CN104389581A - Underground fluid induction device and fluid flow velocity measuring system using same - Google Patents

Underground fluid induction device and fluid flow velocity measuring system using same Download PDF

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Publication number
CN104389581A
CN104389581A CN201410475281.6A CN201410475281A CN104389581A CN 104389581 A CN104389581 A CN 104389581A CN 201410475281 A CN201410475281 A CN 201410475281A CN 104389581 A CN104389581 A CN 104389581A
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China
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fluid
grating
piston
flow
venturi
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CN201410475281.6A
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CN104389581B (en
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陈少华
王伟
赵昆
孟倩
孙世宁
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China University of Petroleum Beijing CUPB
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China University of Petroleum Beijing CUPB
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    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21BEARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B47/00Survey of boreholes or wells

Abstract

The invention provides an underground fluid induction device and a fluid flow velocity measuring system using the device. The underground fluid induction device comprises a pressure guide pipe, a spacing plate, a first piston, a first spring and a first grating arranged at the left side of the spacing plate, a second piston, a second spring and a second grating symmetrically arranged at the right side of the spacing plate, and a venturi pipe. The device uses the gratings for sensing the pressure applied to the pipe wall by the flowing of a fluid in the venturi pipe; and the flow velocity of the fluid in the pipe is obtained according to the characteristic of different flow velocity of the fluid and different pressure applied to the pipe wall. The device can realize precise fluid measurement under the conditions of limited space and severe environment of underground thousands of oil-gas wells.

Description

Downhole fluid induction installation and use the fluid flow measuring systems of this device
Technical field
The invention relates to rate of flow of fluid monitoring technology, particularly about the rate of flow of fluid measuring technique in petroleum industry field, is a kind of downhole fluid induction installation and the fluid flow measuring systems using this device concretely.
Background technology
Flow velocity/the flow of fluid is an Important Parameters in daily life, industrial processes, energy measurement and environment protection and monitoring.Flow velocity/flow sensing conventional is at present in respect of volumetric flowmeter, vortex-shedding meter, turbine flowmeter, electromagnetic current metre, ultrasonic current metre and acoustic Doppler velocimetry etc.These flow velocitys/flow sensing meter has respective characteristics and available field, be widely used in daily life and industrial production, but these flow velocitys/flow sensing meter also has certain limitation, as volumetric flowmeter is bulky, be not suitable for high temperature low temperature situation, although electromagnetic current metre and acoustic Doppler velocimetry certainty of measurement higher, hold easy electromagnetic wave interference, and cost is also high.
Flow velocity/flow sensing meter is the key player promoting to play the part of in industrial and agricultural development process, and therefore it has just received great attention since appearance.Nowadays along with the fast development of modern industrial or agricultural, some special dimensions, exploration and development field, upstream as petroleum industry is just very harsh for the requirement of rate of flow of fluid instrument, because the Oil/gas Well of a few km in underground is limited space but also ambient conditions very severe not only, because flow velocity/flow sensing meter volume conventional is at present large, be subject to the limitation of electromagnetic interference, therefore conventional at present flow velocity/flow sensing meter cannot be applied.
Therefore, how to develop a kind of new rate of flow of fluid measurement mechanism, it can adapt to exploration and development field, petroleum industry upstream, and under the confined space of underground a few km Oil/gas Well and high temperature, hyperbaric environment condition, realize accurate rate of flow of fluid measurement is this area technical problem urgently to be resolved hurrily.
Summary of the invention
The technical problem to be solved in the present invention is to provide a kind of downhole fluid induction installation and uses the fluid flow measuring systems of this device, to tube wall applied pressure when utilizing grating sensing tube fluid to flow, rate of flow of fluid is different, also different to tube wall applied pressure, and then try to achieve tube fluid flow velocity according to this pressure differential, solve the problem that current meter of the prior art is easily disturbed, volume is large, certainty of measurement is low.
