CN103822677A - Constant-volume tube piston type natural gas moisture flowmeter and measuring method - Google Patents

Abstract

The invention provides a constant-volume tube piston type natural gas moisture flowmeter which comprises a constant-volume cylindrical measuring tube and a built-in piston which can move up and down. Two ends of the measuring tube are respectively connected with two electric valves to control air intake and exhaust reversing, and the measuring tube can be controlled to achieve down air intake and up exhaust measuring and up air intake and down exhaust measuring. A temperature and pressure transmitter is further mounted on the measuring tube, and natural gas moisture volume flow measuring can be achieved. Due to the fact that the constant-volume tube piston type natural gas moisture flowmeter is based on the volume measuring, the measuring process is irrelevant with physical parameters and the flowing parameters such as flow speed and flow state of to-be-measured natural gas moisture, measuring flow is not easily influenced by flow fluctuation, and high precision is achieved.

Description

A kind of constant volume tube piston type rock gas flux of moisture is taken into account measuring method

Technical field

The invention belongs to crude oil well recovery and produce associated gas and gasser extraction rock gas flux of moisture metering technical field, the present invention relates to a kind of constant volume tube piston type rock gas flux of moisture and take into account measuring method.

Background technology

In exploitation of oil-gas field process in most cases.The invariably accompany output of liquid hydrocarbon, free water and saturated steam of the output of rock gas.Therefore, rock gas all can relate to moisture metering exploiting from individual well that many wells collection is defeated, purified treatment, the supercharging process of carrying.Because per-well production metering is closely related with the economic interests of exploitation side, and the continuous data of individual well is also the significant data that oil gas field manager understands gas well productive capacity, production status.Therefore. the accuracy and the reliability that improve moisture metering are also more and more subject to the attention of each major oil companies in the world.Since early 1990s, international gas flow laboratory and Major Oil Company have all carried out the correlative study of moisture metering technical elements successively.Moisture measurement technology has experienced the development of more than 20 year, the developed countries such as America and Europe, especially the U.S. and Norway have obtained some achievements in the research aspect accuracy, stability and the versatility of wet gas meter, aspect the applicability of type selecting, test, calibration, operation and maintenance and the various operating modes of flowmeter, are obtaining a large amount of experiences.China's Daqing oil field was also once carried out the research of excess moisture measurement technology in 20 end of the centurys, and some research institutions and flowmeter manufacturer have also carried out the research of this respect on a small scale.

As a rule, through dehydration, purification and process for recovering light hydrocarbon, the rock gas extracting after liquefied gas and lightweight oil is referred to as dry gas.The rock gas of undressed oil gas field extraction contains a small amount of condensation water or oil, saturated steam and light hydrocarbon more, containing drop component, is referred to as moisture.Moisture belongs to the category of polyphasic flow.Single-phase flow relatively, moisture measurement technology is more complicated and difficult, and its main cause is as follows:

1. in pipeline, moisture fluidised form is different because of the gaseous tension in pipeline, flow velocity, content liquid and pipeline installation site (level, inclination or vertical), and fluidised form is comparatively complicated.

2. the variation of moisture metering field working conditions is relatively large, if flowmeter type selecting is unreasonable, easily causes flowmeter used not to be suitable for the on-the-spot working condition of metering, even causes Causing Flowmeter Damages.

3. moisture metering has adopted the mode of Off-line calibration mostly with flowmeter, but the calibrating medium of general calibrating or calibration laboratory and working condition and real medium and working condition have very significantly difference, makes the metering performance of flowmeter in-situ be difficult to guarantee.

In recent years. although some flowmeter production firms also develop the wet gas meter (or multi-phase flowmeter) of some types.But current moisture metering both domestic and external mainly still adopts traditional way flow flow techniques, due to the existence of liquid phase in pipeline. the fluidised form in pipeline has seriously affected the metering performance of flowmeter, and according to up-to-date experimental study, its error in dipping maximum can reach 15%.

Summary of the invention

The object of the present invention is to provide a kind of vaporific fluid constant volume tube piston type rock gas wet gas meter that metering affects on rock gas flux of moisture that can overcome contained a small amount of drop in rock gas.

In order to address the above problem, the invention provides a kind of constant volume tube piston type rock gas wet gas meter, comprise the cylinder gauge line of constant volume, built-in piston moving up and down; Two of described gauge line respectively connects two motorized valve control intake and exhaust commutations, can control described gauge line and realize respectively lower air inlet, upper exhaust metering and upper air, lower exhaust metering; Temperature and pressure transmitter is also installed on described gauge line, realizes the volumetric flow rate metering of rock gas moisture.

Further, between described piston and tube wall, be slip wringing fit, the air seal of piston both sides.

