CN106437682A - Method for predicting oil well indicator diagram - Google Patents

Abstract

The invention discloses a method for predicting an oil well indicator diagram and belongs to the field of oil and gas production. By calculating first pump efficiency and performing decomposition computation on the first pump efficiency, a pump indicator diagram is calculated; the pump indicator diagram serves as boundary conditions, a first preset formula giving consideration to rod pipe eccentric wear and well deviation is applied to calculate displacement and load of each point on a sucker rod upwards from a shaft bottom pump end, a ground indicator diagram is obtained, second pump efficiency is obtained according to the ground indicator diagram, a pump efficiency error is obtained according to the first pump efficiency and the second pump efficiency, and whether the pump efficiency error is smaller than preset value is determined; if the pump efficiency error is smaller than the preset value, calculation is stopped, or else the second pump efficiency replaces the first pump efficiency, and the process after decomposition calculation of the first pump efficiency is obtained repeatedly, until the pump efficiency error is smaller than the preset value; the ground indicator diagram obtained when the pump efficiency error is smaller than the preset value serves as the reference basis for oil well initial production parameter design, and designed production parameters are high in reliability.

Description

A kind of method of prediction oil well indicator card

Technical field

The present invention relates to production of hydrocarbons field, more particularly to a kind of method of prediction oil well indicator card.

Background technology

Oil well indicator card is figure of the polished rod load with the rule of its change in displacement for reacting oil pumper in a pumping cycle, It is the Main Basiss of the working condition for judging oil pumping system down-hole.

The method for obtaining oil well indicator card at present is in oil well production process, is pumped by indicator automatic data collection airborne Lotus and stroke, so as to draw oil well indicator card, oil well indicator card is used as the important reference of oil well production Parameters Optimal Design.

But before bringing in, it is impossible to obtain oil well indicator card by indicator, cause oil well initial production parameter to set Cannot be with oil well indicator card as reference frame during meter, the reliability of the manufacturing parameter that designs is often relatively low.

Content of the invention

In order to solve in prior art before bringing in, it is impossible to obtain oil well indicator card by indicator, cause oil Cannot be with oil well indicator card as reference frame during well initial production parameter designing, the reliability of the manufacturing parameter that designs Often relatively low problem, embodiments provides a kind of method of prediction oil well indicator card.The technical scheme is as follows：

A kind of method of prediction oil well indicator card, methods described includes：

Step 1：According to given pump footpath, stroke, jig frequency, the diameter of per grade of roofbolt of sucker rod and length, tubing diameter, oil The viscosity of relation curve, the density of crude oil, the viscosity of crude oil, the density of natural gas and natural gas that in well, yield is pressed with stream, obtains Take the first pump efficiency E_pi；

Step 2：To the first pump efficiency E_piDecomposition computation is carried out, obtains pump dynamometers；

Step 3：With the pump dynamometers as boundary condition, application considers the first preset formula of rod and tube partial-wear and hole deviation The displacement of each point and load on sucker rod are calculated upwards from shaft bottom pump end, obtain surface dynamometer card；

Step 4：According to the surface dynamometer card, the maximum load being subject on sucker rod and minimum load, plunger is obtained Effective stroke and the second pump efficiency E_pp；

Step 5：According to the first pump efficiency E_piWith the second pump efficiency E_pp, calculate pump efficiency error；

Step 6：Whether the pump efficiency error being judged less than default value, is then to stop calculating, otherwise with second pump Effect E_ppSubstitute the first pump efficiency E_pi, and repeat step 2 is to step 6.

Further, the step 2, carries out decomposition computation to first pump efficiency, obtains pump dynamometers, including：

Maximum load P being subject on sucker rod is calculated according to equation below (1)_pmax：

P_pmax=-W_b+A_pLρ_lg (1)

In formula (1), W_bFor balance weight, A_pFor the cross-sectional area of plunger, L is the length of sucker rod, ρ_lFor the flat of liquid Equal density, g is acceleration of gravity；

The minimum load P being subject on sucker rod is calculated according to equation below (2)_pmin：

P_pmin=-W_b(2)；

The theoretical stroke S of plunger is calculated according to equation below (3)_P：

S_P=S × η_Become(3)

In formula (3), S is the design stroke of plunger, η_BecomeFor deformation pump efficiency；

The effective stroke S of plunger is calculated according to equation below (4)_PE：

In formula (4), K_qFor volume factor；

According to maximum load P being subject on sucker rod_pmax, minimum load P_pmin, plunger theoretical stroke S_PAnd effective stroke S_PE, obtain pump dynamometers.

