Introduction

Nowadays in Kazakhstan autonomous water supply of agricultural consumers both for domestic needs and for irrigation of land plots, especially in southern regions, is provided due to underground waters from specially developed wells, mainly by means of electrical submersible pumps.

However, the existing technology of water lifting from wells by means of electrical submersible pumps requires for water lifting pipes, their weight per one pump facility is 500…1000 kg, it requires high operational expenditures for assembling procedures.

Application of the challenging technology of pipeless water lifting (by well casing) using packers of various designs installed on pump delivery pipe, separating pump suction and delivery portion in the well, makes it possible to reduce specific metal consumption by 2…3 times, to improve power indices of pump facility, to reduce significantly operational costs of assembling activities, to increase operational lifetime of well casing, to exclude water contamination and well clogging.

However, implementation of pipeless water lifting into water supply and melioration is restricted due to the unavailability of required typical sizes of packers for electrical submersible pump as a consequence of insufficient theoretical and experimental researches of technological processes occurring in packer. Thus, development of the required typical sizes of hydraulic packers and appropriate researches, including experimens, with electrical submersible pumps intended for pipeless water lifting in water supply and melioration is an urgent issue.

Review of existing works

While investigating into resource saving technology of pipeless water lifting from wells (by well casing) by means of electrical submersible pumps using hydraulic packers, great attention was paid to experimental studies both of technological process and of processes running in packers [1-8].

Numerous works are devoted to development of designs, theoretical and experimental studies of pipeless water lifting from wells with packers for electrical submersible pumps of domestic and foreign researchers: A. G. Zhelobovsky, V.S. Usenko, A. D. Gurinovich, V. D. Gladkov., M. A. Lavrov (1975-1990) [9-16], A. I. Fabrikov, A. A. Sil’chenko, V. M. Kostyukevich., R. S. Ariel’. (1982-1985) [13,14,15], V. N. Fisenko, M. M. Trusov, V. Ya. Rait (1985-1994) [16,17,18], S. V. Morozov, A. A. Pevzner, Yu. P. Kalmykov, L. A. Kolodyuk, S. S. Poleshchuk(1986-1990) [19], A. A. Yakovlev, A. B. Konyrbaev ( 1986-2000) [1-3,20-23], V. D. Krapivin [24], E. Sarkynov, Zh. Z. Zhakupova [4, 5, 6].

In 1975-95 such companies as TsNIIKIVR (Minsk, Byelorussia) [9-16], Soiuzgiprovodkhoz (Moscow), and YuzhNIIGiM (Novocherkassk, Russia) [16] carried out researches on development of packers for electrical submersible pumps intended for pipeless water lifting from wells with the conventional diameter of 8, 10 and 12 inches. Packer sealing unit is made of self-compressing rubber collar (Fig. 1, a and b), and fixing mechanism in the form of bars with conic grooves, they are driven mechanically by means of rods used for lowering of packer with electrical submersible pump. Experimental specimens demonstrated positive results.

Kazakh R&D Institute of water management (1980-2000, Kazakhstan) [18-20] performed researches of pipeless water lifting and developed packers for electrical submersible pumps of three typical sizes for wells with conventional diameter of 8, 10, and 12 inches intended for melioration. Packer (Fig. 1 c ) is comprised of the body in the form of pipe connected to the pump delivery pipe, equipped with fixing mechanism, made of shims and sealing collar, flanged to the pipe and installed in cylindrical socket moving by the pipe. Fixation and preliminary compression of packer in well is performed mechanically by means of rods used for lowering of packer with electrical submersible pump into well. The project was finished by production of experimental batch of packers, positive results were achieved upon implementation of the devices in Kazakhstan melioration.

Figure 1: Layouts of well known packers for electrical submersible pumps for pipeless water lifting. 1 – pump; 2 – packer; 3 – well casing; 4, 5 – handling and fixing mechanisms. а) YuzhNIIGiM design; b) TsNIIKIVR design; c) KazNIIVKh design. Click here to View figure

In 1986-90 NIS Rovno Pedagogical Institute [21] on contractual terms with Gosagroprom of Kazakhstan performed researches and development of packer for electrical submersible pump: UBV Goryn (Fig. 2, a) for water lifting by well casing with the diameter of 6 inches. sealing portion of the design was the same as in the design of Kazakh R&D Institute of water management: sealing collar, flanged to the pipe and installed in cylindrical socket moving by the pipe. However, some innovations were applied, aimed at simplification of disassembling activities (decrease in detachment of the collar), by means of varying height of socket side wall contacting with the collar. Experimental specimen was manufactured, demonstrating positive results.

