CN111967143B - Critical liquid carrying flow prediction method suitable for deepwater gas well - Google Patents

Critical liquid carrying flow prediction method suitable for deepwater gas well Download PDF

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CN111967143B
CN111967143B CN202010715228.4A CN202010715228A CN111967143B CN 111967143 B CN111967143 B CN 111967143B CN 202010715228 A CN202010715228 A CN 202010715228A CN 111967143 B CN111967143 B CN 111967143B
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刘书杰
刘文远
欧阳铁兵
李相方
范白涛
隋先富
于继飞
文敏
范志利
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CNOOC Research Institute Co Ltd
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Abstract

The invention relates to a method for predicting critical liquid carrying flow suitable for a deepwater gas well, which comprises the following steps: calculating the diameter of the Sauter liquid drop according to the bottom hole condition; obtaining temperature pressure distribution of a shaft along the way according to a preset wellhead output Qg, calculating gas-liquid physical property parameters and flow parameters along the way according to the temperature pressure distribution, and calculating a liquid drop deformation coefficient so as to obtain the deformation degree of liquid drops along the way; calculating drag coefficients of different well depths; according to the temperature and pressure conditions, drag coefficients at different depths of the well are converted to obtain a wellhead critical liquid carrying flow value; and acquiring an accurate value of the critical liquid carrying flow according to the value of the critical liquid carrying flow of the wellhead and the yield of the wellhead. According to the method, the size of the liquid drop and the deformation difference of the liquid drops with different sizes in the liquid carrying process are considered, the relation between the deformation parameter of the liquid drop and the flow condition and the size of the liquid drop is obtained through deduction according to the stress balance condition and the geometric characteristics of the liquid drop, the critical liquid carrying flow expression is obtained, and the gas well critical liquid carrying flow is accurately predicted by combining with the temperature and pressure field distribution of a shaft.

Description

Critical liquid carrying flow prediction method suitable for deepwater gas well
Technical Field
The invention relates to a gas well critical liquid carrying flow measuring method, in particular to a critical liquid carrying flow prediction method suitable for a deepwater gas well.
Background
The method has the advantages that the accurate prediction of the gas well critical liquid carrying flow rate, the optimization of the gas well working system and the prevention of gas well liquid accumulation are of great significance, and the gas well production stop caused by the gas well liquid accumulation can be effectively avoided when the gas well yield is ensured to be above the critical liquid carrying flow rate. The deep water natural gas is an important existing form of offshore oil and gas resources, the efficient development of deep water gas wells has great significance to energy supply in China, and the production of the deep water gas wells is often seriously influenced by the problem of liquid loading in the later production period of the gas wells. In addition, the deep water gas well is large in shaft depth, the temperature and pressure environment outside the shaft is complex in distribution, the gas-liquid flowing state in the shaft in the gas-water co-production period is more complex, the calculated value applicability of the critical flow under an ideal condition is limited, the existing gas well critical liquid carrying calculation model is mainly used for onshore gas wells, and the applicability of the model to deep water gas well liquid carrying calculation is poor.
The accurate prediction of the critical liquid carrying flow of the gas well has important significance for optimizing the working system of the gas well and preventing liquid accumulation at the bottom of the well. In the middle and later stages of the development of the water-containing gas reservoir, along with the reduction of the bottom hole pressure and the increase of the water yield, the produced water at the bottom hole cannot be taken out of the shaft hole under the low gas yield, so that the accumulated water is produced at the bottom hole. The gas well liquid accumulation can further reduce the production pressure difference and the gas production rate, and the gas well can be killed to cause production stop in severe cases. Therefore, an accurate gas well liquid carrying model is established, the gas well critical liquid carrying flow is predicted, and the reasonable control of the gas well working system is of great importance to guarantee the efficient development of the gas well and improve the gas reservoir recovery ratio.
