Fast plungers cause dangerous hard impacts at surface. The magnitude of the impact is not based on velocity of the plunger alone. To properly monitor and control a plunger well and align with the API 11PL standard, you must monitor Kinetic Energy (KE).
In June 2020, a new standard, API 11PL: Plunger Lift Lubricators and Related Equipment was implemented that covers the design, testing, manufacturing, and general specifications for plunger lift well heads.
This standard was a collaborative effort between a number of major oil and gas producers and industry leading plunger lift manufactures in the hopes of creating a standard to add more certainty and safety into plunger lift operations.
One of the key aspects of this standard was to define a well head lubricator rating based around impact force that can be tolerated. This force is the kinetic energy of the impact.
Kinetic Energy (KE)
Kinetic energy is the measurement of energy or force of a moving object. It can be calculated using the mass and velocity of an object.
Implementation in Sasquatch
The calculation and use of Kinetic Energy should be implemented in high level monitoring and control systems. We have included some features in the Sasquatch so that it can be tested and used without additional systems or integrations.
These features can be accessed using the SCADA tab in Vision.
In order to calculate the Kinetic Energy, Sasquatch needs to have access to the plunger mass. This must be written to Modbus register 4:0061.
Kinetic Energy Calculation
Each time that the plunger arrives and the velocity is measured, the Kinetic Energy will be calculated. This is then used for any of the alarms below.
To detect a hard arrival, the Hard Arrival Kinetic Energy Threshold (register 4:0063 – 4:0064) must be set.
When the Kinetic Energy exceeds this threshold, a hard arrival is declared. After a number of consecutive hard arrivals are registered, the Consecutive Hard Arrival Alarm (register 1:00013) is set.
The Consecutive Hard Arrival Alarm Threshold (register 4:0065) is used to define the number of consecutive hard arrivals to set the alarm on.
To detect a dangerous arrival, the Dangerous Arrival Kinetic Energy Threshold (register 4:0067 – 4:0068) must be set.
When the Kinetic Energy exceeds this threshold, a dangerous arrival is declared. After a single dangerous arrival, the Dangerous Arrival Alarm (register 1:00014) is set.
To track spring wear, the Sasquatch adds the Kinetic Energy of each arrival to a Cumulative Kinetic Energy (register 3:0026 – 3:0027).
If the Cumulative Kinetic Energy Threshold (register 4:0070) is set and the total exceeds this threshold, the Cumulative Kinetic Energy Alarm (register 1:0016) is set.