FR2517361A1 - Thermo-acoustic device for oil and gas-wells - uses electrically excited acoustic generator to increase heat conduction from an electric heater which is placed in the well - Google Patents

Abstract

The device is partic. intended for use where the oil is of high viscosity or where there are high concentrations of dissolved salts, and operates by heating the oil, taking advantage of the increase in heat transfer obtained when the fluid is subject to acoustic vibration. The acoustic emitter (4) of the device has a hollow body (11) in which a group of electric coils (14) are fitted. The cores (17) generate an acoustic signal when the coils are excited and an acoustic concentrator (18) intensifies the sound. An electric heater (1) with an enclosed terminal box (3) is attached to the acoustic source. The coils cores are hollow and contain a deflector for acoustic oscillations arranged to intensify the oscillations in a radial direction.

Description

The present invention relates to well drilling techniques, in particular in the field of oil and gas production, and in particular relates to a thermo-acoustic device for wells
The invention is intended in particular for between used in the production of oil and gas to exert a thermo-acoustic action on the area adjacent to the bottom of an oil and gas well in order to intensify the exploitation of deposits highly viscous paraffin oils, as well as deposits containing a large amount of dissolved salts which, by depositing, during the exploitation of the deposit, in the area near the bottom of the well, lower its permeability to oil and gases during exploitation, and to increase its recovery.

 The thermo-acoustic action methods on the area near the bottom of the well are based on the effects of the thermodynamic action of the thermal and acoustic fields in store rocks. The effects mentioned contribute to a notable increase in the effective thermal conductivity of the oil and gas store rocks and, consequently, to an increase in the thermal action zone on the zone close to the bottom of the well. After said thermo-acoustic action on the area near the bottom of the well, the total or partial reestablishment of the permeability of the store rock to oil and gas is noted, the reduction of which is due to deposits of paraffin from the deposit, from salts, or by the invasion of the area near the bottom of the well by mud.

A thermo-acoustic device for wells is known (Simkine EM, "Study of the thermal action of electric bottom heaters", Thesis of candidate for the title of aggregated in science, 1968 (VNII Minnefteprom Fund,
USSR, Moscow) used to exert a thermal electrofl action on the area near the bottom of the oil and gas well, and which comprises a heater with a terminal chamber which is made integral with an emitter of acoustic oscillations constituted by two electromagnets housed inside the cylindrical body on a common axis, the electromagnet aipeneur 0e 1 emitter of acoustic oscillations is stationary, while the lower electromagnet can move jointly with the heater along a common axis During the passage of electric current, the electromagnets attract periodically, but it is only the lower electromagnet which moves with the heater, while the upper electromagnet remains stationary C This is how we create longitudinal acoustic oscillations of the electric heater in the well, thus obtaining an increase in the heating zone.

 However, this thermo-acoustic device for wells produces low intensity oscillations which propagates mainly along the wellhole, which is due to the longitudinal displacement of the lower electromagnet with the electric heater, while, to obtain a effective thermo-acoustic action on the area near the bottom of the well, the oscillations must propagate perpendicular to the axis of the well.

The device in question produces low frequency oscillations (up to 100 Hz), which does not provide a thermo-acoustic effect having a threshold character and manifesting itself in a determined range of frequencies exceeding 3 kHzo
The device does not allow the thermal field to be concentrated, since it is not provided with elements controlling the thermal parameter of the thermo-acoustic field.

Because this device has movable parts and that during work it may not be guaranteed to maintain its tightness, its reliability is not high.
With the increase in hydrostatic pressure inside the well when the device is lowered to the prescribed depth, the damping effect of the well liquid causes a decrease in the acoustic characteristics of the device 0
Due to the longitudinal oscillations of the liquid column in the well, part of the heat is transferred upwards, which affects the operating conditions of the target supplying the device and does not allow it to exert an effective thermal action on the area near the bottom of the well.