The existing liquid carrying models are all corrected on the basis of predecessors, have certain applicability, and still have unreasonable places. Different diameters of liquid drops in a shaft are approximately distributed in a positive mode, the accuracy of liquid drop diameter selection and calculation has great influence on liquid carrying flow, the existing models use the maximum diameter liquid drop obtained by a simple Weber number definition formula as a critical liquid carrying judgment condition, and in fact, under the conditions of higher liquid phase flow rate and lower gas phase flow rate, the maximum liquid drop diameter calculated by the formula is closer to an actual value, and the calculated value under other conditions is far away from the actual value. The prior scholars think that the diameter of the liquid drop is related to physical parameters such as gas-liquid flowing state, gas-liquid viscosity and the like, and the maximum diameter of the liquid drop obtained by only a Weber number definition formula cannot fully meet the actual requirement. Meanwhile, based on a generally accepted ellipsoid model, deformation parameters of liquid drops are key for measuring the stress of the liquid drops, the deformation parameters are related to the environmental conditions of the liquid drops and also have a great relation with the size of the liquid drops, in addition, the critical liquid carrying flow rate is changed along with the temperature and pressure change of a shaft along the way, and the liquid loading of a gas well can be avoided only by taking the maximum liquid carrying flow rate value along the way as the critical liquid carrying flow rate, which is more necessary for the liquid carrying research of the deepwater gas well with complex distribution of a temperature and pressure field, which is not considered in the existing model.
Disclosure of Invention
In view of the above problems, the present invention aims to provide a method for predicting the critical liquid carrying flow rate of a deepwater gas well, which can accurately predict the critical liquid carrying flow rate of the gas well.
In order to realize the purpose, the invention adopts the following technical scheme: a critical liquid carrying flow prediction method suitable for a deepwater gas well comprises the following steps: 1) calculating the diameter of the Sauter liquid drop according to the bottom hole condition; 2) obtaining temperature pressure distribution of a shaft along the way according to a preset wellhead output Qg, calculating gas-liquid physical property parameters and flow parameters along the way according to the temperature pressure distribution, and calculating a liquid drop deformation coefficient so as to obtain the deformation degree of liquid drops along the way; 3) calculating drag coefficients of the liquid drops at different well depths; 4) according to the temperature and pressure conditions, drag coefficients at different depths of the well are converted to obtain a wellhead critical liquid carrying flow value Qg'; 5) and obtaining an accurate value of the critical liquid carrying flow according to the wellhead critical liquid carrying flow value Qg' and the wellhead yield Qg.
Further, in the step 1), the calculation formula of the mean diameter of the Sauter liquid drops is as follows:
Figure BDA0002597903950000021
wherein:
N μ ＝μ l [ρ l σ 3/2 /g 1/2 (ρ l -ρ g ) 1/2 ] -1/2
in the formula (d) s Is the Sauter droplet mean diameter, m; d is the diameter of the round pipe, m; we is the Weber number; re g Is gas phase Reynolds number; re l Is the Reynolds number of the liquid phase; n is a radical of μ Is a defined fluid viscosity number; c w The influence coefficient of the interfacial tension on the gas-liquid flow is shown; g is the acceleration of gravity, m/s 2 ；v sg Is the gas phase apparent flow velocity, m/s; rho g Is gas phase density, kg/m 3 ；ρ l Is liquid phase density, kg/m 3 ；μ l Is the liquid phase viscosity, pas; mu.s g Gas phase viscosity, pas.
Further, the weber number We is:
Figure BDA0002597903950000022
further, the influence coefficient C of the interfacial tension on the gas-liquid flow w ＝max(0.25,0.0283N μ -4/5 )。
Further, in the step 1), the final droplet deformation coefficient K' is:
Figure BDA0002597903950000023
in the formula, K is a droplet deformation coefficient before correction.
Further, the calculation formula of the droplet deformation coefficient K before correction is:
Figure BDA0002597903950000024
in the formula (d) s Is the Sauter droplet mean diameter, m; rho g Is gas phase density, kg/m 3 ；v g Is the gas phase flow velocity, m/s; and sigma is gas-liquid interfacial tension, N/m.
Further, the calculation method of the gas-liquid interfacial tension sigma is that only the gas-liquid density difference is larger than0.4g/cm 3 Fitting the gas phase hydrocarbon phase to obtain gas-liquid interfacial tension sigma as:
Figure BDA0002597903950000031
in the formula, T r Is the comparison temperature; t is the thermodynamic temperature, K; rho g Is gas phase density, kg/m 3 ；ρ l Is liquid phase density, kg/m 3 。
Further, the drag coefficient C D Comprises the following steps:
Figure BDA0002597903950000032
in the formula, Re g Is the gas phase reynolds number.
