CN111898230B - Method and device for determining dimensionless characteristic curve of sucker-rod pump downhole system - Google Patents
Method and device for determining dimensionless characteristic curve of sucker-rod pump downhole system Download PDFInfo
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Abstract
The invention provides a method and a device for determining a dimensionless characteristic curve of a sucker-rod pump downhole system. The method comprises the following steps: determining a relation curve of pump displacement and pump pressure difference according to pumping parameters and equipment parameters; determining an elastic expansion correction parameter of the oil pipe according to the total length of the sucker rod string, the pump pressure difference and the cross sectional area of the oil pipe wall; determining a pump leakage correction parameter according to the pump diameter, the plunger eccentricity, the pump clearance, the fluid kinematic viscosity, the fluid density, the plunger length and the plunger average speed; determining a pump fullness correction parameter according to the clearance ratio and the gas-liquid ratio in the pump; correcting a relation curve of the pump displacement and the pump pressure difference according to the oil pipe elastic expansion correction parameter, the pump leakage correction parameter and the pump fullness correction parameter; and determining the coordinated yield by using the corrected relation curve of the pump displacement and the pump pressure difference. The characteristic curve of the invention can carry out node analysis and optimization design on the system, considers the influence of various factors on the effect, better accords with the field reality, and provides more valuable reference.
Description
Technical Field
The invention relates to the technical field of oil field mechanical oil extraction, in particular to a method and a device for determining a dimensionless characteristic curve of a sucker-rod pump underground system.
Background
The underground system of the sucker-rod pump can be regarded as a special plunger pump, and is characterized in that an elastic rod column of hundreds to thousands of meters is arranged between a polish rod and a plunger, and the sucker-rod pump is greatly influenced by the elastic deformation of a sucker rod and an oil pipe, the filling degree of the pump and the like when working underground, so that the sucker-rod pump has the working characteristics different from a common plunger pump.
The curve representing the relationship between the main performance parameters is often referred to as the pump performance curve or characteristic curve. In essence, the pump characteristic curve is an external representation of the fluid's movement within the pump system, so any pump system should have its own characteristic curve, which can be generally determined by actual measurements, such as an electrical submersible pump. The existing design and calculation method of the underground system of the sucker-rod pump is an API RP 11L method (hereinafter referred to as an API method), but the characteristics of the ultra-long sucker rod of the underground system of the sucker-rod pump, the complex underground working environment and the like do not enable the underground system of the sucker-rod pump to obtain a working characteristic curve by actually measuring the whole machine on the ground like an electric submersible pump. When the API method is used for analyzing the underground system of the sucker-rod pump, the consideration of actual factors on site is lacked, so that the characteristic curve is inaccurate, and the site operation cannot be accurately guided.
Disclosure of Invention
In order to solve the problems of inaccurate working characteristic curve and the like of the existing analysis method of the downhole system of the sucker-rod pump, the embodiment of the invention provides a method for determining the dimensionless characteristic curve of the downhole system of the sucker-rod pump, which comprises the following steps:
determining a relation curve of pump displacement and pump pressure difference according to pumping parameters and equipment parameters, wherein the pumping parameters and the equipment parameters comprise the total length of a sucker rod string, pump pressure difference, the cross section area of a tubing wall, pump diameter, plunger eccentricity, pump clearance, fluid kinematic viscosity, fluid density, plunger length, plunger average speed, clearance ratio and gas-liquid ratio in the pump;
determining an elastic expansion correction parameter of the oil pipe according to the total length of the sucker rod string, the pumping pressure difference and the cross-sectional area of the oil pipe wall; determining a pump leakage correction parameter according to the pump diameter, the plunger eccentricity, the pump gap, the fluid kinematic viscosity, the fluid density, the plunger length and the plunger average speed; determining a pump fullness correction parameter according to the clearance ratio and the gas-liquid ratio in the pump;
correcting a relation curve of the pump displacement and the pump pressure difference according to the oil pipe elastic expansion correction parameter, the pump loss correction parameter and the pump fullness correction parameter;
and determining the coordinated yield of the downhole system of the sucker rod pump by using the corrected relation curve of the pump displacement and the pump pressure difference.
Optionally, in an embodiment of the present invention, the pumping parameters and the equipment parameters further include stroke, stroke frequency, pump cross-sectional area, and sucker rod string natural frequency.
Optionally, in an embodiment of the present invention, the determining a pump displacement versus pump pressure difference curve according to the pumping parameter and the equipment parameter includes: according to the pump differential pressure, the stroke frequency, the pump cross-sectional area and the inherent frequency of the sucker rod string, dimensionless stroke frequency, dimensionless sucker rod elongation, dimensionless piston stroke and dimensionless load are determined; determining a dimensionless characteristic curve of the relation between the effective stroke and the pump pressure difference and a dimensionless characteristic curve of the relation between the polished rod power and the pump pressure difference according to the dimensionless stroke, the dimensionless sucker rod elongation, the dimensionless piston stroke and the dimensionless load; and determining a relation curve of the pump displacement and the pump pressure difference by utilizing the dimensionless characteristic curve of the relation between the effective stroke and the pump pressure difference and the dimensionless characteristic curve of the relation between the polished rod power and the pump pressure difference.