NPO Kazselkhozmehanizatsiya (KazNIIMESKh) (1986-2000, Kazakhstan) [1–3,20–23] performed study of pipeless water lifting including development of three typical sizes of hydraulic packers for electrical submersible pumps, Grade ETsV for wells with conventional diameter of 5, 6, 8 inches for pasture water supply. A distinctive feature of the packer design (Fig. 2, b) for pipeless water lifting includes sealing portion in the form of two alternatively operating sealing collars, installed in the body with axial hole, which is fixed to the pump delivery pipe. The packer is equipped with fixing, detwisting and rope handling interconnected mechanisms, and sealed well head with outlet connection. The project was finished in 1997 by development of experimental specimens, state commissioning tests with UPG-168М typical size for 6-inch wells, and recommendations for their commercial production.

Among other designs the inflatable packer by V. D. Krapivin [24] is of interest (Fig. 2, c), USSR Authors’ certificate No. 252867, however, data on its development are unavailable.

Figurer 2: Layouts of well known packers for electrical submersible pump for pipeless lifting. 1 – pump; 2 – packer; 3 – well casing; 4, 5 – handling and fixing mechanisms a)design of NIS Rovno Pedagogical Institute; b) design of NPO Kazselkhozmehanizatsiya; c) design by V. D. Krapivin. Click here to View figure

Scope of researches

Therefore, the studies were aimed at pipeless water lifting by means of electrical submersible pump and proprietary packer designs with substantiation of parameters; however, no investigations were carried out with regard to processes in the packers and no typical sizes of packers were developed with the aim of efficient implementation for pasture and general purpose water supply and melioration.

No investigations were performed with packers with ejector, involving water intake by the action of vacuum generated in ejector, with subsequent improvement of power indices of pump facility: increase by 20-30 % in comparison with the existing parameters of water lifting and efficiency of pump facility.

Objectives of the study

The work is aimed at investigation into the processes in hydraulic packer upon pipeless water lifting from wells, verification of reliability and adjustment of theoretical assumptions for the processes: fixation of hydraulic packer with electrical submersible pump in well, compression of hydraulic packer with well casing wall and pinching of packer detwisting mechanism in well; adjustment of main parameters of required typical sizes of packers upon experiments.

In Kazakh National Agrarian University (2011-2014, Kazakhstan) [7] we carried out study aimed at improvement of pipeless water lifting in order to increase efficiency of utilization of underground waters in the system of general purpose water supply and melioration.

Flowchart of pipeless underground water lifting was developed and adopted for instigations with innovative hydraulic packer equipped with ejector, providing 20-30 % increase in supply and efficiency of pump facility in comparison with the existing analogues.

General layout of pipeless water lifting from wells by means of electrical submersible pump using the innovative hydraulic packer with ejector is illustrated in Fig. 3.

Figure 3: Flowchart of pipeless water lifting from wells by means of electrical submersible pump using new hydraulic packer with ejector. 1 – electrical submersible pump ; 2 – ejector; 3, 6 – bottom and top cap; 4 body; 5 – bottom and top sealing ring; 7, 9 – back-pressure and relief valves; 8 – fixing stop; 10, 11 – rod and roller of detwisting mechanism; 12, 13 – suspension unit and rope; 14 – well casing well casing; 15 – well head with take-off connection; 16 – take-off pipeline. Click here to View figure

The following notations of process variables of pipeless water lifting and technical parameters of hydraulic packer are applied in Fig, 3: H is the water lifting height; H_p is the pump head; Q,Q_PF is the flow rate of pump and pump facility;d₀, D_p, D_w, d_R  are the diameter of packer through hole, the packer outer diameter, the well internal diameter and the diameter of rubber-coated roller of detwisting mechanism, respectively; ∂_S, ∂_R are the rod lengths of fixing stop and double-armed lever of detwisting mechanism; β, α are the vertical slope angles of fixing stop and double-armed lever of detwisting mechanism; T_SH, T_N  are the shimming forces and normal pressure, acting on the fixing stop; T_T, T_R  are the forces of tension and retraction of the packer sealing ring; ,  are the forces of hydraulic pressure acting on the packer and detachment upon packer disassembling; P_∏  is the excessive water pressure in the sealing ring; R_g, T_det  are the width, height and thickness of the sealing ring; b_r, h_r, δ_r  is the stroke of back-pressure valve; m_p, m_p are the weights of packer and electrical submersible pump, respectively.

In order to achieve the required objective we revealed the most significant factors influencing on the processes in hydraulic packer in the form of functional and analytical equations, the results are given on determination of main process variables of pump facility H, H_P, N, η_H, η_{PF =  f (Q)}with electrical submersible pump ETsV6-10-80 in combination with hydraulic packer with ejector upon water lifting via well casing and pipes [5, 6, 7]:

the main analytical dependencies of processes in hydraulic packer with ejector upon pipeless water lifting from wells in order to verify their reliability:

1) forces of hydrodynamic pressure R_g, shimming T_s and normal pressure T_N, acting on packer and packer fixing stop:

2)  tension forces T_T of sealing ring of hydraulic packer and excessive water pressure P_P in packer in dynamic operation mode:

checking of provisions of reliable fixation

checking of provisions of operation of packer detwisting mechanism in terms of interrelation of friction forces  T’_FR of pressing rollers and force T_R of reactive torque upon pump starting

determination of shimming (detachment) force T_det upon packer disassembling and comparison with theoretical value

where Pπ_max  is the maximum excessive pressure in the packer, kPa; m_fris the spefici weight of rope of handling mechanism, kg/m;  is the water lifting height (rope length), m;

determination of disassembling force of packer with electrical submersible pump and comparison with theoretical value

where , mπ, m_H, m_K are the weights of packer, pump, and rope, respectively, kg; Т_N¹  is the force of normal pressure on pressing roller of detwisting mechanism, N; f_nep  is the friction coefficient of rubber-coated roller along steel pipe; is the number of rods of detwisting mechanism.