In one embodiment of the present of invention, provide a kind of downhole fluid induction installation, wherein, this downhole fluid induction installation comprises: Venturi tube, for guiding downhole fluid, described Venturi tube has an entrance and a venturi section, and the diameter of described entrance is greater than the diameter of described venturi section; Connecting pipe, is connected with described Venturi tube; Dividing plate, is arranged at described connecting pipe center; First spring, be arranged on the left of described dividing plate, one end is connected with described dividing plate, and the other end is connected with a first piston, and fluid acts on described first spring at the pressure of described entrance by described first piston; Second spring, be symmetricly set on the right side of described dividing plate, one end is connected with described dividing plate, and the other end is connected with one second piston, and fluid passes through described second piston action in described second spring at the pressure of described venturi section; First grating, one end is connected with described dividing plate, and the other end is connected with described first piston, and described first grating is in extended state all the time under the acting in conjunction of described first spring force and described entrance fluid pressure, described first grating receives an incident light, and reflects one first reverberation; And second grating, one end is connected with described dividing plate, the other end is connected with described second piston, described second grating is in extended state all the time under the acting in conjunction of described second spring force and described venturi section fluid pressure, described second grating receives described incident light, and reflects one second reverberation.
In another embodiment of the present invention, a kind of fluid flow measuring systems is provided, wherein, this fluid flow measuring systems comprises the downhole fluid induction installation in above-described embodiment, this fluid flow measuring systems also comprises LASER Light Source, grating demodulation instrument and treating apparatus, described LASER Light Source is connected with described downhole fluid induction installation, and described LASER Light Source is for launching described incident light; Described grating demodulation instrument is connected with described downhole fluid induction installation, and described grating demodulation instrument is used for the first reverberation described in demodulation and obtains one first reflectance spectrum, and the second reverberation described in demodulation obtains one second reflectance spectrum; Described treating apparatus is connected with described grating demodulation instrument, and described treating apparatus is used for the rate of flow of fluid determining described venturi tube inlet section place according to described first reflectance spectrum and described second reflectance spectrum.
The invention provides a kind of downhole fluid induction installation and use the fluid flow measuring systems of this device, Venturi tube and grating are organically combined, to tube wall applied pressure when utilizing grating sensing Venturi tube inner fluid to flow, Venturi tube inner fluid speed is different, not identical to tube wall applied pressure yet, fluid is finally applied on grating tube wall applied pressure, the power that grating is subject to is different, not identical by the length of the reflectance spectrum peak wavelength of the laser of grating yet, thus draw this pressure differential according to the length of reflectance spectrum peak wavelength, Bernoulli equation is utilized to try to achieve tube fluid flow velocity according to this pressure differential again, it is simple that this downhole fluid induction installation has structure, easy for installation, with low cost, electromagnetism interference, reliable operation, certainty of measurement is high, take up room little, can be long-time at high temperature, high pressure, noise, the advantage such as work under the adverse circumstances such as deep-etching.
Accompanying drawing explanation
Fig. 1 is the structural representation of downhole fluid induction installation of the present invention.
Fig. 2 is a preferred structure schematic diagram of downhole fluid induction installation of the present invention.
Fig. 3 is the structural representation of the Venturi tube of downhole fluid induction installation of the present invention.
Fig. 4 is the internal construction schematic diagram of the connecting pipe of downhole fluid induction installation of the present invention.
Fig. 5 is the structural representation of fluid flow measuring systems of the present invention.
Fig. 6 is the structural representation of the treating apparatus of fluid flow measuring systems of the present invention.
Symbol description:
1 first grating
2 second gratings
3 first springs
4 second springs
5 first pistons
6 second pistons
7 dividing plates
8 first snap rings
9 second snap rings
10 upstream pilot interfaces
11 downstream pilot interfaces
12 Venturi tubes
13 connecting pipes
14 entrances
15 venturi sections
100 downhole fluid induction installations
200 LASER Light Sources
300 grating demodulation instrument
400 treating apparatus
401 spectrum acquisition unit
402 spectrum peak wavelength determining units
403 wavelength difference determining units
404 pressure differential determining units
405 rate of flow of fluid determining units
406 display units
Detailed description of the invention
For making the object of the embodiment of the present invention, technical scheme and advantage clearly understand, below in conjunction with accompanying drawing, the embodiment of the present invention is described in further details.At this, schematic description and description of the present invention is for explaining the present invention, but not as a limitation of the invention.
