CN1512033A

CN1512033A - Realizing method for steel cable rod oil pumping system

Info

Publication number: CN1512033A
Application number: CNA021594902A
Authority: CN
Inventors: 檀朝东; 张嗣伟
Original assignee: China University of Petroleum Beijing
Current assignee: China University of Petroleum Beijing
Priority date: 2002-12-31
Filing date: 2002-12-31
Publication date: 2004-07-14

Abstract

The realizing method for steel cable rod oil pumping system includes at least calculating data of the liquid supplying capacity of oil well and the dynamic exhaust of pump based on the acquired basic production data; obtaining the supply-exhaust cooperating point based on the calculated data; calculating the well situation index; optimizing system scheme and determining the parameters of the parts in the steel cable rod oil pumping system. The present invention establishes the steel cable rod oil pumping system by means of system engineering process from liquid supplying oil layer to well head via well shaft flow, machine, rod and pump and based on the structure characteristic and surface characteristic of steel cable rod, designs cooperative supply and exhaust, selects reasonable machine and pump work parameters and mixed rod-column combination, analyses the rod-column stress situation and makes the whole well system operate effectively and safely.

Description

Method for realizing steel wire rope rod oil pumping system

Technical Field

The invention relates to a method for realizing a steel wire rope rod oil pumping system, in particular to a method for realizing a steel wire rope rod oil pumping system for acquiring optimal system parameters by processing acquired yield data and working condition indexes of an oil pumping system, and belongs to the technical field of oil acquisition.

Background

Compared with the conventional steel sucker rod, the steel wire rope sucker rod has a series of advantages: because there is no coupling, not only can greatly reduce the accident of pumping rod, but also its resistance is small, can eliminate piston effect and can greatly reduce the phenomenon of wax deposition on the rod string. Therefore, the lifting operation can be continuously carried out, the operation process is simplified, the operation time is saved, the weight of the unit length is light, and the maximum load of the suspension point can be reduced by 20 to 30 percent; and can meet the deep drawing requirement. Because the string is flexible, friction and wear between the string and the tubing wall can be greatly reduced. And can reduce the energy consumption of the oil pumping system. Because the elasticity of the steel wire rope is better, the steel wire rope is beneficial to generating over-stroke, under the same condition, the effective stroke can be improved by 3.5 percent, and the pump efficiency can be greatly improved.

At present, the application of a steel wire rod pumping system is very little, the existing dynamic model adopting the conventional steel pumping rod system is established on the basis of the fluctuation equation of Gibbs, the rod body vibration damping coefficient of the conventional steel pumping rod is completely applied, the structural characteristics of the steel wire rod are not fully considered, and the steel wire rod is not taken into consideration in the whole system of an oil well, a shaft, a machine-rod-pump and a wellhead. Therefore, it is difficult to make a correct and comprehensive analysis on the operation of the wire rod pumping system, and it is also difficult to make an accurate explanation on the reasons for the improvement of the actual yield and the pump efficiency of the wire rod pumping system. Therefore, the application of the wire rope rod oil pumping system is inevitably influenced.

Disclosure of Invention

The invention mainly aims to provide a method for realizing a steel wire rod oil pumping system, which is established by adopting a system engineering method from the whole system of oil layer liquid supply, shaft flowing, a machine-rod-pump and a wellhead according to the structural characteristics and the surface characteristics of the steel wire rod.

The invention also aims to provide a method for realizing the steel wire rod oil pumping system, which can design the coordination of supply and discharge of an oil well, select reasonable pump working parameters to be combined with the mixed rod column group, analyze the stress condition of the rod column and enable the whole underground system to work more efficiently and safely.

The purpose of the invention is realized as follows:

an implementation method of a steel wire rope rod oil pumping system at least comprises the following steps:

step 1: calculating the liquid supply capacity of the oil well and the dynamic data of pump discharge according to the collected basic production data;

step 2: acquiring a supply and discharge coordination point according to an oil well liquid supply capacity curve and a pump discharge dynamic curve; wherein, the intersection point of the two curves is a supply and discharge coordination point;

and step 3: calculating well condition indexes and characteristic parameters of the steel wire rope rod;

and 4, step 4: and optimizing the system scheme, and determining the parameters of each part in the steel wire rope rod oil pumping system.

The calculation of the liquid supply capacity of the oil well is specifically as follows: within the range allowed by the IPR curve, namely: q is more than 0_t＜q_tmaxSelecting a group of liquid production values, and calculating corresponding bottom hole flowing pressure according to the IPR curve; or selecting a group of bottom hole flowing pressure values, and calculating corresponding liquid supply values according to the IPR curve;

q_tmaxm is the maximum fluid production³/d；

q_tM is the amount of liquid produced³/d。

The liquid supply capacity of the oil well is calculated by the following formula:

flow pressure is calculated according to the liquid production amount:

when 0 < q_t≤q_bWhen the temperature of the water is higher than the set temperature,

P_{wf} = P_{r} - \frac{q_{t}}{J}

when q is_b＜q_t≤q_omaxWhen is, P_wf＝F_oP_{wf oil}+F_wP_{wf water}

When q is_omax＜q_t＜q_tmaxWhen the temperature of the water is higher than the set temperature,

P_{wf} = F_{w} (P_{r} - \frac{q_{o \max}}{J}) - (q_{t} - \frac{q_{o \max}}{J}) \frac{CD}{CG}

CD = F_{w} \frac{0.001 q_{o \max}}{J} + 0.125 F_{o} P_{b} [- 1 + \sqrt{81 - 80 \frac{0.999 q_{o \max} - q_{b}}{q_{o \max} - q_{b}}}]

CG＝0.001q_omax

calculating the liquid production amount by the flow pressure:

when P is present_b＜P_wf≤P_rWhen q is greater than q_t＝J(P_r-P_wf)

When P is present_wfG＜P_wf≤P_bWhen B is not equal to 0,

q_{t} = \frac{- C + \sqrt{C^{2} - 4 B^{2} D}}{2 B^{2}}

when B is 0, q_t＝D/C

P_{wfG} = F_{w} (P_{r} - \frac{q_{o \max}}{J})

A = \frac{P_{wf} + 0.125 F_{0} P_{b} - F_{w} P_{r}}{0.125 F_{0} P_{b}}

B = \frac{F_{w}}{0.125 F_{0} P_{b} J}

C = 2 AB + \frac{80}{q_{o \max} - q_{b}}

D = A^{2} - 80 \frac{q_{b}}{q_{o \max} - q_{b}} + 81

When 0 < P_wf＜P_wfGWhen the temperature of the water is higher than the set temperature,

CD = F_{w} \frac{0.001 q_{o \max}}{J} + 0.125 F_{o} P_{b} [- 1 + \sqrt{81 - 80 \frac{0.999 q_{o \max} - q_{b}}{q_{o \max} - q_{b}}}]

CG＝0.001q_omax

wherein: q. q.s_omaxM is the maximum oil production³/d；

q_tmaxM is the maximum fluid production³/d；

q_oFor oil production, m³/d；

q_tM is the amount of liquid produced³/d；

q_bM is the oil production at bubble point pressure³/d；

p_rIs the formation pressure, MPa;

p_wfis bottom hole flowing pressure, MPa;

p_bbubble point pressure, MPa;

F_wwater content,%; f_o＝1-F_w；

J is the fluid production index, m³/d·MPa。

The characteristic parameters of the steel wire rope rod are calculated by the following formula:

damping coefficient of the wire rope rod:

(1) structural damping

The equivalent damping of the vibrations produced by the structural damping is:

omega is the vibration frequency rad/s; alpha is a constant, independent of the omega frequency,

determined by experiments;

(2) fluid viscous damping

The fluid viscous damping of the wire rope rod is:

in the formula: eta is the hydrodynamic viscosity coefficient Pa · s;

f (m) is a damping factor, a parameter related to the diameter ratio of the pipe rod and is dimensionless;

m = \frac{d_{t}}{d_{r}},

wherein:

d_rthe diameter of the steel wire rope sucker rod; d_tThe inner diameter of the oil pipe; psi is a dimensionless correction factor for the surface properties of the steel cord rod, determined experimentally.

The combined length of the steel wire rope mixed rod column is as follows:

for a multi-stage steel wire rope sucker rod string, the stress range of the top end of each stage of steel wire rope rod meets the following conditions:

wherein: [ sigma ]_max]_i＝S_F(0.25T_r+0.5625σ_min.i)

In the formula: s_FThe coefficient of use of the steel wire rope sucker rod is obtained;

T_rthe maximum tensile strength of the steel wire rope sucker rod is N/mm²；

I is the number of stages of the sucker rod from top to bottom;

σ_max.i、σ_min.ithe maximum and minimum stress at the top end of the I-stage sucker rod is N/mm²。

In order to ensure that the steel wire rope sucker rod is always in a stretching state when in lower stroke and the structural extension of the lower end can be eliminated, the added weight of the weighting rod is required to offset the buoyancy W borne by the steel wire rope and the weighting rod_r0Semi-dry friction force W between the bushing and the plunger_dAnd a hydraulic resistance W generated when the mixed liquid flows through the traveling valve_wThe inertia force W of the weight lever itself_vFriction force with liquid W_riAnd can eliminate partial structural elongation W of the steel wire rope_j(ii) a Therefore, the weight bar to be added at the lower end of the pole column at least meets the following requirements:

W_s≥W_d+W_v+W_s+W_w+W_ri+W_j+W_r0

the pump discharge dynamics data is calculated by the following formula:

Q＝0.001131ηSnD_p ²

wherein,

q is the displacement of the pump and Q is the displacement of the pump,

eta is the pump efficiency and is the pump efficiency,

s is the stroke of the oil pumping machine,

n is the stroke frequency of the oil pumping unit,

D_pthe pump diameter.

