RU2516753C1 - Submersible pump for viscous fluid pumping - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: pump contains a variety of in-series pumping steps inside the case. An impeller of each step is axial and made as a barrel with spiral blades. The angle between a line tangent to structural line of blades and the plane perpendicular to the rotation axis is permanent or increasing monotonously from the input to output. Initial value of this angle being the entrance blade angle decreases monotonously from the barrel towards peripherals. Guide vanes of each step are made with a double curvature and the direction of twist opposite to the twist direction of the impeller blades. The ratio of radial width of the flowing channel in the impeller and the guide vanes towards the external radius of the channel lies in the range from 0.2 up to 0.6.

EFFECT: pumping of fluids with large range of viscosity without head loss.

2 cl, 6 dwg

Description

The present invention relates to petroleum engineering, in particular to multi-stage well pumps for pumping high-viscosity formation fluid.

Known multi-stage submersible pump for pumping oil, consisting of centrifugal type steps containing impellers and guide vanes, sequentially located on a common shaft, enclosed in a housing and equipped with end elements (see, for example, A. A. Bogdanov. Submersible centrifugal electric pumps for production oil (calculation and design), Moscow: Nedra, 1968, p.21).

The disadvantage of this pump is a significant decrease in the developed head and efficiency with an increase in the viscosity of the pumped liquid, which leads to a forced increase in the number of pump stages, i.e. rise in the cost of the installation as a whole, as well as to overstated power costs during operation.

Closest to the claimed is a well submersible pump for pumping viscous liquids with solid inclusions (such as algae, pieces of wood, fragments of metal, plastic, pebbles, particles of solid oil products), consisting of one stage and used in the collection of oil spills from damaged oil tankers (US patent No. 5385447A, F04D 3/00, declared. 26.03.1993, publ. 31.01.1995). The pump includes an inlet channel shaped like a venturi in order to reduce cavitation and the growth of a viscous boundary layer in this area, a diagonal impeller installed in the expansion of the inlet channel, an axial guide device located immediately after the impeller, and an electric motor, rotating impeller. To maintain the required pressure level, the outer diameter of the pump is large (12.5 inches). The configuration of the input channel and the flow channels of the impeller is due to the requirement for the required cavitation reserve of the described pump operating at low inlet pressures.

However, for pumping viscous oil from oil wells, when the inlet pressure is about 30-50 atm, this requirement becomes insignificant, therefore the design of the stage, consisting of a diagonal impeller and an axial type guide apparatus, will not work effectively in downhole conditions. The main disadvantage of the described invention is a significant drop in the pump head with increasing viscosity of the pumped liquid, typical for centrifugal and diagonal stages. In addition, the large size of the pump does not allow its use in wells with a limited diameter of the casing.

The basis of the present invention is the task of creating a borehole submersible pump for the production of a viscous fluid that retains pressure in a wide range of viscosities.

To achieve the technical result, a well submersible pump for pumping viscous oil, comprising a pump stage consisting of an axial guide apparatus and an impeller, according to the invention, is made of a plurality of steps sequentially located on a common shaft and placed in a common housing, and the impeller is axially form of a sleeve with spiral blades.

In the meridian section, the flow channel of the impeller is made confuser, and the guide vane is diffuser, while the ratio of the area of the flow annular channel of the impeller at the inlet (S _in ) to the area of the flow annular channel at the outlet (S _out ), and for the guide vane, the inverse ratio S _o / S _in lies in the range from 1.0 to 1.5.

In addition, in the impeller and guide vane, the ratio of the radial width of the flowing annular channel to the outer radius of the channel lies in the range from 0.2 to 0.6.

In any section of the flow channel with a cylindrical surface, coaxial to the axis of rotation, the angle between the tangent to the skeletal line of the impeller blade and the plane perpendicular to the axis of rotation can be made constant or monotonically increasing from entrance to exit, the initial value of this angle, which is the input angle of the blade , - monotonously decreasing from the sleeve to the periphery. The blades in the guide vane may have double curvature and a swirl direction opposite to the swirl direction of the impeller blades.

The essence of the inventive submersible pump for pumping viscous liquids is illustrated by drawings, where figure 1 presents a General diagram of the pump; figure 2 - the impeller in a perspective view; figure 3 is a guide apparatus in a perspective view.

лежало в интервале от 1.0 до 1.5. Угол β между касательной к скелетной линии лопасти 7 и плоскостью, перпендикулярной оси вращения, монотонно увеличивается от входа 8 к выходу 9. Начальное значение угла β, являющееся входным углом лопасти, монотонно уменьшается от втулки 6 к периферии. В некоторых вариантах исполнения угол β может быть одинаков по всей длине лопасти 7.Submersible pump for pumping viscous liquid contains many stages 1, sequentially placed in the housing 2, each of which consists of fixed axially mounted guide rails 3 and impellers of axial type 4 mounted for rotation on a common shaft 5 (figure 1). The impeller 4 contains a sleeve 6, on the lateral surface of which at an equal distance from each other, spiral blades 7 are installed (figure 2). The ratio of the radial width of the flow channel to the outer radius of the channel lies in the range from 0.2 to 0.6, in the meridian section the channel of the impeller 4 is made confuser so that the ratio of the area of the flow annular channel at the entrance 8 to the impeller 4 to the area of the flow ring channel at the exit 9 from the impeller 4 $$S_{\mathrm{at}x}^{R\mathrm{TO}}/S_{\mathrm{at}sx}^{R\mathrm{TO}}$$

lay in the range from 1.0 to 1.5. The angle β between the tangent to the skeletal line of the blade 7 and the plane perpendicular to the axis of rotation monotonously increases from input 8 to output 9. The initial value of the angle β, which is the input angle of the blade, decreases monotonically from the sleeve 6 to the periphery. In some embodiments, the angle β may be the same along the entire length of the blade 7.

