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.
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.
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.
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).
ESP Power Cable Accessories, namely: Cable Bands and Cable Guards, are used to protect and support ESP cable, control lines and injection lines. There are used also to protect the power cable from damage during installation, operation and pulling. In this article, the roles and specifications of these accessory equipment’s are detailed, as well as recommended practices related to their use and selection.
Cable bands are used to attach the cable to the tubing during installation. Bands are provided using three different materials. Black Steel Bands are used in wells with corrosive problems. Stainless Steel Bands are used in moderately corrosive well (with no H2S present in the well). And Monel Bands are used in corrosive environments.
Most cable bands are 3/4 in. (19 mm) wide and approximately .025 in. (0.6 mm) thick.
Cable bands can be installed by using hand-banding tools or by using power-banding tools. The advantage of power banding tools is the bands are attached with the same tension.
The following video shows how to install Cable bands using Power-Banding Tool:
Recommended practices related to cable bands and their use: