A vacuum degasser is one of the most critical pieces of equipment in any modern solids control system.

Its main function is to remove entrapped and cut-in gases from drilling fluids—gases that can seriously damage mud properties, reduce drilling efficiency, and create dangerous wellbore conditions.

As drilling operations become deeper and more complex, an efficient vacuum degasser is no longer optional; it is a mandatory requirement for safe and stable mud circulation.

Although high-performance desilters and desanders improve solids separation, none of them can function correctly if the mud is gas-cut. This is why the vacuum degasser is positioned immediately after the shale shaker and works as the second stage of mud cleaning before the mud enters desanders, desilters, and centrifuges.

✔ Why Gas Removal Is Essential in Drilling Fluids

During drilling operations, the drilling fluid can contain gases such as methane (CH₄), hydrogen sulfide (H₂S), carbon dioxide (CO₂), and air.

These gases enter the mud from:

• High-pressure formations

• Gas-bearing zones

• Cavernous formations

• Poor mud sealing

• Gas influx during drilling

If these gases are not removed immediately, they cause:

1. Incorrect Mud Weight

Gas reduces the density of the fluid, which can lead to loss of well control, kick risk, and difficulty maintaining hydrostatic pressure.

2. Abnormal Rheology and Viscosity

Gas-cut mud behaves unpredictably:

• Lower viscosity

• Unstable gel strength

• Poor carrying capacity for cuttings

3. Inefficient Solids Control

Gas bubbles prevent proper separation inside desanders, desilters, and centrifuges, reducing their efficiency by more than 30–50%.

4. Increased Drilling Cost

Gas-cut mud causes:

• More chemical consumption

• Higher mud maintenance cost

• Faster wear of pumps and equipment

• Potential downtime or wellbore instability

A vacuum degasser directly solves these problems by restoring mud properties before the mud moves to the next treatment stage.

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✔ How a Vacuum Degasser Works

A vacuum degasser uses a negative-pressure chamber to force the drilling fluid to expand and release trapped gases.

Working Process

1. Drilling mud enters the degasser under suction.

2. The internal vacuum pump creates a pressure range of –0.02 to –0.04 MPa.

3. Mud spreads over a special separation tray, forming a thin film for maximum gas extraction.

4. Intruded gases separate rapidly due to the low pressure.

5. Gas is vented safely away from the rig site.

6. Degassed mud is discharged and returned to the active mud tank.

This system ensures more than 95% gas removal efficiency, guaranteeing stable mud weight and consistent performance.

✔ Vacuum Degasser Also Works as a Heavy Agitator

One major advantage is that the vacuum degasser not only removes gas but also stirs the mud vigorously during the circulation process. This agitation helps:

• Prevent barite settlement

• Maintain mud homogeneity

• Improve solids suspension in all tanks

Thus, the equipment performs two roles in one:
Gas removal + Mud agitation, which reduces equipment costs and tank layout complexity.

✔ Key Features of the RVVD Vacuum Degasser Series

The RVVD series degassers are engineered to deliver stable, high-performance results in both onshore and offshore drilling.

1. High Gas Removal Efficiency (≥95%)

Achieves clean mud conditions even in gas-bearing formations.

2. Reliable Vacuum Range (-0.02 to -0.04 MPa)

Ensures effective degassing without aeration or turbulence.

3. Robust Motor System

• Main motor: 22 kW or 37 kW depending on model

• Pump motor: 7.5 kW

• Stable rotation speed (700–860 RPM) maintains constant suction flow.

4. Explosion-Proof Options

Built to meet ExdIIBt4 / IEC EX / ATEX requirements for safe use in hazardous zones.

5. Flexible Mud System Compatibility

Can be installed in:

• Oil & gas rigs

• Geothermal drilling

• HDD mud systems

• Mining and water well drilling

6. Compact Structure with High Durability

Heavy-duty tank body, corrosion-resistant design, and long service life for continuous 24/7 operation.

✔ Relationship Between Vacuum Degasser and Desilter

A vacuum degasser is always placed before desanders and desilters.

Why?

Because gas inside the drilling mud prevents hydrocyclones from building sufficient centrifugal force.
Without degassing:

• Cones lose pressure

• Separation efficiency drops

• Mud weight becomes unstable

• Pump cavitation may occur

Therefore, a degasser is the foundation that ensures desilters operate at ≥95% efficiency.

FAQ – Vacuum Degasser

1. What is the main purpose of a vacuum degasser?

Its purpose is to remove harmful gases (CH₄, H₂S, CO₂, air) from drilling mud, stabilizing mud weight and preventing drilling hazards.

2. Why must the degasser be installed after the shale shaker?

Because the shaker removes large solids first. The degasser then treats the clean flow of liquid mud, ensuring efficient gas removal.

3. Can a degasser replace a mud agitator?

Partially yes.
Since the degasser agitates the mud vigorously during operation, it reduces the number of agitators needed in the tank.

4. What happens if the vacuum degasser is not installed?

You will face:

• Gas-cut mud

• Incorrect density

• Poor solids control performance

• Higher chemical and maintenance cost

• Increased risk of well kicks

5. Are RVVD degassers explosion-proof?

Yes. They meet ExdIIBt4, IEC Ex, and ATEX standards, suitable for hazardous drilling conditions.

6. What is the typical gas removal efficiency?

RVVD vacuum degassers consistently achieve ≥95% gas removal, restoring mud quality effectively.

7. Can the degasser handle both oil-based and water-based mud?

Yes. It is designed for all common drilling mud systems, including WBM, OBM, and SBM.

8. Does the degasser affect mud viscosity?

It actually stabilizes viscosity by removing gas bubbles that cause rheological fluctuations.