Experimental

Procedures

All experiments were carried out by single factor method. The head range of electrical submersible pump ETsV 6-10-80 equaled to  H_p= 20 m; 30 m; 50 m; 70 m; 80 m; 90 m. The diameter limits of well casing were D_CK=152 mm and 203 mm.

The head of electrical submersible pump H_p  was varied by throttling at the outlet of take-off connection of sealed head of bench well casing by means of valve according to pressure gauge. The internal diameter of well casing  D_CK was varied by insertion pipe.

While testing the following measurements were made for at least three times according to known procedures [23-30]: visually — flow rate of pump facility Q_PF by volumetric method using measuring tank and stopwatch; using records on oscilloscope and visually — readings of pressure sensors and reference gauges on packer inlet and outlet (in bench well casing — in the plane of packer outlet); using records on oscilloscope readings of force sensor installed in well casing wall in the contact area with packer fixing stop in order to measure acting force of normal pressure Т_Ν.

The experiments were performed in the following sequence. Packer parameters were determined and, varying pump head H_P in preset intervals, visual measurements and records of oscilloscope readings were carried out.

Fixation and compression of packer upon combined operation with pump were studied by oscillograms recorded by oscilloscope.

Detwisting and handling of packer with pump were studied upon individual experiment, where normal pressure  on the roller T¹_N of detwisting mechanism, lateral force T¹_N, f_fr  rolling force T¹_N f_nep, reactive torque upon starting  of pump electric motor М_R and shimming force T_ofr of packer with pump were measured by dynamometer.

The acquired experimental data were processed and analyzed by known procedures [30-40]. The obtained experimental data were applied for determination of process variables according the following equations [2,7]:

Pump facility flow rate

where

V_t is the lifted water volume per experiment, m³; t_i  is the time of measurement of lifted water volume per experiment, s; m  is the number of experiments.

where k is the conversion factor of instrument readings, W/unit; W_A W_B W_C;  are the phase readings of instrument, units.

Pump efficiency coefficient η_H and pump facility η_PF:

where Q, Q_PF are the flow rate of pump and pump facility at corresponding head and water lifting height, m³/s; ,  are the water lifting height and pump head, m;   is the specific weight of lifted water, N/m³.

where , Pπ_i, P_Kπi are the excessive water pressures at packer inlet and outlet, Pa.

Coefficient of local resistances in packer:

where d₀  is the inner diameter of packer axial hole, m;ℑ₀  is the water velocity in packer, m/s; g=9,81 m/s  is the acceleration of gravity; Q_PF  is the flow rate of pump facility corresponding to local losses in packer е h_wn, m³/S.

Coefficient of friction of packer fixing stops and detwisting device pressing rollers on the well casing surface:

where T_Ni is the force of normal pressure, N; T_FR  is the friction force, N.

Reliability of theoretical dependencies was verified by approximation of experimental data, assuming the correlation coefficient of at least 0.95 as estimation criterion, that is, divergence of experimental data with theoretical is in the range of 5 %.

Layout of test bench for experimental study of hydraulic packer with electrical submersible pump is illustrated in Fig. 4, and general view in Fig. 5 [7].

Figure 4: Layout of test bench for experimental study of hydraulic packer in combination with electrical submersible pump. 1 – shaft well; 2 – electrical submersible pump ; 3 – hydraulic packer; 4 – well casing; 5 – force sensor; 6 – hydraulic hose; 7 – adapter; 8, 14 – pressure sensors; 9, 11, 13 – reference pressure gauges; 10 – head with take-off connection; 12, 19 – valves; 15, 16 – water lifting pipelines;17, 21 – discharge and measuring tanks; 20 – discharge hose; 22 – pump control board. Click here to View figure

Figure 5: General view of the test bench for experimental study of hydraulic packers in combination with electrical submersible pump. Click here to View figure

The bench is comprised of the shaft 1 with the diameter of 1 m and the depth of 3.5 m, filled with tap water, the interchangeable well casing 4 with the height of 1.2 m and internal diameter of 152 mm and 203 mm, corresponding to the considered typical sizes, the electrical submersible pump 2 with cable and the control panel 22, the packers 3, the sealed heads 10 with the pressure gauge 11, the valves 12 and 19, the discharge pipe 15 and the hose 20, the handling mechanism with rope (not shown in the figure), the electrical hoist with the rope installed on pulley above the shaft center (not shown), the measuring tank 21 and the water lifting pipes 16 with height of 18.5 m, the tank 17 and the discharge hose 18.

