Selection of submersible electric centrifugal pumping unit and auxiliary equipment for the well

Contents

Introduction

1. Process Part

1.1 General diagram of installation of submersible electric centrifugal pump

1.2 Erection and operation of ECEP

1.2 Submersible centrifugal pumps

1.3 UETsN grades

Analysis of modern technologies

2. Selection and calculation of submersible electric centrifugal pump unit to the well

Conclusion

List of sources used

Introduction

Operation of wells by submersible centrifugal pumps (UECN) is currently the main method of oil production in Russia. These plants extract to the surface about two-thirds of the total annual oil production in our country.

Electric centrifugal downhole pumps (ECPs) belong to the class of dynamic vane pumps characterized by large supplies and smaller heads compared to volumetric pumps.

The range of supply of downhole electric centrifugal pumps is from 10 to 1000 m3/day and more, head - up to 3500 m. In the area of supply over 80 m3/day ECN has the highest efficiency among all mechanized oil production methods. In the supply range from 50 to 300 m3/day, the pump efficiency exceeds 40%.

One of the most important conditions for the effective use of the EECP is the correct selection of the EECP for the well, that is, the choice for each particular well of such mutually agreed sizes of the pump, electric motor with hydraulic protection, cable, transformer, lifting pipes from the existing equipment fleet, and such a depth of pump descent into the well that will ensure the development of the well and the technological norm of fluid extraction (nominal flow rate) from it in the steady mode of operation of the well system - ECP at the lowest costs.

Selection of ECEP to the well at the modern level is associated with the performance of relatively laborious and bulky calculations and is carried out using computers.

Installation of centrifugal pumps to oil wells is performed according to algorithms, which are based on the provisions and results of work repeatedly tested in the oil industry, dedicated to the study of liquid and gas filtration in the formation and bottomhole zone of the formation, movement of the gas-oil mixture along the casing string, laws of gas content change, pressure, density, viscosity, etc., studying the theory of operation of centrifugal submersible units, first of all - well centrifugal pumps, on real formation fluid.

Selection of pump units to oil wells means determination of standard size or standard sizes of units providing the specified production of formation fluid from the well at optimal or close to optimal operating parameters (supply, head, power, time between failures, etc.). In a broader sense, selection refers to the determination of the main operating parameters of the interconnected oil reservoir-well-pump system and the selection of optimal combinations of these indicators. Optimization can be carried out according to different criteria, but in the end they should all be directed to the same end result

- minimization of unit cost - tons of oil.

Procedure for selection of ECEP to wells is based on knowledge of laws of formation fluid filtration in formation and bottomhole zone of formation, on laws of water-gas-oil mixture movement along well casing and tubing string, on dependencies of hydrodynamics of centrifugal submersible pump. In addition, it is often necessary to know the exact temperature values ​ ​ of both the pumped liquid and the elements of the pumping unit, therefore, thermodynamic processes of interaction of the pump, submersible motor and current-carrying cable with the pumped multicomponent formation fluid, whose thermodynamic characteristics vary depending on the surrounding conditions, occupy an important place in the selection method.

It should be noted that in any method of selection of SEECs, there is a need for some assumptions and simplifications that allow creating more or less adequate models of the operation of the formation-well-pump system.

Purpose: To select such equipment sizes to provide the required rate of fluid withdrawal from the well in steady state operation of the well system - installation at the lowest cost.

1.2 Erection and operation of ECEP

The well must be carefully prepared prior to installation of the electric centrifugal pump unit. To do this, the well is washed, that is, it is cleaned from dirt and sand plug, after which a control chop of the bottomhole is carried out and a sample is taken for the content of mechanical impurities (the EHF content in the solution should not exceed 100 mg/l). The well is then patterned (borehole permeability is checked). The production column is stamped before the EECP descent:

- in wells coming out of drilling or from overhaul associated with repair of production string;

- when the well is put into operation with the help of UETsN (from another method of operation);

- at change of UETsN to standard size of larger diameter;

- at increase of UETsN descent depth;

- in cases of detected mechanical damage of the cable and tightening during lowering lifting operations.

The depth of the template descent should be at least 50 meters lower than the location of the UETsN.

The length of the template must be not less than the length of the ECN installation, but not less than 16 meters. The diameter of the template is determined by the dimensions of the production column and the installation and is within 2-4 mm more than the maximum diameter of the submerged unit. In case of failure of the template or during tightening, the production column is ribbled with subsequent stamping.

At a distance of 25 m from the wells (in the area of ​ ​ the wells), a site is prepared for the placement of terrestrial electrical equipment of the UETsN with a grounding loop associated with the grounding loop of the transformer substation (TP 6/0.4) and the well conductor with a steel belt.

At a distance of 5 to 25 m from the wellhead, a terminal box is installed that meets the safety requirements of the design.

Wellhead valves of the well prepared for start-up of UETsN are equipped with pressure gauges, check valve on the line connecting the annular space with the discharge, a union chamber (if technologically feasible) and a branch pipe for investigation.

The winder is installed at a distance of 1520 m from the wellhead so that the axis of the cable drum is perpendicular to the plane of rotation of the cable roller, the radius of which should be at least 380 mm.

Alignment of lift overhead system relative to well mouth is performed. The cable roller is suspended on the hoist mast at a height of 810 meters so that the axis of rotation of the cable roller and the axis of the drum are perpendicular to the plane of rotation of the roller.