Fig. 1 is the structural representation of downhole fluid induction installation 100 of the present invention, as shown in Figure 1, this downhole fluid induction installation 100 comprises Venturi tube 12, connecting pipe 13, dividing plate 7, first spring 3, second spring 4, first piston 5, second piston 6, first grating 1, second grating 2, Venturi tube 12 is for guiding downhole fluid, described Venturi tube 12 has entrance 14 and a venturi section 15, and the diameter of described entrance 14 is greater than the diameter of described venturi section 15; Connecting pipe 13 is connected with described Venturi tube 12; Dividing plate 7 is arranged at described connecting pipe 13 center; First spring 3 is arranged on the left of described dividing plate 7, and one end of the first spring 3 is connected with described dividing plate 7, and the other end of the first spring 3 is connected with first piston 5, and fluid acts on described first spring 3 at the pressure of described entrance 14 by described first piston 5; Second spring 4 is symmetricly set on the right side of described dividing plate 7, and one end of the second spring 4 is connected with described dividing plate 7, and the other end of the second spring 4 is connected with the second piston 6, and fluid acts on described second spring 4 at the pressure of described venturi section 15 by described second piston 6; One end of first grating 1 is connected with described dividing plate 7, the other end of the first grating 1 is connected with described first piston 5, described first grating 1 is in extended state all the time under the acting in conjunction of described first spring 3 elastic force and described entrance 14 fluid pressure, described first grating 1 receives incident light, and reflects the first reverberation; One end of second grating 2 is connected with described dividing plate 7, the other end of the second grating 2 is connected with described second piston 6, described second grating 2 is in extended state all the time under the acting in conjunction of described second spring 4 elastic force and described venturi section 15 fluid pressure, described second grating 2 receives described incident light, and reflecting the second reverberation, fluid flows through from Venturi tube 12 according to the direction shown in Fig. 1 arrow.
As shown in Figure 1, the stress (spring force deducts fluid pressure) that grating is subject to is different, the incident light of reflection is also different, the diameter of described entrance 14 is greater than the diameter of described venturi section 15, when not having fluid to flow through Venturi tube 12, or when fluid remains static, act on the pressure of first piston 5 at entrance 14 according to the known fluid of Bernoulli equation, equal fluid acts on the second piston 6 pressure in venturi section 15, incident light goes out reverberation through optical grating reflection.When there being fluid to flow through from Venturi tube 12 according to the direction shown in Fig. 1 arrow, diameter due to described entrance 14 is greater than the diameter of described venturi section 15, pressure is large the flow velocity of entrance 14 is little for fluid, pressure is little the flow velocity of venturi section 15 is large for fluid, and the reverberation now through grating will change.
Under normal circumstances, Venturi tube 12 and connecting pipe 13 are positioned at tested scene, and such as Venturi tube 12 and connecting pipe 13 are arranged in a few km Oil/gas Well in underground.Measure because the present invention utilizes laser to realize rate of flow of fluid, laser has the characteristics such as electromagnetism interference, reliable operation, certainty of measurement height, can realize accurate rate of flow of fluid and measure under high temperature, hyperbaric environment condition in a few km Oil/gas Well of underground.
Fig. 2 is a preferred structure schematic diagram of downhole fluid induction installation 100 of the present invention, and as shown in Figure 2, downhole fluid induction installation 100 also comprises: the first snap ring 8, second snap ring 9.Wherein, the first snap ring 8 is fixedly installed on connecting pipe 13 inwall on the left of described first piston 5, and the first snap ring 8, for limiting first piston 5 to left movement, prevents the first grating 1 because of stressed excessive and damage; Second snap ring 9 is fixedly installed on connecting pipe 13 inwall on the right side of described second piston 6, and the second snap ring 9 moves right for limiting the second piston 6, prevents the second grating 2 because of stressed excessive and damage, and the first snap ring 8 and the second snap ring 9 symmetrical relative to dividing plate 7.
As shown in Figure 2, first snap ring 8 and arranging of the second snap ring 9 can protect the first grating 1 and the second grating 2 well, when not having fluid to flow through in Venturi tube 12, fluid is not had to apply pressure to first piston 5 and the second piston 6, the elastic force of spring is all applied on grating, now, the displacement that first snap ring 8 can prevent first piston 5 from occurring left exceeds the maximum tolerance range of described first grating 1, the displacement that second snap ring 9 can prevent the second piston 6 from occurring to the right exceeds the maximum tolerance range of described second grating 2, prevent grating due to stressed excessive and damage.
