circuit of the reservoir capacitors of the borehole tool.

EFFECT: enhanced service life, reliability, reduced specific consumption of power per cycle of investigations and per unity of growth of yield of the borehole.

4 dwg, 4 tbl

Description

The invention relates to the oil and gas industry, methods of exploration geophysics and may find application for cleaning zones of perforation of wells, excitation of productive formations adjacent to wells due to elastic resonant exposure in order to increase the recoverability of hydrocarbons.

In the process of exploitation of oil fields, the development of reserves from the reservoirs occurs, the permeability of the spaces adjacent to the wells decreases, and the water content of the products increases. With long-term operation of wells, their production rate decreases due to asphalt-resinous deposits in zones of productive formations and in reservoirs of wells. At the same time, the possibility of the underdevelopment of significant oil reserves in the interwell spaces is not ruled out. A large number of technologies have been developed to intensify production and increase the recoverability of oil and gas [1, 2]. For example, oil (gas) is displaced by water injected into productive formations, wells are treated with chemical reagents, heat treatment is used, and powder charges explode to create shock waves in the wells. However, the use of such technologies, as a rule, is associated with high costs, the need to maintain a high level of safety, and negative environmental consequences.

A promising technology for increasing the flow rate and extractability of oil and gas is a method of creating shock waves in wells and near-wellbore zones using an electrohydroimpulse discharge. Under the influence of shock waves, there is an increase in the permeability of the near-wellbore zone of the reservoir, cleaning of the perforation holes of the reservoir from mechanical impurities, gas hydrate and asphalt-resinous deposits, the development of additional fracture systems in the reservoir.

Known generator of pulsed currents for installing electro-hydraulic effects on the reservoir [3]. The generator consists of a ground power source and a submersible generator, which are interconnected using a wireline cable. Generator parameters: operating voltage of an electrohydropulse arrestor -30 kV, pulse energy - 0.5-1 kJ, immersion device length - 7320 mm. A shock wave arises as a result of an electric discharge in the liquid medium of a well between two electrodes of an electrohydropulse spark gap. The formation of a voltage pulse with an amplitude of 30 kV in an immersion generator is a difficult task, since it is necessary to provide the necessary electrical isolation of the device. As a result, the dimensions of the submersible device increase, in particular its length, since the diameter is limited by the diameter of the well. In addition, the conversion efficiency of an electrohydroimpulse discharge when using a spark gap of the above type into shock wave energy substantially depends on the physicochemical properties of the liquid and worsens with increasing hydrostatic pressure and temperature. For example, if the electrical conductivity of the liquid is large, then when a voltage pulse is applied to the electrodes of the arrester, it is not the breakdown of the gap, but the so-called “swelling” of the charge without the appearance of a shock wave.

Of the existing methods for initiating a stable discharge in liquids with various physicochemical properties, the optimal method is that in which, before applying a voltage pulse, the spark gap electrodes are closed with a thin metal wire. In the first phase of the current flow, the wire explodes, forming a plasma channel, which ensures stable initiation of the discharge [4]. A significant advantage of these types of arresters is the ability to use power generators for relatively low voltages of the order of 2-5 kV.

Closest to the technical solution to the present invention is a borehole source of elastic vibrations [5], comprising a downhole projectile connected to the ground cable control unit with an energy storage device, a charger, an arrester with an ignition circuit, an electrohydropulse arrester with two electrodes, a feed device into the working interelectrode space of a metal wire, including a drum for storing wire, a mechanism for pulling wire driven by yak A solenoid, a pusher with dogs, connected to the solenoid armature, ratchet wheels in contact with the dogs, spring-loaded pull rollers mounted on the same axles as ratchet wheels and a return spring connected to the solenoid armature. To ensure stable generation of electrohydropulse discharges, an exploding wire is used in this source, which previously closes the gap between the electrodes. When a voltage pulse is applied to the discharge gap closed by a wire, the wire explodes, forming a plasma channel that initiates the discharge. The main disadvantage of this borehole source of elastic vibrations is the complexity of the design of the wire drawing mechanism and its low reliability. In addition, the current in the discharge circuit of the storage capacitors is not controlled in the indicated source. The process of charging the storage capacitors is carried out through the conductive fluid of the well, located between the electrodes of the electrohydropulse spark gap, and practically does not depend on the closure of the electrode gap by a wire. If the gap is not closed by a wire, then when the ignition circuit and the spark gap are triggered, the storage capacitors are discharged through a conductive liquid in the gap between the electrohydro-pulse gap electrodes. In this case, the energy stored in the capacitors is spent on heating the conductive liquid and dissipated in the surrounding space. In this case, elastic vibrations do not occur and there is no effect on the bottomhole zone of the wells. In order to achieve the necessary efficiency of using a downhole source of elastic vibrations, it is necessary to increase the number of working pulses, which will require additional energy costs.

