What is a Vacuum Degasser?
A vacuum degasser, also known as a degasser unit or degassing tank, is a specialized piece of equipment used in the oil and gas industry to remove entrained gases, primarily gases like methane, hydrogen sulfide, and carbon dioxide, from drilling fluids or mud. It is an essential component of the solids control system and plays a crucial role in maintaining the performance and safety of drilling operations. Here's an overview of the vacuum degasser and its function:
Function of a Vacuum Degasser:
During drilling operations, drilling mud or drilling fluid comes into contact with the formation being drilled, and gases can be released and dissolved into the mud. These entrained gases can cause various issues if not removed, including:
Safety Concerns: Gases like methane and hydrogen sulfide are toxic and pose safety risks to personnel on the rig. They can accumulate in the drilling fluid and potentially be released into the atmosphere during mud handling operations.
Impaired Drilling Performance: The presence of entrained gases can adversely affect the performance and stability of the drilling fluid. Gases can reduce the density of the mud, affect the rheological properties, and impair its ability to carry cuttings to the surface.
Equipment Efficiency: Gases can cause air pockets or gas-cut mud, leading to reduced drilling efficiency and decreased wellbore stability. Additionally, gas bubbles in the drilling mud can interfere with the accuracy and reliability of various drilling measurements.
To address these concerns, a vacuum degasser is employed to remove the entrained gases from the drilling fluid, enhancing drilling safety and efficiency.
Operation of a Vacuum Degasser:
A vacuum degasser typically consists of a cylindrical vessel or tank that is partially filled with drilling mud. The tank is equipped with rotating elements, such as a central shaft with vanes or impellers, and operates under a partial vacuum. The degasser unit functions in the following manner:
Mud Entry: The drilling mud, containing entrained gases, is directed into the vacuum degasser tank, typically from the mud return flow line.
Gas Separation: As the mud enters the tank, the rotating elements create a thin film of mud that is exposed to the vacuum. This vacuum lowers the pressure within the tank, promoting the release and expansion of entrained gases from the mud.
Gas Extraction: The released gases, which are now in a gaseous state, are drawn out of the vacuum degasser through a gas vent line. These gases are typically routed to a safe location, such as a flare system, for controlled disposal.
Mud Return: The degassed drilling mud, now free from entrained gases, exits the degasser unit and is directed back into the active mud system for reuse in the drilling process.
The vacuum degasser operates continuously, effectively extracting and removing entrained gases from the drilling mud, improving drilling safety and mud performance.
In summary, a vacuum degasser is a specialized equipment used in the oil and gas industry to remove entrained gases from drilling fluids or mud. By operating under a partial vacuum, the degasser unit helps enhance drilling safety, maintain drilling fluid properties, and ensure efficient drilling operations.