In order to measure the water excessive pressure at packer inlet and outlet the test bench is equipped with the pressure gauges 8 and 14 and the reference gauges 9 and 13, connected via the T-adapters 7 and the hydraulic hose 6 with the packer inlet connection 3 and well casing, the force of normal pressure on fixing stops was measured by the dynamometer 5.

In order to achieve normal height of water lifting the test bench was equipped with the water lifting pipes 16 with the height of 18.5 , and the tank 17 with the discharge hose 18, which made it possible to check activation of the packer sealing ring upon shut down of the pump 2.

The experimental study of hydraulic packers were aided with the following instruments: oscilloscope N-041; reference gauges with scale of 1570 kPa; barometer-aneroid, technical thermometers; dynamometer.

Results

Determination of main process variables of pump facility with electrical submersible pump ETsV6-10-80 upon water lifting by well casing and by pipes

The experimental results of determination of main process variables of pump facility with electrical submersible pump ETsV6-10-80 upon water lifting by well casing (in combination with hydraulic packer) and by pipes are illustrated in Fig. 6, where pump head , water lifting height , power consumption of pump N_H  and pump facility , as well as efficiency η_H and η_PF  and  are shown as a function of flow rate Q , that is,  H, H , N, N, η[2,7].

It can be seen in the figure that application of innovative packer with ejector in pipeless water lifting improves the parameters of pump facility increasing glow rate Q_PF  and efficiency  by 1.2 times at equal power consumption per drive of electrical submersible pump due to effect of water suction in well casing by vacuum generated in packer by ejector.

Figure 6: Experimental results of determination of main process variables of pump facility with electrical submersible pump ETsV6-10-80 upon water lifting by well casing(in combination of hydraulic packer) and upon water lifting by pipes. water lifting height and pump head;power consumption by pump and pump facility; efficiency of pump and pump facility;  – flow rate. ——-experimental curves with well casing; —X–experimental curves with water lifting pipes. Click here to View figure

The following main process variables of pump facility with electrical submersible pump ETsV6-10-80: in combination with packer – upon variation of water lifting height (pump head) H_p=20…90m flow rate Q=5.42…1.35 dm^3_/s, at which power consumption N_PF= 5.85…4.4 kW and efficiency η_PF=022….0.398…0.28  at its maximum QPF = 2.2…4.5 dm³/s ; in combination with water lifting pipes – upon variation of water lifting height (head) Н_р=28.4…89.3 m flow rate Q_H=4.27…1.17 dm^3_/s, at which power consumption N_{H = 5.99…4.5 kW}  and efficiency η_H= 0.20…0.35…0.22  at its maximum Q_H=2…35dm³/s.

Study of fixation of packer and pump in well

The main estimation criteria of fixation of packer and pump in well were selected as follows: in dynamic mode — force of hydraulic pressure R_g and and in static mode — the height of water lifting Н and vertical angle β of slope of fixing stop.

Fixation of packer in dynamic mode is presented by theoretical (4) and experimental dependences in Fig. 7.

Figure 7: Hydraulic pressure force Rg  acting on packer as a function of excessive pressure Рlw of lifted water.   Click here to View figure

The study demonstrated that the force of hydraulic pressure R_g, acting on the packer, increases linearly with increase in excessive pressure of lifted water at packer output P_∏ (increase in water lifting height Н) and with increase in packer working diameter D_np. Thus, upon increase of P_∏ from 0 to 1500 kpa: at D_np= _{154 mm Rg} increases from 0 to 27.8 kN_, and at _Dnp = 205 mm Rg increases from 0 to 49.8 kN.

In order to verify the reliability of theoretical assumptions Rg = f(P_Π), Eq. (4), the curve in fig.7 shows experimental and theoretical dependences for packer with working diameter D_np=154 mm where upon experimental variation of P_Πfrom 196 kPa to 878 kPa and theoretical variation of P_ΠT =199.3…877.9 k_Pa the the force of hydraulic pressure varied in the following range: in terms of experimental data — Rg_э = 3.54 kN…16.24 kN, in terms of theoretical data — Rg_т = 3.71 K_N…16.35. The divergence between experimental and theoretical data was (4.6…0.7) %, thus confirming the reliability of the equation according to definition of Rg_т [6, 7].

Shimming forces Т_з and normal pressure Т_Ν, acting on packer fixing stop, as a function of hydrodynamic pressure Rg are illustrated in Fig. 8 at constant vertical angle of slope of fixing stops β = 1.326 rad (76^о) and internal well diameter D_ск = 154 mm.

Figure 8: Shimming forces Тs and normal pressure ТΝ, acting on packer fixing stop as a function of hydrodynamic pressure Rg . Click here to View figure

The functions Т_з, Т_Ν = f(Rg) are given without accounting for (Т_з, Т_Ν) and with accounting for friction forces (Т_Зт, Т_Νт) of sealing rings of packer body against internal well wall – bottom one upon dynamic mode and top one upon static  mode of operation [2 ,7 ].