Further, the step 3, with the pump dynamometers as boundary condition, application considers rod and tube partial-wear and hole deviation The first preset formula calculate the displacement of each point and load on sucker rod upwards from shaft bottom pump end, obtain surface dynamometer card, including：

According to the hole angle θ of shaft bottom pump end each point upwards, the shaft bottom pump end axle that each point is produced upwards is calculated because of rod and tube partial-wear To power N；

According to shaft bottom pump end the hole angle θ of each point, shaft bottom pump end axial force N that each point is produced because of rod and tube partial-wear upwards upwards Surface dynamometer card is calculated with equation below (5)：

In formula (5), u is the load of each point on roofbolt, and t is the displacement that time, s is each point on roofbolt, and δ is rubbed for rigid body Wipe the sign of power, during upstroke, δ=+ 1, during down stroke, δ=- 1, a, c, h and g ' be intermediate variable, by equation below (6) calculated to formula (9)：

In formula (6) to formula (9), E_rFor material of sucker rod elastic modelling quantity, ρ_rFor material of sucker rod density, ρ_r= 7860kg/m³, υ_eFor the viscous drag coefficient of unit length rod string, A_rFor sucker rod cross-sectional area, f is sucker rod and oil Coefficient of friction between pipe, f is between 0.05～0.1.

Further, the hole angle θ according to shaft bottom pump end each point upwards, calculate shaft bottom pump end upwards each point because of rod tube Axial force N that eccentric wear is produced, including：

When θ ≠ 0, shaft bottom pump end axial force N that each point is produced because of rod and tube partial-wear upwards is calculated by equation below (10)：

In formula (10), q_r' it is buoyant weight of the roofbolt in well liquid,For the azimuth of well, P is that intermediate variable, P leads to Cross equation below (11) to be calculated：

When θ=0, judge whether the roofbolt positioned at the position bottom of θ=0 on sucker rod occurs unstability eccentric wear, if sentenced The roofbolt of position bottom of θ=0 on the sucker rod that breaks can occur unstability eccentric wear, then the attached hole deviation in position again for θ=0 Angle, and substitute into formula (10) carry out calculate relevant position axial force N, if it is determined that on sucker rod the position bottom of θ=0 bar Post will not occur unstability eccentric wear, then take the N=0 in formula (10).

Further, whether the roofbolt of the position bottom for judging θ=0 on the sucker rod there is unstability eccentric wear, bag Include：

According to the minimum load of pump dynamometers, sucker rod is calculated in minimum load P by equation below (12)_pminUnder effect Neutral point to pump end apart from L_cr：

In formula (12), I is the moment of inertia of sucker rod cross section；

Length L that pumping rod made by steel occurs unstability is calculated according to equation below (13)_b：

In formula (13), F_bFor the axial compressive force that sucker rod is subject at pump end, F is taken_b=P_pmin, q is roofbolt unit length Weight；

Neutral point under the comparison rod string pump end minimum load effect is to pump end apart from L_crWith pumping rod made by steel There is length L of unstability_b, work as L_cr＞ L_bWhen, judge that the roofbolt of the position bottom on the sucker rod positioned at θ=0 can lose Steady eccentric wear, otherwise judges that the roofbolt of the position bottom on the sucker rod positioned at θ=0 will not occur unstability eccentric wear.

Further, described according to shaft bottom pump end upwards the hole angle θ of each point, shaft bottom pump end upwards each point because of rod and tube partial-wear Axial force N and equation below (5) of generation calculates surface dynamometer card, including：

Deformation process is made to formula (5), obtains the difference equation shown in equation below (14)：

In formula (14), when required point (i, j) is not the node of two-stage bar, u_i,jCarried out by equation below (15) Calculate：

In formula (2), b, δ_i-1,j、h_i-1Intermediate variable is with g', wherein：

When required point (i, j) is for the node of two-stage bar, u_i,jCalculated by equation below (19)：

In formula (19), α_s、β_s、α_k、β_k、γ_k、v_kIntermediate variable is, wherein：

α_s=α₁+α₂(22)

β_s=β₁+β₂(23)

Formula (in 25) is arrived in formula (14), k is roofbolt series, k=1,2,For the cross-sectional area of kth level roofbolt, i is Depth location point, it is biography of the stress wave in rod string that i=2,3,4 ..., j are time location point, j=1,2,3 ..., m Speed, m=4968m/s is broadcast, it is time step that e is damped coefficient, Δ t, Δ s is depth step；

Determine depth step Δ s and time step Δ t, and depth step Δ s and time step Δ t is substituted into formula (14), the displacement of each point and load on the sucker rod are calculated upwards from shaft bottom pump end, obtains surface dynamometer card.

Specifically, it is determined that when depth step Δ s and time step Δ t, depth step Δ s and time step Δ t needs to meet Relation described in equation below (26)：

Specifically, the default value is 2%.

The beneficial effect that technical scheme provided in an embodiment of the present invention is brought is：

The present invention is by calculating the first pump efficiency E_pi, and to the first pump efficiency E_piDecomposition computation is carried out so that pump dynamometers are obtained, and Afterwards with pump dynamometers as boundary condition, application considers rod and tube partial-wear and the first preset formula of hole deviation is counted upwards from shaft bottom pump end The displacement of each point and load on sucker rod is calculated, surface dynamometer card is obtained, and the second pump efficiency E is obtained according to surface dynamometer card_pp, according to First pump efficiency E_piWith the second pump efficiency E_ppPump efficiency error being obtained, whether pump efficiency error is judged less than default value, is then to stop meter Calculate, otherwise with the second pump efficiency E_ppReplace the first pump efficiency E_pi, repeat to obtain to the first pump efficiency E_piCarry out the mistake after decomposition computation Journey, until pump efficiency error is less than default value, the surface dynamometer card for obtaining when being less than default value using pump efficiency error is used as oil well The reference frame of initial production parameter designing, the reliability of the manufacturing parameter that designs is higher, and the oil for being obtained by the present invention Well indicator card takes into full account every influence factor of oil well, and acquired results are accurate.

