Desander / Desilter

Keeping the Flow Clean: Desanders and Desilters in Drilling & Well Completion

In the world of drilling and well completion, maintaining a clean drilling fluid is paramount. This fluid, often a mixture of water, mud, and other additives, serves several crucial functions:

• Lubricating the drill bit: Preventing friction and wear.
• Carrying cuttings: Removing rock fragments from the wellbore.
• Supporting the wellbore: Preventing cave-ins.
• Controlling pressure: Maintaining stability within the well.

Contamination by sand and silt, collectively referred to as "solids," can significantly disrupt these functions, leading to complications such as:

• Bit wear: Excessive wear on the drill bit, leading to premature failure.
• Reduced penetration rate: Slower drilling progress due to clogged drill bit and circulation system.
• Increased pressure: Build-up of solids can create pressure differentials and potential wellbore instability.
• Equipment damage: Solids can damage pumps, valves, and other equipment.

To combat these challenges, desanders and desilters play a critical role in the drilling process. These devices effectively remove sand and silt from the drilling fluid, ensuring a cleaner and more efficient operation.

Centrifugal Flow Path: The Heart of the Process

Desanders and desilters primarily utilize centrifugal flow paths to achieve their separation goals. This technology relies on the principle that denser particles (like sand and silt) are flung outwards due to centrifugal force when the drilling fluid is rotated.

Here's a simplified breakdown of the process:

1. Fluid Entry: The drilling fluid enters the desander/desilter unit through an inlet.
2. Centrifugal Rotation: The fluid is then directed into a rotating chamber, generating centrifugal force.
3. Particle Separation: Denser solids (sand and silt) are forced outward towards the periphery of the chamber, while lighter fluids remain closer to the center.
4. Discharge: The cleaned fluid exits the unit through a central outlet, while the collected solids are discharged separately.

Common Devices and Their Applications:

• Hydrocyclones: These conical devices are widely used in drilling operations. Their simple design and high efficiency make them a popular choice for removing sand and silt.
• Decanter Centrifuges: These larger, more complex units are typically used for removing finer solids. They are particularly effective for handling large volumes of drilling fluid and achieving high levels of separation.
• Solid Bowl Centrifuges: These units feature a rotating bowl that separates solids from the fluid. They are commonly employed in onshore and offshore drilling operations to remove a wide range of contaminants.

Beyond Separation: Maintaining Efficiency

Proper operation and maintenance are crucial for the success of desanders and desilters. Regular inspection and cleaning are essential to prevent clogging and ensure optimal performance. Additionally, proper selection of the right type and size of desander/desilter is critical based on the specific drilling fluid and well conditions.

By effectively removing sand and silt from drilling fluids, desanders and desilters play a vital role in optimizing drilling operations. They ensure the stability and efficiency of the drilling process, ultimately contributing to the safe and successful completion of oil and gas wells.