It can be seen in the figure that with increase in the force of hydraulic pressure Rg on packer fixing stop the active forces Т_з and Т_Ν also increase. Thus, with increase in  from 0 to 5.4 kN Т_Зт increases from 0.422 kN to 5.9 kN and Т_Ν from 1.7 kN to 23,.6 kN.

In order to verify the reliability of equations for determination of shimming forces Т_з, Eq. (5), and normal pressure Т_Ν, Eq. (6 ), the plot in Fig. 9 shows theoretical and experimental dependences Т_Зт, Т_Νт = f(Rg) at β = 1.326 rad (76^о) and D_ск = 154 mm. Upon experimental variation of Rg_э from 0 to 5.41 kN and theoretical variation of Rg_т=0 to 5.45 kN the forces Т_з and Т_Ν varied in the following ranges: in terms of experimental data — Т_Зэ = 0.42…2.16 kN and Т_Νэ = 1.7…8.85 kN, in terms of theoretical data — Т_Зт = 0.422…2.18 kN and Т_Νт = 1.69…8.736 kN. The divergence between experimental and theoretical data was up to 4.9 % for Т_Ν and up to 1 % to Т_З, thus confirming the reliability of the obtained equations.

Upon static mode of hydraulic packer (inactive pump) Figs. 9 and 10 illustrate normal pressure Т_Ν and shimming force Т_з of packer fixing stop as a function of water lifting height Н at upper limit of optimum vertical angle of slope of fixing stops β = 1.466 rad (84^о) and two typical packer working diameters D_пр = 154 mm and 205 mm, respectively [ 2, 7].

Figure 9: Normal pressure force ТΝ, acting on packer fixing stop as a function of water lifting height Н in static mode.   Click here to View figure

It can be seen in the figure that with increase in the water lifting height Н the forces Т_Ν and Т_з, acting on packer fixing stop increase according to curvelinear relation, increasing with increase in the packer working diameter D_пр.

With variation in the water lifting height Н from 0 to 120 mm the forces Т_Ν and Т_з vary in the following ranges: at D_пр = 154 mm, Т_Ν = 4.01…21.79 kN and Т_з = 0.422…2.29 kN; at D_пр = 205 mm, Т_Ν = 6.84…60.22 kN and Т_з = 0.719…6.33 kN.

In order to verify the reliability of fixation, Eq. (9), that is, validity of the condition Т_fr = Т_Ν ∙ f_fr ≥ Т_з, when the friction forces of fixing stop against internal wall of well casing should be higher than its shimming forces Т_з, Fig. 7 illustrates the dependences Т_fr = f(Н). Calculated values of friction forces Т_fr at the coefficient of friction f_fr = 0.18 (steel against steel) with increase in water lifting height Н from 0 to 120 m increase and equal to: at packer working diameter D_пр = 154 mm, Т_fr = 0.72…3.92 kN >Т_з = 0.422…2.29 kN; at D_пр = 205 mm, Т_fr = 1.23…10.82 kN >Т_з = 0.719…6.33 kN, thus confirming validity of the aforementioned condition with the marginal coefficient of friction forces Т_fr in excess of shimming forces, equaling to 1.71.

Figure 10: Shimming force of packer fixing stop Тз and its friction force Тfr as a function of water lifting height Н in static mode.   Click here to View figure

Aiming at increase in the fixation reliability of packer with pump in well the contacting surface of fixing stops against well wall was made with grooves, when the coefficient of friction increases from 0.15…0.18 to 0.4…0.5 and, respectively, the marginal coefficient of friction force increases to 3.8…4.7. The study established that the reasonable vertical angle of slope β of fixing stop is 1.396…1.466 rad (80^о-84^о) at the coefficient of friction of fixing stop against well  casing f_fr = 0.15…0.18 (steel against steel).

With increase in the coefficient of friction to f_fr = 0.4…0.5 due to grooved surface of fixing stop, which was in fact implemented in experiments, the lower limit of slope angle of fixing stop can be decreased to 76^о (1.226 rad), at which the marginal coefficient of friction forces remains nearly the same at upper limit of the angle (β = 84^о) and f_fr = 0.18 and equals to 1.60…2.0 [2,7].

Investigation into compression of hydraulic packer

Excessive pressure of lifted water in packer Р_п. was selected as the main estimation criterion of compression parameters.

Compression of hydraulic packer against well casing wall by means of hydraulic expansion of sealing ring, bottom one upon dynamic mode and top one upon static mode, was experimentally studied using oscillograms of pressure gauges.

The study revealed that the sealing ring expands in 2.5…3 s after pump start at excessive pressure Р_Пmin = 107.9 kPa and is in steady mode in 1…1.5 s, that is, total time from pump start to steady mode of packer operation equals to 3…4 s. Herewith, the initial pressure of compression does not depend on the water lifting height, and only on elastic properties of the material (rubber) of sealing ring [2, 6].

