FROLOV DMITRY PAVLOVICH (RU)
| RU64274U1 | 2007-06-27 | |||
| SU1794266A3 | ||||
| RU2286587C1 | 2006-10-27 | |||
| US4658897A | 1987-04-21 |
Claims
1. Device for low-frequency wave effect, which comprises an acoustic radiator placed into a sealed housing and containing a vibration source, longitudinal connecting rods for connecting the vibration source with a passive rear pad and an active emitting pad made in the form of a disc with two flat emitting surfaces normal to the connecting rods, as well as a metal reflector with flat surfaces parallel to the flat surfaces of the active emitting pad, which is installed in such a way to provide for possibility to move along the axis of the device and be fixed in a chosen position, where each of the active and the passive pads is made with a cavity of a depth equal at least to 0.5 of the pad thickness, and the connecting rods are installed with a gap in the aforesaid cavities and attached each to the bottom of the pad cavity, where the active pad is placed into a sealed housing at a section, its length being at least 0.3 of the pad thickness.
2. Device according to claim 1 , characterized in that the connecting rods are made with threaded ends, and the active and passive pads each made with a cavity, at the bottom of which there is a threaded hole, in which a threaded end of a connecting rod is fixed. 3. Device according to any of claims 1 and 2, characterized in that the connecting rods are installed in the pad cavities by means of centering rings.
4. Device according to any of claims 1 and 2, characterized in that the active pad is aligned in the housing with the centering rings and sealed with circular packers. 5. Device according to any of claims 1 and 2, characterized in that the acoustic radiator is equipped with two metal conic concentrators located on both sides from the vibration source, where each concentrator has one of its butts connected to the vibration source, and its other butt connected to an end of one of the connecting rods, with the opposite end of one of the connecting rods connected to the radiator's passive pad, and the opposite end of the other connecting rod connected to the radiator's active pad.
6. Device according to any of claims 1 and 2, characterized in that the acoustic radiator comprises a vibration source in the form of a cylindrical piezoceramic pack.
7. Device according to any of claims 1 and 2, characterized in that the acoustic radiator comprises a vibration source in the form of at least two cylindrical piezoceramic packs interconnected with a balancing coupling sleeve.
8. Device according to any of claims 1 and 2, characterized in that the acoustic radiator comprises a vibration source in the form of a cylindrical magnetostrictive pack.
9. Device according to any of claims 1 and 2, characterized in that the acoustic radiator comprises a vibration source in the form of at least two cylindrical magnetostrictive packs interconnected with a balancing coupling sleeve. 10. Device according to any of claims 1 to 5, characterized in that the connecting rods are made of a material from the group: aluminum alloy, titanium. |
Device for low-frequency acoustic effect on perforation area and oil- bearing bed in bottom-hole zone.
Description Field of the Invention
The device refers to extractive industry and may be applied in development of oil and gas fields, as well as cleaning water and ore wells. The device serves for wave vibroacoustic effect and is used for working inside the casing in the perforation area of the bottom-hole zone. Prior Art
Various methods and devices are known for creating mechanical effects on the casing perforation area and the oil bed behind it. (RU 2129659, RU 2161244, RU 2047280, RU 2192651 , RU 2055979, SU 1402991 , SU 1402991 , WO 96/12409, US 5727628, US 4184562, US 4469175). Shortcomings of the known devices are high operating oscillation frequency, low efficiency of affecting the well bottom-hole zone with a small range of vibroacoustic effect.
The technical solution under Patent RU 2161244 suggests using resonant cavities. However, there the rod radiator and the reflector are fixed in a support housing, with the distance between the emitting and reflecting surfaces being equal to the "odd number of half-wave lengths" at the operating frequency. The device does not provide for using the casing walls for creating the resonant volume. "
The shortcomings of this analog are determined by the -fact that technological difficulties of creating the device proposed in the patent grow along with lowering the operating frequency, therefore, expedience of its application is lost in principle. Thus, with the radiator's operating frequency being 150 Hz, the half-wave length is close to 5 meters, and the rod radiator, with the instrument compartment and the resonating chamber taken into account, would have an extremely high length (close to 10 meters).