Further, the expression of the critical liquid carrying flow is as follows:
Figure BDA0002597903950000033
wherein:
Figure BDA0002597903950000034
in the formula, ρ g Is gas phase density, kg/m 3 (ii) a g is gravity acceleration, m/s 2 (ii) a K' is the final deformation coefficient of the liquid drop; rho l Is liquid phase density, kg/m 3 ；μ l Is the liquid phase viscosity, pas; mu.s g Gas phase viscosity, pas; c w The influence coefficient of the interfacial tension on the gas-liquid flow is shown; d is the diameter of the round pipe, m; we is the Weber number; re g Is gas phase Reynolds number; re l Is the Reynolds number of the liquid phase.
Further, in the step 5), judging whether the absolute value of the difference between the wellhead yield Qg and the maximum value of the critical liquid carrying flow rate value Qg' is smaller than a preset value epsilon, and if so, taking the wellhead yield Qg as a critical liquid carrying flow rate accurate value; otherwise, the wellhead production Qg is reset.
Due to the adoption of the technical scheme, the invention has the following advantages: aiming at the actual production of the deepwater gas well, the method establishes a liquid carrying judgment basic equation based on a particle balance theory, considers the size of the liquid drop and the deformation difference of the liquid drops with different sizes in the liquid carrying process, deduces the relation between the deformation parameter of the liquid drop and the flow condition and the size of the liquid drop according to the stress balance condition and the geometric characteristics of the liquid drop, preferably selects a drag coefficient and an air-water surface tension calculation formula to obtain a critical liquid carrying flow expression, and finally calculates the gas well critical liquid carrying flow by combining the temperature-pressure field distribution of a shaft, thereby effectively improving the prediction accuracy of the gas well critical liquid carrying flow.
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FIG. 1 is a schematic overall flow diagram of the present invention.
Figure 2 is a plot of volume fractions of droplets of different diameters.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the drawings of the embodiments of the present invention. It should be apparent that the described embodiments are only some of the embodiments of the present invention, and not all of them. All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the invention, are within the scope of the invention.
As described above, the existing gas well critical liquid carrying calculation method is limited in applicability to deep water gas wells because firstly, based on a generally accepted ellipsoid model, the deformation parameter of the liquid drop is a key for measuring the stress of the liquid drop, and besides being related to the environmental condition of the liquid drop, the deformation parameter has a great relationship with the size of the liquid drop, secondly, along with the temperature and pressure change along the shaft, the critical liquid carrying flow rate is changed, and the gas well liquid accumulation can be avoided by taking the maximum liquid carrying flow rate value along the way as the critical liquid carrying flow rate, which is more necessary for the deep water gas well liquid carrying research with complex temperature and pressure field distribution. Therefore, the invention provides a method for predicting critical liquid carrying flow rate of a deepwater gas well, and the method is further described in detail with reference to the accompanying drawings and the embodiment.
As shown in fig. 1, the method for predicting the critical liquid carrying flow rate of the deepwater gas well comprises the following steps:
1) calculating the diameter of the Sauter liquid drop according to the bottom hole condition;
because the influence of the difference of the size and the deformation of the liquid drop on the critical liquid carrying flow calculation under the condition of mist flow in the shaft at the initial stage of water breakthrough production of the deepwater gas well needs to be considered, the diameter of the liquid drop is calculated firstly.
2) Obtaining temperature pressure distribution of a shaft along the way according to a preset wellhead yield Qg, calculating gas-liquid physical property parameters and flow parameters along the way according to the temperature pressure distribution, and calculating a liquid drop deformation coefficient so as to obtain the deformation degree of liquid drops along the way;
3) calculating drag coefficients of the liquid drops at different well depths;
4) according to the temperature and pressure conditions, drag coefficients at different depths of the well are converted to obtain a wellhead critical liquid carrying flow value Qg';
5) and acquiring an accurate value of the critical liquid carrying flow according to the value Qg' of the critical liquid carrying flow of the wellhead and the yield Qg of the wellhead.