The present invention solves the problem of intensifying production and increasing the recoverability of oil and gas from reservoirs with reduced permeability, cleaning filters of artesian wells due to the electrohydropulse effect on the bottom-hole zone of wells with a device with increased resource, reliability and simplicity of the design solution.

In the proposed borehole source of elastic vibrations, a device for supplying a metal wire with an increased resource and reliability to the interelectrode space is used. To register the current in the discharge circuit of the storage capacitors, a Rogowski belt is installed, which is simultaneously used as a shaper of an electric signal for a counter of working pulses. The use of the Rogowski belt allows you to control the amplitude of the current of the discharge circuit and, accordingly, the efficiency of the device feeding into the working interelectrode space of a metal wire. The use of a device for feeding a metal wire into the working interelectrode space with an increased service life and reliability in combination with a discharge current control reduces the number of inefficient discharges in which a shock wave does not occur and, accordingly, reduce the specific energy consumption for each geophysical research cycle and unit growth rate of oil and gas wells.

This is achieved by the fact that the source of elastic vibrations is made in the form of a borehole projectile, in which there is an energy storage device, a charger, an arrester with an ignition circuit, an electrohydropulse arrester with two electrodes, a device for supplying a metal wire into the working interelectrode space, which includes a drum for storing stock wire, wire pulling mechanism, made in the form of two metal plates, fixed at one end on diametrically opposite sides of the rod, springs with opposite pointed ends to the wire located on the guide platform, oriented at an angle to the wire, providing its alternate engagement and movement towards the interelectrode space due to the reciprocating antiphase movement of the pointed ends of the plates during the reciprocating movement of the rod connected by the axis and traction with a movable anchor of the solenoid.

To register the current in the discharge circuit of the downhole tool, a Rogowski belt is installed, which is simultaneously used to form an electrical signal for the counter of working pulses. In order to reduce the size of the borehole projectile, the solenoid and the rod connected to the armature of the solenoid are located on one side of the dielectric plate, and the wire storage drum, two metal plates with springs, the wire guide platform and the rod are located on the other side of the dielectric plate, while the rod and the connected with an anchor of the solenoid, the rod is connected by an axis passing through the hole in the dielectric plate.

In order to increase the functionality of communication between the ground power supply unit, discharge control and monitoring and the downhole tool with a limited number of conductive wireline wires, the relays installed in the downhole tool are used, which ensure the corresponding switching of the electrical circuit in a given time sequence.

The device is illustrated by drawings, where in FIG. 1 schematically shows a borehole source of elastic vibrations; FIG. 2 is an electrical diagram of a downhole projectile; FIG. 3 and 4 - the mechanism of pulling the wire feeder in two projections.

The source of elastic vibrations consists of a borehole projectile 1, lowered into the borehole on a wireline 2. In the borehole projection there are an electrohydropulse arrestor 3 with two electrodes 4, 5, a charger 6, an energy storage device 7, a discharge device 8, mounted in a pipe 9 in the form of a pipe with an external diameter smaller than the internal diameter of the well, and a feed device into the working interelectrode space of a metal wire 10 mounted in a separate closed housing 11 of the same diameter, filled with dielectric liquid to eliminate the negative impact on the operation of the mechanism of wire drawing, fluid filling the well, including aggressive ones, and connected to the main pipe of the casing 9 by metal rods 12, practically not attenuating the shock wave passing from the interelectrode gap in the direction of the walls of the wells. The total length of the downhole projectile is about 2600 mm. The power supply, control and monitoring unit is located in the ground device 13 in the form of a mobile logging station, in which there is an autonomous power source, a logging elevator and other geophysical equipment.