лежит в интервале от 1.0 до 1.5. Такие параметры рабочего колеса 4 и направляющего аппарата 3 минимизируют вероятность отрывных и вихревых течений в проточных каналах ступени в целом, а значит способствуют сохранению напора и КПД насоса. Скважинный погружной насос работает следующим образом. Перекачиваемая вязкая жидкость поступает в проточные каналы рабочего колеса 4, приводимого в движение валом 5, ,и обтекая лопасти 7, приобретает кинетическую энергию, которая преобразуется в потенциальную энергию напора, при переходе жидкости в направляющий аппарат 3, с выхода 12 которого поток жидкости далее попадает в рабочее колесо 4 следующей ступени 1.The axial guide apparatus 3 (Fig. 3) has a sleeve 10 with blades 11 placed on its side surface. The blades 11 can be made of double curvature and have a swirl direction opposite to the swirl direction of the blades 7 of the impeller 4. In the meridian section, the flow channel of the guide apparatus 3 is made diffuser, and the ratio of the area of the flow channel at the outlet 12 of the guide apparatus 3 to the area of the flow channel on it inlet 13 $$S_{\mathrm{at}sx}^{N\mathrm{BUT}}/S_{\mathrm{at}x}^{N\mathrm{BUT}}$$

lies in the range from 1.0 to 1.5. Such parameters of the impeller 4 and the guiding apparatus 3 minimize the likelihood of separated and eddy flows in the flow channels of the stage as a whole, and therefore contribute to the preservation of the pressure and efficiency of the pump. Well submersible pump operates as follows. The pumped viscous liquid enters the flow channels of the impeller 4, driven by the shaft 5, and flowing around the blades 7, acquires kinetic energy, which is converted into potential energy of the head, when the liquid passes into the guide apparatus 3, from the output of which 12 the liquid flow then enters into the impeller 4 of the next stage 1.

Figure 4, 5, 6 shows the results of bench tests of the inventive pump and analog pumps with increasing viscosity of the pumped liquid. Figure 4 shows the pressure-flow characteristics of the stage of the inventive axial type pump obtained for liquids with different viscosities: 1-300 cSt, 2-200 cSt, 3-100 cSt 4-1 cSt .; figure 5 - shows the discharge characteristics of the pump stage of the diagonal type (prototype) obtained for liquids with different viscosities: 1-300 cSt, 2-60 cSt, 3-40 cSt, 4-1 cSt; figure 6 - pressure-flow characteristics of the centrifugal pump stage obtained for liquids with different viscosities: 1-450 cSt, 2-220 cSt, 3-55 cSt, 4-40 cSt, 5-1 cSt.

From the figures it can be seen that the inventive axial stages retain the pressure value in a wide range of viscosities, while diagonal and centrifugal stages significantly decrease in pressure with an increase in the viscosity of the liquid.

Thus, the claimed design in comparison with analogues can effectively pump liquids in a wide range of viscosities without loss of pressure.

Claims (2)

1. A downhole submersible pump for pumping viscous oil, comprising a pumping stage consisting of an axial guide apparatus and an impeller, characterized in that the pump consists of a plurality of stages sequentially located on a common shaft and placed in a common housing, the impeller is made axial in the form bushings with spiral blades, the angle between the tangent to the skeletal line of which and the plane perpendicular to the axis of rotation, is made constant or monotonically increasing from input to output, the initial value is about the angle, which is the input angle of the blade, monotonously decreasing from the sleeve to the periphery, while the blades of the guide apparatus are made with double curvature and the direction of rotation opposite to the direction of rotation of the blades of the impeller, and the ratio of the radial width of the flow channel in the impeller and guide apparatus to the outer the radius of the channel lies in the range from 0.2 to 0.6. 2. The pump according to claim 1, characterized in that in the meridian section the flow channel of the impeller is made confuser and the guide apparatus is diffuser, while the ratio of the area of the flow annular channel of the impeller at the entrance to the area of the flow annular channel at the output S $${}_{\mathrm{at}x}^{R\mathrm{TO}}$$

/ S $${}_{\mathrm{at}sx}^{R\mathrm{TO}}$$

and the ratio of the area of the flow channel of the guide apparatus at the outlet to the area of the flow channel at the inlet S $${}_{\mathrm{at}sx}^{N\mathrm{BUT}}$$

/ S $${}_{\mathrm{at}x}^{N\mathrm{BUT}}$$

does not exceed 1.5.

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