In the step 1), gas and liquid in the well cylinder flow in an annular fog flow type in the production process of the gas well, and according to previous researches, the diameters of liquid drops in the gas core are approximately distributed in a logarithmic positive-power mode, as shown in figure 2. At present, the maximum droplet diameter is mainly used as a critical liquid carrying calculation standard in the existing liquid carrying model, a simple Weber number definition method is adopted to calculate the maximum droplet diameter, and the maximum droplet diameter value is obtained according to a Weber number definition formula on the basis of the viewpoint that the maximum Weber number range of the droplet without splitting is 20-30, as shown in the formula (1).
Figure BDA0002597903950000051
In the formula, We' is a critical Weber number; ρ is a unit of a gradient g Is gas phase density, kg/m 3 ；v g Is the gas phase flow velocity, m/s; sigma is gas-liquid interfacial tension, N/m; d max Maximum droplet diameter, m.
However, experimental data prove that a simple weber number definition method has large deviation in the aspect of calculation accuracy, a calculated critical liquid carrying flow rate value is inconsistent with the actual value due to the diameter value of a droplet with an error, and in addition, the diameter of the droplet is inevitably related to the liquid flow rate in the gas-liquid two-phase flow process, and the weber number definition formula does not reflect the relation. Therefore, more reliable droplet diameter values and computational models are needed for liquid carrying calculations.
As shown in fig. 2, it can be seen that the volume fraction of the large-diameter droplets is small, which means that the number of the maximum droplet diameters is small, and most of the large-diameter droplets are medium-sized droplets, so that the calculation of the liquid carrying flow based on the maximum droplet diameters is too conservative, and the calculation of the invention only needs to use the average droplet diameter as the liquid carrying standard to meet the liquid carrying requirement. This is because the number of large diameter droplets is much smaller than the diameter of medium droplets, and when the lifting force is insufficient to lift the large droplets, the droplets will fall and collide with other droplets and converge to further increase the volume of the droplets, and when the droplet volume is too large and the weber number of the droplets exceeds a critical value, the large droplets will be broken into small droplets and scatter and distribute, and at this time, most of the broken droplets will be lifted again and carried out of the wellbore.
In the study on the diameter of the liquid drop under the circular fog flow, Tatterso et al (1977), Azzopadi (1985), Kocamusafaogullari et al (1994) respectively propose different circular fog flow type liquid drop diameter calculation models, and model verification is carried out by using the existing experimental data, and experiments prove that the calculation model of the diameter of the liquid drop, which is also obtained based on the critical Weber number and is proposed by Kocamusafaoglari et al, has higher prediction accuracy and stability, and can well describe the size of the average diameter of the actual liquid drop, the invention adopts the model to carry out liquid calculation, and the calculation formula of the average diameter of the liquid drop is as follows:
Figure BDA0002597903950000052
wherein:
Figure BDA0002597903950000053
C w ＝max(0.25,0.0283N μ -4/5 ) (4)
N μ ＝μ l [ρ l σ 3/2 /g 1/2 (ρ l -ρ g ) 1/2 ] -1/2 (5)
in the formula (d) s Is the Sauter droplet mean diameter, m; d is the diameter of the round pipe, m; we is the Weber number; re g Is gas phase Reynolds number; re l Is liquid phase Reynolds number; n is a radical of μ Is a defined fluid viscosity number; c w The influence coefficient of the interfacial tension on the gas-liquid flow is shown; g is the acceleration of gravity, m/s 2 ；v sg Is the gas phase apparent flow velocity, m/s; ρ is a unit of a gradient g Is gas phase density, kg/m 3 ；ρ l Is liquid phase density, kg/m 3 ；μ l Is the liquid phase viscosity, Pa.s; mu.s g Gas phase viscosity, pas.