As shown in Figure 1 and Figure 2, connecting pipe 13 is arranged along Venturi tube 12, connecting pipe 13 is tube element, effectively can control the lateral dimension of downhole fluid induction installation 100, so the present invention can measure rate of flow of fluid in limited environment space, as the Real-Time Monitoring of Oil/gas Well downhole fluid flow velocity.In addition, each element (spring, grating, piston etc.) in connecting pipe 13 is conventional physical component, and therefore downhole fluid induction installation 100 also has that structure is simple, easy for installation, the advantage of reliable operation, improves certainty of measurement further.
Fig. 3 is the internal construction schematic diagram of the connecting pipe of downhole fluid induction installation 100 of the present invention, as shown in Figure 3, described dividing plate 7 has through hole (not indicating in figure), can ensure that the pressure in the cavity of dividing plate both sides is in equilibrium state all the time like this.
As shown in Figure 3, through hole (not indicating in figure) is established due to dividing plate 7 having, the left cavity between dividing plate 7 and first piston 5 can be ensured, equal all the time with the air pressure in the right cavity between dividing plate 7 with the second piston 6, air pressure in left cavity and right cavity is equal can prevent effects of air pressure measurement result, improves certainty of measurement further.
In one embodiment of the present of invention, as shown in Figure 2 and Figure 3, the material of described first piston 5 and described second piston 6 and shape identical.Be subjected to displacement in the scope that first piston 5 and the second piston 6 can limit at the first snap ring 8, second snap ring 9 but strictly stop fluid to circulate.
As shown in Figure 2 and Figure 3, material and the shape of first piston 5 and the second piston 6 are identical, ensure that the pressure that first piston 5 and the second piston 6 are subject to is only relevant with rate of flow of fluid, do not affect by the material of first piston 5 and the second piston 6 and shape, improve certainty of measurement further.
In one embodiment of the present of invention, as shown in Figure 2 and Figure 3, the shape of described first grating 1 and described second grating 2 and parameters identical.
As shown in Figure 2 and Figure 3, shape and the parameters of the first grating 1 and the second grating 2 are identical, ensure the reverberation that incident light is formed after the first grating 1 and the second grating 2 reflect, only relevant with the stress (spring force deducts fluid pressure) that the first grating 1 and the second grating 2 are subject to, improve certainty of measurement further.
In one embodiment of the present of invention, as shown in Figure 2 and Figure 3, the shape of described first spring 3 and described second spring 4 and parameters identical.
As shown in Figure 2 and Figure 3, shape and the parameters of the first spring 3 and the second spring 4 are identical, ensure that the first spring 3 and the deformation of the generation of the second spring 4 are only subject to first piston 5 with it relevant with the second piston 6 pressure, improve certainty of measurement further.In addition, detection range of the present invention can be changed by the modulus of elasticity changing the first spring 3 and the second spring 4, expand of the present invention being suitable for further, select more widely for user provides.
Fig. 4 is the structural representation of the Venturi tube 12 of downhole fluid induction installation 100 of the present invention, as shown in Figure 4, Venturi tube 12 has entrance 14 and venturi section 15, the diameter of described entrance 14 is greater than the diameter of described venturi section 15, described entrance 14 offers a upstream pilot interface 10, described venturi section 15 offers a downstream pilot interface 11, upstream pilot interface 10 is connected with the left end of connecting pipe 13, downstream pilot interface 11 is connected with the right-hand member of connecting pipe 13, fluid in Venturi tube 12 flows along described entrance 14 to the direction of described venturi section 15.
As shown in Figure 2, the left end of connecting pipe 13 and upstream pilot interface 10 thread connection, the right-hand member of connecting pipe and downstream pilot interface 11 thread connection.In other embodiments of the invention, the left end of connecting pipe 13 welds with upstream pilot interface 10, and the right-hand member of connecting pipe welds with downstream pilot interface 11, as long as ensure that connecting pipe 13 is combined with Venturi tube 12 secure seal, the present invention is not as limit.
As shown in Figure 2, connecting pipe 13 and Venturi tube 12 adopt thread connection, convenient disassembly, if just connecting pipe 13 or Venturi tube 12 are damaged, need not all abandon, energy-conserving and environment-protective, and reduce maintenance cost.In addition, if do not need induced flow rate of flow of fluid, only connecting pipe 13 can be unloaded, then with the stopper of fitting screw thread mutually, the upstream pilot interface 10 in Venturi tube 12 and downstream pilot interface 11 be sealed up, Venturi tube 12 need not be removed immediately simultaneously, easy to use.