Optionally, in an embodiment of the present invention, the determining the coordinated production of the sucker-rod pump downhole system by using the corrected pump displacement versus pump pressure difference curve includes: carrying out node analysis on the underground system of the sucker-rod pump by using the corrected relation curve of the pump displacement and the pump pressure difference to obtain an inflow and outflow curve of a node; determining a coordinated production of the sucker-rod pump downhole system based on the inflow and outflow curves.
The embodiment of the invention also provides a device for determining the dimensionless characteristic curve of the sucker-rod pump downhole system, which comprises:
the system comprises a curve determining module, a pumping parameter calculating module and a pumping parameter calculating module, wherein the curve determining module is used for determining a relation curve of pump displacement and pump pressure difference according to pumping parameters and equipment parameters, and the pumping parameters and the equipment parameters comprise the total length of a sucker rod string, pump pressure difference, the cross section area of a tubing wall, pump diameter, plunger eccentricity, pump clearance, fluid kinematic viscosity, fluid density, plunger length, plunger average speed, clearance ratio and gas-liquid ratio in a pump;
the parameter determining module is used for determining the elastic expansion correction parameter of the oil pipe according to the total length of the sucker rod string, the pump pressure difference and the cross section area of the oil pipe wall; determining pump leakage correction parameters according to the pump diameter, the plunger eccentricity, the pump clearance, the fluid kinematic viscosity, the fluid density, the plunger length and the plunger average speed; determining a pump fullness correction parameter according to the clearance ratio and the gas-liquid ratio in the pump;
the curve correction module is used for correcting a relation curve of the pump displacement and the pump pressure difference according to the oil pipe elastic expansion correction parameter, the pump leakage correction parameter and the pump fullness correction parameter;
and the coordinated yield module is used for determining the coordinated yield of the downhole system of the sucker rod pump by utilizing the corrected relation curve of the pump displacement and the pump pressure difference.
Optionally, in an embodiment of the present invention, the pumping parameters and the equipment parameters further include stroke, stroke frequency, pump cross-sectional area, and sucker rod string natural frequency.
Optionally, in an embodiment of the present invention, the curve determining module includes: the dimensionless parameter unit is used for determining dimensionless stroke frequency, dimensionless sucker rod elongation, dimensionless piston stroke and dimensionless load according to the pump differential pressure, stroke frequency, pump cross-sectional area and sucker rod string inherent frequency; the dimensionless characteristic curve unit is used for determining a dimensionless characteristic curve of the relation between the effective stroke and the pump pressure difference and a dimensionless characteristic curve of the relation between the polished rod power and the pump pressure difference according to the dimensionless stroke, the dimensionless sucker rod elongation, the dimensionless piston stroke and the dimensionless load; and the curve determining unit is used for determining a relation curve between the pump displacement and the pump pressure difference by utilizing the dimensionless characteristic curve of the relation between the effective stroke and the pump pressure difference and the dimensionless characteristic curve of the relation between the polished rod power and the pump pressure difference.
Optionally, in an embodiment of the present invention, the coordination yield module includes: the inflow and outflow curve unit is used for carrying out node analysis on the underground system of the sucker-rod pump by using the corrected relation curve of the pump displacement and the pump pressure difference to obtain an inflow and outflow curve of a node; and the coordinated production unit is used for determining the coordinated production of the sucker rod pump downhole system according to the inflow and outflow curves.
The embodiment of the present invention further provides a computer device, which includes a memory, a processor, and a computer program stored in the memory and capable of running on the processor, and when the processor executes the computer program, the following steps are implemented:
determining a relation curve of pump displacement and pump pressure difference according to pumping parameters and equipment parameters, wherein the pumping parameters and the equipment parameters comprise the total length of a sucker rod string, pump pressure difference, the cross section area of a tubing wall, pump diameter, plunger eccentricity, pump clearance, fluid kinematic viscosity, fluid density, plunger length, plunger average speed, clearance ratio and gas-liquid ratio in the pump;
determining an elastic expansion correction parameter of the oil pipe according to the total length of the sucker rod string, the pumping pressure difference and the cross-sectional area of the oil pipe wall; determining a pump leakage correction parameter according to the pump diameter, the plunger eccentricity, the pump gap, the fluid kinematic viscosity, the fluid density, the plunger length and the plunger average speed; determining a pump fullness correction parameter according to the clearance ratio and the gas-liquid ratio in the pump;
correcting a relation curve of the pump displacement and the pump pressure difference according to the oil pipe elastic expansion correction parameter, the pump loss correction parameter and the pump fullness correction parameter;
and determining the coordinated yield of the downhole system of the sucker-rod pump by using the corrected relation curve of the pump displacement and the pump pressure difference.
An embodiment of the present invention further provides a computer-readable storage medium, on which a computer program is stored, where the computer program, when executed by a processor, implements the following steps:
determining a relation curve of pump displacement and pump pressure difference according to pumping parameters and equipment parameters, wherein the pumping parameters and the equipment parameters comprise the total length of a sucker rod string, pump pressure difference, the cross section area of a tubing wall, pump diameter, plunger eccentricity, pump clearance, fluid kinematic viscosity, fluid density, plunger length, plunger average speed, clearance ratio and gas-liquid ratio in the pump;
determining an oil pipe elastic expansion correction parameter according to the total length of the sucker rod string, the pump pressure difference and the cross-sectional area of the oil pipe wall; determining a pump leakage correction parameter according to the pump diameter, the plunger eccentricity, the pump gap, the fluid kinematic viscosity, the fluid density, the plunger length and the plunger average speed; determining a pump fullness correction parameter according to the clearance ratio and the gas-liquid ratio in the pump;
correcting a relation curve of the pump displacement and the pump pressure difference according to the oil pipe elastic expansion correction parameter, the pump loss correction parameter and the pump fullness correction parameter;
and determining the coordinated yield of the downhole system of the sucker rod pump by using the corrected relation curve of the pump displacement and the pump pressure difference.