Description of the drawings

For the technical scheme being illustrated more clearly that in the embodiment of the present invention, below will be to making needed for embodiment description Accompanying drawing is briefly described, it should be apparent that, drawings in the following description are only some embodiments of the present invention, for For those of ordinary skill in the art, on the premise of not paying creative work, other can also be obtained according to these accompanying drawings Accompanying drawing.

Fig. 1 is the method flow diagram of the prediction oil well indicator card that one embodiment of the invention is provided；

Fig. 2 is the method flow diagram of the prediction oil well indicator card that further embodiment of this invention is provided；

Fig. 3 is the schematic diagram of the pump dynamometers of the oil well in feed flow deficiency state that further embodiment of this invention is provided；

Fig. 4 is the signal of the surface dynamometer card of the oil well in feed flow deficiency state that further embodiment of this invention is provided Figure.

Specific embodiment

For making the object, technical solutions and advantages of the present invention clearer, below in conjunction with accompanying drawing to embodiment party of the present invention Formula is described in further detail.

Embodiment one

As shown in figure 1, embodiments providing a kind of method of prediction oil well indicator card, the method includes：

In a step 101, according to given pump footpath, stroke, jig frequency, the diameter of per grade of roofbolt of sucker rod and length, oil pipe Relation curve, the density of crude oil, the viscosity of crude oil, the density of natural gas and the natural gas that in diameter, oil well, yield is pressed with stream Viscosity, obtains the first pump efficiency E_pi.

In embodiments of the present invention, pump footpath can be directly read from the manufacturing parameter table of selected oil well pump, stroke, jig frequency Can directly read from the manufacturing parameter table of oil pumper with the diameter of per grade of roofbolt of sucker rod and length, tubing diameter is by surveying Amount or the manufacturing parameter table of oil wells in field directly read, the relation curve of yield and stream pressure in oil well, the density of crude oil, crude oil The viscosity of viscosity, the density of natural gas and natural gas can be gathered by being arranged on the internet of things equipment of oil wells in field.

In a step 102, to the first pump efficiency E_piDecomposition computation is carried out, obtains pump dynamometers.

In embodiments of the present invention, by the first pump efficiency E_piDecomposition computation is carried out to obtain indicator card, gained indicator card State of the oil well with the presence or absence of feed flow deficiency can be reflected, more meet the production status of oil well most of production period.

In step 103, with pump dynamometers as boundary condition, application considers the first default public affairs of rod and tube partial-wear and hole deviation Formula calculates the displacement of each point and load on sucker rod upwards from shaft bottom pump end, obtains surface dynamometer card.

In embodiments of the present invention, application considers the first preset formula of rod and tube partial-wear and hole deviation from shaft bottom pump end upwards The displacement of each point and load on sucker rod is calculated, according to displacement and the load of each point on sucker rod, you can draw out ground and show work( Figure.And as the first preset formula considers the problem of rod and tube partial-wear and hole deviation, improve the accuracy of result of calculation.

At step 104, according to surface dynamometer card, the maximum load and minimum load, plunger being subject on sucker rod is obtained Effective stroke and the second pump efficiency E_pp.

In embodiments of the present invention, the effective stroke of the maximum load being subject on sucker rod and minimum load and plunger can Directly to read from surface dynamometer card, the second pump efficiency E_ppCan be by being integrated obtaining to surface dynamometer card.

In step 105, according to the first pump efficiency E_piWith the second pump efficiency E_pp, calculate pump efficiency error.

In embodiments of the present invention, pump efficiency error DE is calculated by equation below (27).

In step 106, pump efficiency error is judged whether less than or equal to default value, be then to stop calculating, otherwise with the Two pump efficiency E_ppSubstitute the first pump efficiency E_pi, repeat step 102 is to step 106.

In embodiments of the present invention, it will be understood by those skilled in the art that ideally, the first pump efficiency E_piEqual to second Pump efficiency E_pp, but the impact due to the factor such as rod and tube partial-wear, hole deviation or measurement error, the first pump efficiency E_piWith the second pump efficiency E_ppBetween There is pump efficiency error, pump efficiency error is less, it was demonstrated that the degree of accuracy of result of calculation is higher, according to the production that the result of calculation is designed The reliability of parameter is higher.

In embodiments of the present invention, it is preferable that default value is 2%, in the error model that the degree of accuracy of result of calculation is allowed In enclosing, it is to avoid affect computational efficiency because pursuing too high degree of accuracy.

The present invention is by calculating the first pump efficiency E_pi, and to the first pump efficiency E_piDecomposition computation is carried out so that pump dynamometers are obtained, and Afterwards with pump dynamometers as boundary condition, application considers rod and tube partial-wear and the first preset formula of hole deviation is counted upwards from shaft bottom pump end The displacement of each point and load on sucker rod is calculated, surface dynamometer card is obtained, and the second pump efficiency E is obtained according to surface dynamometer card_pp, according to First pump efficiency E_piWith the second pump efficiency E_ppPump efficiency error being obtained, whether pump efficiency error is judged less than default value, is then to stop meter Calculate, otherwise with the second pump efficiency E_ppReplace the first pump efficiency E_pi, repeat to obtain to the first pump efficiency E_piCarry out the mistake after decomposition computation Journey, until pump efficiency error is less than default value, the surface dynamometer card for obtaining when being less than default value using pump efficiency error is used as oil well The reference frame of initial production parameter designing, the reliability of the manufacturing parameter that designs is higher, and the oil for being obtained by the present invention Well indicator card takes into full account every influence factor of oil well, and acquired results are accurate.

Embodiment two

As shown in Fig. 2 embodiments providing a kind of method of prediction oil well indicator card, the method includes：

In step 201, according to given pump footpath, stroke, jig frequency, the diameter of per grade of roofbolt of sucker rod and length, oil pipe Relation curve, the density of crude oil, the viscosity of crude oil, the density of natural gas and the natural gas that in diameter, oil well, yield is pressed with stream Viscosity, obtains the first pump efficiency E_pi.

In embodiments of the present invention, pump footpath can be directly read from the manufacturing parameter table of selected oil well pump, stroke, jig frequency Can directly read from the manufacturing parameter table of oil pumper with the diameter of per grade of roofbolt of sucker rod and length, tubing diameter is by surveying Amount or the manufacturing parameter table of oil wells in field directly read, the relation curve of yield and stream pressure in oil well, the density of crude oil, crude oil The viscosity of viscosity, the density of natural gas and natural gas can be gathered by being arranged on the internet of things equipment of oil wells in field.

In step 202., to the first pump efficiency E_piDecomposition computation is carried out, obtains pump dynamometers.

The schematic diagram of the pump dynamometers of the oil well for being in feed flow deficiency state flatly is illustrated in figure 3, wherein, line segment BC is Upper loaded line, its height is maximum load P_pmax, the theoretical stroke s of its length as plunger_P, line segment AG is lower loaded line, its It is highly minimum load P_pmin, its length is the effective stroke s of plunger_PE.Therefore in embodiments of the present invention, to the first pump efficiency E_pi Decomposition computation is carried out, obtaining pump dynamometers mainly includes to calculate maximum load P being subject on sucker rod_pmaxWith minimum load P_pmin And the theoretical stroke s of plunger_PWith effective stroke s_PE, then according to maximum load P being subject on sucker rod_pmaxAnd minimum load P_pminAnd the theoretical stroke s of plunger_PWith effective stroke s_PEObtain pump dynamometers.Wherein, calculated according to equation below (1) maximum Load p_pmax：

P_pmax=-W_b+A_pLρ_lg (1)

In formula (1), P_pmaxFor the maximum load being subject on sucker rod, unit is thousand newton (kN), W_bFor balance weight, Unit is thousand newton (kN), A_pFor the cross-sectional area of plunger, unit is square metre (m²), L is the length of sucker rod, and unit is rice (m), ρ_lFor the average density of liquid in pipe, unit is kilograms per cubic meter (kg/m³), g be acceleration of gravity, unit for kilogram/ Newton (kg/N)；

Minimum load P is calculated according to equation below (2)_pmin：

P_pmin=-W_b(2)

In formula (2), P_pminFor the minimum load being subject on sucker rod, unit is thousand newton (kN)；

The theoretical stroke S of plunger is calculated according to equation below (3)_P：

S_P=S × η_Become(3)

In formula (3), S_PFor the theoretical stroke of plunger, unit is design stroke of rice (m), the S for plunger, and unit is rice (m), η_BecomeFor deformation pump efficiency, unit is rice (m)；

The effective stroke S of plunger is calculated according to equation below (4)_PE：

In formula (4), K_qFor volume factor；

According to maximum load P being subject on sucker rod_pmaxWith minimum load P_pminAnd the theoretical stroke S of plunger_PWith effective Stroke S_PE, obtain pump dynamometers.

In embodiments of the present invention, deformation pump efficiency η_BecomeCalculated by equation below (28)：

η_Become=(S- λ)/S (28)

In formula (28), it is rice (m) that λ is loss of plunger stroke, unit, wherein, when sucker rod is for single-stage bar and multistage bar, Loss of plunger stroke λ is calculated respectively as follows：

When sucker rod is for single-stage bar, loss of plunger stroke λ is calculated by equation below (29)：

In formula (29), W_lThe fluid column load on plunger is acted on for upstroke, unit is newton (N), L_pFor pump depth, Unit is rice (m), E_rFor the elastic modelling quantity of steel, unit is handkerchief (Pa), A_tFor the cross-sectional area of oil pipe, unit is square metre (m²). Wherein, upstroke acts on fluid column load W on plunger_lCalculated by equation below (30)：

W_l=(A_p-A_r)Lρ_lg (30)

In formula (30), ρ_lFor the average density of liquid, unit is kilograms per cubic meter (kg/m³).

When sucker rod is for multistage bar, λ is calculated by equation below (31)：

In formula (31), n is total series of the roofbolt of sucker rod, and k is the series of each roofbolt of sucker rod, 1<k≤ N, wherein, makes sucker rod be located at the one-level roofbolt of the roofbolt of the top, now, k=1,Horizontal stroke for the kth level roofbolt of sucker rod Sectional area, unit is square metre (m²).And when sucker rod is for multistage bar, W_lCalculated by equation below (32)：

In formula (32), L_kFor the length of the kth level roofbolt of sucker rod, unit is rice (m).

In step 203, according to the hole angle θ of shaft bottom pump end each point upwards, calculate shaft bottom pump end upwards each point because of rod tube Axial force N that eccentric wear is produced.

In the embodiment of the present invention, hole angle θ can be obtained by measurement after the completion of well cementation.Wherein, when θ ≠ 0, shaft bottom Pump end axial force N that each point is produced because of rod and tube partial-wear upwards is calculated by equation below (10)：

In formula (10), it is degree, q that θ is hole angle, unit_rBuoyant weight for roofbolt in well liquid, unit is handkerchief (Pa), For the azimuth of well, unit is degree, the azimuth of wellAlso can be obtained by measurement after the completion of well well cementation, P is Intermediate variable, P is calculated by equation below (11)：

When θ=0, judge whether the roofbolt positioned at the position bottom of θ=0 on sucker rod occurs unstability eccentric wear, if sentenced On disconnected sucker rod, the roofbolt of the position bottom of θ=0 can occur unstability eccentric wear, then the attached hole angle in position again for θ=0, And substitute into formula (10) carry out calculate relevant position axial force N, if it is determined that on sucker rod the position bottom of θ=0 roofbolt Unstability eccentric wear will not occur, then take the N=0 in formula (10).

Wherein, judge whether the roofbolt of the position bottom on sucker rod positioned at θ=0 occurs unstability eccentric wear, including：

According to the minimum load of pump dynamometers, sucker rod is calculated in minimum load P by equation below (12)_pminUnder effect Neutral point to pump end apart from L_cr：

In formula (12), I is the moment of inertia of sucker rod cross section, and unit is biquadratic rice (m⁴)；

Length L that pumping rod made by steel occurs unstability is calculated according to equation below (13)_b：

In formula (13), F_bFor the axial compressive force that sucker rod is subject at pump end, unit is newton (N), in reality of the present invention Apply in example, take F_b=P_pmin, q is the weight of roofbolt unit length, and unit is Newton/meter (N/m)；

Relatively neutral point of the sucker rod under the effect of pump end minimum load is to pump end apart from L_crOccur with pumping rod made by steel Length L of unstability_b, work as L_cr＞ L_bWhen, judge that the roofbolt on sucker rod positioned at the position bottom of θ=0 can occur unstability eccentric wear, no Then judge that the roofbolt of the position bottom on sucker rod positioned at θ=0 will not occur unstability eccentric wear.

Wherein, be θ=0 position appended by the effect of hole angle and rod string pump end minimum load under neutral point to pump End apart from L_crThere is length L of unstability with pumping rod made by steel_bRelated.

In step 204, according to shaft bottom pump end upwards the hole angle θ of each point, shaft bottom pump end upwards each point because of rod and tube partial-wear Axial force N and equation below (5) of generation calculates surface dynamometer card：

In formula (5), u is the load of each point on roofbolt, and it is the time that unit is newton (N), t, and unit is that second (s), s is The displacement of each point on roofbolt, unit is sign of rice (m), the δ for rigid body frictional force, during upstroke, δ=+ 1, during down stroke, δ =-1, a, c, h and g ' are intermediate variable, are calculated to formula (9) by equation below (6)：

In formula (6) to formula (9), E_rFor material of sucker rod elastic modelling quantity, unit is handkerchief (Pa), ρ_rFor pole stock of pumping Material density, ρ_r=7860kg/m³, υ_eFor the viscous drag coefficient of unit length rod string, A_rFor sucker rod cross-sectional area, f is Coefficient of friction between sucker rod and oil pipe, f between 0.05～0.1, g be.

Wherein, in step 204, according to shaft bottom pump end upwards the hole angle θ of each point, shaft bottom pump end upwards each point because rod tube inclined Axial force N that mill is produced and equation below (5) calculate surface dynamometer card, including：

Deformation process is made to formula (5), obtains the difference equation shown in equation below (14)：

In formula (14), A_rFor the cross-sectional area of point (i, j) place sucker rod, when required point (i, j) is not two-stage bar During node, u_i,jCalculated by equation below (15)：

In formula (15), b, δ_i-1,jAnd h_i-1Intermediate variable is, wherein：

When required point (i, j) is for the node of two-stage bar, u_i,jCalculated by equation below (19)：

In formula (19), α_s、β_s、α_k、β_k、γ_k、v_kIntermediate variable is, wherein：

K=1 and k=2 is substituted in formula (20) and formula (21) respectively, solves α₁、α₂、β₁And β₂, and will calculate α₁、α₂、β₁And β₂Substitute into equation below (22) and (23) and calculate α_sAnd β_s：

α_s=α₁+α₂(22)

β_s=β₁+β₂(23)

Formula (in 25) is arrived in formula (14), k is roofbolt series, k=1,2, i is depth location point,For kth level roofbolt Cross-sectional area, unit be square metre (m²), it is stress wave that i=2,3,4 ..., j are time location point, j=1,2,3 ..., m Spread speed in rod string, it is time step that m=4968m/s, e are damped coefficient, Δ t, and unit is that second (s), Δ s is Depth step, unit is rice (s)；

Determine depth step Δ s and time step Δ t, and depth step Δ s and time step Δ t is substituted into formula (14), the displacement of each point and load on sucker rod are calculated upwards from shaft bottom pump end, obtains surface dynamometer card.

Wherein it is determined that when depth step Δ s and time step Δ t, depth step Δ s and time step Δ t need to meet such as The relation of lower formula (26), to ensure that formula (14) has solution：

In step 205, according to surface dynamometer card, the maximum load and minimum load, plunger being subject on sucker rod is obtained Effective stroke and the second pump efficiency E_pp.

The surface dynamometer card of the oil well being illustrated in figure 4 in feed flow deficiency state, is taken out when being calculated by formula (14) On beam hanger from after pump the end upwards displacement of each point and load, you can draw out surface dynamometer card, and can read on surface dynamometer card The maximum load and minimum load being subject on sucker rod, and the effective stroke of plunger is taken, and the second pump efficiency is obtained by calculating E_pp.

In step 206, according to the first pump efficiency E_piWith the second pump efficiency E_pp, calculate pump efficiency error.

In embodiments of the present invention, pump efficiency error DE is calculated by equation below (27).

In step 207, whether pump efficiency error being judged less than default value, is then to stop calculating, otherwise with described second Pump efficiency E_ppSubstitute the first pump efficiency E_pi, repeat step 202 is to step 207.

In embodiments of the present invention, when pump efficiency error is less than or equal to default value, you can gone out with pump efficiency error DE Before now, the surface dynamometer card of gained is used as the reference frame of oil well production parameter designing；When pump efficiency error is more than default value When, repeat step 202 is needed to step 206.

The embodiments of the present invention are for illustration only, do not represent the quality of embodiment.

The foregoing is only presently preferred embodiments of the present invention, not in order to limit the present invention, all spirit in the present invention and Within principle, any modification, equivalent substitution and improvement that is made etc., should be included within the scope of the present invention.

Claims (8)

1. a kind of prediction oil well indicator card method, it is characterised in that methods described includes：

Step 1：According in given pump footpath, stroke, jig frequency, the diameter of per grade of roofbolt of sucker rod and length, tubing diameter, oil well The relation curve of yield and stream pressure, the density of crude oil, the viscosity of crude oil, the viscosity of the density of natural gas and natural gas, obtain the One pump efficiency E_pi；

Step 2：To the first pump efficiency E_piDecomposition computation is carried out, obtains pump dynamometers；

Step 3：With the pump dynamometers as boundary condition, application considers the first preset formula artesian well of rod and tube partial-wear and hole deviation Bottom pump end calculates the displacement of each point and load on sucker rod upwards, obtains surface dynamometer card；

Step 4：According to the surface dynamometer card, obtain the maximum load being subject on sucker rod and minimum load, plunger effective Stroke and the second pump efficiency E_pp；

Step 5：According to the first pump efficiency E_piWith the second pump efficiency E_pp, calculate pump efficiency error；

Step 6：Whether the pump efficiency error being judged less than default value, is then to stop calculating, otherwise with the second pump efficiency E_pp Substitute the first pump efficiency E_pi, and repeat step 2 is to step 6.

2. method according to claim 1, it is characterised in that the step 2, carries out decomposition meter to first pump efficiency Calculate, pump dynamometers are obtained, including：

Maximum load P being subject on sucker rod is calculated according to equation below (1)_pmax：

P_pmax=-W_b+A_pLρ_lg (1)

In formula (1), W_bFor balance weight, A_pFor the cross-sectional area of plunger, L is the length of sucker rod, ρ_lFor the averagely close of liquid Degree, g is acceleration of gravity；

The minimum load P being subject on sucker rod is calculated according to equation below (2)_pmin：

P_pmin=-W_b(2)；

The theoretical stroke S of plunger is calculated according to equation below (3)_P：

S_P=S × η_Become(3)

In formula (3), S is the design stroke of plunger, η_BecomeFor deformation pump efficiency；

The effective stroke S of plunger is calculated according to equation below (4)_PE：

In formula (4), K_qFor volume factor；

According to maximum load P being subject on sucker rod_pmax, minimum load P_pmin, plunger theoretical stroke S_PWith effective stroke S_PE, Obtain pump dynamometers.