 It follows that the thermo-acoustic device for wells which we have just examined does not make it possible to create, because of the mentioned drawbacks, a thermoacoustic field with a high intensity of the acoustic emission, propagating radially.

It has therefore been proposed to develop a thermo-acoustic device for wells, provided with an emitter of acoustic oscillations whose design would ensure obtaining a thermo-acoustic field of high intensity propagating radially, and at the same time, the concentration of the acoustic field in accordance with the thermal parameter, as well as the protection of the heater and the cable tette against acoustic oscillators,
The problem thus posed is solved using a thermo-acoustic device for wells, comprising an emitter of acoustic oscillations and a heater provided with a terminal chamber and connected to the emitter, characterized, according to the invention , in that the acoustic oscillation emitter comprises a hollow body inside which is installed a longitudinal axis carrying coils arranged successively one behind the other and whose cores comprise at least one active element intended to generate acoustic oscillations.

 It is advantageous that in the thermoacoustic device for wells according to the invention, the core of the coil is executed hollow and that an acoustic oscillator deflector, intended to intensify the acoustic oscillations in the radial direction, is housed at the inside the core, on said longitudinal axis.

To obtain a more thermo-acoustic action
effective on the area near the bottom of the well, it is
preferable, according to the invention, to place between said
coils, on said longitudinal axis, elements for
sound field concentration.

To protect the heater and the cable
power against acoustic action it's
reasonable, according to the invention, to install in the
lower and upper parts of the hollow body, on
said longitudinal axis, damping elements
intended to dampen acoustic oscillations.

It is possible, in the thermo-acoustic device
for wells according to the invention, to place between the
terminal chamber of the heater and the oscillation emitter
acoustic, a heat-insulating element intended to evacuate the
heat from the acoustic oscillator.

It is advantageous that, in the thermoacoustic device for wells according to the invention, the element
active coil is executed as a ring
flat in magnetostrictive material.

It is also possible, in the thermo device
acoustic for wells according to the invention, to realize
the active element of the coil in the form of a cylinder
hollow in a piezoelectric ceramic material.

It is desirable that in the thermo device
acoustic for wells according to the invention, the active element
of the coil is made of ferrite with properties
magnetostrictive.

It is reasonable that in the thermo device
acoustic for wells according to the invention, the deflector
of acoustic oscillations is made tubular.

It is desirable that in the thermo device
acoustic for wells according to the invention, the element
sound field concentration is executed under
shape of a socket.

It is advantageous that, in the thermo device
acoustic for wells according to the invention, the sound field concentration element is executed in the form of a socket in a material having damping properties.

 It is preferable that, in the thermoacoustic device for wells according to the invention, the damping elements are executed in the form of sockets made of an elastic material.

 To ensure more efficient heat dissipation, it is desirable that, in the device according to the invention, the heat-insulating element is executed in the form of a sleeve with finned surface.

 It is admissible that, in the thermoacoustic device for a well, in accordance with the invention, the interior enclosure of the body of the emitter of acoustic oscillations is filled with a composition (or "compound") resistant to heat.

 The thermo-acoustic device proposed ensures the production of acoustic oscillations in a determined frequency range, with a high intensity of the radially propagating sound field. Thanks to the introduction of elements for concentrating the acoustic field in the thermo-acoustic device proposed), the possibility was also obtained of concentrating the thermal field.

 The thermo-acoustic device proposed does not include any moving parts which increases its reliability while retaining its acoustic characteristics. The acoustic cscillations generated by the thermo-acoustic device for wells are preferably radially predicted. Consequently, the thermal conditions for the operation of the power cable remain satisfactory and its mechanical strength increases.

The invention will be better understood and other objects, details and advantages thereof will appear better in the light of the explanatory description which will follow of different embodiments given only by way of nonlimiting examples, with references to the drawing. single nonlimiting annexed-in which
- Figure 1 shows an overview of the thermoelectric device for wells, according to the invention
- Figure 2 shows an overview of the acoustic oscillation emitter of the thermo-acoustic device with cutaway and partial longitudinal sections, according to the invention.