Tension force Т_р of bottom sealing ring as a function of excessive pressure of lifted water Р_п in packer upon dynamic mode of its operation is illustrated in Fig. 11 for various packer working diameters D_пр = 154 mm and 205 mm. it can be seen in the figure that Т_р increases with Р_п according to linear relationship and increases with D_пр. With increase in Р_п from 298 kPa to 887 kPa the force Т_р varies in the following ranges: at D_пр = 154 mm Т_р = 6.58…19.35 kN; at D_пр = 205 mm Т_р = 9.0…26.5 kN.

In order to verify reliability of theoretical Eqs. (7) and (8) according to definition of Т_р = f(Р_п) and Р_п = f(Н) Fig. 10 illustrates their theoretical and experimental dependences for packer with  working diameter D_пр = 154 mm. In terms of experimental data at Р_Пэ = 298.2…886.8 kPa, Т_Рэ = 6.5…19.35 kN, in terms of theoretical data Р_Пт = 301.4…887 kPa, Т_Рт = 6.58…19.35 kN.

At water lifting height Н = 20…89.5 m the excessive pressure of lifted water in packer varies as follows: in terms of theoretical data Р_Пт = 301.4…887 kPa, in terms of experimental data Р_Пэ = 298.2…886.6 kPa.

The divergence between experimental and theoretical data in terms of Т_р is up to 1.1 %, in terms of Р_п up to 1.06%, which confirms the validity of the equations according to definition of Т_р = f(Р_п) и Р_п = f(Н).

Figure 11: Tension force Тten of bottom sealing ring and water lifting height Н as a function of excessive pressure of lifted water Рlw in packer in dynamic mode of its operation.   Click here to View figure

For static mode of operation the compression of packer Fig. 12 illustrates tension forces Т_р of top sealing ring as a function of water lifting height Н.

It follows from the figure that Т_р with increase in Н increases as well as with increase in packer working diameter аD_пр.

Thus, at Н = 30…120 m Тр equals to: at D_пр = 154 mm Т_р = 4.35…25.68 kN; at D_пр = 205 mm Т_р = 5.85…35.10 kN. Herewith, for D_п = 154 mm Т_Рэк = 4.15…20.65 kN. The divergence between experimental data at D_п = 154 mm  with theoretical data is not higher than 4.6 %, thus confirming the validity of equation according to definition of Тр in static mode of packer operation.

It has been established experimentally that the condition at initial compression Т_р ≥ Т_retr.  (tension force of sealing ring should be higher or equal to retraction force due to its  elastic properties) is satisfied. Thus, according to experimental data Т_р= 2.33 kN ﺤТ_retr. = 2.21 kN.

Figure 12: Tension force Тten of packer bottom sealing ring as a function of water lifting height Н in static mode of its operation.   Click here to View figure

Investigation into shimming of packer detwisting mechanism

Experimental study was restricted mainly by verification of compliance with the main condition: Eq. (10) of operation of packer detwisting mechanism  (cumulative force of lateral friction of pressing rollers should be higher or equal to the twisting force of packer with pump after reactive torque of pump motor upon its start) and definition of rolling friction coefficient and rolling of rubber-coated roller of  detwisting mechanism along internal surface of well casing [2, 7].

According to the experiments the main condition of operation of packer detwisting mechanism is satisfied:  T’TP^∋= 289Н…299Н >  = М_R/D_СК = 179Н…172Н for internal well diameter D_СК = 154 mm  with marginal coefficient of 1.61…1.73; 173.2Н…200Н > = М_R/D_СК = 84.5Н…97.5Н for internal well diameter D_СК = 205 mm with marginal coefficient of 2.04…2.05.

The rolling friction coefficient of rubber-coated roller along internal steel casing according to experimental data was f_к = (0.000175…0.00021), and the coefficient of rolling friction with accounting for  the roller diameter was f_пер = 0.010…0.012. The coefficient of sliding friction of rubber-coated roller at its lateral displacement along steel casing upon pump start was f_тр = 0.78…0.80, that is, complied with the known coefficients of rubber sliding against steel f_тр = 0.8.

Investigation into pinching forces and lifting of packer with pump

Experimental results confirmed that upon relief of excessive pressure of lifter water in packer and above packer due to elastic properties of the material (rubber) the sealing rings are retracted to initial position and do not hinder disassembling of packer with pump, that is, there are no friction forces between sealing rings and internal surface of well casing during assembling and disassembling.

The force of packer pinching (detachment of relief valve) according to experimental data corresponds to calculations by Eq. (11) according to definition of T_OTP∋ , the divergence does not exceed 4 %. Thus, at Н = 110 m according to experimental data T_OTP∋ = 0.56 kN, according to calculations  T_OTPT = _{0,54 kN,} the divergence is 3.7 %.

It has been experimentally established that the force required for disassembling (lifting)  of packer with pump from well is composed mainly of the weight of pump, packer, electric cable and disassembling rope, the force of rolling of rubber-coated rollers against well casing is negligible (2.5Н…8Н).