3. method according to claim 2, it is characterised in that the step 3, with the pump dynamometers as boundary condition, Application consider the first preset formula of rod and tube partial-wear and hole deviation from shaft bottom pump end calculate on sucker rod upwards the displacement of each point with Load, obtains surface dynamometer card, including：

According to the hole angle θ of shaft bottom pump end each point upwards, the shaft bottom pump end axial force that each point is produced upwards is calculated because of rod and tube partial-wear N；

According to the shaft bottom pump end hole angle θ of each point, shaft bottom pump end axial force N that each point is produced because of rod and tube partial-wear upwards and such as upwards Lower formula (5) calculate surface dynamometer card：

$\frac{{\&part;}^{2}u}{\&part;t^2}=a^2\frac{{\&part;}^{2}u}{\&part;s^2}-c\frac{\&part;u}{\&part;t}-\mathrm{\&delta;}hN+g^{\&prime;}cos\mathrm{\&theta;}---\left(5\right)$

In formula (5), u is the load of each point on roofbolt, and t is the displacement that time, s is each point on roofbolt, and δ is rigid body frictional force Sign, during upstroke, δ=+ 1, during down stroke, δ=- 1, a, c, h and g ' be intermediate variable, by equation below (6) extremely Formula (9) is calculated：

$a=\sqrt{\frac{E_r}{{\mathrm{\&rho;}}_r}}---\left(6\right)$

$c=\frac{v_e}{{\mathrm{\&rho;}}_r{A}_r}---\left(7\right)$

$h=\frac{f}{{\mathrm{\&rho;}}_r{A}_r}---\left(8\right)$

$g^{\&prime;}=\frac{g({\mathrm{\&rho;}}_r-{\mathrm{\&rho;}}_l)}{{\mathrm{\&rho;}}_r}---\left(9\right)$

In formula (6) to formula (9), E_rFor material of sucker rod elastic modelling quantity, ρ_rFor material of sucker rod density, ρ_r=7860kg/ m³, υ_eFor the viscous drag coefficient of unit length rod string, A_rFor sucker rod cross-sectional area, f is between sucker rod and oil pipe Coefficient of friction, f is between 0.05～0.1.

4. method according to claim 3, it is characterised in that the hole angle θ according to shaft bottom pump end each point upwards, meter Shaft bottom pump end axial force N that each point is produced upwards is calculated because of rod and tube partial-wear, including：

When θ ≠ 0, shaft bottom pump end axial force N that each point is produced because of rod and tube partial-wear upwards is calculated by equation below (10)：

In formula (10), q_r' it is buoyant weight of the roofbolt in well liquid,For the azimuth of well, P is intermediate variable, P by such as Lower formula (11) are calculated：

$P=E_r{A}_r\frac{\&part;u}{\&part;s}---\left(11\right);$

When θ=0, judge whether the roofbolt positioned at the position bottom of θ=0 on sucker rod occurs unstability eccentric wear, if it is determined that institute The roofbolt for stating the position bottom of θ=0 on sucker rod can occur unstability eccentric wear, then the attached hole angle in position again for θ=0, And substitute into formula (10) carry out calculate relevant position axial force N, if it is determined that on sucker rod the position bottom of θ=0 roofbolt Unstability eccentric wear will not occur, then take the N=0 in formula (10).

5. method according to claim 4, it is characterised in that the position bottom of θ=0 on the judgement sucker rod Whether roofbolt there is unstability eccentric wear, including：

According to the minimum load of pump dynamometers, sucker rod is calculated in minimum load P by equation below (12)_pminIn under effect Property point is to pump end apart from L_cr：

$L_{cr}=\sqrt{\frac{36.75E_{r}I}{P_{pmin}}}---\left(12\right)$

In formula (12), I is the moment of inertia of sucker rod cross section；

Length L that pumping rod made by steel occurs unstability is calculated according to equation below (13)_b：

$L_b=\frac{F_P}{q}---\left(13\right)$

In formula (13), F_bFor the axial compressive force that sucker rod is subject at pump end, F is taken_b=P_pmin, q is the weight of roofbolt unit length Amount；

Neutral point of the comparison sucker rod under minimum load effect is to pump end apart from L_crThere is unstability with pumping rod made by steel Length L_b, work as L_cr＞ L_bWhen, judge that the roofbolt on the sucker rod positioned at the position bottom of θ=0 can occur unstability eccentric wear, no Then judge that the roofbolt of the position bottom on the sucker rod positioned at θ=0 will not occur unstability eccentric wear.