The well condition indicators include at least: beam-pumping unit suspension load, beam-pumping unit torque, effective stroke, pump efficiency, hydraulic power, polished rod power and downhole system efficiency; wherein, each index is calculated as follows:

calculating the suspension point load of the oil pumping unit:

F_{\max} = (F_{r} + F_{L}) (1 + \frac{s n^{2}}{1790}) + F_{w}

F_{\min} = F_{r} (1 - \frac{d_{L}}{d_{r}} - \frac{s n^{2}}{1790}) + F_{w}

and (3) calculating the torque of the pumping unit: m_max＝1800s+0.202s(P_max-P_min)

Calculation of effective stroke: s_p＝S+λ_{Inertial force measuring device}+λ_Rod

Pump efficiency: eta_p＝η_{Qi (Qi)}η_Becomeη_{Leakage net}

η_{Qi (Qi)}＝η_{Gas 1}η_{Gas 2}；

η_{Leakage net}＝η_{Drain 1}η_{Drain 2}

Hydraulic power:

polished rod power:

downhole system efficiency:

{EFF}_{down} = \frac{{HP}_{H}}{{HP}_{PR}}

the system scheme optimization is as follows: and (3) calculating:

and determining the decision coefficient of each part in the steel wire rod oil pumping system by taking the best scheme with the maximum bi as the best scheme.

According to the structural characteristics and the surface characteristics of the steel wire rope rod, a system engineering method is adopted to establish a steel wire rope rod oil pumping system from oil layer liquid supply, shaft flowing, a machine-rod-pump and a whole system to a wellhead; and the coordination of supply and discharge of the oil well can be designed, reasonable pump working parameters are selected to be combined with the mixed rod column group, and the stress condition of the rod column is analyzed, so that the whole underground system can work more efficiently and safely.

Drawings

FIG. 1 is a schematic diagram of an IPR curve according to the present invention;

FIG. 2 is a schematic illustration of the effect of pump depth on system index according to the present invention;

FIG. 3 is a schematic illustration of the effect of stroke on system index according to the present invention;

FIG. 4 is a schematic diagram illustrating the effect of the number of strokes on system metrics in accordance with the present invention;

FIG. 5 is a schematic illustration of the effect of pump diameter on system performance;

FIG. 6 is a schematic flow chart of the present invention.

Detailed Description

The invention is described in further detail below with reference to the following figures and specific examples:

the invention compiles the optimization design software of the wire rope mixed sucker rod string oil pumping system, and designs and analyzes the result of the wire rope rod oil pumping system under the condition of a given oil well.

Project computation

Referring to fig. 1 and 6, firstly, data preparation is carried out, and the liquid supply capacity of the oil well is calculated according to basic data of the oil well (see table 1), and referring to table 1, a scheme group is formed by combining different rod column collocation forms, pump depths, pump diameters, strokes and stroke times (see table 2).

And performing multi-scheme design calculation based on the well IPR curve. Judging whether each scheme is coordinated in supply and discharge, automatically calculating the optimal rod column combination of each scheme, predicting system indexes of different schemes, and selecting the schemes by respectively taking daily liquid production, stroke efficiency, pump efficiency and underground efficiency as targets, so that the reasonable design of the steel wire rope rod oil pumping system of one oil well can be obtained.

The specific calculation includes:

calculating the liquid supply capacity of the oil well: within the range allowed by the IPR curve, namely: q is more than 0_t＜q_tmaxSelecting a group of liquid production values, and calculating corresponding bottom hole flowing pressure according to the IPR curve; or selecting a group of bottom hole flowing pressure values, and calculating corresponding liquid supply values according to the IPR curve;

q_tmaxm is the maximum fluid production³/d；

q_tM is the amount of liquid produced³/d。

flow pressure is calculated according to the liquid production amount:

P_{wf} = P_{r} - \frac{q_{t}}{J}

when q is_b＜q_t≤q_omaxWhen is, P_wf＝F_oP_{wf oil}+F_wP_{wf water}

P_{wf} = F_{w} (P_{r} - \frac{q_{o \max}}{J}) - (q_{t} - \frac{q_{o \max}}{J}) \frac{CD}{CG}

CD = F_{w} \frac{0.001 q_{o \max}}{J} + 0.125 F_{o} P_{b} [- 1 + \sqrt{81 - 80 \frac{0.999 q_{o \max} - q_{b}}{q_{o \max} - q_{b}}}]

CG＝0.001q_omax

calculating the liquid production amount by the flow pressure:

when P is present_b＜P_wf≤P_rWhen q is greater than q_t＝J(P_r-P_wf)

