Device for cleaning water wells

Abstract

A device for cleaning water wells comprises a downhole tool composed of an electrohydraulic unit (7) with an oscillatory circuit and an ultrasonic unit (4) with an electroacoustic transducer (3) arranged successively in a single housing, sensors of pressure (10) and flow (11), a hydrophone (12), a pump, an ultrasonic generator (13), a pulse generator (14), monitoring equipment (15) for the sensors, a downhole tool control unit (16) equipped with a synchronizer of operation of the electrohydraulic unit (7) and the ultrasonic unit (4), and also with a device for controlling pulse width, beating frequency and spectrum of the signal of the oscillatory circuit of the electrohydraulic unit in order to change the treatment zone. Furthermore, a discharge chamber (8) and a protective cap (9) are arranged in the bottom part of the downhole tool.

Claims

1. A device for cleaning a water well, comprising: a downhole tool comprising a housing, an electrohydraulic unit in the housing, including an oscillatory circuit for generating a shockwave, and an ultrasonic unit in the housing above the electrohydraulic unit, comprising one or more electroacoustic transducers for generating an ultrasonic acoustic wave; and a downhole tool control unit comprising a synchronizer for synchronizing operation of the electrohydraulic unit and the ultrasonic unit, and a device for controlling the oscillatory circuit to vary a pulse width and a frequency spectrum of the shockwave so as to change a treatment zone.

2. The device according to claim 1, wherein the electroacoustic transducers of the ultrasonic unit are arranged in parallel.

3. The device according to claim 1, wherein the electroacoustic transducers of the ultrasonic unit are arranged perpendicular-parallel.

4. The device according to claim 1, wherein the electroacoustic transducers of the ultrasonic unit are arranged in series.

5. The device according to claim 1, comprising a pressure sensor, a flow sensor, and monitoring equipment for the pressure sensor and the flow sensor.

6. The device according to claim 1, comprising an ultrasound generator for supplying an ultrasonic power signal to the ultrasonic unit.

7. The device according to claim 1, comprising a pulse generator for supplying a pulse power signal to the electrohydraulic unit.

8. The device according to claim 1, wherein the electrohydraulic unit comprises a discharge chamber and a protective cover covering a bottom of the discharge chamber.

9. The device according to claim 1, wherein the ultrasonic unit comprises a pressure compensator for equalizing a pressure inside the ultrasonic unit and a pressure outside of the ultrasonic unit.

10. The device according to claim 1, further comprising a pump for removing clogging material from the water well.

11. The device according to claim 1, further comprising a hydrophone.

12. A method for cleaning a water well, comprising: generating an ultrasonic acoustic wave to treat a first treatment zone in the water well and generating a shockwave to treat a second treatment zone in the water well; synchronizing generation of the ultrasonic acoustic wave and the shockwave to simultaneously treat the first and second treatment zones, and controlling generation of the shockwave to change a frequency spectrum of the shockwave so as to change the second treatment zone; and removing clogging material from the first and second treatment zones.

13. The method of claim 12, comprising using the device of claim 5 to generate, and control the generation of, the ultrasonic acoustic wave and the shockwave.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 and FIG. 2 show a diagram of the proposed device. The device consists of a downhole part and a surface part.

(2) FIG. 3 schematically shows possible arrangements [a), b), and c)] of electroacoustic transducers in an ultrasonic unit.

(3) FIG. 4 is a block diagram illustrating schematically components in the upper unit of the downhole part shown in FIG. 2.

(4) FIG. 5 is a block diagram illustrating schematically relationship and connections between components in the device of FIGS. 1 to 4.

DETAILED DESCRIPTION

(5) The downhole part includes a downhole tool 100 and an upper unit 20 connected to the surface part of the equipment via a logging cable 1. Wherein in the housing of the downhole tool the electrohydraulic unit 7 and the ultrasonic unit 4 with electroacoustic (magnetostrictive) transducers 3 are installed sequentially from the bottom upwards, above the ultrasonic unit the cable lug 2 is arranged and between the electrohydraulic unit 7 and the ultrasonic unit 4 the pressure compensator 5 and the connection unit 6 are arranged. In addition, in the upper unit 20 above the housing of the downhole tool 100, pressure sensors 10, flow sensors 11, a hydrophone 12 and also a pump 21 are installed, as illustrated in FIG. 4. At the bottom part of the downhole tool the discharge chamber 8 and a protective cover 9 are arranged.