6. method according to claim 3, described according to shaft bottom pump end, the hole angle θ of each point, shaft bottom pump end be upwards upwards Axial force N that each point is produced because of rod and tube partial-wear and equation below (5) calculate surface dynamometer card, including：

Deformation process is made to formula (5), obtains the difference equation shown in equation below (14)：

In formula (14), when required point (i, j) is not the node of two-stage bar, u_i,jCalculated by equation below (15)：

$\begin{array}{c}{u}_{i,j}=b(u_{i-1,j+1}-2u_{i-1,j}+u_{i-1,j-1})+2u_{i-1,j}-u_{i-2,j}+b\frac{e\mathrm{\&Delta;}t}{2}(u_{i-1,j+1}-u_{i-1,j-1})\\ +{\mathrm{b\&Delta;t}}^2\left({\mathrm{\&delta;}}_{i-1,j}{h}_{i-1}{N}_{i-1,j}-\frac{{\mathrm{\&rho;}}_r-{\mathrm{\&rho;}}_l}{{\mathrm{\&rho;}}_r}{\mathrm{cos\&theta;}}_{i-1}\right)\end{array}---\left(15\right)$

In formula (2), b, δ_i-1,j、h_i-1Intermediate variable is with g', wherein：

$b={\left(\frac{\mathrm{\&Delta;}s}{m\mathrm{\&Delta;}t}\right)}^2---\left(16\right)$

${\mathrm{\&delta;}}_{i-1,j}=\frac{u_{i-1,j}-u_{i-1,j-1}}{|u_{i-1,j}-u_{i-1,j-1}|}---\left(17\right)$

$h_{i-1}=\frac{f}{{\mathrm{\&rho;}}_r{A}_r}---\left(18\right)$

When required point (i, j) is for the node of two-stage bar, u_i,jCalculated by equation below (19)：

$\begin{array}{c}{u}_{i,j}=\frac{({\mathrm{\&alpha;}}_s+{\mathrm{\&beta;}}_s)}{v_2}{u}_{i-1,j+1}-\frac{2{\mathrm{\&alpha;}}_s-v_1-v_2}{v_2}{u}_{i-1,j}+\frac{({\mathrm{\&alpha;}}_s+{\mathrm{\&beta;}}_s)}{v_2}{u}_{i-1,j-1}-\frac{v_1}{v_2}{u}_{i-2,j}\\ +\frac{{\mathrm{\&gamma;}}_1\left({\mathrm{\&delta;}}_{i-1,j}{h}_{1(i-1)}{N}_{i-1,j}-\frac{{\mathrm{\&rho;}}_r-{\mathrm{\&rho;}}_l}{{\mathrm{\&rho;}}_r}{\mathrm{cos\&theta;}}_{i-1}\right)+{\mathrm{\&gamma;}}_2\left({\mathrm{\&delta;}}_{i-1,j}{h}_{2(i-1)}{N}_{i-1,j}-\frac{{\mathrm{\&rho;}}_r-{\mathrm{\&rho;}}_l}{{\mathrm{\&rho;}}_r}{\mathrm{cos\&theta;}}_{i-1}\right)}{v_2}\end{array}---\left(19\right)$

In formula (19), α_s、β_s、α_k、β_k、γ_k、v_kIntermediate variable is, wherein：

${\mathrm{\&alpha;}}_k=\frac{{\mathrm{\&Delta;sE}}_r{A}_{r_k}}{2{\left({\mathrm{\&alpha;}}_k\mathrm{\&Delta;}t\right)}^2}---\left(20\right)$

${\mathrm{\&beta;}}_k=\frac{{\mathrm{\&Delta;sE}}_r{A}_{r_k}e}{4{\left({\mathrm{\&alpha;}}_k\right)}^2\mathrm{\&Delta;}t}---\left(21\right)$

α_s=α₁+α₂(22)

β_s=β₁+β₂(23)

${\mathrm{\&gamma;}}_k=\frac{{\mathrm{\&Delta;sE}}_r{A}_{r_k}}{2{\left({\mathrm{\&alpha;}}_k\right)}^2}---\left(24\right)$

$v_k=\frac{E_r{A}_{r_k}}{\mathrm{\&Delta;}s}---\left(25\right)$

Formula (in 25) is arrived in formula (14), k is roofbolt series, k=1,2, A_rkFor the cross-sectional area of kth level roofbolt, i is depth Location point, it is propagation speed of the stress wave in rod string that i=2,3,4 ..., j are time location point, j=1,2,3 ..., m Degree, it is time step that m=4968m/s, e are damped coefficient, Δ t, and Δ s is depth step；

Determine depth step Δ s and time step Δ t, and depth step Δ s and time step Δ t is substituted into formula (14), from Shaft bottom pump end calculates the displacement of each point and load on the sucker rod upwards, obtains surface dynamometer card.

7. method according to claim 6, it is characterised in that when determining depth step Δ s and time step Δ t, depth Step delta s and time step Δ t need to meet the relation described in equation below (26)：

$\frac{\mathrm{\&Delta;}s}{m\mathrm{\&Delta;}t}<1---\left(26\right).$

8. the method according to claim 1-7 any one claim, it is characterised in that the default value be.