RU2242771C2 - Method and device for inducing seismic waves - Google Patents

Abstract

FIELD: on-ground and naval seismic prospecting.

SUBSTANCE: discharge current while flowing through winding of inductor results in to interaction of magnetic field of inductor with armature. As a result mechanical force pulse generates running along the axis of source. The pulse is transmitted by armature through casing of source to ground (bottom) in form of pressure pulse in the point where source is mounted to excite elastic vibrations in the source. Inductor moves up along guiding pins till it meets armature and overcomes compressive strength of damping springs. When electric pulse stops to apply to excitation coil, inductor gets back to initial position under effect of damping springs. Device has air-tight case where power electromagnet is located. Electromagnet has armature core and inductor core separated with gap from armature core and provided with excitation coil. Inductor core is mounted for movement at vertical direction onto pins mounted in case between at least two pairs of damping springs.

EFFECT: simplified design; improved reliability.

3 cl, 1 dwg

Description

The invention relates to seismic exploration of minerals, in particular oil and gas, with non-explosive sources and can be used when conducting seismic surveys both on land and in marine seismic exploration in conditions of transit zones and extreme shallow water.

A known method of exciting seismic waves (RF patent No. 2029319, prior. 04.06.1992, IPC G 01 V 1/02). Seismic waves are excited using an electromechanical transducer containing the active and reactive parts. The method includes the creation of a reserve of kinetic energy in the reactive part of the converter and the transfer of force to the medium under study by the mechanically connected active part, the formation and supply of an electric pulse to the control winding of the reactive part of the converter installed on its active part. The active and reactive parts of the transducer are rotatably mounted relative to one another. The reactive part of the converter is rotationally driven at a constant speed. Power action is carried out by applying an electrical impulse to the control winding.

This method is energetically uneconomical, since the rotation of the reactive part of the Converter with a constant speed requires a large energy consumption. The device for its implementation should have a fairly complex design (the presence of rotating parts and mechanical bonds of the active part with the medium under study), as well as labor-intensive and energy-intensive in production. The method is not applicable in marine seismic exploration.

Known pneumatic generator of seismic waves (RF patent No. 2046372, prior. 04.09.1992, IPC G 01 V 1/02, 1/04, 1/137). comprising a casing with a movable cylinder placed inside it, inside which a rod with pistons is mounted, rigidly fixed in the casing, forming an exhaust slot, a control and a working chamber connected by channels through an electro-pneumatic valve to a source of compressed air, and an annular nozzle with throttle openings mounted outside the exhaust gap . A reflector of generated systematic vibrations is mounted above the annular nozzle. The reflector is made in the form of a shield. This generator is designed to operate in extremely shallow waters only.

A source of seismic signals is also known (RF patent No. 1633997, prior. 07.25.1988, IPC G 01 V 1/133), which can be used to excite seismic signals in shallow water, including a lifting screen with steering planes, vibration exciters in the form of hollow cylinders with air emitters placed in them. The whole structure is covered by a frame, to which a tow rope and a float are attached through an elastic element. Before the start of radiation, the source is lowered to the bottom, while charging the pneumatic emitters and corking the hollow cylinders with water. Then, at the same time, compressed air is emitted from the pneumatic emitters, thereby expelling water from the hollow cylinders, and steering forces are immersed into the ground by steering forces until the bottom touches the bottom of the lifting screen. After that, the pneumatic emitters are recharged, the hollow cylinders are corked with water, and longitudinal and transverse waves are excited by sequentially ejecting water from the hollow cylinders installed at an acute angle to the screen.

The disadvantages of these seismic sources are the design complexity, large mass and dimensions, use mainly in the aquatic environment, low efficiency due to the air bubble breaking into the atmosphere when working in the land-sea transit zone, and, if necessary, the excitation of seismic waves near the coastline on land the source must be “immersed” in shallow blast holes, due to which the development time at one blast point, taking into account the time to move the blast-point and drilling a new well, increases, the sources do not have enough chnymi overall reliability and service life due to ingress of abrasive particles and slurries in sealing assemblies.

Closest to the proposed one is a pulsed source of seismic signals (RF patent No. 2028646, prior. 05.29.1991, IPC G 01 V 1/02), containing a radiating plate, a load with a magnetic system, made in the form of a magnetic circuit with a direct current winding with a ring the gap between its poles, and a pulse winding. The pulse winding is fixed at the poles of the magnetic circuit from the side of the non-magnetic gap. In the gap between the poles placed with the possibility of movement in the axial direction along the gap of the sleeve of an electrically conductive material with a low value of electrical resistivity, the lower end of which is attached to the radiating plate. The pulse winding is placed in the grooves on the surface of the poles made of plates of electrical steel, lined in the radial direction. The central part of the composite sleeve is made of strong magnetic material. The upper end of the sleeve extends beyond the poles.

The disadvantage of this seismic source is the design complexity due to the large number of coils, a large mass due to the presence of a load, the use of the source only on land.

Currently, the world has developed a large number of various systems of excitation of seismic waves for seismic operations, including transit zones, but there is not a single unified one. The inconsistency of land seismic surveys carried out on the coasts with similar works performed in shallow areas creates numerous problems with the interpretation of seismic materials and the determination of the contours of the deposits of the identified deposits.

The task is to create a fairly simple and convenient way to excite seismic waves, allowing you to work both on land and in transit zones and extreme shallow water, and a simple, reliable and mobile device for its implementation.