(6) The electroacoustic transducers 3 mounted in the ultrasonic unit 4 may be installed in parallel (see FIG. 3, a)), perpendicular-parallel (see FIG. 3, b)) or in series (see. FIG. 3, c))in order to ensure the most effective directivity characteristics corresponding to the conditions of colmatation of the well to be cleaned.

(7) The ultrasonic unit 4 is equipped with a device for pressure compensation 5 (for pressure equalization inside and outside the unit), in order to prevent cavitation within the block. Cable 1 is introduced into the electrohydraulic unit 7 through the ultrasonic unit 4.

(8) This design of the device is optimal to create short discharges inside the well to form an effective shock wave. Combined ultrasound and electrohydraulic treatment can improve the cleaning efficiency of wells, because in this case it has a larger impact area.

(9) The surface part of the device includes: an ultrasonic generator 13 connected via a cable with the ultrasonic unit 4 of the downhole tool; a pulse generator 14 connected via the cable 1 with the electrohydraulic block 7 of the downhole tool; monitoring equipment for the sensors 15 and a signal control unit 16 for the downhole tool with a device 24 for controlling the pulse width, beating frequency and spectrum of the signal of the oscillatory circuit 22 of the electrohydraulic unit 7 and a synchronizer 25 of operation of the ultrasonic generator 13 and the electro-hydraulic unit 7.

(10) The communication or connection relationship among various components in the device are schematically illustrated in FIG. 5.

(11) The device (see. FIG. 1) works as follows.

(12) The downhole tool is lowered into the well (see. FIG. 2). With the help of the monitoring unit of the sensors 15 the degree (parameters) of contamination of the well is determined. Then, using the control unit 16, a signal of an appropriate frequency from the ultrasonic generator 13 is supplied through the logging cable 1 to the electroacoustic transducers 3 of the ultrasonic unit 4. Wherein the ultrasonic unit 4 is connected to the surface ultrasonic generator 13 with the following optimal parameters obtained experimentally: a) frequency range17-24 kHz; b) the voltage at the output420-1200 V; c) the maximum output power10 kW; d) the maximum bias current15 ; d) active cable resistance20-80 Ohm; e) Power3*380 V, 50.60 Hz; g) Possible change of the supply voltage 10%-+10%; h) Power consumptionno more than 13.8 kW; u) the generator can be operated in manual and computer control.

(13) Simultaneously, the signal from the pulse generator 14 is supplied through the geophysical cable 1 to the electro-hydraulic unit 7. The signal has the following optimal parameters obtained experimentally: a) output pulse amplitude120-240 V; b) pulse duration5-50 seconds; c) the interval between pulses50-600 seconds; g) the amplitude of the current pulseno more than 2.5 A; d) power supply220\380 V, 50 Hz; e) possible change of the supply voltage 10%-+10%; g) power consumptionno more than 2.3 kW; h) the generator can work in manual and computer control.

(14) Exposure to the high frequency signal, which is carried out by the ultrasonic unit 4, and a low frequency signal, carried out by the electrohydraulic unit 7, is carried out jointly (synchronously), which leads to a change in the mutual arrangement of the particles in the gravel pack of the wells, whereby the colmatant is removed. Furthermore, changing the configuration of the gravel particles leads to a change in the interference pattern of the ultrasonic waves, and therefore, a shift of the maxima of sonication. This leads to a more thorough cleaning.

(15) The treatment zone of the electrohydraulic unit 7 varies with the parameters of the oscillatory circuit in said unit (inductance, capacitance and resistance). Due to this, it is possible to change the pulse width and its beating frequency, and thereforethe signals spectrum, which leads to a change of the treatment zone. Due to this the exposure is performed for various colmatation zones (predominantly in the filter tube and on the boundary of the gravel pack).

(16) The location of the electrohydraulic unit 7 at the bottom part of the downhole tool enables dual shock front: reflected from the bottom of the well and outgoing from the actual electro-hydraulic unit 7. In this case, the front is a kind of sphere. Experiments have shown that the described combined treatment, carried out by the proposed device, is significantly improves the cleaning performance as compared to single frequency treatment.

(17) Thus, the described device allows effective cleaning of water wells with the smallest possible dimensions of the device.