Oil-gas-water three-phase fluid modeling method applied to pipeline transportation process simulation

Abstract

The invention belongs to the technical field of sliding vane type air compressors, and particularly relates to an oil-gas-water three-phase fluid modeling method applied to pipeline transportation process simulation, which comprises the following steps: inputting a pipeline track; inputting multi-phase fluid parameters and pipe wall heat transfer coefficient parameters; inputting pipeline inlet parameters; flow state prediction: calculating the number of Froude, and determining the content of liquid at the inlet of the pipeline; calculating the friction coefficient and the liquid holdup; inputting production data and correcting parameters; according to pipeline pressure gradient calculation, the defects in the prior art are overcome, friction coefficient and liquid holdup parameters influencing pipeline multiphase flow pressure gradient calculation are corrected in real time through production data, and the calculation precision of the pipeline pressure gradient is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of vane air compressors, and in particular relates to an oil-gas-water three-phase fluid modeling method applied to pipeline transportation process simulation. Background Art

[0002] Oil, gas and water three-phase flow calculation is the core calculation process of pipeline transportation design and operation and maintenance, especially for the efficiency and safety of high-drop pipeline transportation.

[0003] Since the pressure and temperature of oil, gas and water pipelines change dramatically during transportation, the accurate calculation of pipeline pressure and temperature becomes a key factor in pipeline strength safety, pipeline transportation efficiency, real-time pipeline operation and maintenance, and pipeline flow assurance.

[0004] Standard pipeline three-phase flow calculation models including Beggs-Brill and Hagedorn-Brown have been proven to have sufficient calculation accuracy in the calculation of pipeline pressure and temperature in most flow states. However, in most applications of pipeline flow with high water content and high drop, it is found that the calculation error of pressure difference and temperature difference exceeds 20%. One of the main reasons is that the gas-liquid ratio related parameters and friction coefficient in the model are not corrected for different flow states and pipeline topologies. Another main reason is that the existing model does not consider the flow assurance issues such as wax deposition and corrosion of the pipeline as the operating cycle increases. The core issue of the model should use real-time data to perform real-time correction of key parameters in the model including friction coefficient and heat transfer coefficient. Summary of the invention

[0005] The purpose of the present invention is to provide an oil-gas-water three-phase fluid modeling method for simulating pipeline transportation process, which overcomes the shortcomings of the prior art and performs real-time correction of the friction coefficient and liquid holdup parameters that affect the calculation of pipeline multiphase flow pressure gradient through production data, thereby improving the calculation accuracy of pipeline pressure gradient.

[0006] To solve the above problems, the technical solutions adopted by the present invention are as follows:

[0007] A three-phase fluid modeling method for oil, gas and water applied to pipeline transportation process simulation includes the following steps:

[0008] S1, input pipeline trajectory;

[0009] S2, input multiphase fluid parameters and tube wall heat transfer coefficient parameters;

[0010] S3, pipeline inlet parameter input;

[0011] S4. Flow pattern prediction: calculate the Froude number and determine the liquid content at the pipeline inlet;

[0012] S5, calculation of friction coefficient and liquid holdup;

[0013] S6. Production data input and parameter correction;

[0014] S7. Calculation of pipeline pressure gradient.

[0015] Furthermore, the expression of the Froude number is:

[0016]

[0017] Where g is the acceleration due to gravity.

[0018] Furthermore, after the flow pattern prediction in S4, the flow domain boundary is determined by the liquid content at the pipeline inlet, and its expression is:

[0019]

[0020] Among them, λ L is the inlet liquid content; L1-L4 are the boundaries of different basins.

[0021] Furthermore, the liquid holdup calculation in S5 is performed through a horizontal pipeline, and then the pipeline angle is considered through a correction method, and its expression is:

[0022]

[0023] Among them, H L(0) is the liquid holdup of the horizontal pipeline, a1, a2, a3 are the liquid holdup model constants, and ψ(a, t) is the correction parameter for the liquid holdup calculation that changes with time and pipeline angle.

[0024] Further, the production data input and parameter correction in S6 use a simulated annealing algorithm to perform parameter correction on the friction coefficient and liquid holdup calculation results, and the specific steps include:

[0025] S61, setting initial parameters;

[0026] S62, generating a group of random solutions to form an initial solution set, taking the production pressure at the outlet of the pipeline as the objective function, and calculating the target value of each solution in the initial solution set;

[0027] S63. Compare the target value calculated by the initial solution set with the production pressure data, and reversely calculate the friction coefficient and liquid holdup model parameters.