The characteristic curve of the sucker-rod pump established and corrected by the method is beneficial to better performing node analysis and optimal design on the underground system of the sucker-rod pump, the corrected characteristic curve considers the influence of various factors on the effect, is more in line with the field reality, and provides more valuable reference for performing node analysis and optimal design on the sucker-rod pump well on the field.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without inventive labor.
FIG. 1 is a flow chart of a method for determining a dimensionless characteristic curve for a sucker-rod pump downhole system in accordance with an embodiment of the present invention;
FIG. 2 shows an API method in an embodiment of the present invention
A graph;
FIG. 3 is a non-dimensional characteristic graph of effective stroke versus pump pressure differential for an embodiment of the present invention;
FIG. 4 shows an API method in an embodiment of the present invention
A graph;
FIG. 5 is a graph of a dimensionless characteristic of polished rod power versus pump pressure differential for an embodiment of the present invention;
FIG. 6 is a graph illustrating characteristics of a sucker-rod pump given equipment parameters and pumping parameters according to an embodiment of the present invention;
FIG. 7 is a graph illustrating a modification of the characteristic curve of a sucker-rod pump in accordance with an embodiment of the present invention;
FIG. 8 is a graph illustrating a relationship between pump displacement and pump pressure difference for different pumping parameter combinations according to an embodiment of the present invention;
FIG. 9 is a graph of the inflow and outflow curves with the pump inlet as a node in an embodiment of the present invention;
fig. 10 is a schematic structural diagram of a dimensionless characteristic curve determining apparatus for a sucker-rod pump downhole system according to an embodiment of the present invention.
Detailed Description
The embodiment of the invention provides a method and a device for determining a dimensionless characteristic curve of a sucker-rod pump downhole system.
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without inventive step based on the embodiments of the present invention, are within the scope of protection of the present invention.
The API RP 11L method is a design calculation method of a sucker-rod oil pumping system, is provided on the basis of summarizing electric simulation research results, and comprises a series of charts expressed by dimensionless quantities and simple calculation relational expressions. The method is modified for 5 times and a wave equation analysis method is introduced, and the method can be used for designing and predicting the sucker rod oil pumping system.
Fig. 1 is a flow chart illustrating a method for determining a dimensionless characteristic of a sucker-rod pump downhole system according to an embodiment of the present invention, wherein the method includes: s1, determining a relation curve of pump displacement and pump pressure difference according to pumping parameters and equipment parameters, wherein the pumping parameters and the equipment parameters comprise the total length of a sucker rod string, pump pressure difference, the cross section area of a tubing wall, pump diameter, plunger eccentricity, pump clearance, fluid kinematic viscosity, fluid density, plunger length, average plunger speed, clearance ratio and gas-liquid ratio in a pump;
s2, determining an elastic expansion correction parameter of the oil pipe according to the total length of the sucker rod string, the pump pressure difference and the cross section area of the oil pipe wall; determining a pump leakage correction parameter according to the pump diameter, the plunger eccentricity, the pump gap, the fluid kinematic viscosity, the fluid density, the plunger length and the plunger average speed; determining a pump fullness correction parameter according to the clearance ratio and the gas-liquid ratio in the pump;
s3, correcting a relation curve of the pump displacement and the pump pressure difference according to the oil pipe elastic expansion correction parameter, the pump leakage correction parameter and the pump fullness correction parameter;
and S4, determining the coordinated yield of the underground system of the sucker-rod pump by using the corrected relation curve of the pump displacement and the pump pressure difference.
The pumping parameters and equipment parameters also include stroke, stroke frequency, pump cross-sectional area, and sucker rod string natural frequency, as one embodiment of the present invention.
In this embodiment, the determining the pump displacement versus pump pressure difference curve according to the pumping parameter and the equipment parameter includes: according to the pump differential pressure, the stroke frequency, the pump cross-sectional area and the inherent frequency of the sucker rod string, dimensionless stroke frequency, dimensionless sucker rod elongation, dimensionless piston stroke and dimensionless load are determined; determining a dimensionless characteristic curve of the relation between the effective stroke and the pump pressure difference and a dimensionless characteristic curve of the relation between the polished rod power and the pump pressure difference according to the dimensionless stroke, the dimensionless sucker rod elongation, the dimensionless piston stroke and the dimensionless load; and determining a relation curve of the pump displacement and the pump pressure difference by utilizing the dimensionless characteristic curve of the relation between the effective stroke and the pump pressure difference and the dimensionless characteristic curve of the relation between the polished rod power and the pump pressure difference.
As an embodiment of the present invention, the determining the coordinated production of the sucker-rod pumping downhole system using the corrected pump displacement versus pump pressure difference curve comprises: carrying out node analysis on the underground system of the sucker-rod pump by using the corrected relation curve of the pump displacement and the pump pressure difference to obtain an inflow and outflow curve of a node; determining a coordinated production of the sucker-rod pump downhole system based on the inflow and outflow curves.
