CN101666770A - Device and method for measuring crude oil with low air void - Google Patents

Abstract

The invention discloses a device and a method for measuring crude oil with low air void, belonging to the technical field of fluid measurement. The device for measuring crude oil with low air void comprises a measurement pipeline, a capacitance transducer at the front end of the measurement pipeline, a flow mixer at the middle of the measurement pipeline, a Coriolis mass-flow meter and a pressuretransducer at the rear end of the measurement pipeline, an A/D switch card and a computer. The capacitance transducer, the Coriolis mass-flow meter and the pressure transducer are connected with the computer via the A/D switch card. The invention also provides a measurement method adopted by the device. The invention has the advantages of small volume, simple structure, convenient installation, more obtained measurement parameters, high detection precision of the parameters, good real time measurement, high reliability, easy implementation and the like, and is suitable for measuring crude oilwith low air void in oil field.

Description

Crude oil with low air void measurement mechanism and method

Technical field

The invention belongs to the fluid measurement technical field, be specifically related to the phase content of a crude oil with low air void and the apparatus and method that every phase flow rate is measured.

Background technology

Crude oil is typical polyphasic flow, generally comprises oil, gas, water three-phase material.Oil, gas, water three-phase interact in flow process, and the detection difficulty of separate phase flow rate is very big.Yet,, must grasp oil offtake, water production rate and the gas production rate of every mouthful of oil well for the reasonable development in oil field.At present, the separate phase flow rate of most Oilfield using separate measurement method metering crude oil.The separate measurement method generally is divided into complete partition method and part partition method.

Partition method is the traditional metering method in oil field fully, this method is used efficient metering separator crude oil is separated into oil phase, water and gas phase, adopt each single-phase measurement instrument or device to obtain the content separately of three components again, and then mix and be transported to pumping plant and produce processing.Fully partition method has changed into the monophasic fluid flow measurement to the measurement of crude oil separate phase flow rate, has reliable operation, measuring accuracy height, measurement range is wide and is not subjected to the advantages such as influence of crude oil flow state variation.But the oil that this kind method relates to, moisture are subjected to multiple factor affecting easily from effect, are difficult to accomplish high separation, and this will influence single-phase measuring accuracy.And the separation equipment that this method adopts is bulky, separates and needs the regular hour, can not on-line measurement, thus restricted production efficiency greatly.

The part partition method comprises shunting split-phase method and simple separation device method.The shunting split-phase method at first distributes a part of fluid by divider, use separation vessel that this part three-phase fluid is separated into single phase gas and single-phase liquid then, measure with single phase gas flowmeter and single-phase liquid flowmeter respectively again, and be converted into the flow and the component of detected fluid under a proportional relationship, respectively this part single phase gas and single-phase liquid are returned in the flow duct at last.The problem that this method exists be sampling part fluid gas-liquid ratio often with former flowing in the gas-liquid ratio there is some difference, sampling ratio is subject to influences such as flow pattern, flow rate fluctuation.Simple separation device method is to utilize small-sized gas-liquid separator that three-phase stream is carried out pre-separation, obtain based on gas phase a road and based on a road of liquid phase, measure with combination instrument and correction correlation respectively on each road, find the solution fuel-displaced, gas, water three-phase flow, the fluid after the metering is admixed together again to send back to former pipeline.This partition method has been dwindled the volume of equipment to a certain extent, has improved the real-time of metering, and therefore, the multi-phase flowmeter product major part of Tui Chuing all is to adopt the part partition method in recent years.But the gas-liquid separation effect of part partition method is relatively poor, often is mixed with a certain amount of gas in liquid phase, and the gas that is mixed with has a significant impact the measuring accuracy of liquid phase flow, also has influence on the accurate measurement of gas flow simultaneously.

Summary of the invention

The objective of the invention is to overcome the above-mentioned deficiency of prior art, a kind of measurement mechanism and method of crude oil with low air void is provided.Device volume provided by the invention is little, and is simple in structure, easy for installation, and it is many to obtain measurement parameter, parameter detecting precision height, and real-time is good, and is reliable, is easy to realize.Be applicable to that crude oil separates the measurement of back crude oil with low air void.

For this reason, the present invention adopts following technical scheme:

A kind of crude oil with low air void measurement mechanism, comprise metering pipeline (1), capacitive transducer (2), mixed flow device (3), Coriolis mass flowmeter (4), pressure transducer (5), A/D transition card (6), computing machine (7), on metering pipeline (1), be provided with capacitive transducer (2), mixed flow device (3), Coriolis mass flowmeter (4), pressure transducer (5) successively, A/D transition card (6) links to each other with capacitive transducer (2), Coriolis mass flowmeter (4), pressure transducer (5), and computing machine (7) links to each other with A/D transition card (6).