The electrical circuit of the downhole projectile (Fig. 2) contains a charger 6, consisting of a high-voltage transformer 14, a rectifier 15, a limiting resistance 16, an energy storage device 7, a discharge device 8 in the form of a spark gap 77 with a start electrode 18 and a pulse generating unit 19 for triggering a spark gap with a step-up transformer 20, an electrohydropulse arrestor 3 with two electrodes 4 and 5, while one of the electrodes 5 is grounded, a relay 27 for switching the cores of cable 2, Rogowski belt 22 and a metal feed device die operating in the interelectrode space 10. The electrically conductive core of the cable 2 connected to the terminals 23, 24 and 25, and armor - 26 to the terminal connector 27.

A device for feeding a metal wire between the electrodes 4 and 5 into the working interelectrode space consists of two metal plates 28 and 29, fixed at one end with a rod 30 with diametrically opposite sides and with other pointed ends, pressed against a wire 31 located on a guide pad 32 using springs 33 and 34. The edges of the plates are pointed in the form of a bevel on the side of the interelectrode space. Relative to the wire 31 and, accordingly, the plane of the guide pad 32, the plates 28 and 29 are oriented at an angle that provides meshing of the wire and its movement towards the interelectrode space. In the interelectrode space between the electrodes 4 and 5, the wire 37 is fed through the hole 35 in the grounded electrode 5 and the gland 36. In the process of the rotational movement of the rod 30 counterclockwise, the pointed end of the plate 28, pressed by the spring 33 to the wire 31, catches it and moves it to the direction of the interelectrode space, while the pointed end of the plate 29, pressed by a spring 34 to the wire 31, slides along the wire in the opposite direction without a hook. In the process of reciprocating rotation of the rod 30 in a clockwise direction, the pointed end of the plate 29, pressed by a spring 33 to the wire 31, catches it and moves in the direction of the interelectrode space, while the pointed end of the plate 28, pressed by a spring 33 to the wire 37, slides along the wire in reverse direction without hook. Thus, in one cycle of the reverse-rotational movement of the rod 30 there are two engagement of the wire 31 and its movement in the direction of the interelectrode space. The reciprocating movement of the rod 30 is provided by the reciprocating movement of the armature 37 of the solenoid 38 when voltage pulses are supplied to it from the ground power and control unit 13. The armature 37 is connected by a rod 39 to the axis 40, at the end of which the shaft 30 is fixed. The drum 41 serves to provide wire stock 37. The constituent elements of the wire pulling device are mounted on a dielectric plate 42 connected to a dielectric disk 43.

Downhole source of elastic vibrations works as follows. From the power supply unit, control and discharge control of the ground device 73, three signals and the armor of the wireline cable 2 are supplied with electrical signals that perform the following operations:

- actuation of the wire feed mechanism;

- charge energy storage;

- launch of an air gap;

and also receives a control signal from the Rogowski belt 22 about the amplitude of the discharge current of the energy storage device (storage capacitors), followed by registration of the pulse number counter, which is installed in the power supply, control and discharge control unit of the ground device 13.

From the ground power supply unit, control and monitoring of the discharge of the device 73 through the conductor 24 of the wireline cable 2 voltage pulses are supplied to the solenoid 38 of the wire pulling mechanism for the time required for the wire 31 to close the interelectrode space between the electrodes 4 and 5. The time is set experimentally during commissioning. The movement of the wire 31 and its feeding into the interelectrode space between the electrodes 4 and 5 are provided by two steel plates 28 and 29.

After the specified time, the input of the step-up transformer 14 is fed through the conductor 23 of the wireline cable 2 and the energy storage device 7 is charged.

Then, along the core 25 of the logging cable 2, an electrical signal is supplied to the relay 21, which switch the conductors 23 and 25 of the logging cable 2. After that, a trigger signal is supplied to the input of the trigger pulse generation block 19 through the conductor 24, then it is increased by a transformer 20 and fed to starting electrode 18 of the spark gap 17. After the spark gap 17 is triggered, a high voltage pulse is supplied to the electrode 4 of the electrohydropulse spark gap 3. The wire heats up, it explodes and a plasma channel forms between the electrodes 4 and 5. The electric energy stored in the storage ring (capacitors) is released in the interelectrode gap, forming a shock wave, which propagates in the surrounding space inside the well and beyond. The discharge is recorded according to the signal level from the Rogowski belt 22 installed in the current circuit of the storage capacitors.