In one embodiment of the present invention, the API method includes two dimensionless arguments: 1) Dimensionless number of strokes
Number of strokes n and sucker rod string natural frequency n 0 ' to a ratio; 2) Dimensionless elongation of sucker rod
Elongation of sucker rod column
The ratio of the rod stroke S. Note that F in this variable 0 It represents the liquid column load acting on the whole piston cross section after considering the sinking pressure, i.e. the difference between the upper and lower loads acting on the piston in the up stroke is equal to the difference between the upper and lower pressure differences delta P and the cross section f of the pump p The product of the two. This variable can be called dimensionless pump differential, i.e.:
wherein S is the stroke of the polish rod, K r Representing the spring constant of the entire rod string.
In an API approachTwo dimensionless dependent variables are: 1)
Dimensionless piston stroke for calculating piston stroke, where S p Representing the plunger stroke of the oil well pump; 2)
Dimensionless loading for calculating the power of the polish rod, where F 3 Representing the polished rod power load coefficient.
FIG. 2 shows the API
A curve in which the abscissa is a dimensionless stroke, the ordinate is a dimensionless plunger stroke, the series of terms is a dimensionless pump pressure difference, in order to highlight the relationship between the dimensionless plunger stroke and the dimensionless pump pressure difference, the family of curves is transformed into a dimensionless pump pressure difference, the ordinate is still a dimensionless plunger stroke, and the dimensionless stroke is a series of terms, as shown in fig. 3, a dimensionless characteristic curve reflecting the relationship between the effective stroke and the pump pressure difference:
it can be seen that there is no tendency for the dimensional plunger stroke to decrease with increasing dimensionless pump differential pressure, i.e. the pump displacement decreases with increasing pump differential pressure, which is consistent with the tendency of the characteristic curves of submersible and progressive cavity pumps.
FIG. 4 shows the API
The curve, where the abscissa is the dimensionless number of strokes, the ordinate is the dimensionless load used to calculate the polished rod power, and the series of terms is the dimensionless pump differential pressure. Similarly, in order to highlight the relationship between the polished rod power and the pump pressure difference, the curve family is transformed into the dimensionless pump pressure difference in abscissa, the ordinate is unchanged, and the dimensionless stroke is used as a series of terms, as shown in fig. 5, a dimensionless characteristic curve which can reflect the relationship between the polished rod power and the pump pressure difference is shown:
the two sets of curves shown in fig. 3 and 5, which are composed of dimensionless variables, reflect the relationship between the effective stroke, the polished rod power and the pump differential pressure, and further calculate the relationship between the downhole efficiency and the pump differential pressure, so that the two sets of curves can be used as dimensionless characteristic curves of the sucker rod oil pump.
In a specific embodiment of the present invention, after the pumping parameters and equipment parameters such as stroke, stroke frequency, pump diameter, sucker rod string, etc. are known, the relationship between the plunger stroke, polished rod power and pump differential pressure can be obtained by using the dimensionless characteristic curve of the sucker rod pump, and the relationship between the pump displacement, polished rod power, downhole efficiency and pump differential pressure can be further obtained by calculation, so as to obtain the characteristic curve of the sucker rod pump under the current parameters. The characteristics of the sucker-rod pump are plotted below by way of example, with the basic calculation parameters as follows: vertical well bore, pump down depth 903.8m, rod column combination (19mm 903.8m), oil pipe inner diameter 0.062m, oil pipe outer diameter 0.073m, oil pipe anchoring, pump gap 0.1mm, pump diameter 44mm, stroke 1.8m, stroke 8min -1 。
Fig. 6 is a characteristic curve of the sucker-rod pump when a set of equipment parameters and pumping parameters are given, wherein a pump differential pressure-displacement curve and a pump differential pressure-polished rod power curve can be directly obtained by using the dimensionless characteristic curve of the sucker-rod pump shown in fig. 3 and 5 and a calculation formula in an API method, and a pump differential pressure-downhole efficiency curve can be obtained by using the pump differential pressure-displacement curve and the pump differential pressure-polished rod power curve. The calculation formula is as follows:
the effective power of the pump can be calculated from the pump displacement and the pump pressure difference: n is a radical of e = Q Δ P, calculation formula for downhole efficiency as follows:
in the formula, N p Is the power of a polish rod, KW.
As can be seen from the displacement-pump pressure difference curve in fig. 6, as the pump pressure difference increases, the stroke loss caused by the elastic expansion and contraction of the sucker rod increases, and the actual displacement of the pump decreases, which is consistent with the trend of the characteristic curves of the submersible pump and the screw pump. It can be seen from the polished rod power-pump pressure difference curve that as the pump pressure difference increases, the polished rod power increases, but the increase amplitude decreases, and under some conditions, the polished rod power also decreases as the pump pressure difference increases. As can be seen from the downhole efficiency-pump pressure difference curve, in addition to the low pump pressure difference zone, the efficiency is higher, even higher than 90%, which is not in accordance with the actual situation, and the reasons for this are related to the high mechanical efficiency of the sucker rod pump on the one hand and the assumed conditions of the API method on the other hand: 1) leak-off of pump not considered, 2) assuming tubing anchored, 3) pump completely full (gas influence not considered).