The measuring method that the present invention provides a kind of above-mentioned crude oil with low air void measurement mechanism to be adopted simultaneously comprises the following steps:

Tube section is divided into N pixel, the capacitance profile on the capacitive transducer measuring tube cross section, and according to

Determine the gray-scale value of j pixel on the tube section, in the formula, f _jThe gray-scale value an of-Di j pixel, the electric capacity number on tube section of the measurement that the N-capacitive transducer provides during capacitance profile (for example, for capacitive transducer with n electrode,

c _i-Di i the normalized value of measuring electric capacity measured s by capacitive transducer _Ij-Di j pixel is with respect to i the weight coefficient (being sensitivity) of measuring capacitance, and concrete numerical value is proofreaied and correct by finite element analysis and auxiliary actual measurement and obtained.Then, according to

Calculate the gas volume fraction of crude oil with low air void, in the formula, φ _gThe gas volume fraction of-crude oil with low air void, A _jThe area an of-Di j pixel, the area of section of A-measuring channel.

The pressure P that temperature T that records according to Coriolis mass flowmeter and pressure transducer record is calculated gas density ρ _g, and according to

Calculate density of liquid, in the formula, ρ _l-density of liquid, ρ _mThe hybrid density of-crude oil with low air void is measured by Coriolis mass flowmeter.Then, according to

The volume calculated oil content is according to φ _w=1-φ _oThe volume calculated water percentage, in the formula, φ _o, φ _w-be respectively the volume oil content and the volumetric water content of crude oil with low air void, ρ _o, ρ _w-be respectively the density of pure crude oil, pure water under temperature T and the pressure P.

According to

Calculate the volumetric flow rate of crude oil with low air void, in the formula, Q _vThe volumetric flow rate of-crude oil with low air void, Q _mThe mass rate of-crude oil with low air void is measured by Coriolis mass flowmeter.

According to Q _Vg=Q _vφ _g, Q _Vo=Q _vφ _o, Q _Vw=Q _vφ _wCalculate the volumetric flow rate of gas, oil, water respectively, according to Q _Mg=Q _Vgρ _g, Q _Mo=Q _Voρ _o, Q _Mw=Q _Vwρ _wCalculate the mass rate of gas, oil, water respectively.

Beneficial effect of the present invention and advantage are, need not to adopt high efficient gas and liquid separator to carry out gas-liquid separation, adopt the mixed flow device that crude oil with low air void is stirred into homogeneous flow, adopt the oil content and oil, gas, each separate phase flow rate of water of mixed flow device and Coriolis mass flowmeter multiple measurement crude oil with low air void.Utilize Coriolis mass flowmeter to measure mass rate, hybrid density and oil content, do not need to carry out the separation fully of profit two-phase, solved the difficult problem that the profit two-phase is difficult to separate fully in oil based on complete partition method, gas, the water three-phase flow measurement.Utilize the mixed flow device that fluid agitation to be measured is become homogeneous flow, make Coriolis mass flowmeter can measure the low gas content medium, solved the difficult problem of gas-liquid separator separates weak effect.This apparatus structure is simple, and parameter detecting precision height is easy to realize.Be applicable to that oil field mining liquid separates the measurement of back crude oil with low air void.

Description of drawings

Accompanying drawing is a crude oil with low air void measurement mechanism structural representation.

Embodiment

The crude oil with low air void measurement mechanism has metering pipeline (1), on metering pipeline (1), be provided with capacitive transducer (2), mixed flow device (3), Coriolis mass flowmeter (4), pressure transducer (5) successively, A/D transition card (6) links to each other with capacitive transducer (2), Coriolis mass flowmeter (4), pressure transducer (5), and computing machine (7) links to each other with A/D transition card (6).

The present invention is described further below by embodiment.