 Figure 1 is an overview of the thermo-acoustic device for wells. The thermoacoustic device for wells comprises, in the case under consideration, a heater 1 with electric heater elements 2.

The heater 1 is connected via a sealed terminal chamber 3 to the emitter of acoustic oscillations 4 A heat-insulating element 5 is placed between the emitter 4 and the terminal chamber 3 and is intended to dissipate the heat of the acoustic oscillation transmitter 4 and protect it against overheating.

The thermo-acoustic device for wells also includes a cable head 6, mounted on one of the ends of the acoustic oscillation transmitter 4, The cable head 6 is intended to ensure a tight connection of the power cable 7 with the acoustic oscillation emitter 4, as well as making the connection of the thermo-acoustic device for wells with the extraction casing (not shown in FIG. 1), on which the device is lowered into the well. The conical tubular thread 8 formed on the cable head 6 is intended for its connection to the casing. It is possible to produce the thermo-acoustic device so as to allow the descent of the latter attached to a target inside the heat-insulating element 5, are arranged electrical conductors 9 resistant to heat and used for amending the electrical energy from a power source arranged on the surface (not shown in FIG. 1) and to the heater 1. The heat-insulating element 5 , executed in the form of a socket, is electrically and mechanically connected with the aid of 1O threaded reduction fittings, to the acoustic oscillation emitter 4. To improve the evacuation of heat, the surface of the heat-insulating element 5 includes, in the case considered, a thread
FIG. 2 represents an overall view of the acoustic oscillation transmitter 4, with cutaway and partial longitudinal sections. This comprises a hollow body 11 inside and in the center of which is mounted, using washers 12, a longitudinal axis 13 on which is placed a coil 14 provided with a conductor 15.

 An output of the conductor 15 is connected to the hollow body 11, while the poor end of the conductor 15 of each of the coils 14 is connected to a common supply bar 16. The core of each of the coils 14 is constituted by active elements 17 intended to generate ultrasonic acoustic oscillations. ores.

Each of the active elements 17 is produced, in the case considered, in the form of a flat ring made of magnetostrictive material, for example of an alloy known by the trade name "Permendurn. Each active element 17 creates ultrasonic oscillations which are propagated mainly radially. Inside each coil 14 is placed an acoustic deflector 18, having, in the case considered, a tubular shape and intended to increase the acoustic efficiency in the radial direction. dampen the acoustic oscillations and ensure reliable electrical and mechanical connections with the heater 1 (figure 1) and with the casing arranged above (not shown in figure 2), are placed in the upper and lower parts of the cavity of the hollow body 11 .

According to the variant considered embodiment of the thermo-acoustic device for wells, the damping element 19 is executed in the form of a sleeve made of an elastic material, which ensures preservation of the seal and of the mechanical strength during the
the functioning of the entire thermo-acoustic device
for wells0
An element 20 for concentrating the acoustic field
is mounted inside the cylindrical body 11, on
the longitudinal axis 13, between the coils 14, and serves to
change the width of the field orientation diagram
acoustic ; thanks to this particularity, we can com
request the thermal parameter of the thermo-acoustic field.

Element 20 is executed, in the case considered,
in the form of a socket. To enhance the effect
damping element 20
in the form of a sleeve made of an elastic material.

The nuts 21 tighten the parts in the
hollow body 11, forming a single package or
monobloc assembly. The electrical connection of the transmitter
of acoustic oscillations 4 and of the heater 1 with the
cable 7 (figure 1) is made using conductors
electrical 22 (Figure 2) via waterproof connectors 23 heat resistant. The inner enclosure of the hollow body Il of the acoustic oscillation transmitter 4 and ree urie oemposiiion (or "oempamd! 9 heat resistant and driven back under pressure, which increases the
operational reliability of the oscillation transmitter
acoustics 4, as well as its electrical and mechanical resistances and, consequently, the reliability of operation of the entire device under the conditions
of Wells.