It can be seen from the assumed conditions of the API that the characteristic curve of the sucker rod pump obtained by the API method mainly reflects the influence of the sucker rod on the characteristics of the entire downhole system, and does not consider the influences of the leakage of the tubing and the plunger pump and the filling degree of the pump. For example, the line (1) in fig. 7 represents the theoretical displacement line, and the line (2) is the Q- Δ P characteristic curve considering only the effect of the elastic expansion of the sucker rod. These assumption conditions bring certain errors, and the characteristic curve of the API sucker-rod pump needs to be corrected according to actual conditions in application.
1) Effects of tubing anchoring
If the tubing is not anchored, the elastic expansion of the tubing will reduce the effective stroke of the sucker rod pump, and for convenient calculation, the stroke loss e caused by the tubing not anchored t Can be calculated using the following formula:
in the formula: e.g. of the type t Respectively the stroke loss, m, caused by the elastic expansion of the oil pipe; l is the total length of the sucker rod string, m; delta P is pump outlet pressure difference Pa; e is the elastic modulus of the steel, pa; f. of i Is the cross-sectional area of tubing wall, m 2 (ii) a As shown by the line (3) in fig. 7, the characteristic curve Q to Δ P is obtained by further considering the elastic expansion and contraction of the oil pipe.
2) Correction of pump loss
In practice, when the sucker rod pump works in the well, especially when the pressure difference between the upper part and the lower part of the pump is large, some leakage can occur between the plunger and the lining of the pump, and the leakage quantity of the pump can be calculated by the following formulaCalculating:
in the formula: q. q.s loss Is the leakage between plunger bushes, m 3 S; d is the pump diameter m; epsilon is the eccentricity of the plunger; h is the pump clearance, m; v kinematic viscosity of fluid, m 2 S; density of rho fluid, kg/m 3 (ii) a l length of plunger, m; u is the average speed of the plunger, m/s. From the above formula, it can be seen that the leakage of the pump is proportional to the pump pressure difference, and the larger the pump pressure difference is, the larger the leakage is. As shown by the line (4) in FIG. 7, the Q.DELTA.P characteristic curve when the pump leakage is further considered.
3) Correction of gas effects
When the pressure at the suction port of the pump is lower than the bubble point pressure, gas can enter the pump and the pump cannot be filled. When only the characteristics of a downhole equipment system consisting of a sucker rod, tubing, pump are studied, it can be assumed that the pump is full. When the characteristic curve is applied to carry out node analysis and optimal design, an electric submersible pump well method can be adopted, and the influence of gas on the characteristic curve of the sucker-rod pump needs to be corrected. The method of correction may be by calculating the degree of pump fullness η c Is realized by the method of (1) the pump filling degree eta c Can be expressed as:
in the formula: k is a clearance ratio; r is the gas-liquid ratio in the pump. As shown by the line (5) in fig. 7, this is a Q- Δ P characteristic curve in consideration of the pump full level.
FIG. 8 shows the Q- Δ P curves for different stroke-stroke pump diameter combinations. In fig. 8 3 × 4 × 44 represents the pumping parameter combination: the stroke is 3m, the stroke time is 4min-1, and the pump diameter is 44mm.
In a specific embodiment of the invention, the application of the characteristic curve is described by taking the analysis of a certain well node in the north China oil field as an example. The solution nodes can be placed at the well bottom, the pump suction inlet, the pump discharge outlet and the like. During node analysis, a Vogel method is selected to describe the seepage rule of the fluid in an oil layer, a Beggs-Brill correlation formula is used to describe the flow rule of the multiphase fluid in a well bore, and the characteristic curve is used to describe the working characteristic of the sucker rod pump downhole equipment system.
If the pump inlet is taken as a node, the calculation steps are as follows: firstly, a series of production Q is given, and then inflow pressure and outflow pressure corresponding to pump inlet nodes at different production are respectively calculated from two ends of the system, wherein the calculation formula of the inflow pressure is as follows:
P inflow ＝P wf (Q)－ΔP dnow (Q)
in the formula: p is inflow Representative of the inflow pressure, P wf (Q) represents the bottom hole flow pressure at different production rates,. DELTA.P dnow And (Q) represents the pressure drop in the borehole under the pump, and is calculated by a well pipe multiphase pipe flow pressure drop model.
The outflow pressure is calculated as follows:
P outflow ＝P wh +ΔP up (Q)－ΔP pump (Q)
in the formula: p outflow Representing the discharge pressure, P wh Representative of wellhead pressure, Δ P up (Q) represents the pressure drop in the tubing from wellhead to pump outlet. Delta P pump (Q) represents the pressure difference supplied by the pump, calculated from the characteristic curve.
Fig. 9 shows inflow and outflow curves of the pump inlet node under several sets of pumping parameters, and the coordinated yield under the current production condition can be obtained by using the intersection points of the inflow and outflow curves.
In summary, the characteristic curve of the sucker-rod pump in the invention is convenient for node analysis and optimal design of the sucker-rod pumping system. Has important practical significance for practical production.
The characteristic curve of the sucker-rod pump is established and corrected by the method for determining the dimensionless characteristic curve of the underground system of the sucker-rod pump, so that node analysis and optimal design of the underground system of the sucker-rod pump can be better performed, the influence of various factors on the effect is considered by the corrected characteristic curve, the method is more in line with the field reality, and more valuable reference is provided for node analysis and optimal design of the sucker-rod pump well on the field.
