ePAC™ Vector Flux Drive Rod Pumping System

Quick Links to Information Below

• ePAC Vector Flux Drive Rod Pumping System Overview
• Why use an ePAC with Rod Pump Systems?
• Cost Saving Features of using ePAC Vector Flux Drive with Rod Pumping
• ePAC Vector Flux Drive with Rod Pumping Performance Features
• Operational Modes of the ePAC Vector Flux Drive

ePAC Vector Flux Drive Rod Pumping System Highlights

Reduces power consumption Minimizes mechanical stress on equipment Eliminates excessive rod force Uses pump fill algorithms to optimize    production Maximum torque from 0 to base speed Does not require external load cell input Adjustable dynamic braking Independent up and down stroke speed

• ePAC Vector Flux Drive Rod Pumping System Automatic Monitoring
• ePAC Vector Flux Drive Rod Pumping System Control Monitoring
• User Interfaces of the ePAC Vector Flux Drive Rod Pumping System
• Programmable Logic Controller of the ePAC Vector Flux Drive Rod Pumping System
• Specification of the ePAC Vector Flux Drive Rod Pumping System

PDF Documents

• ePAC Rod Pumping System
• ePAC Rod Pumping System - Spanish Version
• Case Study: ePAC Flux Vector Rod Pump Controller Variable-Speed Control

ePAC Vector Flux Drive Rod Pumping System Overview

eP’s ePAC drive is specifically designed for oilfield pumping applications. The ePAC offers performance enhancement beyond that of conventional variable frequency or variable speed drives as it incorporates Flux Vector Drive (VFD) technology for the precision control of both speed and torque. This improved control can aid the optimization of electrically driven artificial lift systems.

The ePAC has a proven track record of performance enhancement with traditional pump jacks and long-stroke pumping units such as the Weatherford Rotaflex. The ongoing development, deployment, and enhancement of VFD technology can result in a higher economic return from the operation of rod pumped wells.

Why use an ePAC with Rod Pump Systems?

eP’s ePAC drive can be used to improve pump performance and well productivity in most oilfield rod pumping applications. The advanced control algorithm can increase productivity and extend the life of both new and existing artificial lift systems.

The ePAC is able to deliver this functionality by providing precise control of motor voltage, current, speed, and torque. This provides continuous monitoring of operational parameters and allows the ePAC to quickly adapt to dynamic downhole conditions at all speeds.

ePAC can further aid optimization by:

• Automatically adjusting speed to match well inflow performance
• Offering infinite speed control
• Providing independent up/down stroke speeds
• Reducing total rod pumping system power consumption
• Reducing rod parts
• Offering a 20% increase in SPM over conventionally controlled units (Rotaflex)
• Utilizing an integral tracker system that controls bridle separation from the sucker rod

The ePAC overcomes the inefficient production problems found with the traditional control systems used for slow pumping in heavy oil applications. Precise torque and speed control allow the system to operate at all speeds while offering protection to the system.

Conventional Pumping Units

A proven technology that has been used worldwide for decades, conventional pumping units are still in demand today. Conventional pumping units are particularly suited to slow-pumping, heavy-oil applications requiring steam injection. Conventional speed control has yielded inefficient production, and separate speeds are required for the up and down strokes.

With variable speed and torque control, eP's VFD package overcomes the problems of traditional controls. These features have been added to optimize conventional pumping unit production:

• Independent operator-adjustable up-and down-stroking speed set points
• Synchronization of the sucker rod return speed and conventional pumping unit speed
• Set point speed based on beam position sensor that senses the direction of the polish rod
• Optional tracker sensor eliminates separation of the bridle from the sucker rod - no more rod hang-up

Rotaflex Long-Stroke Pumping Unit

A unique pumping system sold and manufactured by Weatherford, the Rotaflex unit is an efficient, long-stroking pumping unit that eliminates conventional stroke limitations. It uses long, slow strokes to keep pace with high-volume producers or to coax oil from deep wells.