The problem is solved due to the fact that in the method of excitation of seismic waves, based on the transfer of force to the medium under study at the point of contact of the emitting device with the medium in the form of pressure pulses created using an electromechanical transducer, which is a power electromagnet consisting of an armature and an inductor with by the excitation winding, pressure pulses that are transmitted by the armature directly through the housing of the emitting device rigidly connected to it to the medium under study create due to reobrazovaniya electrical energy in the form of a powerful current pulses which are supplied to the inductor coil of the electromagnet into mechanical energy, realized in the form of impulse, the displacement under the action of the electromagnetic force of the armature to the housing provide that provide resistance to movement of the inductor toward the armature.

To implement this method, it is proposed in a device for exciting seismic waves, comprising a radiating body with a flat magnetic system including an inductor magnetic circuit with a direct current excitation winding and an armature magnetic circuit separated by a gap, to use a device body rigidly connected to the armature magnetic conductor as a radiating body, and install the inductor magnetic circuit under the magnetic circuit of the armature between at least two pairs of damper spacer elements with the possibility of moving in rtikalnom direction.

The installation of the inductor with the possibility of moving in the vertical direction between at least two pairs of damper spacer elements provides the redistribution of force pulses between the inductor and the armature and the armature and the medium, which allows to do without the use of inert additional masses such as a load, i.e. a sufficiently powerful pressure pulse is created with small mass-dimensional characteristics of the emitter and does not depend on the mass (weight) of the emitter. This, in turn, makes it possible to use it when working in a submerged state. Light weight and simplicity of design provide reliability, durability, mobility and portability of the device. The conversion of an electrical impulse into a force action occurs without the use of complex elements of rotation or reciprocating motion. This ensures the stability of the shape and amplitude of the seismic signal. To excite seismic waves, it is not necessary to bury the source in the ground or use additional devices to ensure its operation.

The drawing shows a possible embodiment of a device for exciting seismic waves.

The device comprises a sealed cylindrical housing 1, in which there is a power electromagnet containing the armature 2 of the armature, separated by a gap of the inductor 3 with the field winding 4, and the armature of the armature 2 is rigidly connected to the upper part of the housing 1, and the core of the inductor 3 is movable in the vertical direction on the studs 5 installed in the upper part of the body between at least two pairs of damper springs: internal springs 6 and external springs 7. Internal springs Inas 6 abut against the base of the magnetic circuit of the armature 2, and the outer springs 7 - into the support-adjusting nuts 8, screwed onto the studs 5. Thanks to the damper springs 6, 7, the inductor 3 is suspended under the armature 2.

The excitation of seismic waves occurs as follows. The energy from a direct current source stored in a capacitive energy storage device is supplied as a powerful current pulse to the winding of an electromagnet inductor 3, in which it is converted into a force pulse. The force impulse is transmitted by the anchor 2 through the source body 1 in the form of a pressure impulse to the soil (bottom) at the point of contact of the source with the medium under study, exciting elastic vibrations in it. This process does not proceed continuously, but discretely, for short periods of time of no more than five milliseconds. This mode of operation allows you to receive in the pulse effort, many times higher than those that develop conventional electric motors that operate continuously. The working element of the device is a flat electromagnet mounted in the source housing. In the initial position, the inductor and the armature of the electromagnet are separated from each other by an air gap. When the discharge current flows through the inductor winding, the magnetic field of the inductor interacts with the armature iron, as a result of which a mechanical force impulse acting along the axis of the source arises, which is transmitted by the armature through the source body in the form of a pressure pulse to the ground (bottom) at the source installation point, exciting there are elastic vibrations. In turn, the inductor moves up the guide pins until it meets the anchor, overcoming the compression resistance of the internal damping springs. When the supply of an electric pulse to the excitation coil is stopped, the electromagnetic forces of the interaction of the inductor with the armature disappear and the inductor returns to its original position under the action of damping springs.

A seismic wave source was manufactured using the proposed solution, in which the maximum amplitude of the pressure pulse was 1500 kPa with a maximum pulse force of 60 kN, while the contact surface area of the source with soil is 0.04 m ² and the source mass is 25 kg. The source is powered by a 12 V, 55 Ah battery. The source can be used both on land and in transit zones and extreme shallow water.

Claims (2)

1. A method of exciting seismic waves, based on the transfer of force to the medium under study at the point of contact of the emitting device with the medium in the form of pressure pulses generated by an electromechanical transducer, which is a power electromagnet consisting of an armature and an inductor with an excitation winding, characterized in that pressure pulses that are transmitted by the anchor directly through the housing of the radiating device rigidly connected to it to the medium under study create due to Electric energy in the form of powerful current pulses, which are fed to the coil of an electromagnet inductor, into mechanical energy sold in the form of force pulses, while the movement of the armature with the body under the influence of electromagnetic forces ensures that it creates resistance to the movement of the inductor towards the armature. 2. A device for exciting seismic waves, comprising a radiating body with a magnetic system including an inductor magnetic circuit with a direct current excitation winding and an armature magnetic circuit separated by a gap, characterized in that the device body is used as a radiating body, rigidly connected to the armature magnetic circuit, and a magnetic circuit the inductor is mounted with the possibility of movement in the vertical direction between at least two pairs of damper spacer elements.