Fig. 10 is a schematic structural diagram of a device for determining a dimensionless characteristic curve of a sucker-rod pump downhole system according to an embodiment of the present invention, where the device includes: the curve determination module 10 is configured to determine a relation curve between pump displacement and pump pressure difference according to pumping parameters and equipment parameters, where the pumping parameters and the equipment parameters include a total length of a sucker rod string, a pump pressure difference, a cross-sectional area of a tubing wall, a pump diameter, an eccentricity of a plunger, a pump gap, a fluid kinematic viscosity, a fluid density, a length of the plunger, an average speed of the plunger, a clearance ratio, and a gas-liquid ratio in the pump;
the parameter determining module 20 is used for determining the elastic expansion correction parameter of the oil pipe according to the total length of the sucker rod string, the pump pressure difference and the cross-sectional area of the oil pipe wall; determining a pump leakage correction parameter according to the pump diameter, the plunger eccentricity, the pump gap, the fluid kinematic viscosity, the fluid density, the plunger length and the plunger average speed; determining a pump fullness correction parameter according to the clearance ratio and the gas-liquid ratio in the pump;
the curve correction module 30 is configured to correct a relation curve between the pump displacement and the pump pressure difference according to the oil pipe elastic expansion correction parameter, the pump loss correction parameter, and the pump fullness correction parameter;
and the coordinated production module 40 is used for determining the coordinated production of the sucker rod pump downhole system by using the corrected relation curve of the pump displacement and the pump pressure difference.
The pumping parameters and equipment parameters also include stroke, stroke frequency, pump cross-sectional area, and sucker rod string natural frequency, as one embodiment of the present invention.
In this embodiment, the curve determining module includes: the dimensionless parameter unit is used for determining dimensionless stroke frequency, dimensionless sucker rod elongation, dimensionless piston stroke and dimensionless load according to the pump differential pressure, stroke frequency, pump cross-sectional area and sucker rod string inherent frequency; the dimensionless characteristic curve unit is used for determining a dimensionless characteristic curve of the relation between the effective stroke and the pump pressure difference and a dimensionless characteristic curve of the relation between the polished rod power and the pump pressure difference according to the dimensionless stroke number, the dimensionless sucker rod elongation, the dimensionless piston stroke and the dimensionless load; and the curve determining unit is used for determining a relation curve of the pump displacement and the pump pressure difference by utilizing the dimensionless characteristic curve of the relation between the effective stroke and the pump pressure difference and the dimensionless characteristic curve of the relation between the polished rod power and the pump pressure difference.
As an embodiment of the invention, the coordinated yield module comprises: the inflow and outflow curve unit is used for carrying out node analysis on the underground system of the sucker-rod pump by using the corrected relation curve of the pump displacement and the pump pressure difference to obtain an inflow and outflow curve of a node; and the coordinated production unit is used for determining the coordinated production of the sucker rod pump downhole system according to the inflow and outflow curves.
Based on the same application concept as the method for determining the dimensionless characteristic curve of the downhole system of the sucker rod pump, the invention also provides a device for determining the dimensionless characteristic curve of the downhole system of the sucker rod pump. The principle of solving the problems of the device for determining the dimensionless characteristic curve of the downhole system of the sucker rod pump is similar to the method for determining the dimensionless characteristic curve of the downhole system of the sucker rod pump, so the implementation of the device for determining the dimensionless characteristic curve of the downhole system of the sucker rod pump can refer to the implementation of the method for determining the dimensionless characteristic curve of the downhole system of the sucker rod pump, and repeated parts are not repeated.
The characteristic curve of the sucker-rod pump established and corrected by the device for determining the dimensionless characteristic curve of the underground system of the sucker-rod pump is beneficial to better performing node analysis and optimal design on the underground system of the sucker-rod pump, the corrected characteristic curve considers the influence of various factors on the effect, better accords with the field reality, and provides more valuable reference for performing node analysis and optimal design on the sucker-rod pump well on the field.
An embodiment of the present invention further provides a computer device, which includes a memory, a processor, and a computer program stored in the memory and capable of running on the processor, where the processor implements the following steps when executing the computer program:
determining a relation curve of pump displacement and pump pressure difference according to pumping parameters and equipment parameters, wherein the pumping parameters and the equipment parameters comprise the total length of a sucker rod string, pump pressure difference, the cross section area of a tubing wall, pump diameter, plunger eccentricity, pump clearance, fluid kinematic viscosity, fluid density, plunger length, plunger average speed, clearance ratio and gas-liquid ratio in the pump;
determining an oil pipe elastic expansion correction parameter according to the total length of the sucker rod string, the pump pressure difference and the cross-sectional area of the oil pipe wall; determining a pump leakage correction parameter according to the pump diameter, the plunger eccentricity, the pump gap, the fluid kinematic viscosity, the fluid density, the plunger length and the plunger average speed; determining a pump fullness correction parameter according to the clearance ratio and the gas-liquid ratio in the pump;
correcting a relation curve of the pump displacement and the pump pressure difference according to the oil pipe elastic expansion correction parameter, the pump leakage correction parameter and the pump fullness correction parameter;
and determining the coordinated yield of the downhole system of the sucker rod pump by using the corrected relation curve of the pump displacement and the pump pressure difference.