The unit is also very popular in the shallow, steam-flood heavy-oil fields. In the past, electrical controls were very inefficient and difficult to match with varying well characteristics.

ePAC is ideal for providing the speed and torque control required for the very long, slow strokes of the Rotaflex unit. To provide a reliable, flexible, intelligent means of controlling the Rotaflex pumping units, eP's VFD package interfaces with the Rotaflex control.

This combination further optimizes production by:

• Providing infinite speed control from .1 - 5.5 SPM
• Independent up/down stroke speeds
• Increase max SPM by up to 20% over conventionally controlled units
• Optional tracker sensor eliminates separation of the bridle from the sucker rod - no more rod hang up

Cost Saving Features of the ePAC Vector Flux Drive Rod Pumping System

As a result of more efficient use of electrical power the use of an ePAC drive will significantly reduce the lift cost per barrel of fluid produced to surface as well as reducing maintenance costs for the primary method of artificial lift. The high efficiency operation of the pumping unit can limit the amount of stress placed on the rods during normal operations and as a result of this can significantly reduce the number of repairs required during the life of the rod pumping system.

• Uses high efficiency (92% - 96%) standard motors in place of low efficiency (82% - 86%) high slip motors
• ePAC drives incorporate unique design features that reduce electric utility costs and improve power quality
• The drives provide near-unity power factor at all speeds and loads, to avoid utility power factor penalties
• Gearbox torque limiter protects the gearbox from excessive torque loads, reducing the possibility of gearbox damage
• Rod force limiter reduces the possibility of rod part
• Eliminates the high in-rush currents of across the line motor starting
• Smoothes energy consumption by reducing excessive rod forces and counter balance errors

ePAC Vector Flux Drive Rod Pumping System Performance Features

The ePAC is designed to operate with 230, 380, 460, or 575 Volt 50/60 Hz power sources. Units are also available for operation from single-phase power lines.

• Minimum fill controller provides simple pump off control of wells with poor inflow characteristics
• Gearbox ratio monitor automatically computes the overall ratio between the motor and crankshaft with each stroke of the pump
• Pump speed monitor provides instantaneous and average pump speeds
• Independent operator-adjustable up and down stroking speed set points
• Set point speed based on pump fill and feed back from the beam position sensor, that senses the direction of the polished rod
• Internal limit switch provides adjustable crank angle points for changing pump upstroke, downstroke, and cornering speed on Rotaflex jack pumps
• Integral tracker system controls separation of the bridle from the sucker rod
• Pump fill optimizer maximizes well production and eliminates fluid pound by independently adjusting up and down stroke speeds
• Heavy-gauge Nema 3R enclosures seal the ePAC electronics from environmental factors such as sand, moisture, and small organisms
• Optional graphic display for viewing real-time surface and pump cards

Operational Modes of the ePAC Vector Flux Drive Rod Pumping System

Single Speed

In single speed mode, the user sets one speed for the up and down stroke. The pump speed monitor uses the motor velocity and overall gear ratio to calculate both the instantaneous and average pump speed.

In addition, other parameters ensure the efficient operation of the pump. These parameters are explained as follows.

The Gear Ratio Monitor automatically computes the overall gear ratio between the motor and the crankshaft each stroke of the pump. The user can set gearbox stress limit that will not be exceeded.

The Rod Force Limiter reduces rod breaks by limiting maximum stress and increases rod life by reducing fatigue. It eliminates bridle separation and rod compression damage by controlling minimum rod force. Maximum and minimum rod forces and associated rod positions are captured with each stroke of the pump, and the rod force is adjusted automatically to stay within preset parameters.

The Bridle Separation Controller uses a sensor on the bridle to detect separation on the down stroke due to rod float. The separation limiter automatically adjusts down stroke speed to track rod float while maximizing production.

Pump jack imbalance is displayed to the operator as positive (overbalanced) or negative (underbalanced) crankshaft torque. Imbalance information allows the operator to easily position or change the counterweights to minimize gearbox stress and energy consumption.

The Pump Flow Monitor uses well parameters and drive information to estimate pump flow. The estimated well production is displayed to the operator in BPD and is available for remote well monitoring through the serial communication channel.