Fig. 5 is the structural representation of fluid flow measuring systems of the present invention.As shown in Figure 5, this fluid flow measuring systems comprises the downhole fluid induction installation 100 in above-described embodiment, and this fluid flow measuring systems also comprises LASER Light Source 200, grating demodulation instrument 300, treating apparatus 400.Described LASER Light Source 200 is connected with described downhole fluid flow velocity induction installation 100, and LASER Light Source 200 is for launching incident light; Described grating demodulation instrument 300 is connected with described downhole fluid induction installation 100, and grating demodulation instrument 300 obtains one first reflectance spectrum for the first reverberation described in demodulation, and described in demodulation, the second reverberation obtains one second reflectance spectrum; Described treating apparatus 400 is connected with described grating demodulation instrument 300, treating apparatus 400 is for obtaining the rate of flow of fluid at Venturi tube 12 entrance 14 place according to described first reflectance spectrum and described second reflectance spectrum, diameter due to Venturi tube 12 entrance 14 equals the diameter of fluid transmission pipe, so the rate of flow of fluid at Venturi tube 12 entrance 14 place for the treatment of apparatus 400 acquisition is the rate of flow of fluid (tube fluid flow velocity) in fluid transmission pipe.
The laser direction launched due to LASER Light Source 200 and unicity good, and not by the impact of electromagnetic interference, improve certainty of measurement of the present invention further; The good stability of grating demodulation instrument 300 (FBG) demodulator more non-optical than other, electromagnetism interference, improves fluid measurement precision further.
As shown in Figure 5, specifically, LASER Light Source 200 launches incident light through Optical Fiber Transmission in the first grating 1 and the second grating 2; Incident light forms described first reverberation after the first grating 1 reflects, and incident light forms the second reverberation after the second grating 2 reflects; Described first reverberation and described second reverberation through Optical Fiber Transmission in grating demodulation instrument 300; Described in grating demodulation instrument 300 demodulation, the first reverberation obtains the first reflectance spectrum, described in the demodulation of grating demodulation instrument, the second reverberation obtains one second reflectance spectrum, the change of the first reflectance spectrum peak wavelength is proportional to the change of stress suffered by the first grating 1, and the change of the second reflectance spectrum peak wavelength is proportional to the change of stress suffered by the second grating 2.
Fig. 6 is the structural representation of the treating apparatus 400 of fluid flow measuring systems of the present invention.As shown in Figure 6, described treating apparatus 400 comprises spectrum acquisition unit 401, spectrum peak wavelength determining unit 402, wavelength difference determining unit 403, pressure differential determining unit 404, fluid flow velocity determining unit 405 and a display unit 406.Spectrum acquisition unit 401 is for receiving described first reflectance spectrum and described second reflectance spectrum; Spectrum peak wavelength determining unit 402 is connected with described spectrum acquisition unit 401, and spectrum peak wavelength determining unit 402 is for the second reflectance spectrum peak wavelength of the first reflectance spectrum peak wavelength and described second reflectance spectrum of determining described first reflectance spectrum; Wavelength difference determining unit 403 is connected with described spectrum peak wavelength determining unit 402, and wavelength difference determining unit 403 is for determining the difference of described first reflectance spectrum peak wavelength and described second reflectance spectrum peak wavelength; Pressure differential determining unit 404 is connected with described wavelength difference determining unit 403, and pressure differential determining unit 404 is for determining the pressure differential that described first grating 1 and described second grating 2 are subject to according to the difference of described wavelength; Rate of flow of fluid determining unit 405 is connected with described pressure differential determining unit 404, and rate of flow of fluid determining unit 405 is for determining the flow velocity of described Venturi tube 12 inner fluid according to described pressure differential; Display unit 406 is connected with described rate of flow of fluid determining unit 405, and display unit 406 is for showing rate of flow of fluid.Due to when wavelength of transmitted light, grating specifications, the elastic coefficient are determined, the stress that the corresponding grating of the wavelength of reflectance spectrum peak is subject to, therefore, pressure differential determining unit 404, according to the difference of described first reflectance spectrum peak wavelength and described second reflectance spectrum peak wavelength, obtains the pressure differential (also referred to as stress difference) that described first grating and described second grating are subject to.
