Electrical submersible pump with
dual-pad stages (ESPD) and single-pad stages with elongated hub of impeller (ESPMIK)

Borets manufactures pumps in several modular designs. ESPD type is manufactured with dual-pad stages.Type ESPMIK has single-pad stages with elongated hub of impeller.
For operation in severe conditions radial bearings made of tungsten carbide are installed. The design of the pumps type 10ESPD and 10ESPMIK does not include shaft thrust bearings in the pump sections. Thrust loads from the shafts of the pump sections are transferred to the shaft of the protector, which is equipped with a reinforced thrust bearing. In order to decrease shaft overhang and rotor vibration of the pump the radial bearings of the shaft ends are moved to the pump base and head.
ESPD and ESPMIK pumps may be manufactured as floater, semi-floater and compression type of pumps. A special cable protector installed on the base of pump section provides protection for motor lead extension.
These solutions substantially enhance shaft stability, decrease vibration loads on the shaft and make pump operation more reliable, thus increasing the pump life.

10ESPD pumps are manufactured with capacity from 30 to 400 m³/day (189 to 2516 BPD). Dual-pad stages substantially improve pump performance characteristics, enhance shaft radial and axial stability and decrease vibration loads. Thus, pump operation is more reliable and the pump runs longer.

Dual-pad stages features the following advantages:

• impeller lower thrust bearings have longer run life
• more reliable shaft protection against abrasives and corrosive fluids
• extended pump runlife

10ESPMIK pumps are manufactured with capacity 2013 to 7862 BPD (320 to 1250 m3/day).

10.1ESPD and 10.1 ESPMIK pumps are equipped with intermediate radial bearings made of hard alloys.

Operational conditions of the pumps

pH value	6.0-8.5
Solids particles content in formation fluid, g/l	0.5
Particles micro-hardness according to Mohs scale	not more than 7 points
Maximum free gas content at the pump intake, by volume	25%
- with gas separator or dispersant module	55%
- with "gas separator-dispersant unit"	68%
- with multiphase pump units	70%
Temperature of pumped-out fluid, °F (°C)	not more than 284 (140), 302 (150)*

* - special order

The well deviation angle a at the setting point of the ESP shall not be more than the numeric value, calculated with the use of the following formula:

α = 2 arcsin	40 S	, degrees per 33 ft (10 m)
	4S²+ L²

where,
      S - is the clearance between the casing inside diameter ID and ESP maximum outside diameter, m.
      L - total length of the ESP system, m.

The allowable rate of deviation of the borehole shall be not more than 2° per 33 ft (10 m). The well bore vertical inclination shall be not more than 60° in the setting point of the ESP system.

Encryption of the pump coding

ESPD

ESPMIK

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Electrical submersible pumps with stages made by powder technology (ESPDP)

Pumps of this type are manufactured with the using powdered metal technology. This technology is innovatively applied in the manufacturing of stages for submersible pumps and has many advantages.
Some examples of the advantages are:

• the possibility to change the chemical composition and structure of the material in the course of production for obtaining the required objective
• enabling the manufacturing of stages with higher accuracy, surface finish and durability
• pump parts manufactured with the use of this technology are highly competitive in comparison to conventional technology.

The material PK90D25 was specially developed for manufacturing of pump stages. The application of the copper infiltration technology allows making absolutely nonporous parts with high operating characteristics:

• if abrasive content of the pumping fluid is 10%, the wear of the stages produced with the use of powder metallurgy is 20-30% less that those made of Ni-resist and 2 times less than those made of cast iron
• the thermal conductivity of stages produced using powder metallurgy is 1.5-2 times higher than Ni-resist or cast iron stages thus provides better heat emission from friction parts
• the composite powder material of the stages has a value of impact viscosity and hardness almost 1.5 times higher than the Ni-resist and cast iron stages which ensures reliable operation in case of increased loads on the stage
• the corrosion resistance of the stages produced with the use of powder metallurgy are similar to Ni-resist stages and several times higher than of the cast iron.

Pumps of ESPDP type are equipped with high-performance pressure-dispersant (HPPD) stages made with the use of powder metallurgy technology. All HPPD type stages have a dual-pad design and are manufactured using the principle of a double centrifugal stage. In this design the blades on the upper disc of the impeller provide higher head due to increased centrifugal flow rate. There are no stagnation zones of the formation fluid in the clearance between the diffuser and the impeller, so the amount of the abrasive content between the friction surfaces of impeller hub and diffuser bushing is minimized.

The design of the stage with additional dispersant blades on the upper surface of the impeller provides higher dispersant characteristics of the stage and that’s why it can be recommended for operation in wells with higher gas-oil ratios. High accuracy of the parts manufactured using powered metal technology and the vibration damping characteristics of the material enable minimum disbalance of the stages, thus decreasing the overall vibration level of the ESP systems. Excellent surface finish in the channels of the diffuser and impeller and a film layer of the pyrolized carbon reduce the possibility of salt crystallization. That’s why powder stages are very effective in environments with higher salt content. Due to their specific material properties, the powder stages do not expand or contact and also do not reduce their hardness in high temperature environments (from -94 °F up to +482 °F (from -70 °C up to +250 °C) in comparison with stages made of Ni-resist. The best application of pumps with stages manufactured with the use of powder metallurgy technology is in wells with low production.

Pumps using powered metal stages are particularly useful in the following applications:

• oilfields in later development stage that are characterized with reservoir depletion and high water cut
• starting up low productivity wells that are either in conservation or temporarily shut
• substitution of sucker-rod pumps with low production centrifugal  pumps in the depths of more than 4921 ft (1500 m).

The designs of the powder stages are protected with several patents. Repair costs can be reduced by supplementing Ni-resist diffusers with those made by PM technology and combining them with Ni-resist impellers. We have made successful tests in our repair facility in Siberia. Another advantage is that the PM stages are less expensive than Ni-resist.

Currently Borets manufactures the following pumps with powder stages:

• in size 5" – with nominal capacities 94.4, 125.8, 157.2, 220.1, 314.5, 377.4 BPD (15, 20, 35, 50, 60 m ³/day) and heads from 180 to 10663 ft (from 550 up to 3250 m)
• in size 5À" – with nominal capacities 157.2, 220.1, 1,257.9 BPD (25, 35, 200 m³/day) and heads from 1969 to11975 ft (from 600 up to 3650 m)

Encryption of the pump coding

Electrical submersible pumps with compression-dispersing stages installed in lower section.

Design: pumps include upper and middle sections of 20.1 type and lower section 20.9DMS of   specific design.

Specific features of lower section are as follows:

• screw is installed in the lower part of section that ensures flow of gas-liquid mixture to compression-dispersing stage
• installed are compression-dispersing stages that disperse gas-liquid mixture and compress gas bubbles at main stage intake
• installed is radial bearing that carries both axial and radial load of compression-dispersing stages to avoid wear of impeller washers
• reinforced housing provides longer run-life.

Advantages:

• ability to operate wells with 30…35% of free gas at pump intake (with gas separator up to 60…65%)
• extended run-life of equipment due to equal reliability of parts, devices of pump and capability to operate without as separator.

Designs of parts and devices included in the specific lower section 20.9DMS were patented according to the laws of the FR.

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