When P is present_wfG＜P_wf≤P_bWhen and whenB≠0，

q_{t} = \frac{- C + \sqrt{C^{2} - 4 B^{2} D}}{2 B^{2}}

When B is 0, q_t＝D/C

P_{wfG} = F_{w} (P_{r} - \frac{q_{o \max}}{J})

A = \frac{P_{wf} + 0.125 F_{0} P_{b} - F_{w} P_{r}}{0.125 F_{0} P_{b}}

B = \frac{F_{w}}{0.125 F_{0} P_{b} J}

C = 2 AB + \frac{80}{q_{o \max} - q_{b}}

D = A^{2} - 80 \frac{q_{b}}{q_{o \max} - q_{b}} + 81

CD = F_{w} \frac{0.001 q_{o \max}}{J} + 0.125 F_{o} P_{b} [- 1 + \sqrt{81 - 80 \frac{0.999 q_{o \max} - q_{b}}{q_{o \max} - q_{b}}}]

CG＝0.001q_omax

wherein: q. q.s_omaxM is the maximum oil production³/d；

q_tmaxM is the maximum fluid production³/d；

q_oFor oil production, m³/d；

q_tM is the amount of liquid produced³/d；

q_bM is the oil production at bubble point pressure³/d；

p_rIs the formation pressure, MPa;

p_wfis bottom hole flowing pressure, MPa;

p_bbubble point pressure, MPa;

F_wwater content,%; f_o＝1-F_w；

J is the fluid production index, m³/d·MPa。

damping coefficient of the wire rope rod:

(1) structural damping

The equivalent damping of the vibrations produced by the structural damping is:

determined by experiments;

(2) fluid viscous damping

The fluid viscous damping of the wire rope rod is:

in the formula: eta is the hydrodynamic viscosity coefficient Pa.s;

m = \frac{d_{t}}{d_{r}},

wherein:

The combined length of the steel wire rope mixed rod column is as follows:

wherein: [ sigma ]_max]_i＝S_F(0.25T_r+0.5625σ_min.i)

T_rthe maximum tensile strength of the steel wire rope sucker rod is N/mm²；

I is the number of stages of the sucker rod from top to bottom;

W_s≥W_d+W_v+W_s+W_w+W_ri+W_j+W_r0

pump discharge dynamics data is calculated by the following formula:

Q＝0.001131ηSnD_p ²

wherein,

q is the displacement of the pump and Q is the displacement of the pump,

eta is the pump efficiency and is the pump efficiency,

s is the stroke of the oil pumping machine,

n is the stroke frequency of the oil pumping unit,

D_pthe pump diameter.

The well condition indicators are: beam-pumping unit suspension load, beam-pumping unit torque, effective stroke, pump efficiency, hydraulic power, polished rod power and downhole system efficiency; wherein, each index is calculated as follows:

calculating the suspension point load of the oil pumping unit:

F_{\max} = (F_{r} + F_{L}) (1 + \frac{s n^{2}}{1790}) + F_{w}

F_{\min} = F_{r} (1 - \frac{d_{L}}{d_{r}} - \frac{s n^{2}}{1790}) + F_{w}

Pump efficiency: eta_p＝η_{Qi (Qi)}η_Becomeη_{Leakage net}

η_{Qi (Qi)}＝η_{Gas 1}η_{Gas 2}；

η_{Leakage net}＝η_{Drain 1}η_{Drain 2}

Hydraulic power:

polished rod power:

downhole system efficiency:

{EFF}_{down} = \frac{{HP}_{H}}{{HP}_{PR}}

optimizing the system scheme: by calculation of

And (b) selecting the (bi) with the largest element value in the result set as the optimal scheme, and determining the decision coefficient of each part in the steel wire rod oil pumping system.

TABLE 1

Static pressure of oil layer (Mpa)	32	Deep in oil layer (m)	3480.5
Static pressure of oil layer (Mpa)	32	Deep in oil layer (m)	3480.5	Saturated pressure (Mpa)	11.87	Crude oil density (g/cm ^3)	0.864
Water content (%)	65.6	Crude oil viscosity (m MPs)	24.5	Saturated pressure (Mpa)	11.87	Crude oil density (g/cm ^3)	0.864
Water content (%)	65.6	Crude oil viscosity (m MPs)	24.5	Wellhead pressure (Mpa)	0.5	Oil-gas ratio (m ^3/m ^3)	34.5
Modulus of elasticity of wire rope	1.6	Working fluid level (m)	1550	Wellhead pressure (Mpa)	0.5	Oil-gas ratio (m ^3/m ^3)	34.5
Modulus of elasticity of wire rope	1.6	Working fluid level (m)	1550	Wire rope density (Kg/m ^3)	7050	Oil well liquid production rate (m ^3/d)	32.5