Dual Speed

Dual speed control mode allows the operator to manually optimize the performance of the well by adjusting both the up and down stroke speeds to the required speeds.

Optimize

The pump fill optimizer offers an advanced form of pump fill control without the traditional requirement of separate devices or control hardware.

The ePAC automatically adapts to changing well inflow characteristics by adjusting up and down stroke speeds to maximize well production while avoiding fluid pound.

The pump fill monitor uses information from the motor and crank to determine pump fill percentage. Pump fill is displayed to the operator as a percent fill number and is used to automatically optimize well production.

ePAC Vector Flux Drive Rod Pumping System Automatic Monitoring

The ePAC’s embedded programming allows the user to preset limits to customize the control to the application.

These controls are active in all operational modes and include:

• Minimum and maximum SPM
• Gear ratio monitor automatically computes the overall gear ratio between the motor and the crankshaft each stroke of the pump and is used to monitor belt slip. Gearbox torque limits can be preset to limit gearbox stress.
• Rod force limiter reduces rod breaks by limiting the maximum stress that can be placed on the rods and as such increases rod life by reducing fatigue. It also can reduce rod compression damage by controlling the minimum rod force. Maximum and minimum rod forces, and associated rod positions, are captured with each stroke of the pump, and the rod force is adjusted automatically to stay within preset parameters.
• Bridle separation controller uses an internal calculation to detect loss of rod weight on the pump downstroke due to rod fl oat. The separation limiter automatically adjusts downstroke speed to track rod fl oat while maximizing production.
• Pump jack imbalance is displayed to the operator as positive (overbalanced) or negative (underbalanced) crankshaft torque. Imbalance information allows the operator to easily position or change the counterweights to minimize gearbox stress and energy consumption.
• The pump flow monitor uses well parameters and drive information to estimate pump flow. The estimated well production is displayed to the operator in BPD.

ePAC Vector Flux Drive Rod Pumping System Control Monitoring

UEDIT software allows the system to be monitored through one of the ePAC’s serial ports. Various screens provide configuration and operational interfaces, including:

• The dynagraph screen can be used to display both surface and pump card.
• Data in the ePAC can be uploaded to an archive as a backup or downloaded to the drive from the archive to restore prior setup information.

User Interfaces the of ePAC Vector Flux Drive Rod Pumping System

• An operator interface provides access to system parameters that are organized into logical groupings for easy navigation.
• On-line setup instructions, prompts, warnings, bar graph displays, and logical data groupings result in fast startups, smooth operation, and minimum downtime.
• Pump fill monitor continuously measures and displays the pump fill percentage.
• 16-button keypad allows simple menu navigation and data entry.
• 2-line by 24-character display provides easily read text/graphics.
• Optional graphics display available for viewing real-time surface and pump cards.
• Password protection is used to prevent unauthorized access to drive parameters.
• Fault log is used to capture time-stamped diagnostic information to aid in troubleshooting drive or pump problems.
• Additional parameters that can be monitored include:
  • Input power monitor
  • Lift power monitor
  • Input power meter
  • Pumping efficiency
  • Production monitor
  • Pump cycle monitor
  • Balance monitor
• Enhanced RTU protocol allows efficient transfer of both 16- and 32-bit data through local or remote networks

Programmable Logic Controller of the ePAC Vector Flux Drive Rod Pumping System

UEDIT also incorporates a Programmable Logic Controller (PLC) that can be used to monitor drive operation, customize the drive to unique system needs, and provide a simple migration path for future upgrades.

Ladder Diagram Screen	Function Block Screen	Input/Output Screen
Logic type signals can be programmed and monitored in familiar ladder diagram formats.	Analog type signals can be manipulated and monitored using a rich variety of function blocks.	Input and output signals can be forced and monitored using a convenient I/O display panel.

Specifications of the ePAC Vector Flux Drive Rod Pumping System

Our case study ePAC Flux Vector Rod Pump Controller Variable-Speed Control shows how companies have benefited from our rod pump and VFD solutions.