An embodiment of the present invention further provides a computer-readable storage medium, on which a computer program is stored, where the computer program, when executed by a processor, implements the following steps:
determining a relation curve of pump displacement and pump pressure difference according to pumping parameters and equipment parameters, wherein the pumping parameters and the equipment parameters comprise the total length of a sucker rod string, pump pressure difference, the cross section area of a tubing wall, pump diameter, plunger eccentricity, pump clearance, fluid kinematic viscosity, fluid density, plunger length, plunger average speed, clearance ratio and gas-liquid ratio in the pump;
determining an elastic expansion correction parameter of the oil pipe according to the total length of the sucker rod string, the pumping pressure difference and the cross-sectional area of the oil pipe wall; determining a pump leakage correction parameter according to the pump diameter, the plunger eccentricity, the pump gap, the fluid kinematic viscosity, the fluid density, the plunger length and the plunger average speed; determining a pump fullness correction parameter according to the clearance ratio and the gas-liquid ratio in the pump;
correcting a relation curve of the pump displacement and the pump pressure difference according to the oil pipe elastic expansion correction parameter, the pump loss correction parameter and the pump fullness correction parameter;
and determining the coordinated yield of the downhole system of the sucker rod pump by using the corrected relation curve of the pump displacement and the pump pressure difference.
The invention also provides the computer equipment and a computer readable storage medium based on the same application concept as the determination method of the dimensionless characteristic curve of the sucker rod pump downhole system. Since the principle of solving the problem by the computer device and the computer-readable storage medium is similar to the method for determining the dimensionless characteristic curve of the sucker rod pump downhole system, the implementation of the computer device and the computer-readable storage medium can be referred to the implementation of the method for determining the dimensionless characteristic curve of the sucker rod pump downhole system, and repeated parts are not repeated.
The characteristic curve of the sucker-rod pump established and corrected by the computer equipment and the computer readable storage medium is beneficial to better performing node analysis and optimal design on the underground system of the sucker-rod pump, the corrected characteristic curve considers the influence of various factors on the effect, better accords with the field reality, and provides more valuable reference for performing node analysis and optimal design on the sucker-rod pump well on the field.
Those skilled in the art will appreciate that all or part of the steps in the method according to the above embodiments may be implemented by a program instructing relevant hardware, and the program may be stored in a computer-readable storage medium, such as a ROM/RAM, a magnetic disk, an optical disk, and the like.
The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are only exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (10)
1. A method of determining a dimensionless characteristic of a sucker-rod pump downhole system, the method comprising:
determining a relation curve of pump displacement and pump pressure difference according to pumping parameters and equipment parameters, wherein the pumping parameters and the equipment parameters comprise the total length of a sucker rod string, pump pressure difference, the cross section area of a tubing wall, pump diameter, plunger eccentricity, pump clearance, fluid kinematic viscosity, fluid density, plunger length, plunger average speed, clearance ratio and gas-liquid ratio in the pump;
determining an oil pipe elastic expansion correction parameter according to the total length of the sucker rod string, the pump pressure difference and the cross-sectional area of the oil pipe wall; determining a pump leakage correction parameter according to the pump diameter, the plunger eccentricity, the pump gap, the fluid kinematic viscosity, the fluid density, the plunger length and the plunger average speed; determining a pump fullness correction parameter according to the clearance ratio and the gas-liquid ratio in the pump;
correcting a relation curve of the pump displacement and the pump pressure difference according to the oil pipe elastic expansion correction parameter, the pump loss correction parameter and the pump fullness correction parameter;
and determining the coordinated yield of the downhole system of the sucker-rod pump by using the corrected relation curve of the pump displacement and the pump pressure difference.
2. The method of claim 1, wherein the pumping parameters and equipment parameters further include stroke, stroke frequency, pump cross-sectional area, and sucker rod string natural frequency.
3. The method of claim 2, wherein determining a pump displacement versus pump pressure differential curve based on pumping parameters and equipment parameters comprises:
according to the pump differential pressure, the stroke frequency, the pump cross-sectional area and the inherent frequency of the sucker rod string, dimensionless stroke frequency, dimensionless sucker rod elongation, dimensionless piston stroke and dimensionless load are determined;
determining a dimensionless characteristic curve of the relation between the effective stroke and the pump pressure difference and a dimensionless characteristic curve of the relation between the polished rod power and the pump pressure difference according to the dimensionless stroke number, the dimensionless sucker rod elongation, the dimensionless piston stroke and the dimensionless load;
and determining a relation curve of the pump displacement and the pump pressure difference by utilizing the dimensionless characteristic curve of the relation between the effective stroke and the pump pressure difference and the dimensionless characteristic curve of the relation between the polished rod power and the pump pressure difference.
4. The method of claim 1, wherein determining a coordinated production of a sucker-rod pump downhole system using the corrected pump displacement versus pump pressure differential curve comprises:
carrying out node analysis on the underground system of the sucker-rod pump by using the corrected relation curve of the pump displacement and the pump pressure difference to obtain an inflow and outflow curve of a node;
determining a coordinated production of the sucker-rod pump downhole system according to the inflow and outflow curves.