According to experimental data the force, required for disassembling of packer with electrical submersible pump ETsV6-10-80 from bench well with the diameter of 154 mm , without accounting for the weight of cable and rope, was 1.30 kN, according to theoretical data, Eq. (12) данным: 1ю27 kN, the divergence is 2.4 %
[2,7 ]

Investigation into verification and adjustment of main parameters of hydraulic packer

The main parameters of hydraulic packer of two typical sizes were experimentally verified and adjusted, they mainly corresponded to their substantiated values: d_o= 50mm, ζ_π= 5.6, S= 15 mm, b_k = 50 mm,  h_K= 15 mm, δ_K = 7.5 mm, P_∏min = 107.9 k_Pa, β= 760- 840, α 13⁰ – 19⁰ D_∏p = 154 mm and 205 mm.

The substantiated and adjusted parameters were applied for development of two typical sizes of hydraulic packers [7].

Therefore, on the basis of the performed experiments of two typical sizes of hydraulic packers UPG-168М and UPG-219М intended for pipeless water lifting in combination with electrical submersible pump ETsV 6-10-80 the involved processes were studied: fixation and compression of packer in well, of pinching detwisting device of hydraulic packer, the main parameters of the considered hydraulic packer were determined, the reliability of theoretical assumptions was experimentally verified with regard to each involved process, their parameters were adjusted with subsequent possibility of application for development of the required typical sizes of innovative hydraulic packers upon improvement of pipeless water lifting tewchnology.

Discussions

As a consequence of the performed experiments with two typical sizes of hydraulic packers UPG-168М and UPG-219М with ejector applied for pipeless water lifting in combination with electrical submersible pump ETsV 6-10-80 the involved processes have been studied: fixation and compression of packer in well, pinching of detwisting device of hydraulic packer, and main process variables have been  established.

Upon fixation of packer in well, during variation of pressure in packer P_π from from 0 to 1500 kPa (dynamic mode): at the packer diameter D_пр = 154 mm  the force of hydrodynamic pressure Rg, acting on packer, varied from 0 to 27.8 kN, and shimming forces Т_з and normal pressure Т_Ν, acting on packer fixing stop, Т_З = 0.42…5.9 kN and Т_Ν = 1.7…23.6 kN; at packer diameter D_пр = 205 mm  the force Rg varied from 0 to 49.8 kN, and Т_З = 0.7…6.3 kN and Т_Ν = 6.8…60.2 kN. In static mode of packer fixation in well during variation of water lifting height Н from 0 to 120 m (water column above packer): at packer diameter D_пр = 154 mm  the shimming forces Т_з and normal pressure Т_Ν, acting on packer fixing stop, Т_З = 0.42…2.29 kN and Т_Ν = 4.01…21.79 kN; at packer diameter D_пр = 205 mm  Т_З = 0.72…6.33 kN and Т_Ν = 6.84…60.22 kN. It has been experimentally established that the reasonable vertical angle of slope β of fixing stop is 1.396…1.466 rad (80^о-84^о) at the friction coefficient of fixing stop along well casing f_тр = 0.15…0.18 (steel against steel). Aiming at increase in fixation reliability of packer with pump in well the portion of fixing stops contacting with well wall is made with grooves, hence, the friction coefficient increases to 0.4…0.5, and, respectively, the marginal coefficient of  friction forces increases to 3.8…4.7 or the angle β decreases to 76⁰.

Compression of hydraulic packer against well casing well by hydraulic expansion of sealing ring (bottom one in dynamic mode, and top one in static mode) has been studied; it has been established that the sealing ring expands in 2.5…3 s after pump start at excessive pressure Р_Пmin = 107.9 kPa and is in steady mode in 1…1.5 s, that is, total time from pump start to steady mode of packer operation equals to 3…4 s. Herewith, the initial pressure of compression does not depend on the water lifting height, and only on elastic properties of the material (rubber) of sealing ring. In dynamic mode of compression (operation of bottom sealing ring) upon establishment of excessive water pressure in packer Р_п from 298 kPa to 887 kPa the tension force of sealing ring Т_р varies in the following ranges: at the packer diameter D_пр = 154 mm  Т_р = 6.58…19.35 kN; at D_пр = 205 mm  Т_р = 9.0…26.5 kN. In static mode of compression (operation of top sealing ring) upon establishment of water lifting height Н = 30…120 m Тр equals to: at D_пр = 154 mm  Т_р = 4.35…25.68 kN; at D_пр = 205 mm  Т_р = 5.85…35.10 kN. It has been experimentally established that the condition at initial compression Т_р ≥ Т_retr.  (the tension force of sealing ring should be higher or equal to retraction force due to its elastic properties) is satisfied. Thus, according to experimental data Т_р= 2.33 kN ﺤТ_retr. = 2.21 kN.