[0028] Further, the expression for calculating the pipeline pressure gradient in S7 is:

[0029]

[0030] ρ s =ρ L HL(α) +ρ g (1-H L(α) )

[0031] Where ρ and L are pressure and pipe length, respectively; d is the inner diameter of the pipe, α is the pipe angle; f(t) is the time-varying pipe friction coefficient; v m With v sg are the mixed medium velocity and gas superficial velocity respectively; ρ n It is assumed that there is no slip in the gas-liquid mixed medium density; E k is the dimensionless kinetic energy; ρ s , ρ L ,ρ g are the density of the mixed medium, the density of the liquid and the gas under the relative slip of gas and liquid, H L(α) is the liquid holdup at pipe angle .

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The oil-gas-water three-phase fluid modeling method for pipeline transportation process simulation adopts a universal simulated annealing algorithm and combines real-time production data to correct the key friction coefficient and liquid holdup parameters that affect the pressure gradient calculation, thereby greatly improving the calculation accuracy of the pipeline multiphase flow pressure gradient, and also improving the calculation accuracy of other design and operation parameters including temperature gradient. It effectively improves the application value of pipeline multiphase flow calculation in pipeline design and operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 The figure is a flow chart of a method for modeling oil, gas and water three-phase fluids for simulating pipeline transportation processes.

[0035] Figure 2 The figure is a flow chart of a simulated annealing algorithm in an oil-gas-water three-phase fluid modeling method used in pipeline transportation process simulation.

[0036] Figure 3 This is the overall flow chart of pipeline multiphase flow calculation in Example 1.

[0037] Figure 4 This is a line chart comparing the calculated data of the pipeline multiphase flow pressure gradient in Example 1.

[0038] Figure 5 This is a line chart comparing the temperature gradient calculation data of the pipeline multiphase flow in Example 1. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] The oil-gas-water three-phase fluid modeling method for simulating a pipeline transportation process described in the present invention comprises the following steps:

[0041] S1, input pipeline trajectory;

[0042] S2, input multiphase fluid parameters and tube wall heat transfer coefficient parameters;

[0043] S3, pipeline inlet parameter input;

[0044] S4. Flow pattern prediction: calculate the Froude number and determine the liquid content at the pipeline inlet;

[0045] The flow domain boundary is determined by the liquid content at the pipe inlet, and its expression is:

[0046]

[0047] Among them, λ L is the inlet liquid content; L1-L4 are the boundaries of different basins.

[0048] The flow pattern prediction is determined by the liquid content at the pipeline inlet and the Froude number, as shown in Table 1:

[0049] Table 1 Schematic diagram of flow state

[0050]

[0051] After the flow pattern is predicted, the flow domain boundary is determined by the liquid content at the pipe inlet, and its expression is:

[0052]

[0053] Among them, λ L is the inlet liquid content; L1-L4 are the boundaries of different basins.

[0054] S5, calculation of friction coefficient and liquid holdup;

[0055] The liquid holdup is calculated through the horizontal pipeline, and then the pipeline angle is considered by the correction method. The expression is:

[0056]

[0057] Among them, H L(0)is the liquid holdup of the horizontal pipeline, a1, a2, a3 are the liquid holdup model constants, and ψ(a, t) is the correction parameter for the liquid holdup calculation that changes with time and pipeline angle.

[0058] S6. Production data input and parameter correction;

[0059] Production data input and parameter correction The simulated annealing algorithm is used to perform parameter correction on the friction coefficient and liquid holdup calculation results. The specific steps include:

[0060] S61, setting initial parameters;

[0061] S62, generating a group of random solutions to form an initial solution set, taking the production pressure at the outlet of the pipeline as the objective function, and calculating the target value of each solution in the initial solution set;

[0062] S63. Compare the target value calculated by the initial solution set with the production pressure data, and reversely calculate the friction coefficient and liquid holdup model parameters.

[0063] S7, pipeline pressure gradient calculation;

[0064] The expression for calculating the pipeline pressure gradient is:

[0065]

[0066] ρ s =ρ L H L(α) +ρ g (1-H L(α) )

[0067] Where ρ and L are pressure and pipe length, respectively; d is the inner diameter of the pipe, α is the pipe angle; f(t) is the time-varying pipe friction coefficient; v m With v sg are the mixed medium velocity and gas superficial velocity respectively; ρ n It is assumed that there is no slip in the gas-liquid mixed medium density; E k is the dimensionless kinetic energy; ρ s , ρ L ,ρ g are the density of the mixed medium, the density of the liquid and the gas under the relative slip of gas and liquid, H L(α) is the liquid holdup at pipe angle .

[0068] Example 1

[0069] This embodiment is explained by a specific pipeline case of an oil field:

[0070] like Figure 3 Shown is the overall flow chart of the pipeline multiphase flow case of this embodiment;

[0071] The calculation of the pressure gradient of multiphase flow in pipelines needs to be included in the pipeline calculation process. The entire process includes physical property selection, pipeline / pipeline network process construction, inlet boundary condition setting, etc.

[0072] The data requirements for the pipeline multiphase flow case are shown in Table 2 and Table 3:

[0073]

[0074] Table 2 Calculation of physical properties of pipeline multiphase flow

[0075] Liquid Volume 52.2 m3 / day Massflow 5055.743 kg / h Outlet temperature 23 ℃ Outlet pressure 7.6 MPa Ambient temperature 8 ℃ Roughness 0.04572 mm Overall heat transfer coefficient 0.77 W / mK

[0076]

[0077] Table 3 Calculation trajectory and boundary conditions of pipeline multiphase flow The calculation requirements are: the starting flow is 120,000 cubic meters / day, and it is transported to the end point through a DN150, 9km long, 1 / 1.5m buried depth pipeline (different buried depths are counted as one each), the end point pressure is 7.6MPa, and the end point temperature is required to be no less than 23℃. The starting pressure and the required temperature of the starting point are calculated by hydraulic and thermal calculation.

[0078] The calculation results are shown in Figure 4 and Figure 5 .

[0079] like Figure 4 As shown, the patent of this invention greatly improves the calculation accuracy of pipeline multiphase flow pressure gradient by correcting the friction coefficient and liquid holdup calculation parameters, and promotes the application of pipeline multiphase flow calculation and pipeline design and operation and maintenance control.

[0080] like Figure 5 As shown in the figure, the patent of this invention not only greatly improves the calculation accuracy of pipeline multiphase flow pressure gradient, but also greatly improves the accuracy of the model in temperature calculation. Compared with the main competing products in the market, the accuracy is improved by more than 20%.

[0081] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A three-phase oil-gas-water fluid modeling method for pipeline transportation simulation, characterized by: The following steps are involved: S1, input pipeline trajectory; S2, input multiphase fluid parameters and tube wall heat transfer coefficient parameters; S3, pipeline inlet parameter input; S4. Flow pattern prediction: calculate the Froude number and determine the liquid content at the pipeline inlet; S5, calculation of friction coefficient and liquid holdup; S6. Production data input and parameter correction; S7. Calculation of pipeline pressure gradient.

2. The oil-gas-water three-phase fluid modeling method for pipeline transportation process simulation according to claim 1 is characterized by: The expression of the Froude number is: Where g is the acceleration due to gravity.

3. The oil-gas-water three-phase fluid modeling method for pipeline transportation process simulation according to claim 2 is characterized by: After the flow pattern prediction in S4, the flow domain boundary is determined by the liquid content at the pipeline inlet, and its expression is: Among them, λ L is the inlet liquid content; L1-L4 are the boundaries of different basins.

4. The oil-gas-water three-phase fluid modeling method for pipeline transportation process simulation according to claim 1 is characterized by: The liquid holdup calculation described in S5 is calculated through the horizontal pipeline, and then the pipeline angle is considered by the correction method, and its expression is: Among them, H L(0) is the liquid holdup of the horizontal pipeline, a1, a2, a3 are the liquid holdup model constants, and ψ(a, t) is the correction parameter for the liquid holdup calculation that changes with time and pipeline angle.

5. The oil-gas-water three-phase fluid modeling method for pipeline transportation process simulation according to claim 1 is characterized by: The production data input and parameter correction described in S6 use simulated annealing algorithm to perform parameter correction on the friction coefficient and liquid holdup calculation results. The specific steps include: S61, setting initial parameters; S62, generating a group of random solutions to form an initial solution set, taking the production pressure at the outlet of the pipeline as the objective function, and calculating the target value of each solution in the initial solution set; S63. Compare the target value calculated by the initial solution set with the production pressure data, and reversely calculate the friction coefficient and liquid holdup model parameters.

6. The oil-gas-water three-phase fluid modeling method for pipeline transportation process simulation according to claim 1 is characterized by: The expression for calculating the pipeline pressure gradient in S7 is: r s =ρ L H L(α) +r g (1-H L(α) ) Where ρ and L are pressure and pipe length, respectively; d is the inner diameter of the pipe, α is the pipe angle; f(t) is the time-varying pipe friction coefficient; v m With v sg are the mixed medium velocity and gas superficial velocity respectively; ρ n It is assumed that there is no slip in the gas-liquid mixed medium density; E k is the dimensionless kinetic energy; ρ s , ρ L ,ρ g are the density of the mixed medium, the density of the liquid and the gas under the relative slip of gas and liquid, H L(α) is the liquid holdup at pipe angle .

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