Fundamental principles of physics used in artificial lift design

In the present article, we discuss a couple of physical quantities used in artificial lift design such as the concept of stress, pressure, work, power, energy, machine, and efficiency.

Stress is defined as force divided by area. So that, to reduce the stress you can either reduce the force or increase the cross sectional area it acts on.

Stress = Force / Area

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Y-tool system – A solution to enable well access below ESP

The Y-tool is a solution to enable production-logging and well intervention below a working ESP at any point in time during production without pulling the completion string. The Y-tool is installed on the production tubing, providing two separate conduits. One conduit concentric with the production tubing and enables access to the reservoir below the ESP. The second conduit is offset and used to support the ESP system. Flow rates in different perforation intervals and other valuable geophysical information could be collected for production optimization and enhanced recovery plans.

With an ESP Y-tool in place, Operators are able to carry out wireline or coiled tubing logging, memory gauge deployment, tubing-conveyed perforation, well treatment and stimulation operations, effectively managing production operations and reservoir performance without pulling the ESP, dual ESP installation and bridge plug setting for water shutoff, etc.

Wireline or coiled tubing plugs can be used to seat in a nipple profile in the Y-tool to enable intervention or logging operation without retrieval of the completion. If required, the ESP can be run with these plugs in place to perform production logging or other well interventions.

 

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ESP submersible pumping system

The ESP submersible pumping system consists of both downhole and surface components. The surface components are transformers, motor controllers, junction box and wellhead.

The wellhead accommodates the passage of the power cable from the surface to the wellbore.

The main down-hole components are the motor, seal, pump, and cable. Additional accessory equipment may include the gas separators, check and drain valves, cable bands and protectors, and downhole sensors.

Technologies, types, recommended practices and selection criteria of each compound of the ESP pumping system are discussed in the following list of 22 posts.

ESP Pump:

01- Submersible Pump System Overview

02- Centrifugal Pump ( ESP Pump)

03- ESP: Pump Stage

04- Pump impeller types

05- Pump Performance Curves – part 01

06- Pump Performance Curves – part 02

07- Pump Construction: Compression Pump vs. Floater Pump

08- Pump Shaft

Pump Intake:

09- Pump Intake

10- ESP Motor Shroud: Applications, Configurations and Selection Criteria

11- ESP: Gas handling device

Seal Section:

12- Motor Seal

ESP Motor:

13- ESP Motor

ESP Cable:

14- ESP Cable

15- Power losses in cables

16- Motor Lead Extension

17- ESP Power Cable Accessories

Motor Controller:

18- ESP Motor Switchboard

19- Variable Frequency Drive Basics

Transformer:

20- Introduction to transformer: How it works?

Wellhead Equipment:

21- Wellhead Equipment for ESP

Accessory Equipment:

22- ESP Accessory Equipment

ESP Accessory Equipment

Junction box, Check and Drain Valves, Downhole Sensor and Centralizers are some kinds of  ESP Accessory Equipment. These type of equipment could play an important role to operate the ESP efficiently and maximize it run lifetime.

Junction Box:

The power cable coming from the well is connected to a surface electric cable leading to the switchboard. As seen in the figure below, the two cables are joined in the junction box, also called a “vent box”. The surface cable connects the junction box to the motor control panel and the motor control panel to the secondary side of the transformers.

It is a ventilated, weatherproof box performing the following three important functions:

  • Provides the electrical connection between the downhole and the surface electric cable.
  • Vents any gas to the atmosphere which might reach this point due to migration of well gases up the ESP power cable. The venting of gas eliminates the danger of fire or explosion that could happen if gases travel in the cable to the switchboard.
  • Acts as an easily accessible test point for electric checks of the downhole equipment.

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Wellhead Equipment for ESP

Wellhead Equipment for ESP provides a tubing support and allows the power cable to pass from the surface into the well bore. The wellhead is equipped with a wellhead feed through mandrel or pack-off method. It provides a positive seal around the cable. Wellheads and cable pack-offs are available in various pressure ratings and hanging load capacities.

Wellhead Feedthrough, Penetrator, lower and upper pigtails:

The electrical connection of surface and downhole power cables is detailed in figures below. The tubing hanger holds a feed-through mandrel (also called: well penetrator) equipped with the proper seals. Feed-through mandrel seals contain well pressure and prevent gas leaks at the surface. Power cables are connected to the two ends of this device via their three-phase connectors (also called: lower and upper pigtails).

 

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