Further, commutation is controlled flow direction by the switching order of 4 motorized valves of Controlled by Programmable Controller, realizes respectively the lower air inlet of rock gas moisture, upper instroke and upper air, lower instroke; Shuttling movement and so forth, while coordinating stroke counter between the upper and lower stop of piston movement, can realize the metering of the volumetric flow rate of rock gas moisture.

The present invention also provides a kind of measuring method of piston type rock gas wet gas meter, comprises the steps:

Measurement column plug tube volume V, plunger barrel pressure P ₁, plunger barrel temperature T ₁, run duration t between the upper and lower stop of piston;

In high temperature, low pressure, be less than under the operating mode of 2.5Mpa and calculate gas flow by following formula:

$F_A=\frac{P_{1}V(T_S+273.15)}{P_S(T_1+273.15)t};$

In the time that pressure is larger, is greater than under the operating mode of 2.5Mpa and calculates gas flow by following formula:

$F_A=\frac{P_{1}V(T_S+273.15)}{{\mathrm{ZP}}_S(T_1+273.15)t};$

Wherein: standard atmospheric pressure P _s=101.325kpa, standard atmospheric pressure temperature T _s=0 ℃;

Z is by equation Z ³-Z ²-(B ²+ B-A) Z-AB=0 determine, wherein

$B=0.084467\frac{P_R}{T_R},T_R=\frac{T_s}{T_{\mathrm{CR}}},P_R=\frac{P_s}{P_{\mathrm{CR}}},$ T _cR, P _cRbe respectively critical temperature and the emergent pressure of gas, its value depends on that the one-tenth of rock gas is grouped into.

With respect to prior art, the present invention has following technique effect:

Constant volume tube piston type rock gas wet gas meter provided by the invention is the flowmeter based on volumetric measurement, can overcome the vaporific fluid of contained a small amount of drop in rock gas to rock gas flux of moisture metering impact, thereby the flow parameter such as physical parameter and flow velocity, fluidised form of measuring process and tested rock gas moisture is irrelevant, measuring flow is not subject to flow rate fluctuation impact, has higher precision.

Accompanying drawing explanation

Structural representation when Fig. 1 is air inlet under the constant volume tube piston type rock gas wet gas meter of the embodiment of the present invention, upper instroke.

Structural representation when Fig. 2 is the constant volume tube piston type rock gas wet gas meter upper air of the embodiment of the present invention, lower instroke.

Embodiment

Hereinafter in connection with accompanying drawing, embodiments of the invention are elaborated.It should be noted that, in the situation that not conflicting, the combination in any mutually of the feature in embodiment and embodiment in the application.

Embodiment mono-:

The invention provides a kind of constant volume tube piston type rock gas wet gas meter as shown in accompanying drawing 1-2, comprise the cylinder gauge line of constant volume, built-in piston moving up and down, is slip wringing fit between piston and tube wall, the air seal of piston both sides; Two of gauge line respectively connects two motorized valve control intake and exhaust commutations, can control gauge line and realize respectively lower air inlet, upper exhaust metering and upper air, lower exhaust metering; Temperature and pressure transmitter is also installed on gauge line, realizes the volumetric flow rate metering of rock gas moisture.

Commutation is controlled flow direction by the switching order of 4 motorized valves of Controlled by Programmable Controller, realizes respectively the lower air inlet of rock gas moisture, upper instroke and upper air, lower instroke; Shuttling movement and so forth, while coordinating stroke counter between the upper and lower stop of piston movement, can realize the metering of the volumetric flow rate of rock gas moisture.

One, lower air inlet, upper instroke

Gas flow direction when lower air inlet, upper instroke is as shown by the arrows in Figure 1:

The valve open that in figure, black line passes through, remaining is closed.After gas is come in by below, under pressure promotes, upwards promote piston movement.It is t (HOUR) that piston arrives the top dead centre used time by lower dead center, and piston arrives after top dead center stops, and position switch provides stop signal, at this moment reads pressure signal P ₁with temperature signal T ₁; After completing, PLC sends commutation instruction, and motorized valve action, realizes the commutation of flowing.

Two, upper air, lower instroke

Gas flow direction when upper air, lower instroke is as shown by the arrows in Figure 2:

After commutation, the valve open that in figure, black line passes through, remaining is closed.After gas is come in by top, under pressure promotes, promote piston movement downwards.It is t (HOUR) that piston arrives the lower dead center used time by top dead centre, and piston arrives stops after bottom dead center, and position switch provides stop signal, at this moment reads pressure signal P ₁with temperature signal T ₁; After completing, PLC sends commutation instruction, and motorized valve action, realizes the commutation of flowing.

Three, flow rate calculation

Under the operating mode of high temperature, low pressure (being less than 2.5Mpa in this example), can use the equation of gaseous state of ideal gas to calculate.

Plunger barrel volume V (M ³), measurement instrument records plunger barrel pressure P ₁(kpa), measurement instrument records plunger barrel temperature T ₁(℃), the run duration between the upper and lower stop of piston recording is t (HOUR); Standard atmospheric pressure P _s=101.325kpa, standard atmospheric pressure temperature T _s=0 ℃, constant R=8.31, gas volume when standard atmospheric pressure is V _s(M ³).