Technical parameters of the model of the downhole projectile:

- Energy content per pulse, J 1000

- Charging voltage of storage capacitors, kV 2.5-3.0

- The primary voltage supplied to the generator through the conductors of the logging cable from the ground block, V, Hz 220.50

- The average duration of one full cycle of operation of the downhole generator, with 30

- Estimated number of hydraulic pulses without lifting the generator to the surface 2000

- The length of the generator housing, m 2,6

- External diameter of the case, mm 102

- Weight, kg 90

The use of a borehole source of elastic oscillations in geophysical studies allows us to get an idea of the density of the distribution of hydrocarbon reserves in the reservoirs of both new and old oil fields. For new deposits, the horizons of the location of productive formations and their saturation with hydrocarbons are determined. In the process of exploitation of oil fields, the development of reserves from the reservoirs occurs, the permeability of the spaces adjacent to the wells decreases, and the water content of the products increases. At the same time, the possibility of the underdevelopment of significant oil reserves in the interwell spaces is not ruled out. With the help of a borehole source of elastic vibrations, studies of the space near the well and between the wells are conducted. To do this, a borehole source of elastic vibrations is placed in one of the boreholes, and a receiving antenna is placed in the other, which records shock waves resulting from an electric discharge in the borehole fluid.

Successful tests of a model of a borehole source of elastic vibrations at several fields in Russia have shown the high efficiency of using the technology of acoustic impact on the bottom-hole zone of wells in order to increase the flow rate of wells. The effectiveness of using a pilot model of a borehole source of elastic vibrations when processing production and injection wells at several oil fields at a relatively low cost of time and money is illustrated by the results given in the attached table. The oil and gas production rate and injection well intake are increased (2-6 times), the oil-water ratio of the produced fluid increases, the oil and gas recovery coefficient increases by 10-15%. At the same time, complete safety of work is achieved and environmentally harmful consequences are eliminated.

The high level of the proposed technical solution is determined by the structural simplicity of the main components of the device, for example, the mechanism of pulling the wire into the electrode gap of the spark gap, the proposed option for registering the discharge current level with the Rogowski belt, which ensures the reliability of the device, reduces its overall dimensions compared to devices of a similar purpose, promptly increase the level of well treatment efficiency.

Sources of information:

1. Guly A.G. The scientific basis of pulse-discharge processes. Kiev, Naukova Dumka, 1990, pp. 148-149.

2. E.V. Zezekalo, O.A. Ivankiv, A.N. Zolotous. The technology of thermogas-acid effect on the bottom-hole formation zone of low-permeable terrigenous, carbonate and clay reservoirs // The latest methods of increasing oil recovery - theory and practice of their application // Abstracts of the scientific-practical conference of the YIII International Exhibition “Oil, Gas. Petrochemicals -2001 ”, September 5-8, 2001, Kazan, pp. 69-71.

3. V.I. Vorobyov, S.I. Zaslavsky, A.M. Kurach, Yu.I. Kurashko. Pulse current generator for installing electro-hydraulic action on the reservoir // Electronic material processing // 1988, No. 1, pp. 79-80.

4. L.A. Yutkin. Electro-hydraulic effect and its application in industry. L .: Engineering, Leningrad. Department 1986, p. 51-59.

5. Copyright certificate of the USSR No. 247530, cl. G 01 v, 1969.

Claims (3)

1. A downhole source of elastic vibrations containing a downhole projectile with an energy storage device, a charger, an arrester with an ignition circuit, an electrohydropulse arrester with two electrodes, a feed device and a working interelectrode space of a metal wire, including a drum for storing wire stock, a mechanism wire drawing, characterized in that the wire drawing mechanism is made in the form of two metal plates fixed at one end diametrically the opposite sides of the rod, pressed by springs with opposite pointed ends to the wire located on the guide pad, oriented at an angle to the wire, providing its alternate engagement and movement towards the interelectrode space due to the reciprocating antiphase movement of the pointed ends of the plates during the reciprocating rotation of the rod connected using the axis and traction with a movable armature of the solenoid. 2. The source according to claim 1, characterized in that the solenoid and the rod connected to the armature of the solenoid are located on one side of the dielectric plate, and the wire storage drum, two metal plates with springs, the guide wire for the wire and the rod are located on the other side of the dielectric plate while the rod and the rod connected to the armature of the solenoid are connected by an axis passing through the hole in the dielectric plate. 3. The source according to claim 1, characterized in that the Rogowski belt is installed in the discharge circuit of the downhole energy storage device.

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