It should be added that each active element 17 can
be executed as a hollow cylinder of material
piezoelectric ceramic or in the form of ferrite sockets with magnetostrictive properties.

 The device operates as follows.

Energy supplied by an ultrasonic generator
(not shown in FIGS. 1, 2) arranged on the surface,
via cable 7 (figure 1), conductors
22 and connectors 23-, is applied to the heater 1 and to the coils 14 of the acoustic oscillation transmitter 4. Electric oscillations are generated in the coils 14 as a result of the variation of the radial dimensions of the active elements 17, which , dens in the case considered, are in the form of flat rings of magnetostrictive material. The variation of the radial dimensions of the active elements 17 takes place under the action of the alternating magnetic field generated in the coils 14. The direction and the orientation diagram of the acoustic field are adjusted by the deflectors 18 and the elements 20 for concentrating the field. acoustic0 The coincidence of the thermal edge produced by the heater and the acoustic field generated by the acoustic oscillation emitter 4 causes an effect of multiple elevation of the effective conductivity of the layer in the area near the bottom of the oil well and gas

Claims (14)

 1. Thermo-acoustic device for wells, of the type comprising an acoustic oscillation transmitter (4) and an electric heater (1) provided with a terminal chamber (3) and connected to said transmitter, characterized in that the emitter - acoustic oscillator includes a hollow body (îi) inside which is installed a longitudinal axis (13) carrying coils (14) arranged successively one after the other and whose cores comprise at least one element active (17) intended to generate acoustic oscillations.  2. thermo-acoustic device according to claim 1, characterized in that the core of the coil (14) is executed hollow and that an acoustic oscillation deflector (18) intended to intensify the acoustic oscillations in the radial direction is mounted inside said core.  3. thermo-acoustic device according to one of claims i and 2, characterized in that at least one element (20) for concentrating the acoustic field is mounted inside the hollow body (11) on the axis longitudinal (13), between the coils (14)  4. Thermo-acoustic device according to one of claims 1, 2 and 3, characterized in that elements (19) for damping acoustic oscillations are mounted in the upper and lower parts of the hollow body (it).  5, thermo-acoustic device according to one of claims 1, 2, 3 and 4, characterized in that a heat-insulating element (5) intended for removing heat from the emitter of acoustic oscillations (4) is placed between the terminal chamber (3) of the heater (1) and the acoustic oscillator transmitter (4).  6. thermo-acoustic device according to one of claims 1, 2, 3, 4 and 5, characterized in that the core of each coil (14) comprises several active elements (17) each of which is executed in the form of a flat ring in magnetostrictive materialO  7. Device according to one of claims 1, 2, 3, 4 and 5, characterized in that the active element (17) of the coil (14) is executed in the form of a hollow cylinder made of piezo ceramic material -electric.  8. Thermo-acoustic device according to one of claims <, 2, 3, 4 and 5, characterized in that said active cylindrical element (17) of the coil (14) is made of ferrite with magnetostrictive propertiesO  9. Tiio-actoustic device according to one of claims 1 to 8, characterized in that the deflector of acoustic oscillations (18) has a tubular shape  10. Thermo-acoustic device according to one of claims 1 to 9, characterized in that the element (20) for concentrating the acoustic field is executed in the form of a socket.  11. Thermo-acoustic device according to one of claims 1 to 10, characterized in that the element (20) for concentrating the acoustic field is executed in the form of a sleeve made of a material having damping properties.  12. Thermo-acoustic device according to one of claims 1 to 105 characterized in that the damping elements (19) are executed in the form of a sleeve made of elastic material.  13. Thermo-acoustic device according to one of claims 1 to 12, characterized in that the heat-insulating element (5) is executed in the form of a sleeve with a threaded surface  14. Thermo-acoustic device according to one of claims 1 to 155 characterized in that the inner enclosure (4) of the hollow body II of the acoustic oscillation emitter is filled with a composition resistant to heat.