TABLE 2

Oil pumping machine model	CYJ14-4.8-73HB
Oil pumping machine model	CYJ14-4.8-73HB			Series stroke (m)	4.2、3.6、3.0	Series jig times (r/min)	6、8、10
Series pump diameter (mm)	44、57、70、83	Series pump depth (m)	1200-2000	Series stroke (m)	4.2、3.6、3.0	Series jig times (r/min)	6、8、10
Series pump diameter (mm)	44、57、70、83	Series pump depth (m)	1200-2000	Automatic software-provided rod column collocation form sequence	Phi 19mm steel wire rope rod + phi 25mm conventional steel rod phi 22mm steel wire rope rod + phi 25mm conventional steel rod phi 25mm steel wire rope rod + phi 25mm conventional steel rod phi 22mm steel wire rope rod + phi 19mm steel wire rope rod + phi 25mm conventional steel rod phi 25mm steel wire rope rod + phi 22mm steel wire rope rod + phi 25mm conventional steel rod

Table 3 gives the predicted system index results for the different scenarios. Table 4 gives the results of the software auto-optimizing the spar combination calculations.

TABLE 3

Plan numbering	Design parameters of a project		System index calculation result
	Design parameters of a project		System index calculation result					Pump depth (m)	Pumping parameters (SXNXD)_P)	Supply and exhaust coordination	Fluid production volume (T/D)	Stroke efficiency (%)	Pump efficiency (%)	And the efficiency (%)
	LP-1	1200	4.8×6×57	Insufficient liquid supply	37.0	82.5	35.0	Pump depth (m)	Pumping parameters (SXNXD)_P)	Supply and exhaust coordination	Fluid production volume (T/D)	Stroke efficiency (%)	Pump efficiency (%)	And the efficiency (%)	30.1
LP-2	LP-1	1200	4.8×6×57	Insufficient liquid supply	37.0	82.5	35.0	1300	4.8×6×57	Coordination of	41.0	79.4	38.3	34.3	30.1
LP-2	LP-3	1500	4.8×6×57	Coordination of	46.3	72.4	47.9	1300	4.8×6×57	Coordination of	41.0	79.4	38.3	34.3	38.1
LP-4	LP-3	1500	4.8×6×57	Coordination of	46.3	72.4	47.9	1700	4.8×6×57	Coordination of	54.2	72.1	48.7	45.2	38.1
LP-4	LP-5	2000	4.8×6×57	Coordination of	62.1	69.6	57.1	1700	4.8×6×57	Coordination of	54.2	72.1	48.7	45.2	50.0
LP-6	LP-5	2000	4.8×6×57	Coordination of	62.1	69.6	57.1	2100	4.8×6×57	Coordination of	62.1	66.4	58.4	47.9	50.0
LP-6	LP-7	2300	4.8×6×57	Coordination of	64.8	65.7	60.7	2100	4.8×6×57	Coordination of	62.1	66.4	58.4	47.9	47.0
LP-8	LP-7	2300	4.8×6×57	Coordination of	64.8	65.7	60.7	2400	4.8×6×57	Coordination of	62.1	62.7	59.5	41.6	47.0
LP-8	LP-9	2500	4.8×6×57	Coordination of	59.5	59.5	57.4	2400	4.8×6×57	Coordination of	62.1	62.7	59.5	41.6	36.0
S-1	LP-9	2500	4.8×6×57	Coordination of	59.5	59.5	57.4	2000	4.8×6×57	Coordination of	62.1	69.6	57.1	50.0	36.0
S-1	S-2	3.8×6×57	Coordination of	46.3	58.0	55.2	35.2		4.8×6×57	Coordination of	62.1	69.6	57.1	50.0
S-3	S-2	3.8×6×57	Coordination of	46.3	58.0	55.2	35.2		2.8×6×57	Coordination of	25.1	43.0	42.1	14.2
S-3	N-1	2000	4.8×6×57	Coordination of	62.1	69.6	57.1		2.8×6×57	Coordination of	25.1	43.0	42.1	14.2	50.0
N-2	N-1		4.8×6×57	Coordination of	62.1	69.6	57.1	4.8×8×57	Coordination of	62.0	73.8	42.2	37.5		50.0
N-2	N-3		4.8×10×57	Coordination of	56.9	73.4	31.4	4.8×8×57	Coordination of	62.0	73.8	42.2	37.5	25.2
DP-1	N-3		4.8×10×57	Coordination of	56.9	73.4	31.4	2000	4.8×6×38	Coordination of	38.3	84.9	82.2	25.2	43.1
DP-1	DP-2	4.8×6×44	Coordination of	48.9	79.9	76.7	52.3		4.8×6×38	Coordination of	38.3	84.9	82.2		43.1
DP-3	DP-2	4.8×6×44	Coordination of	48.9	79.9	76.7	52.3		4.8×6×57	Coordination of	62.1	69.6	57.1	50.0
DP-3	DP-4	4.8×6×70	Coordination of	67.4	61.1	43.8	38.9		4.8×6×57	Coordination of	62.1	69.6	57.1	50.0