Pressure differential determining unit 404, according to the difference of described first reflectance spectrum peak wavelength and described second reflectance spectrum peak wavelength, directly obtains pressure differential, calculates simple, is easy to realize, and reduces of the present inventionly to realize cost; Rate of flow of fluid determining unit 405 directly obtains rate of flow of fluid according to pressure differential, calculates simple, is easy to realize, and reduction is of the present invention further realizes cost; Display unit 406 can simultaneous display rate of flow of fluid (entrance 14 rate of flow of fluid), facilitates tester's observed and recorded, makes measurement result more directly perceived.
As shown in Figure 6, rate of flow of fluid determining unit 405 utilizes the flow velocity (i.e. Venturi tube 12 entrance 14 rate of flow of fluid) of Bernoulli equation determination tube fluid according to the pressure differential that pressure differential determining unit 404 obtains.Following formula discloses the relation of equality of entrance 14 fluid flow and venturi section 15 fluid flow:
A 1v 1=A 2v 2(formula 1)
Wherein, A 1v 1for entrance fluid flow, A 2v 2for venturi section fluid flow; V 1for entrance rate of flow of fluid, V 2for venturi section rate of flow of fluid, A 1for entrance cross-sectional area, A 2for venturi section cross-sectional area.
Following formula gives entrance 14 cross-sectional area:
A 1 = πd 1 2 4 (formula 2)
Wherein, A 1for entrance cross-sectional area, d 1for entrance diameter.
Following formula gives venturi section 15 cross-sectional area:
A 2 = πd 2 2 4 (formula 3)
Wherein, A 2for venturi section cross-sectional area, d 2for venturi section diameter.
Following formula is Bernoulli equation:
P 1 + ρV 1 2 2 + ρgh 1 = P 2 + ρV 2 2 2 + ρgh 2 (formula 4)
Wherein, V 1for entrance rate of flow of fluid, V 2for venturi section rate of flow of fluid; P 1for entrance fluid pressure, P 2for venturi section fluid pressure; ρ is fluid density; h 1for the vertical height of entrance fluid, h 2for the vertical height of venturi section fluid, h in the present invention 1=h 2; G is acceleration of gravity.
Can be determined by formula 1:
V 2 = A 1 A 2 V 1 (formula 5)
Wherein, A 1v 1for entrance fluid flow, A 2v 2for venturi section fluid flow; V 1for entrance rate of flow of fluid, V 2for venturi section rate of flow of fluid, A 1for entrance cross-sectional area, A 2for venturi section cross-sectional area.
V can be determined by formula 2, formula 3, formula 5 2:
V 2 = ( d 1 d 2 ) 2 V 1 (formula 6)
Wherein, d 1for entrance diameter, d 2for venturi section diameter, V 1for entrance rate of flow of fluid, V 2for venturi section rate of flow of fluid.
V can be determined by formula 4, formula 6 1:
V 1 = 2 P ρ [ ( d 1 d 2 ) 4 - 1 (formula 7)
Wherein, P is pressure differential, P=P 1-P 2, ρ is fluid density, d 1for entrance diameter, d 2for venturi section diameter.
Can find out according to formula 7: when the diameter of Venturi tube 12 is known, rate of flow of fluid (i.e. entrance 14 rate of flow of fluid) in Venturi tube 12 is only relevant with pressure differential P, and rate of flow of fluid determining unit 405 can draw rate of flow of fluid (the i.e. Venturi tube 12 entrance 14 rate of flow of fluid V in pipe easily according to pressure differential P 1).
As shown in Figure 5, when Venturi tube 12 inner fluid remains static, or when there is no fluid by Venturi tube 12, fluid equals fluid to the second piston 6 applied pressure to first piston 5 applied pressure, namely first piston 5 is identical with the pressure that the second piston 6 is subject to, now, the pulling force that first grating 1 is subject to is that the elastic force of the first spring 3 deducts fluid to first piston 5 applied pressure, the pulling force that second grating 2 is subject to is that the elastic force of the second spring 4 deducts fluid to the second piston 6 applied pressure, because the first spring 3 is identical with the second spring 4, first piston 5 is identical with the second piston 6, so the pulling force that the first grating 1 is subject to equals the pulling force that the second grating 2 is subject to.Because the first grating 1 is identical with the second grating 2, the first reflectance spectrum peak wavelength that incident light is formed after the first grating 1 reflects with the second grating 2 is identical with the second reflectance spectrum peak wavelength, now shows that the flow velocity of fluid is 0.