Oil field mining liquid is through after the gas-liquid separator initial gross separation, and crude oil with low air void enters metering pipeline 1, the capacitance profile that capacitive transducer 2 is gathered on the pipeline sections, and the capacitance measurement signal sent into computing machine 7 through A/D transition card 6.Because testing medium contains gas, gas forms bigger bubble or gas bullet easily in pipeline, thereby reduces the measuring accuracy of Coriolis mass flowmeter, simultaneously, because oil-water separation is relatively poor, therefore, generally contains a certain amount of water in the crude oil.Might there be phase interface in moisture crude oil, thereby, oil, water two-phase are in the separated flow state, this flow state reduces the density measurement accuracy of Coriolis mass flowmeter, thereby reduce the computational accuracy of oil content, therefore, in the present invention, fluid is earlier by mixed flow device 3, and mixed flow device 3 mixes fluid to become homogeneous flow.Coriolis mass flowmeter 4 is measured mass rate, hybrid density and the temperature of fluid, and the mass rate that records, hybrid density and temperature signal are sent into computing machine 7 through A/D transition card 6.Pressure transducer 5 be used for test fluid pressure and change pressure signal into the standard electric signal and send into computing machine 7 through A/D transition card 6.In computing machine 7, be provided with memory module, store pure oil, gas, the pure water density value under different temperatures and different pressures and the weight coefficient data such as (being sensitivity) of each capacitance of recording of capacitive transducer.Computing machine 7 is handled in real time, obtains the branch phase content and the separate phase flow rate of crude oil with low air void.

It needs to be noted, the flow state more complicated of crude oil, though carried out preliminary separation through gas-liquid separator, the liquid after separating still contains portion gas.When the testing liquid void fraction less than 5% the time, bubble is less and less in the liquid, bubble is less to the measuring accuracy influence of Coriolis mass flowmeter.But when the testing liquid void fraction surpassed 5%, bubble became big in the liquid, and the mass flow meter measurement precision obviously descends.Simultaneously, the crude oil in the fluid (be liquid phase medium, or be called oil water mixture) also exists with different states.When the water percentage of liquid hangs down, liquid is in and disperses under the flow pattern (being water is present in the external phase of oil with the form of bubble), at this moment, the water percentage that calculates according to the density measurement of Coriolis mass flowmeter is more accurate, but when the water percentage of liquid and oil content were more or less the same, liquid was in and separates under the flow pattern (promptly oily, water with different speed separated flow), at this moment, the water percentage precise decreasing of calculating according to the density measurement of Coriolis mass flowmeter.During design, adopt the mixed flow device that crude oil with low air void is stirred into homogeneous flow.

In addition, Coriolis mass flowmeter is a kind of driect type mass flowmeter, can directly measure mass rate, density and temperature, has precision height, good reproducibility, advantages such as range ratio is wide, inner structure is simple, no-movable part.

Concrete measurement model and to find the solution scheme as follows:

1, void fraction measurement model

${\mathrm{\φ}}_g=[1-\left(\underset{j=1}{\overset{N}{\mathrm{\Σ}}}{f}_j\frac{A_j}{A}\right)]\×100\%---\left(1\right)$

$f_j=\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{c}_i{s}_{\mathrm{ij}}/\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{s}_{\mathrm{ij}}---\left(2\right)$

Above-mentioned various in, φ _gThe gas volume fraction of-crude oil with low air void, the electric capacity number on tube section of the measurement that the N-capacitive transducer provides during capacitance profile (for example, for capacitive transducer with n electrode,

A _jThe area an of-Di j pixel, the area of section of A-measuring channel, f _jThe gray-scale value an of-Di j pixel, c _i-Di i the normalized value of measuring electric capacity measured s by capacitive transducer _Ij-Di j pixel is with respect to i the weight coefficient (being sensitivity) of measuring capacitance, and concrete numerical value is proofreaied and correct by finite element analysis and auxiliary actual measurement and obtained.

2, oil content measurement model

${\mathrm{\φ}}_o=\frac{{\mathrm{\ρ}}_l-{\mathrm{\ρ}}_w}{{\mathrm{\ρ}}_o-{\mathrm{\ρ}}_w}---\left(3\right)$

${\mathrm{\ρ}}_l=\frac{{\mathrm{\ρ}}_m-{\mathrm{\ρ}}_g{\mathrm{\φ}}_g}{1-{\mathrm{\φ}}_g}---\left(4\right)$

Above-mentioned various in, φ _oThe volume oil content of-crude oil with low air void, ρ _o, ρ _g, ρ _w-be respectively the density of pure crude oil, gas, pure water under temperature T and the pressure P, ρ _l-density of liquid, ρ _mThe hybrid density of-crude oil with low air void is measured by Coriolis mass flowmeter.

3, measurement of water ratio model

φ _w＝1-φ _o (5)

In the formula, φ _wThe volumetric water content of-crude oil with low air void.