In the step 2), in the production process of the gas well, the gas and the liquid phases flow along the wellbore in different forms, the liquid phase is mainly carried and ascended by the gas core in the form of liquid drops, the liquid drops in the gas core are approximately in normal distribution with different sizes, each liquid drop is in an ellipsoid shape with different deformation degrees, the liquid drop deformation parameter is an important parameter for measuring the deformation degree of the liquid drop on the basis of the sphere, and the liquid drop deformation coefficient is defined as:
K＝d/d s (6)
wherein d is the diameter of the spherical liquid drop, m; k is the deformation coefficient of the liquid drop and is dimensionless.
According to the geometrical relationship, the volume and the surface area of the ellipsoidal droplet can be calculated by the following equations (7) and (8):
Figure BDA0002597903950000061
Figure BDA0002597903950000062
wherein V is the volume of the droplet, m 3 (ii) a S' is the surface area of the ellipsoidal droplet, m 2 (ii) a h is the height of the minor axis of the ellipsoid, m.
Surface area of ellipsoidal liquid drops obtained in the united type (6), (7) and (8):
Figure BDA0002597903950000063
wherein S is the surface area of a spherical droplet, m 2 ；
When the liquid drop moves in the air core with a speed v, a pressure difference exists due to different pressures of the front and the back, and the pressure difference can be calculated by a Bernoulli equation:
Figure BDA0002597903950000064
where Δ p is the pressure difference, Pa, across the interface before and after the moving droplet.
The liquid drop presents the ellipsoid type under the effect of this pressure differential, according to the hypothesis, takes liquid in-process liquid drop ellipsoid shape to reach stably under the effect of upper and lower pressure differential and surface tension, satisfies mechanical balance this moment, and convolution (9) simultaneously can:
Figure BDA0002597903950000065
the volume of the liquid drop is kept unchanged in the deformation process, and the volume of the ellipsoid represented by the cross section area of the long half shaft is as follows:
Figure BDA0002597903950000066
the formula (11) and the formula (12) can be arranged to obtain:
Figure BDA0002597903950000071
in combination with formula (10) to yield:
Figure BDA0002597903950000072
bringing formula (14) into formula (12) can result:
Figure BDA0002597903950000073
combining the above formula (7) and formula (15), to obtain:
Figure BDA0002597903950000074
and correcting the obtained K value, wherein the K' value is used as a final calculated value of the deformation coefficient of the liquid drop as shown in a formula (17):
Figure BDA0002597903950000075
from the equation (16), it can be seen that the droplet deformation coefficient is related to the droplet equivalent diameter, the gas-liquid surface tension, the gas phase density, the gas phase flow rate, and the like.
The method for acquiring the gas-liquid interfacial tension sigma comprises the following steps:
as the gas-water interfacial tension is mainly related to the gas-liquid density and the temperature, a great deal of research is carried out by domestic and foreign scholars aiming at the gas-liquid interfacial tension, and the existing hydrocarbon/water interfacial tension model is mainly divided into a global fitting model and a partial fitting model. Wherein the global fitting is an integral fitting to the gas-liquid phase hydrocarbon/water interfacial tension, and the main fitting formula is as follows:
danesh interfacial tension model:
σ＝111(ρ l -ρ g ) 1.024 T r -1.25 (18)
sutton obtains an improved model on the basis of the Danesh model:
Figure BDA0002597903950000076
only for gas-liquid density difference larger than 0.4g/cm 3 Fitting the gas phase hydrocarbon phase to obtain gas-liquid interfacial tension:
Figure BDA0002597903950000081
in the formula, T r Is the comparison temperature; t is the thermodynamic temperature, K.
Experimental data show that for the gaseous hydrocarbon/liquid two-phase flow, the accuracy is higher by adopting a partial fitting formula, so that the liquid carrying calculation is carried out by adopting the fitting formula (20).
In the step 3), the drag coefficient is mainly related to the shape of the liquid drop and the reynolds number, and the existing research mainly uses the existing experimental data to fit the relational expression between the drag coefficient and the reynolds number, and is also divided into two types, namely segmented fitting and full-domain fitting. The universal fitting relational expression widely applied at present mainly comprises the following 3 types:
brauer global fitting correlation:
Figure BDA0002597903950000082
clift & Gauvin gamut fitting correlation:
Figure BDA0002597903950000083
the shore is based on a nonlinear fitting correlation:
Figure BDA0002597903950000084
in the formula, C D Is the drag coefficient.
The existing experimental data are utilized to carry out simulation verification on the 3 models, the simulation result is the same as the conclusion provided by Weina et al, and the nonlinear fitting correlation of Shao Ming et al has higher fitting precision.
The prior experimental data and the fitting curve are obtained based on a rigid sphere, the deformed liquid drop in an ellipsoid is greatly different from the rigid sphere, and Helenbrook and Edwards are researched to obtain that the drag coefficient of the liquid drop is smaller than that of the rigid sphere with the same volume due to the flow in the liquid drop, so that the drag coefficient of the ellipsoid liquid drop is calculated by reducing 10% on the basis of a Shore expectation formula, and the final calculation formula is as follows:
Figure BDA0002597903950000085
in the step 4), the method for calculating the critical liquid carrying flow rate is as follows:
the liquid drop is subjected to stress analysis, the liquid drop is subjected to upward drag force caused by gas phase flow, upward buoyancy force naturally existing in a gas phase environment and downward gravity of the liquid drop, and when the liquid drop can just keep balance, the stress meets the following relational expression:
Figure BDA0002597903950000091
the gravity and the lifting force that small-size liquid drop received are all very little, but lifting force is greater than liquid drop gravity, satisfy very easily and take the liquid condition, and along with the increase of liquid drop volume, gravity and lifting force all increase gradually, but the speed of gravity increase will be higher than the increase speed of lifting force, therefore the liquid drop carries the degree of difficulty and increases gradually. As the droplet diameter increases, the critical liquid-carrying flow rate increases monotonically, and thus, larger diameter droplets are more difficult to carry.
Based on the above analysis, the expressions of critical fluid-carrying flow rate can be obtained by combining the expressions (2), (16), (24) and (25) 4:
Figure BDA0002597903950000092
wherein:
Figure BDA0002597903950000093
in the past, most of liquid carrying models determine a critical liquid carrying value according to a wellhead condition or an average temperature and pressure condition, while the temperature and pressure distribution of a gas well along the way is complex, particularly for a deepwater gas well, therefore, the critical liquid carrying position does not necessarily appear at the same depth of a shaft, the critical liquid carrying flow obtained by calculation only according to the oil pressure of the wellhead and fluid physical property parameters under the wellhead condition is unreliable, and the temperature and pressure distribution of the shaft should be considered, so that the critical liquid carrying value of the gas well is determined.
In the step 5), judging whether the absolute value of the difference between the wellhead yield Qg and the maximum value of the critical liquid carrying flow value Qg' is smaller than a preset value epsilon, and if so, taking the wellhead yield Qg as the critical liquid carrying flow accurate value; otherwise, the wellhead production Qg is reset.
In conclusion, the method establishes a liquid carrying determination basic equation based on a particle balance theory, considers the difference of the sizes of liquid drops and the deformation of the liquid drops with different sizes in the liquid carrying process, deduces the relation between the deformation parameters of the liquid drops, the flowing conditions and the sizes of the liquid drops according to the stress balance conditions and the geometrical characteristics of the liquid drops, preferably selects a drag coefficient and an air-water surface tension calculation formula to obtain a critical liquid carrying flow expression, and finally accurately predicts the critical liquid carrying flow of the gas well by combining with the temperature and pressure field distribution of a shaft.
The above embodiments are only for illustrating the present invention, and the steps may be changed, and on the basis of the technical solution of the present invention, the modification and equivalent changes of the individual steps according to the principle of the present invention should not be excluded from the protection scope of the present invention.

Claims (10)

1. A critical liquid carrying flow prediction method suitable for a deepwater gas well is characterized by comprising the following steps:
1) calculating the diameter of the Sauter liquid drop according to the bottom hole condition;
2) obtaining temperature pressure distribution of a shaft along the way according to a preset wellhead yield Qg, calculating gas-liquid physical property parameters and flow parameters along the way according to the temperature pressure distribution, and calculating a liquid drop deformation coefficient so as to obtain the deformation degree of liquid drops along the way;
3) calculating drag coefficients of the liquid drops at different well depths;
4) according to the temperature and pressure conditions, drag coefficients at different depths of the well are converted to obtain a wellhead critical liquid carrying flow value Qg';
5) and acquiring an accurate value of the critical liquid carrying flow according to the value Qg' of the critical liquid carrying flow of the wellhead and the yield Qg of the wellhead.
