What is VLT SALT?
SALT stands for Sensorless Artificial Lift Technology. SALT is a versatile technology that offers significant advantages for all types of down-hole pumps, including beam, progressive cavity and submersible. Designed specifically for oilfield applications, SALT incorporates patented algorithms and built-in pump-off control into a Sensorless Vector Variable Frequency Drive (VFD).
SALT simplifies well automation and is capable of running ALL types of artificial lift pumping systems, as well as surface pumps and compressors.
Easy to use
- SALT has been designed specifically to be user friendly. It takes as little as 15 minutes to set system parameters during initial setup procedures. Basic information and control components are displayed prominently on the front of the unit, providing instant access to system status. Additional levels of control and data retrieval are available using a variety of access methods.
- With onboard help and an intuitive menu structure, the SALTkeypad provides graphical information and access to all parameter settings. These settings can be uploaded to and downloaded from the keypad, which greatly simplifies restart procedures and minimizes downtime in service situations. LED indicators provide basic status information and dedicated buttons enable one-touch access to commonly used functions.
In any well, the higher the casing pressure, the less fluid is allowed into the well bore. Any time the pumping system is stopped, the pressure increases, reducing flow into the well. SALT maintains minimum intake pressure to the well by varying the speed to match the well’s productivity, thereby minimizing the shutdowns that reduce well productivity.
SALT automatically adjusts speed to match the variable fluid volumes caused by:
- Changes in reservoir level
- Shutdown of adjacent wells
- Artificial stimulation methods such as water floods,“Huff and Puff" steam or CO2 injection
- Pump wear
Upon pump-off (under load), SALT does not stop but rather slows the pump until fluid levels have recovered. This greatly increases production. SALT eliminates shutdowns and their resulting periods of well recovery and pump-down. Maintaining consistent fluid production results in optimal flow from the reservoir into the well, maximizing its production capacity. On rod pumps, SALT will dynamically vary the pump speed within each stroke to maximize efficiency, regulate rod stress and maintain the appropriate average strokes per minute based on reservoir level.
The use of a VFD allows operating the motor above base speed. This allows for a faster pump-down of high fluid levels.
Lower Equipment Costs
- Using SALT on any pump system can reduce or, in some cases, eliminate altogether the costs related to additional equipment. In addition, its sophisticated control technology is designed to be easy to implement, installing in less than ¼ of the time required for traditional pump-off controllers. The result is a more efficient, reliable and streamlined installation.
- SALT increases system efficiency, allowing the use of smaller motors and transformers.
- SALT replaces the standard pump panel and requires no field end devices, such as load cells, encoders or pump cards. SALT’s ability to automatically optimize the fluid level and prevent cavitation is superior to bottom-hole pressure control.
Reduce mechanical stress
- On rod pumps SALT reduces or eliminates rod overloading and compression by dynamically adjusting pump speed within each stroke. As SALT regulates down the pump strokes per minute based on reservoir levels, mechanical stress is reduced. Furthermore, SALT soft starts do not exceed the load limits of the rod or gearbox even if the pump is stuck due to solids or mechanical problems. In fact, by slowing the unit down rather than stopping entirely, SALT eliminates altogether the potential for solids to fall back into the pump.
- Four-quadrant control for rod pumps provides adjustable speeds and load limits within portions of each stroke. This function can be used to eliminate rod float and rod compression, allowing the use of fiberglass rod. SALT decreases speed during peak mechanical loads, eliminating peak load setting violations.
- Traditional pump-off controllers cause wide temperature and pressure variations in the pump motor. Because SALT operates continuously, motor temperature and pressure are more consistent, prolonging the longevity of submersible pump motors.
Minimize energy consumption
- Traditional pump-off systems allow fluid to flow back down through the pump every time the pump shuts off. By operating the pump continuously, SALT eliminates this problem altogether. Fluid that has already been produced does not have to be produced again. Upon gas detection, SALT increases speed to pass the gas through the pump. If this fails, the pump is slowed to minimum speed to let the gas pass while allowing the fluid level to increase. The system will then repeat the process until the gas is eliminated.
- SALT provides a power factor of 0.97, eliminating the need for power correction and the power losses associated with such equipment. SALT’s soft start and load limit features also reduce peak demand charges by as much as 50% when compared to standard pump-off controllers.
- SALT reduces the excess power delivered to rod pumps by slowing down during peak demands. Any excess energy delivered to the rod pump is then retained as mechanical energy instead of being converted back to electrical energy. Since the excess energy is kept within the system instead of returning to the power grid, less energy from the power grid is required for the next peak demand. This patented system reduces kilowatt usage by 22% or more. In unbalanced systems, the kilowatt usage is reduced even further.