When direction flows through Venturi tube 12 to fluid as arrows in fig. 5, the internal diameter due to entrance 14 is greater than the internal diameter of venturi section 15 and throttling action occurs; Entrance 14 internal diameter is large and flow velocity is little, and venturi section 15 internal diameter is little and flow velocity large, and the pressure that entrance 14 place is subject to fluid is greater than the pressure that venturi section 15 place is subject to.Now, the pulling force (stress) that first grating 1 is subject to is that the elastic force of the first spring 3 deducts fluid to first piston 5 applied pressure, the pulling force (stress) that second grating 2 is subject to is that the elastic force of the second spring 4 deducts fluid to the second piston 6 applied pressure, because the first spring 3 is identical with the second spring 4, first piston 5 is identical with the second piston 6, so the pulling force that the first grating 1 is subject to is less than the pulling force that the second grating 2 is subject to.Because the first grating 1 is identical with the second grating 2, the first reflectance spectrum peak wavelength that incident light is formed after the first grating 1 and the reflection of the second grating 2 is no longer equal with the second reflectance spectrum peak wavelength, and pressure differential determining unit 404 just can obtain the pressure differential of entrance 14 and venturi section 15 fluid according to the difference of two reflectance spectrum peak wavelength.
Rate of flow of fluid determining unit 405 utilizes Bernoulli equation to try to achieve the flow velocity of tube fluid according to the pressure differential that pressure differential determining unit 404 obtains.From formula 7, when entrance 14 is decided with the cross-sectional area of venturi section 15, entrance 14 or venturi section 15 inner fluid speed are directly proportional to the evolution of described pressure differential P, such as, when the known diameter when entrance 14 is 2 times of venturi section 15 diameter, venturi section 15 inner fluid speed is 4 times of entrance 14 inner fluid speed, supposes that oil density is 1000kg/m 3, the rate of flow of fluid (entrance 14 rate of flow of fluid) in an embodiment pipe is as shown in table 1 below:
Table 1
Pressure differential determining unit 404 can determine rate of flow of fluid easily according to pressure differential as shown in Table 1, and display unit 406 can simultaneous display rate of flow of fluid (entrance 14 rate of flow of fluid), and facilitate tester's observed and recorded, measurement result is more directly perceived.
At this, because first piston 5 is identical with the second piston 6, the first spring 3 is identical with the second spring 4, and the first grating 1 is identical with the second grating 2, so the impact that the environmental factor such as air pressure, temperature causes measurement result can be considered, make survey data result more accurate.
Downhole fluid induction installation provided by the present invention and fluid flow measuring systems compared with prior art, have following beneficial effect:
1, because sensing element grating is placed along connecting pipe 13, the internal diameter of connecting pipe 13 can be accomplished very little, therefore the lateral dimension of downhole fluid induction installation 100 can effectively be controlled, so the present invention can be applicable to the measurement of rate of flow of fluid in limited environment space, as the Real-Time Monitoring of Oil/gas Well downhole fluid flow velocity.
2, the present invention adopts and does poor method and ask for pressure differential before and after Venturi tube 12 throttling, and the pressure detecting element of dividing plate 7 left and right sides is identical, thus in use do not need to consider that the environmental factors such as temperature are on the impact of measurement result, thus effectively simplify the processing procedure of survey data.
3, utilize after the present invention carries out rate of flow of fluid measurement, the part residual fluid to section between piston and pilot interface may have is not needed to process, fluid because of section for this reason only plays the effect of conducting pressure, this considerably simplifies the maintenance process of fluid flow measuring systems.
The foregoing is only the schematic detailed description of the invention of the present invention, under the prerequisite not departing from design of the present invention and principle, the equivalent variations that any those skilled in the art makes and amendment, all should belong to the scope of protection of the invention.