Pinching of packer detwisting mechanism has been studied; the compliance of the main condition of operation of packer detwisting mechanism has been experimentally confirmed: T’_TP > T_R (cumulative force of lateral friction of pressing rollers should be higher or equal to twisting force of packer with pump due to reactive torque of pump motor at its start): for internal well diameter DСК=154 mm T’_TP^∋ = 289Н…299Н > T’_R^∋ =МR/DСК=179Н…172Н with the marginal coefficient of 1.61…1.73; for internal well diameter _{DСК=205 mm T’TP^∋} =173,2Н…200Н> T’_R^∋= МR/DСК=84.5Н…97.5Н with the marginal coefficient of 2.04…2.05. We experimentally determined the coefficient of rolling friction fк=0.000175…0.00021; of rolling of rubber-coated roller fпер=0.010…0.012 and sliding friction of rubber-coated roller at its lateral displacement along steel pipe upon pump start fтр=0.78…0.80, which corresponded to the know coefficients for rubber against steel.

Reliability of the proposed theoretical assumptions has been verified with regard to each running process. The packer fixation in well: the divergence between theoretical and experimental data was not higher than: for  – Eq. (4) to 4.6…0.7 % at Rg_т = 3.71 kN…16.35 kN and Rg_э = 3.54 kN…16.24 kN; for Т_з–Eq. (5) up to 1 % at Т_Зт = 0.422…2.18 kN and Т_Зэ = 0.42…2.16 kN; for Т_Ν – Eq. ( 6 ) up to 4.9 % at Т_Νт = 1.69…8.736 kN and Т_Νэ = 1.7…8.85 kN, that is, the reliability of the proposed theoretical equations was confirmed.

With regard to compression of packer in well: the divergence between theoretical and experimental data was not higher than: for Т_р = f(Р_п) – Eq. (7) in dynamic mode up to 1.1 % at Т_Рт = 6.58…19.35 kN and Т_Рэ = 6.5…19.35 kN; for Р_П = f(Н) – Eq. (8) up to 1.06 % at Р_Пт = 301.4…887 kPa and Р_Пэ = 298.2…886.6 kPa; for Т_р = f(Н) – Eq. (9) in static mode up to 4.6 % at Т_р = 4.35…25.68 kN and Т_Рэк = 4.15…20.65 kN, that is, the reliability of the proposed theoretical equations was confirmed.

According to definition of forces for pinching and lifting of packer with pump: the divergence between theoretical and experimental data was not higher than: for pinching force of packer (detachment of relief valve) Т_отр =f(Н) – Eq. (11) up to 3.7 % at  kN and  kN; for the force of lifting of packer with pump ETsV 6-10-80 without accounting for the weight of cable and rope Т_ТР – Eq. (12) up to 2.4 % at Ттр_т =1.30 kN and Ттр_э = 1.27 kN, that is, the reliability of the proposed theoretical equations was confirmed.

Main parameters of hydraulic packer of two typical sizes were experimentally verified and adjusted, they mainly corresponded to their substantiated values: internal diameter of packer through hole d₀ = 50 mm; coefficient of local losses in packer ζ_п = 5.6; stroke of back-pressure valve in packer  S = 15 mm; the sealing ring dimensions: width b_к = 50 mm, sealing portion height h_к = 15 mm, sealing wall thickness δ_к = 7.5 mm; minimum excessive pressure for sealing ring operation = 107.9 kPa; vertical angle of slope of fixing stops β = 76 ^о -84 ^о; horizontal angle of slope of rods with rollers of detwisting mechanism α =13^о-19^о; external packer diameters in operation position of the stipulated typical sizes: D_пр = 154 mm  and 205 mm .

The innovative character of packer for electrical submersible pump was confirmed by decision to issue the KZ patent [30].

Conclusions

1. On the basis of the performed experiments of two typical sizes of hydraulic packers UPG-168М and UPG-219М with ejector based in pipeless water lifting in combination with electrical submersible pump ETsV 6-10-80, the involved processes have been studied: fixation and compressing of packer in well, pinching of detwisting device of hydraulic packer, and major technological and technical parameters have been determined.
2. The performed experimental study of dynamic processes running in the proposed new type of hydraulic packer with ejector based on pipeless water lifting from wells by means of electrical submersible pump has confirmed reliability of the assumed theoretical backgrounds applied upon development of required typical sizes upon improvement of pipeless water lifting.
3. The following issues have been experimentally determined: coefficient of packer local resistances ζ_p = 5.5…5.6, coefficient of friction of rubber-coated roller along steel pipe f_fr=0.8, excessive minimum pressure of lifted water required for expansion of sealing ring – 107.9 kPa, force for packer shimming – not higher than 0.75 kN. Major parameters of hydraulic packers of two typical sizes have been experimentally verified and adjusted, which mainly correspond to their substantiated values.
4. Application of an innovative type of hydraulic packer with ejector makes it possible to improve main process variables of pump facility: flow rate Q_PF and efficiency η_PF by 1.2 times at steady technological process and satisfied specifications.
5. The experimental results can be recommended for practical application.

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