TABLE 4

Plan numbering	Rope pole		Weighting rod		Maximum load (KN)	Minimum load (KN)	Remarks for note
	Rope pole		Weighting rod					Combination of	Stress range ratio (%)	Combination of	Stress range ratio (%)
	LP-1	Φ22×598+Φ19×352	55	Φ25×250				Combination of	Stress range ratio (%)	Combination of	Stress range ratio (%)	34	62	23
LP-2	LP-1	Φ22×598+Φ19×352	55	Φ25×250	Φ22×641+Φ19×389	60	Φ25×271	38	67	25		34	62	23
LP-2	LP-3	Φ25×668+Φ22×473	60	Φ25×359	Φ22×641+Φ19×389	60	Φ25×271	38	67	25		45	88	36
LP-4	LP-3	Φ25×668+Φ22×473	60	Φ25×359	Φ25×717+Φ22×594	69	Φ25×389	52	100	41		45	88	36
LP-4	LP-5	Φ25×797+Φ22×834	83	Φ25×369	Φ25×717+Φ22×594	69	Φ25×389	52	100	41		60	117	49
LP-6	LP-5	Φ25×797+Φ22×834	83	Φ25×369	Φ25×812+Φ22×886	86	Φ25×402	60	120	51		60	117	49
LP-6	LP-7	Φ25×1829	＞100	Φ25×471	Φ25×812+Φ22×886	86	Φ25×402	60	120	51		60	143	67	Machine for workingRod overload
LP-8	LP-7	Φ25×1829	＞100	Φ25×471	/	/	/	/	/	/	Overload of machine rod	60	143	67	Machine for workingRod overload
LP-8	LP-9	/	/	/	/	/	/	/	/	/	Overload of machine rod	/	/	/	Overload of machine rod
S-1	LP-9	/	/	/	Φ25×797+Φ22×834	83	Φ25×369	60	117	49		/	/	/	Overload of machine rod
S-1	S-2	Φ22×1644	87	Φ25×357	Φ25×797+Φ22×834	83	Φ25×369	60	117	49		45	98	45
S-3	S-2	Φ22×1644	87	Φ25×357	Φ22×1657	61	Φ25×343	28	85	46		45	98	45
S-3	N-1	Φ25×797+Φ22×834	83	Φ25×369	Φ22×1657	61	Φ25×343	28	85	46		60	117	49
N-2	N-1	Φ25×797+Φ22×834	83	Φ25×369	Φ25×1608	100	Φ25×392	64	140	52	Overload of machine rod	60	117	49
N-2	N-3	Φ25×1522	100	Φ25×478	Φ25×1608	100	Φ25×392	64	140	52	Overload of machine rod	72	148	44	Overload of machine rod

DP-1	Φ22×1647	56	Φ25×353	21	79	44
DP-1	Φ22×1647	56	Φ25×353	21	79	44	DP-2	Φ22×1614	70	Φ25×386	31	89	44
DP-3	Φ25×797+Φ22×834	83	Φ25×369	60	117	49	DP-2	Φ22×1614	70	Φ25×386	31	89	44
DP-3	Φ25×797+Φ22×834	83	Φ25×369	60	117	49	DP-4	Φ25×1620	＞100	Φ25×380	91	170	51	Overload of machine rod

Referring to fig. 2 to 5, the influence results of the main pumping operation parameters (pump depth, stroke frequency and pump diameter) on the system index are shown.

Analysis of results

Effect of Pump depth on System index

As can be seen from fig. 2 and table 3: as the pump depth is increased from 1200 m to 2400 m, the stroke efficiency is gradually reduced, and the liquid production amount, the pump efficiency and the underground efficiency are gradually increased; the pole column combination is sequentially increased according to (phi 22+ phi 19) steel wire rope pole + phi 25 weighted pole, (phi 25+ phi 22) steel wire rope pole + phi 25 weighted pole, and phi 25 steel wire rope pole + phi 25 weighted pole, and the stress range ratio of the rope poles and the suspension point load of the oil pumping unit are gradually increased. However, after the pump depth is increased by 2000m, the yield and the pump efficiency are hardly increased, and the downhole efficiency is reduced. Indicating that the production cannot be increased by increasing the pump depth alone, the reasonable pump depth for this well at this pumping parameter is 2000 meters.

Influence of stroke on System index

As can be seen from fig. 3 and table 3: as the stroke is increased from 2.8 meters to 3.8 meters, the stroke efficiency, the liquid production amount, the pump efficiency and the underground efficiency are gradually increased, and the increase amplitude is larger; the pole column combination is sequentially increased according to phi 22 steel wire rope pole + phi 25 weighting pole, (phi 25+ phi 22) steel wire rope pole + phi 25 weighting pole, and the stress range ratio of the rope poles and the suspension point load of the oil pumping unit are gradually increased. The pumping parameter selection should be described with consideration first of all for selecting a long stroke.