Ideal gas equation of gaseous state: PV=NRT

Gaseous mass: $N=\frac{\mathrm{PV}}{\mathrm{RT}}$

Mass conservation while being converted into the plunger gas volume that normal atmosphere depresses:

$\frac{P_{1}V}{R(T_1+273.15)}=\frac{P_S{V}_S}{R(T_S+273.15)}$

Standard atmospheric pressure lower volume:

$V_S=\frac{P_{1}V(T_S+273.15)}{P_S(T_1+273.15)}$

Gas flow: $F_A=\frac{V_S}{t}$

$F_A=\frac{P_{1}V(T_S+273.15)}{P_S(T_1+273.15)t}$ (M ³/H)

In the time that in pipeline, gas pressure is larger, rock gas is no longer observed the Ideal-Gas Equation, now introduces compressibility coefficient Z

Z=1 when ideal gas, for actual gas, pressure is hour Z<1, Z>1 when pressure is larger.

According to corresponding states theory, the gas under identical corresponding states is identical to the departure degree of ideal gas state, has identical compressibility coefficient, and corresponding states refers to that gas is at identical reduced temperature T _rwith reduced pressure P _runder

$T_R=\frac{T_s}{T_{\mathrm{CR}}},P_R=\frac{P_s}{P_{\mathrm{CR}}}$

T in formula _cR(K), P _cR(Mpa) be respectively critical temperature and the emergent pressure of gas, its value depends on that the one-tenth of rock gas is grouped into.

The size of compressibility coefficient Z only depends on T _rand P _r, i.e. Z=f (T _r, P _r)

Utilize contrast Redlich-Kwong to generalize equation solution Z

Z ³-Z ²-(B ²+B-A)Z-AB＝0

Wherein $A=0.42748\frac{P_R}{{T_R}^{2.5}}B=0.084467\frac{P_R}{T_R}$

Gas flow: $F_A=\frac{P_{1}V(T_S+273.15)}{{\mathrm{ZP}}_S(T_1+273.15)t}$ (M ³/H)

The foregoing is only the preferred embodiments of the present invention, be not limited to the present invention, for a person skilled in the art, the present invention can have various modifications and variations.Within the spirit and principles in the present invention all, any modification of doing, be equal to replacement, improvement etc., within all should being included in protection scope of the present invention.

Claims (4)

1. a constant volume tube piston type rock gas wet gas meter, is characterized in that: comprise the cylinder gauge line of constant volume, built-in piston moving up and down; Two of described gauge line respectively connects two motorized valve control intake and exhaust commutations, can control described gauge line and realize respectively lower air inlet, upper exhaust metering and upper air, lower exhaust metering; Temperature and pressure transmitter is also installed on described gauge line, realizes the volumetric flow rate metering of rock gas moisture.

2. a kind of constant volume tube piston type rock gas wet gas meter as claimed in claim 1, is characterized in that: between described piston and tube wall, be slip wringing fit, and the air seal of piston both sides.

3. a kind of constant volume tube piston type rock gas wet gas meter as claimed in claim 2, it is characterized in that: commutation is controlled flow direction by the switching order of 4 motorized valves of Controlled by Programmable Controller, realizes respectively the lower air inlet of rock gas moisture, upper instroke and upper air, lower instroke; Shuttling movement and so forth, while coordinating stroke counter between the upper and lower stop of piston movement, can realize the metering of the volumetric flow rate of rock gas moisture.

4. a measuring method for a kind of piston type rock gas wet gas meter as claimed in claim 1, is characterized in that, comprises the steps:

Measurement column plug tube volume V, plunger barrel pressure P ₁, plunger barrel temperature T ₁, run duration t between the upper and lower stop of piston;

In high temperature, low pressure, be less than under the operating mode of 2.5Mpa and calculate gas flow by following formula:

$F_A=\frac{P_{1}V(T_S+273.15)}{P_S(T_1+273.15)t};$

In the time that pressure is larger, is greater than under the operating mode of 2.5Mpa and calculates gas flow by following formula:

$F_A=\frac{P_{1}V(T_S+273.15)}{{\mathrm{ZP}}_S(T_1+273.15)t};$

Wherein: standard atmospheric pressure P _s=101.325kpa, standard atmospheric pressure temperature T _s=0 ℃;

Z is by equation Z ³-Z ²-(B ²+ B-A) Z-AB=0 determine, wherein

$B=0.084467\frac{P_R}{T_R},T_R=\frac{T_s}{T_{\mathrm{CR}}},P_R=\frac{P_s}{P_{\mathrm{CR}}},$ T _cR, P _cRbe respectively critical temperature and the emergent pressure of gas, its value depends on that the one-tenth of rock gas is grouped into.

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