The submersible equipment is mounted directly at the wellhead. During installation, the master (driller, senior operator) of the well repair team monitors:

- checks the compliance of the standard size of the imported plant with the ordered one, as well as the number of the units recorded in the operating certificate;

- monitors the PED current lead tightening by the value of 5 kgf/cm2 during 10 minutes, at which pressure drop, oil leakage and misting are not allowed;

- checks the installation of splined couplings and easy rotation of shafts;

- checks the insulation resistance of the assembly, which should be at least 100 MOhm, the presence of marking and phasing of the cable ends;

- checks the cable length according to the records in the protocol for cable and on the cable tag (stamp) with this mark in the UECN operating certificate;

- during installation of ECEP with PED with power of 90 kW and higher requires phasing at the mouth;

- controls the use of a new fastener (bolts, nuts, screws, spring washers) during installation instead of transportation and production of their tightening with torque keys with the force value equal to 5 kgf for nuts M12 and 3.5 kgf - M10;

- confirms the quality of the erection performed and readiness of the UECS equipment for descent, as indicated in the UECS operating certificate.

The ECP unit is lowered into the well at a speed of not more than 0.25 m/s (with an average pipe length of 8 m, its descent time will be 32 s).

During lowering of the plant, the alignment of the elevator relative to the well head is periodically checked, if necessary, its alignment is performed.

When lowering the plant, it is necessary to comply with the following requirements:

- grinding with metal brush and lubrication of tubing string threads;

- template each pipe (using repair and reusable pipes);

- measurement of length of each pipe with recording of tubing string measure;

- cleaning of external surface of tubing string from sand and paraffin.

When the EECP is lowered into the well, the installation and suspension of the tubing is not allowed to turn. To this end, when using keys without retarding devices, the first 2030 pipes above the EECP are manually screwed using the retainer key.

In the process of descent, jerking or tensioning and bending of the cable with a radius of less than 380 mm are unacceptable, the cable from the automatic winder to the mouth should be in a constantly sagging state under its own weight, but at the same time not draw on the ground, but be in the racks.

The cable to the tubing is fixed with steel belts (clamps) at a distance of 250300 mm above and below each tubing coupling, while preventing cable slacks and sagging inside the well. Steel belts are also installed above and below the cable splices at a distance of 150200 mm from them. If the splice is on the tubing clutch, then the pipe is replaced with another required length. The steel belts are tightened until the cable armor is initially deformed. Buckles of steel belt should be located in free space between tubing and cable. - Check and knock-down valves are supplied to the well complete with ECEP. The check valve seat shall have a rubber seal. Check valve shall provide fluid tightness.

1-2 pcs are screwed between the check and drain valves. Tubing to avoid shutting-off of the drain valve with precipitating sand or other mechanical particles,

. Through every 300 meters of UETsN descent resistance of UETsN insulation by megaohmmeter is checked with recording of measurement results in the operating certificate of the unit.

If insulation resistance decreases to less than 5 MOhm or damage is detected on the cable line, as well as if complications occur, descent stops.

After completion of EECP descent, the insulation resistance of the unit is measured before and after sealing of the gland cable entry, the value of which must be at least 5 MOhm. Free end of cable armor is secured under nut of wellhead reinforcement. The cable is routed from the mouth to the control station or terminal box (if any).

During operation of submersible electric pumps the following parameters of plant operation are measured with record in the operating certificate:

- well flow rate;

- buffer, annulus and linear pressures;

- operating current;

- insulation resistance:

• - in 1 day - after setting to mode (check measurement);

• - weekly - up to 60 days of work;

• - monthly - after 60 days of work;

- dynamic level:

• - 1 day after setting the plant to stable mode;

• - quarterly - during operation. Sampling for EHF content in products is performed:

- at setting to mode (killing fluid);

- two days after setting to mode;

- once a half year during further operation.

Sampling for watering is performed after setting to the mode, then at least twice a month with recording of analysis results in the UECN operation passport.

In accordance with the schedule, operations are carried out to prevent deposits of paraffin, salts in lifting elevators of wells with a mark in the UECN operating certificate.

Conclusion

The conditions under which submersible electric pumps are to be operated at the field are peculiar and complex, both geologically and technologically. Therefore, the equipment in operation has to experience enormous loads of various factors that cause many failures. Factors that reduce the reliability of the EECP:

- mechanical impurities;

- salt deposits;

- temperature;

- curvature of the barrel;

- gas content;

- paraffin deposits.

A large percentage of ECEP at the field is operating below optimal, as it should be, which also leads to premature failures and a decrease in operating efficiency.

The most important factor for the optimal operation of the EECP is the correct selection of the EECP for the well. When selecting ECEP to the well, they are guided by the passport characteristic of the pump - dependencies of head, consumed power and efficiency factor from the pump supply. The probable performance of the pump in a particular well may differ significantly from the nominal, due to the quality of the pump production, the difference in viscosity of the pumped liquid from the viscosity of water, and the presence of free gas in the well production.

UECN is selected for the well by means of calculations during commissioning from drilling, transfer to mechanized production, optimization and intensification according to the methodology adopted in NGDU, which does not contradict the UECN operating specification.

When selecting ECEP to the well, it is necessary to take into account the decrease in the power of the submersible motor due to an increase in the temperature of the surrounding reservoir fluid, in accordance with the current specifications of the manufacturers.

After receiving the results of selection of ECEP to the well, the request for installation of this ECEP is given, and determines the type of engine, hydraulic protection, cable, gas separator and ground equipment necessary for configuration in accordance with the current specification and operating manual of ECEP.

Электродвигатель ЭД40,,,70-117М сборочный чертеж.cdw

УЭЦН схема комбинированная, принципиальная.cdw

рабочее колесо.cdw