2. The method for predicting critical liquid carrying flow as claimed in claim 1, wherein: in the step 1), the calculation formula of the mean diameter of the Sauter liquid drop is as follows:
Figure FDA0002597903940000011
wherein:
N μ ＝μ l [ρ l σ 3/2 /g 1/2 (ρ l -ρ g ) 1/2 ] -1/2
in the formula (d) s Is the Sauter droplet mean diameter, m; d is the diameter of the round pipe, m; we is the Weber number; re g Is gas phase Reynolds number; re l Is liquid phase Reynolds number; n is a radical of hydrogen μ Is a defined fluid viscosity number; c w The influence coefficient of the interfacial tension on the gas-liquid flow is shown; g is the acceleration of gravity, m/s 2 ；v sg Is the gas phase apparent flow velocity, m/s; rho g Is gas phase density, kg/m 3 ；ρ l Is liquid phase density, kg/m 3 ；μ l Is the liquid phase viscosity, Pa.s; mu.s g Gas phase viscosity, pas.
3. The method of claim 2, wherein the critical liquid-carrying flow prediction method comprises: the Weber number We is as follows:
Figure FDA0002597903940000012
4. the method for predicting critical liquid carrying flow as claimed in claim 2, wherein: coefficient of influence C of the interfacial tension on gas-liquid flow w ＝max(0.25,0.0283N μ -4/5 )。
5. The method of claim 1, wherein the method comprises: in the step 1), the final deformation coefficient K' of the liquid drop is as follows:
Figure FDA0002597903940000013
in the formula, K is a droplet deformation coefficient before correction.
6. The method of claim 5, wherein the critical liquid-carrying flow prediction method comprises: the calculation formula of the deformation coefficient K of the liquid drop before correction is as follows:
Figure FDA0002597903940000021
in the formula (d) s Is the Sauter droplet mean diameter, m; ρ is a unit of a gradient g Is gas phase density, kg/m 3 ；v g Is the gas phase flow velocity, m/s; and sigma is gas-liquid interfacial tension N/m.
7. The method for predicting the critical liquid-carrying flow according to claim 6, wherein the gas-liquid interfacial tension σ is calculated only for a gas-liquid density difference larger than 0.4g/cm 3 Fitting the gas-phase hydrocarbon stage to obtain a gas-liquid interfacial tension sigma:
Figure FDA0002597903940000022
in the formula, T r Is the comparison temperature; t is the thermodynamic temperature, K; rho g Is gas phase density, kg/m 3 ；ρ l Is liquid phase density, kg/m 3 。
8. The method for predicting critical liquid carrying flow as claimed in claim 1, wherein: drag coefficient C D Comprises the following steps:
Figure FDA0002597903940000023
in the formula, Re g Is the gas phase reynolds number.
9. The method of claim 8, wherein the critical liquid-carrying flow prediction method comprises: the expression of the critical liquid carrying flow is as follows:
Figure FDA0002597903940000024
wherein:
Figure FDA0002597903940000025
in the formula, ρ g Is gas phase density, kg/m 3 (ii) a g is gravity acceleration, m/s 2 (ii) a K' is the final deformation coefficient of the liquid drop; rho l Is liquid phase density, kg/m 3 ；μ l Is the liquid phase viscosity, Pa.s; mu.s g Is gas phase viscosity, pas; c w The influence coefficient of the interfacial tension on the gas-liquid flow is shown; d is the diameter of the round pipe, m; we is the Weber number; re g Is the gas phase Reynolds number; re l Is the Reynolds number of the liquid phase.
10. The method of claim 9, wherein the critical liquid-carrying flow prediction method comprises: in the step 5), judging whether the absolute value of the difference between the wellhead yield Qg and the maximum value of the critical liquid carrying flow value Qg' is smaller than a preset value epsilon, and if so, taking the wellhead yield Qg as the critical liquid carrying flow accurate value; otherwise, the wellhead production Qg is reset.
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