5. An apparatus for determining a dimensionless characteristic of a sucker rod pump downhole system, the apparatus comprising:
the system comprises a curve determining module, a pumping parameter determining module and a pumping parameter determining module, wherein the curve determining module is used for determining a relation curve of pump displacement and pump pressure difference according to the pumping parameter and equipment parameter, and the pumping parameter and the equipment parameter comprise the total length of a sucker rod string, pump pressure difference, the cross section area of a tubing wall, pump diameter, plunger eccentricity, pump clearance, fluid kinematic viscosity, fluid density, plunger length, plunger average speed, clearance ratio and gas-liquid ratio in the pump;
the parameter determining module is used for determining the elastic expansion correction parameter of the oil pipe according to the total length of the sucker rod string, the pump pressure difference and the cross section area of the oil pipe wall; determining pump leakage correction parameters according to the pump diameter, the plunger eccentricity, the pump clearance, the fluid kinematic viscosity, the fluid density, the plunger length and the plunger average speed; determining a pump fullness correction parameter according to the clearance ratio and the gas-liquid ratio in the pump;
the curve correction module is used for correcting a relation curve of the pump displacement and the pump pressure difference according to the oil pipe elastic expansion correction parameter, the pump leakage correction parameter and the pump fullness correction parameter;
and the coordinated yield module is used for determining the coordinated yield of the downhole system of the sucker rod pump by utilizing the corrected relation curve of the pump displacement and the pump pressure difference.
6. The apparatus of claim 5, wherein the pumping and equipment parameters further include stroke, stroke frequency, pump cross-sectional area, and sucker-rod string natural frequency.
7. The apparatus of claim 6, wherein the curve determining module comprises:
the dimensionless parameter unit is used for determining dimensionless stroke, dimensionless sucker rod elongation, dimensionless piston stroke and dimensionless load according to the pump differential pressure, stroke, pump cross-sectional area and sucker rod string inherent frequency;
the dimensionless characteristic curve unit is used for determining a dimensionless characteristic curve of the relation between the effective stroke and the pump pressure difference and a dimensionless characteristic curve of the relation between the polished rod power and the pump pressure difference according to the dimensionless stroke, the dimensionless sucker rod elongation, the dimensionless piston stroke and the dimensionless load;
and the curve determining unit is used for determining a relation curve of the pump displacement and the pump pressure difference by utilizing the dimensionless characteristic curve of the relation between the effective stroke and the pump pressure difference and the dimensionless characteristic curve of the relation between the polished rod power and the pump pressure difference.
8. The apparatus of claim 5, wherein the coordinated yield module comprises:
the inflow and outflow curve unit is used for carrying out node analysis on the underground system of the sucker rod pump by utilizing the corrected relation curve of the pump displacement and the pump pressure difference to obtain an inflow and outflow curve of a node;
and the coordinated production unit is used for determining the coordinated production of the sucker-rod pump downhole system according to the inflow and outflow curves.
9. A computer device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor when executing the computer program implements the steps of:
determining a relation curve of pump displacement and pump pressure difference according to pumping parameters and equipment parameters, wherein the pumping parameters and the equipment parameters comprise the total length of a sucker rod string, pump pressure difference, the cross-sectional area of a tubing wall, pump diameter, plunger eccentricity, pump clearance, fluid kinematic viscosity, fluid density, plunger length, plunger average speed, clearance ratio and gas-liquid ratio in a pump;
determining an elastic expansion correction parameter of the oil pipe according to the total length of the sucker rod string, the pumping pressure difference and the cross-sectional area of the oil pipe wall; determining pump leakage correction parameters according to the pump diameter, the plunger eccentricity, the pump clearance, the fluid kinematic viscosity, the fluid density, the plunger length and the plunger average speed; determining a pump fullness correction parameter according to the clearance ratio and the gas-liquid ratio in the pump;
correcting a relation curve of the pump displacement and the pump pressure difference according to the oil pipe elastic expansion correction parameter, the pump leakage correction parameter and the pump fullness correction parameter;
and determining the coordinated yield of the downhole system of the sucker rod pump by using the corrected relation curve of the pump displacement and the pump pressure difference.
10. A computer-readable storage medium, on which a computer program is stored, which computer program, when being executed by a processor, carries out the steps of:
determining a relation curve of pump displacement and pump pressure difference according to pumping parameters and equipment parameters, wherein the pumping parameters and the equipment parameters comprise the total length of a sucker rod string, pump pressure difference, the cross section area of a tubing wall, pump diameter, plunger eccentricity, pump clearance, fluid kinematic viscosity, fluid density, plunger length, plunger average speed, clearance ratio and gas-liquid ratio in the pump;
determining an oil pipe elastic expansion correction parameter according to the total length of the sucker rod string, the pump pressure difference and the cross-sectional area of the oil pipe wall; determining a pump leakage correction parameter according to the pump diameter, the plunger eccentricity, the pump gap, the fluid kinematic viscosity, the fluid density, the plunger length and the plunger average speed; determining a pump fullness correction parameter according to the clearance ratio and the gas-liquid ratio in the pump;
correcting a relation curve of the pump displacement and the pump pressure difference according to the oil pipe elastic expansion correction parameter, the pump leakage correction parameter and the pump fullness correction parameter;
and determining the coordinated yield of the downhole system of the sucker-rod pump by using the corrected relation curve of the pump displacement and the pump pressure difference.
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| CN100513738C (en) * | 2005-07-19 | 2009-07-15 | 中国石油天然气股份有限公司 | Method for determining system parameters of rod-pumped well |
| CN103498663B (en) * | 2013-09-26 | 2016-02-10 | 中国石油天然气股份有限公司 | Method and device for determining pumping process parameters of sucker-rod pump lifting system |
| CN104153982B (en) * | 2014-07-18 | 2016-08-17 | 中国石油天然气股份有限公司 | Method and device for acquiring characteristic curve of underground system of rod-pumped well |
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