4, separate phase flow rate measurement model

$Q_v=\frac{Q_m}{{\mathrm{\ρ}}_m}---\left(6\right)$

Q _vg＝Q _vφ _g (7)

Q _vo＝Q _vφ _o (8)

Q _vw＝Q _vφ _w (9)

Q _mg＝Q _vgρ _g (10)

Q _mo＝Q _voρ _o (11)

Q _mw＝Q _vwρ _w (12)

Above-mentioned various in, Q _vThe volumetric flow rate of-crude oil with low air void, Q _mThe mass rate of-crude oil with low air void is measured by Coriolis mass flowmeter, Q _Vg, Q _Vo, Q _Vw-be respectively the volumetric flow rate of gas, pure crude oil, pure water, Q _Mg, Q _Mo, Q _Mw-be respectively the mass rate of gas, pure crude oil, pure water.

Claims (2)

1, a kind of crude oil with low air void measurement mechanism, it is characterized in that: it has metering pipeline (1), on metering pipeline (1), be provided with capacitive transducer (2), mixed flow device (3), Coriolis mass flowmeter (4), pressure transducer (5) successively, A/D transition card (6) links to each other with capacitive transducer (2), Coriolis mass flowmeter (4), pressure transducer (5), and computing machine (7) links to each other with A/D transition card (6).

2, the measuring method that adopted of the described crude oil with low air void measurement mechanism of a kind of claim 1 is characterized in that, comprises the following steps:

(1) tube section is divided into N pixel, the capacitance profile on the capacitive transducer measuring tube cross section, and according to $f_j=\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{c}_i{s}_{\mathrm{ij}}/\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{s}_{\mathrm{ij}}$ Determine the gray-scale value of j pixel on the tube section, in the formula, f _jThe gray-scale value an of-Di j pixel, the electric capacity number on tube section of the measurement that the N-capacitive transducer provides during capacitance profile (for example, for capacitive transducer with n electrode, $N=\frac{n(n-1)}{2}),$ c _i-Di i the normalized value of measuring electric capacity measured s by capacitive transducer _Ij-Di j pixel is with respect to i the weight coefficient (being sensitivity) of measuring capacitance, and concrete numerical value is proofreaied and correct by finite element analysis and auxiliary actual measurement and obtained.Then, according to ${\mathrm{\φ}}_g=[1-\left(\underset{j=1}{\overset{N}{\mathrm{\Σ}}}{f}_j\frac{A_j}{A}\right)]\×100\%$ Calculate the gas volume fraction of crude oil with low air void, in the formula, φ _gThe gas volume fraction of-crude oil with low air void, A _jThe area an of-Di j pixel, the area of section of the last measuring channel of A.

(2) pressure P that records of temperature T that records according to Coriolis mass flowmeter and pressure transducer is calculated gas density ρ _g, and according to ${\mathrm{\ρ}}_i=\frac{{\mathrm{\ρ}}_m-{\mathrm{\ρ}}_g{\mathrm{\φ}}_g}{1-{\mathrm{\φ}}_g}$ Calculate density of liquid, in the formula, ρ _l-density of liquid, ρ _mThe hybrid density of-crude oil with low air void is measured by Coriolis mass flowmeter.Then, according to ${\mathrm{\φ}}_o=\frac{{\mathrm{\ρ}}_i-{\mathrm{\ρ}}_w}{{\mathrm{\ρ}}_o-{\mathrm{\ρ}}_w}$ The volume calculated oil content is according to φ _w=1-φ _oThe volume calculated water percentage, in the formula, φ _o, φ _w-be respectively the volume oil content and the volumetric water content of crude oil with low air void, ρ _o, ρ _w-be respectively the density of pure crude oil, pure water under temperature T and the pressure P.

(3) basis $Q_v=\frac{Q_m}{{\mathrm{\ρ}}_m}$ Calculate the volumetric flow rate of crude oil with low air void, in the formula, Q _vThe volumetric flow rate of-crude oil with low air void, Q _mThe mass rate of-crude oil with low air void is measured by Coriolis mass flowmeter.

(4) according to Q _Vg=Q _vφ _g, Q _Vo=Q _vφ _o, Q _Vw=Q _vφ _wCalculate the volumetric flow rate of gas, pure crude oil, pure water respectively, according to Q _Mg=Q _Vgρ _g, Q _Mo=Q _Voρ _o, Q _Mw=Q _Vwρ _wCalculate the mass rate of gas, pure crude oil, pure water respectively.