Impact of Impulse frequency on System index

As can be seen from fig. 4 and table 3: the stroke efficiency and the liquid yield are slowly increased with a small amplitude along with the increase of the stroke frequency from 6r/min to 8r/min, and the stroke efficiency and the liquid yield are reduced after the stroke frequency exceeds 8 r/min. The pumping efficiency and the underground efficiency are greatly reduced along with the increase of the stroke frequency, and the required diameter of the rod column and the load of the pumping unit are gradually increased. The yield can not be increased by a method of increasing the stroke frequency, and the stable operation of the pumping unit is facilitated by selecting the low stroke frequency of 6r/min for production.

Influence of pump diameter on system index

As can be seen from fig. 5 and table 3: the liquid production amount is greatly increased along with the increase of the pump diameter from 38mm to 57mm, but the increase of the liquid production amount is reduced after the pump diameter exceeds 57 mm; the stroke efficiency and the pump efficiency are greatly reduced along with the increase of the pump diameter; downhole efficiency increases first and then decreases. The required rod string diameter and pumping unit load are increasing. The diameter of the well pump should not be too large, and phi 44 and phi 57 pumps are preferred.

Comprehensively considering multiple objective and multiple factors such as liquid production amount, stroke efficiency, pump efficiency, underground efficiency, load limitation of a pumping unit and the like, the optimization design result of the well is as follows: a pump is designed to have a deep 2000m stroke, a stroke of 4.8m and a stroke frequency of 6r/min, a rod column combined steel wire rope rod (phi 25 multiplied by 797+ phi 22 multiplied by 834) and a conventional rod (phi 25 multiplied by 369), namely an LP-5 scheme is selected.

(1) The invention can comprehensively and quantitatively calculate the supply and discharge coordination of the pumping well of the steel wire rope and the conventional rod-mixed rod column, select reasonable machine-pump working parameters and the mixed rod column combination, analyze the stress condition of the rod column and predict the system index by applying the system engineering analysis method.

(2) According to the preset sequence of the combination form of the mixed rods and the columns, the rod and column combination of the oil well under specific working parameters is economical and reliable, and the optimal combination of the rod and column design is achieved.

(3) The working parameters of the oil well have great influence on the indexes of the oil pumping system of the steel wire rope and the conventional rod mixed rod string, scientific pumping parameters are determined according to the requirements of target liquid production quantity, pump efficiency, underground system efficiency and the like, and the calculation and practice show that: the combination of a steel wire rope rod with long stroke, low stroke frequency, large pump depth, small pump diameter and equal stress range ratio and a conventional rod with larger diameter are reasonable modes of an oil pumping system of a steel wire rope and conventional rod mixed rod string.

(4) The choice of pump depth should be very careful in the design. A problem with reasonable pump depth for a given well operating parameter is that beyond this pump depth not only does not increase production, but it also causes a decrease in downhole system efficiency, increases equipment energy consumption and instability.

Finally, it should be noted that: the above embodiments are only used to illustrate the present invention and do not limit the technical solutions described in the present invention; thus, while the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted; all such modifications and variations are intended to be included herein within the scope of this disclosure and the present invention and protected by the following claims.

Claims

1. An implementation method of a steel wire rope rod oil pumping system is characterized in that: the method at least comprises the following steps:

2. The method for realizing the steel wire rope rod oil pumping system according to claim 1, is characterized in that: the calculation of the liquid supply capacity of the oil well is specifically as follows: within the range allowed by the IPR curve, namely: q is more than 0_t＜q_tmaxSelecting a group of liquid production values, and calculating corresponding bottom hole flowing pressure according to the IPR curve; or selecting a group of bottom hole flowing pressure values, and calculating corresponding liquid supply values according to the IPR curve;

q_tmaxm is the maximum fluid production³/d；

q_tM is the amount of liquid produced³/d。

3. The method for implementing the steel wire rope rod oil pumping system according to claim 2, is characterized in that: the liquid supply capacity of the oil well is calculated by the following formula:

flow pressure is calculated according to the liquid production amount:

P_{wf} = P_{r} - \frac{q_{t}}{J}

when q is_b＜q_t≤q_omaxWhen is, P_wf＝F_oP_{wf oil}+F_wP_{wf water}

P_{wf} = F_{w} (P_{r} - \frac{q_{o \max}}{J}) - (q_{t} - \frac{q_{o \max}}{J}) \frac{CD}{CG}

CD = F_{w} \frac{0.001 q_{o \max}}{J} + 0.125 F_{o} P_{b} [- 1 + \sqrt{81 - 80 \frac{0.999 q_{o \max} - q_{b}}{q_{o \max} - q_{b}}}]

CG＝0.001q_omax

calculating the liquid production amount by the flow pressure:

when P is present_b＜P_wf≤P_rWhen q is greater than q₁＝J(P_r-P_wf)