The device, which is the closest to the claimed one is a device for low- frequency wave effect comprising an acoustic radiator placed into a sealed housing and longitudinal rods for connecting the radiator with a passive rear
pad and an active front pad made in the form of a disc with two flat emitting surfaces normal to the connecting rods, as well as a metal reflector with flat surfaces parallel to the flat surfaces of the active emitting pad, which is installed in such a way to provide for possibility to move along the device axis and be fixed in a chosen position, where the whole active pad is placed outside the housing (RU Ns 2263203, 2005, prototype).
The operational description of this known device notes that "the reflectors are installed away from the emitting pad" at a distance "multiple of the half- wave length in liquid at the radiator's operating frequency". The shape of the active pad chosen in the device is not optimum for practical creation of a device to operate in the low-frequency band, from the point of view of minimizing its length. The device is implemented with a "rigid" metal reflector, which unambiguously appears from a reference to using the distance between the surface of the active emitting pad and the reflector equal to a whole number of half-wave lengths in liquid. The device comprises a symmetrical composite radiator, its central section consisting of piezoceramic packs and smooth round metal rods. The operating frequency range of this device lies around 600í800 Hz.
Another shortcoming of this device is a pre-determined frequency range, which results in insufficient efficiency of effect on the well bottom-hole zone owing to a small range of vibroacoustic effect determined by high absorption of emitted oscillations by the ground.
This known device was manufactured and efficiently used for wave effect on perforation area and productive oil-bearing bed at fields in Tatarstan (Tat- RITEK-neft) in June-July of 2005 (producing well No. 2576) and in October- December of 2006 (producing wells: No. 2567,3609; injecting well: No.2504). The device is 2.5 meters long with the outer diameter of the sealed housing being 70 mm, and the internal diameter 50 mm. It has a central section, which consists of piezoceramic packs and round duralumin rods. To raise the range of vibroacoustic effect on productive bed, the range of operating resonance frequencies is required to be further lowered.
Equations for calculation of a radiator with a layout corresponding to the prototype model are given in numerous scientific sources related to design of hydroacoustic antennas, see e.g. "Underwater acoustics" Kamp L., M, MIR,
1972, pp. 50-56; and the course "Hydroacoustic transducers and antennas" Sverdlin GM., L. Sudostroeniye, 1988.
The resonance frequency is found from any of the equations below: tgk 2 tgk 3 b=Zm 2 / Zm 3 or tgk 2 qtgkiL= Zm 2 / Zmi, where: ki is wave number in medium 1. ki=2ττ/λi=2πf p /ci; k 2 is wave number in medium 2. k 2 =2π/λ 2 =2π f p /c 2 ; k 3 is wave number in medium 3. k 3 =2τr/λ 3 =2π f p /c 3 ; f p is resonance operating frequency
Z 1 , Z 2 , Z 3 are mechanical impedances equal to piCiS-ι, P 2 C 2 S 2 , P 3 C 3 S 3 , respectively. c is speed of sound wave propagation in media 1 ,2,3. S 1 , S 2 , S 3 are sectional areas of elements 1 , 2, and 3.
Pi, 92, p3, are areas of media 1 ,2,3, respectively.
Analysis shows that the resonance operating frequency may be reduced mostly through increasing the length of connecting rods of the middle (central) section of the oscillator. The same effect may be achieved by reducing "rigidity" of the central section, reducing its section area or choosing a "soft" material with a low Young's modulus. This results in lowering the ratio Zm 2 /,
Zm 3 or Zm 2 / Zm 1 .
In practice, the aforesaid possibilities are very limited. These are only metals (virtually, it is nothing but steel), which may be used as a material for the pads. Internal diameters of production casing is 5í6 inches, i.e. 127í152 mm.
It is inexpedient to make the central section thin, as this would impair mechanical strength of the radiator.
Therefore, considerable reduction of operating frequency of this acoustic radiator is practically difficult, as it requires unacceptable enlargement of its dimensions, in particular, increasing its length.
Summary of the Invention
The technical objective of the invention is to create an efficient device for low-frequency wave effect on perforation area of the well casing and expansion of the arsenal of devices for low-frequency wave effect on perforation area of the well casing.
The technical result to ensure solving the specified problem lies in lowering resonance frequency of the wave effect and raising the range of vibroacoustic effect, with concurrent reduction of the device dimensions.
The physical premise for possibility of solving the specified problem is the fact that absorption of elastic oscillations generated by the radiator in the ground medium is reduced along with lowering the oscillation frequency. Therefore, to raise the range of efficient vibroacoustic effect on the productive bed, operating frequencies are required to be further lowered. Calculations of vibroacoustic effect in the ground medium are presented, e.g., in the monograph "Physical principles of vibrating and acoustic effects on oil and gas beds". Kuznetsov O. L., Silkin E. M., Chilingar J., M, Mir, 2001. As it appears from this scientific material, it is possible and expedient to excite the natural frequencies in the productive bed, within the range of 90í200 Hz, which will bring about the maximum growth of oil or gas recovery of the productive bed. Specific optimum value of operating frequency depends on the depth of particular bed.
The essence of the invention is that a device for low-frequency effect comprises an acoustic radiator placed into a sealed housing and containing a vibration source, longitudinal connecting rods for connecting the vibration source with a passive rear pad and an active emitting pad made in the form of a disc with two flat emitting surfaces normal to the connecting rods, as well as a metal reflector with flat surfaces parallel to the flat surfaces of the active emitting pad, which is installed in such a way to provide for possibility to move along the axis of the device and be fixed in a chosen position, where each of the active and the passive pads is made with a cavity of a depth equal at least to 0.5 of the pad thickness, and the connecting rods are installed with a gap in the aforesaid cavities and attached each to the bottom of the pad cavity,
where the active pad is placed into a sealed housing at a section, its length being at least 0.3 of the pad thickness.
In specific cases of implementation, the connecting rods may have threaded ends, and the active and passive pads each made with a cavity, at the bottom of which there is a threaded hole, in which a threaded end of a connecting rod is fixed, where the connecting rods are installed in the pad cavities by means of centering rings, the active pad is aligned in the housing with the centering rings and sealed with circular packers, and the acoustic radiator is equipped with two metal conic concentrators located on both sides from the vibration source, where each concentrator has one of its butts connected with to the vibration source, and its other butt connected to an end of one of the connecting rods, with the opposite end of one of the connecting rods connected to the radiator's passive pad, and the opposite end of the other connecting rod connected to the radiator's active pad. Here, the acoustic radiator may comprise a vibration source in the form of a cylindrical piezoceramic pack, or in the form of at least two cylindrical piezoceramic packs interconnected with a balancing coupling sleeve, or in the form of a cylindrical magnetostrictive pack, or in the form of at least two cylindrical magnetostrictive packs interconnected with a balancing coupling sleeve.
The connecting rods are preferably made of a material from the group: aluminum alloy, titanium.
Preferred embodiment Detailed Description of the invention The drawing of Fig.1 presents the diagram of equivalent half-wave composite resonator, Fig. 2 - the curve of vibrational displacement of the resonator elements, Fig.3 - the schematic diagram of the waveguide, Fig.4 - the structural layout of the device for low-frequency effect on perforation zone of the well casing, Fig.5 - the diagram of installation of the device on the site ■ of operation.
The device for low-frequency wave effect designed for low-frequency acoustic effect on perforation area and oil-bearing bed in the bottom-hole zone
comprises in its central section an acoustic radiator, which may contain a vibration source made in the form of a cylindrical piezoceramic pack, or in the form of at least two piezoceramic packs interconnected with a balancing coupling sleeve, or in the form of a cylindrical magnetostrictive pack, or in the form of at least two cylindrical magnetostrictive packs interconnected with a balancing coupling sleeve. Fig.4 presents a device, in which a vibration source is made in the form of two cylindrical piezoceramic or magnetostrictive packs 1 , 2 interconnected with coupling sleeve 3. Vibration source (1 , 2) is connected to passive rear pad 9 and is placed into a sealed housing consisting of two parts 10, 11. Through sealed connector 12, the device is supplied with conductor-and-support cable 13 of the KG-3 type.
The device also contains active emitting pad 8 in the form of a disc with two flat emitting surfaces normal to the device's longitudinal axis, located partially inside and partially outside sealed housing 10, as well as, at least, one metal reflector 15 with flat surfaces parallel to the flat surfaces of active emitting pad 8, installed in such a way to provide for possibility to move along the device axis and be fixed in a chosen position. Metal reflector 15 is mounted on holder 14. The central section of acoustic radiator is equipped with two matching conic concentrators 4, 5 placed on both sides from vibration source (1 , 2), and two cylindrical connecting rods 6, 7 of the central section. Each of concentrators 4, 5 has one of its butts connected to vibration source (1 , 2), and its other butt connected to an end of one of rods 6, 7. The other end of rod 6 is connected to passive pad 9 of radiator, and the other end of rod 7 is connected to active pad 8 of radiator. Active pad 8, at a section, its length being at least 0.3 of the pad thickness, is placed in sealed housing 10, aligned in it by means of centering rings 18, 19 and sealed with circular packers 20, 21.
Each of active and passive pads 8, 9 are made with deep cylindrical cavity 24, 25, respectively, its depth being at least 0.5 of thickness of pad 8, 9. In the bottom of each of cavities 24, 25, there is a threaded hole (not shown), in which the threaded end of respective connecting rod (6 or 7) is fixed. Here, rods 6, 7 of the central section are mounted with centering rings 16, 17
concentrically, with a circular gap between their lateral surfaces and surfaces of cavities 24, 25 of pads 8, 9. Each of rods 6, 7 is mechanically, through a threaded joint, attached to the bottom of cavity 24 or 25 of pad 8 or 9, respectively. The connecting rods are made of aluminum alloy or titanium. The device is located in the zone of holes 23 (perforation) of casing 22.
To provide for operation of the radiator, there are generator 26 and amplifier 27 of power, connected to geophysical machine 28 located at oil well 29. The device operates as follows. The device with reflector 15 is lowered with KG-3 conductor-and- support cable 13 into perforation area 23 of casing 22 of oil well 29. Electric power supply of radiator is delivered through geophysical machine 28 with a hoist from amplifier 27 of power and generator 26 setting the operating mode and operating frequency.
Exciting voltage in the area of radiator's resonance frequency is supplied to packs 1 , 2 through cable 13. Inside the volume of liquid, a standing-wave field is formed between active pad 8 and reflector 15. Sleeve 3 ensures equal elasticity on both sides from radiator 1 , 2. Active emitting pad 8 emits acoustic vibrations in phase opposition by its upper and lower flat surfaces in the opposite directions. Inside the volume of liquid, a standing- wave field is formed between active pad 8 and reflector 15. Passive pad 9 provides the device with symmetry relative to the central section. Two metal conic concentrators 4, 5 located on both sides from vibration source 1 , 2 match the radiator's load through waveguides 6, 7 with pads 8, 9. As rigidity of steel walls of casing 22 is considerably higher than elasticity of the liquid, and the total area of holes 23 is much smaller than the area of the lateral surface of casing 22, raising intensity of oscillation effect inside the resonating volumes may be substantially higher, compared to intensity created by radiator (1 , 2) in free space. Dissipation of acoustic energy from the resonating cavity limited by the surface of active emitting pad 8, the lateral surface of casing 22 with holes 23 and reflector 15 has useful and negative components. The energy dissipated through the lateral surface of casing 22 affects oil contained in the productive bed. As rigidity of steel walls of casing
22 is considerably higher than elasticity of the liquid filling the well, and the total area of holes 23 is much smaller than the area of the lateral surface of casing 22, raising intensity of oscillation effect inside the resonating volumes may be substantially higher, compared to intensity created by radiator in free space. Compared to the prototype, the achievable lowering of frequency is up to 3 times as much, with lengths of radiators being approximately the same.
Therefore, an efficient device is created for low-frequency effect on perforation area of the well casing, and the arsenal of devices for low- frequency effect on perforation area of the well casing is expanded.
At the same time, the resonance frequency of wave effect is lowered, and the range of vibroacoustic effect is raised, with the device dimensions concurrently reduced owing to making connections of pads 8, 9 with rods 6, 7 inside pads 8, 9 and locating the central section (from rod 6 to rod 7) inside pads 8, 9 placed as close as possible to packs 1 , 2 of the radiator.
Industrial Applications
The present invention is embodied with multipurpose equipment extensively employed by the industry.