Claims (10)

1. a downhole fluid induction installation, is characterized in that, this downhole fluid induction installation comprises:
One Venturi tube, for guiding downhole fluid, described Venturi tube has an entrance and a venturi section, and the diameter of described entrance is greater than the diameter of described venturi section;
One connecting pipe, is connected with described Venturi tube;
One dividing plate, is arranged at described connecting pipe center;
One first spring, be arranged on the left of described dividing plate, one end is connected with described dividing plate, and the other end is connected with a first piston, and fluid acts on described first spring at the pressure of described entrance by described first piston;
One second spring, be symmetricly set on the right side of described dividing plate, one end is connected with described dividing plate, and the other end is connected with one second piston, and fluid passes through described second piston action in described second spring at the pressure of described venturi section;
One first grating, one end is connected with described dividing plate, the other end is connected with described first piston, described first grating is in extended state all the time under the acting in conjunction of described first spring force and described entrance fluid pressure, described first grating receives an incident light, and reflects one first reverberation; And
One second grating, one end is connected with described dividing plate, the other end is connected with described second piston, described second grating is in extended state all the time under the acting in conjunction of described second spring force and described venturi section fluid pressure, described second grating receives described incident light, and reflects one second reverberation.
2. downhole fluid induction installation as claimed in claim 1, it is characterized in that, this downhole fluid induction installation also comprises:
One first snap ring, is arranged on the connecting pipe inwall on the left of described first piston; And
One second snap ring, is symmetricly set on the connecting pipe inwall on the right side of described second piston.
3. downhole fluid induction installation as claimed in claim 1, is characterized in that, described dividing plate offers through hole.
4. downhole fluid induction installation as claimed in claim 1, it is characterized in that, described first piston is identical with described second piston; Described first grating is identical with described second grating; Described first spring is identical with described second spring.
5. downhole fluid induction installation as claimed in claim 1, it is characterized in that, described entrance offers a upstream pilot interface, described venturi section offers a downstream pilot interface, the left end of described connecting pipe is connected with described upstream pilot interface, and the right-hand member of described connecting pipe is connected with described downstream pilot interface.
6. downhole fluid induction installation as claimed in claim 5, it is characterized in that, the left end of described connecting pipe connects with described upstream pilot interface thread, and the right-hand member of described connecting pipe connects with described downstream pilot interface thread.
7. a fluid flow measuring systems, is characterized in that, this fluid flow measuring systems comprise as arbitrary in claim 1-6 as described in downhole fluid induction installation, this fluid flow measuring systems also comprises a LASER Light Source, a grating demodulation instrument, a treating apparatus,
Described LASER Light Source, is connected with described downhole fluid induction installation, for launching described incident light;
Described grating demodulation instrument, is connected with described downhole fluid induction installation, obtains one first reflectance spectrum for the first reverberation described in demodulation, and the second reverberation described in demodulation obtains one second reflectance spectrum; And
Described treating apparatus, is connected with described grating demodulation instrument, for determining the rate of flow of fluid at described venturi tube inlet section place according to described first reflectance spectrum and described second reflectance spectrum.
8. fluid flow measuring systems as claimed in claim 7, it is characterized in that, described treating apparatus comprises:
One spectrum acquisition unit, for receiving described first reflectance spectrum and described second reflectance spectrum;
One spectrum peak wavelength determining unit, is connected with described spectrum acquisition unit, for determining described first reflectance spectrum peak wavelength and described second reflectance spectrum peak wavelength;
One wavelength difference determining unit, is connected with described spectrum peak wavelength determining unit, for determining the difference of described first reflectance spectrum peak wavelength and described second reflectance spectrum peak wavelength;
One pressure differential determining unit, is connected with described wavelength difference determining unit, for determining the pressure differential that described first grating and described second grating are subject to according to the difference of spectrum peak wavelength; And
Fluid flow velocity determining unit, is connected with described pressure differential determining unit, for determining the rate of flow of fluid at described venturi tube inlet section place according to described pressure differential.
9. fluid flow measuring systems as claimed in claim 8, it is characterized in that, described rate of flow of fluid determining unit utilizes following formula to determine the rate of flow of fluid at described venturi tube inlet section place:
V 1 = 2 P ρ [ ( d 1 d 2 ) 4 - 1 ] ,
Wherein, V 1for entrance rate of flow of fluid, P is pressure differential, and ρ is fluid density, d 1for entrance diameter, d 2for venturi section diameter.
10. fluid flow measuring systems as claimed in claim 8, it is characterized in that, described treating apparatus also comprises a display unit, is connected, for showing rate of flow of fluid with described rate of flow of fluid determining unit.
CN201410475281.6A 2014-09-17 2014-09-17 Underground fluid induction device and fluid flow velocity measuring system using same Expired - Fee Related CN104389581B (en)

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