When P is present_wfG＜P_wf≤P_bWhen B is not equal to 0,

q_{t} = \frac{- C + \sqrt{C^{2} - 4 B^{2} D}}{2 B^{2}}

when B is 0, q_t＝D/C

P_{wfG} = F_{w} (P_{r} - \frac{q_{o \max}}{J})

A = \frac{P_{wf} + 0.125 F_{0} P_{b} - F_{w} P_{r}}{0.125 F_{0} P_{b}}

B = \frac{F_{w}}{0.125 F_{0} P_{b} J}

C = 2 AB + \frac{80}{q_{o \max} - q_{b}}

D = A^{2} - 80 \frac{q_{b}}{q_{o \max} - q_{b}} + 81

CD = F_{w} \frac{0.001 q_{o \max}}{J} + 0.125 F_{o} P_{b} [- 1 + \sqrt{81 - 80 \frac{0.999 q_{o \max} - q_{b}}{q_{o \max} - q_{b}}}]

CG＝0.001q_omax

wherein: q. q.s_omaxM is the maximum oil production³/d；

q_tmaxTo the maximum yieldLiquid amount, m³/d；

q_oFor oil production, m³/d；

q_tM is the amount of liquid produced³/d；

q_bM is the oil production at bubble point pressure³/d；

p_rIs the formation pressure, MPa;

p_wfis bottom hole flowing pressure, MPa;

p_bbubble point pressure, MPa;

F_wwater content,%; f_o＝1-F_w；

J is the fluid production index, m³/d·MPa。

4. The method for realizing the steel wire rope rod oil pumping system according to claim 1, is characterized in that: the characteristic parameters of the steel wire rope rod are calculated by the following formula:

damping coefficient of the wire rope rod:

(1) structural damping

The equivalent damping of the vibrations produced by the structural damping is:

determined by experiments;

(2) fluid viscous damping

The fluid viscous damping of the wire rope rod is:

in the formula: eta is the hydrodynamic viscosity coefficient pa · s;

m = \frac{d_{t}}{d_{r}},

wherein:

The combined length of the steel wire rope mixed rod column is as follows:

wherein: [ sigma ]_max]_i＝S_F(0.25T_r+0.5625σ_min.i)

T_rthe maximum tensile strength of the steel wire rope sucker rod is N/mm²；

I is the number of stages of the sucker rod from top to bottom;

σ_max.i、σ_min.iis the pumping rod of the I-levelMaximum and minimum stress at the tip, N/mm²。

In order to ensure that the steel wire rope sucker rod is always in a stretching state when in lower stroke and the structural extension of the lower end can be eliminated, the added weight of the weighting rod is required to offset the buoyancy W borne by the steel wire rope and the weighting rod_r0Semi-dry friction force W between the bushing and the plunger_dAnd a hydraulic resistance W generated when the mixed liquid flows through the traveling valve_wThe inertia force W of the weight lever itself_vFriction force with liquid W_riAnd can eliminate partial structural elongation W of the steel wire rope_j. Therefore, the weight bar to be added at the lower end of the pole column at least meets the following requirements:

W_s≥W_d+W_v+W_s+W_w+W_ri+W_j+W_r0

5. the method for realizing the steel wire rope rod oil pumping system according to claim 1, is characterized in that: the pump discharge dynamics data is calculated by the following formula:

Q＝0.001131ηSnD_p ²

wherein,

q is the displacement of the pump and Q is the displacement of the pump,

eta is the pump efficiency and is the pump efficiency,

s is the stroke of the oil pumping machine,

n is the stroke frequency of the oil pumping unit,

D_pthe pump diameter.

6. The method for realizing the steel wire rope rod oil pumping system according to claim 1, is characterized in that: the well condition indicators include at least: beam-pumping unit suspension load, beam-pumping unit torque, effective stroke, pump efficiency, hydraulic power, polished rod power and downhole system efficiency; wherein, each index is calculated as follows:

calculating the suspension point load of the oil pumping unit:

F_{\max} = (F_{r} + F_{L}) (1 + \frac{s n^{2}}{1790}) + F_{w}

F_{\min} = F_{r} (1 - \frac{d_{L}}{d_{r}} - \frac{s n^{2}}{1790}) + F_{w}

Pump efficiency: eta_p＝η_{Qi (Qi)}η_Becomeη_{Leakage net}

η_{Qi (Qi)}＝η_{Gas 1}η_{Gas 2}；

η_{Leakage net}＝η_{Drain 1}η_{Drain 2}

Hydraulic power:

polished rod power:

downhole system efficiency:

{EFF}_{down} = \frac{{HP}_{H}}{{HP}_{PR}}

7. the method for realizing the steel wire rope rod oil pumping system according to claim 1, is characterized in that: the system scheme optimization is as follows: and (3) calculating: