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Wellhead Screen-Filter – Purpose, Design, and Comparison to Multiphase Desander (B-FSM-101)


Purpose: The Wellhead Screen-Filter, commonly called a Dual-Pot Sand Filter, is a service tool used to capture coarse solids from well flow during flow-back and cleanup.

Definition: A unit process device consisting of a batch, constant-pressure, surface (cake) filter with a cylindrical rigid metal screen medium, and used to clarify coarse (>150 µm) solids from multiphase well flow.

 Comparison to Multiphase Desander:

  • The Wellhead Screen-Filter and Wellhead Desander are both used as a service tool during well flow-back and clean-up operations
  • The WSF is not used in permanent production operations. The multiphase desander in Wellhead or Wellstream version, are commonly installed as a permanent part of facilities to deal with long-term sand production.
  • Both devices work in multiphase or liquid-only flow.
  • The WSF has infinite turndown as the separation mechanism is not pressure drop dependent. The multiphase desander has a finite (~5:1 turndown) based on the flow-pressure relationship.
  • The WSF separate solids effectively down to 100-150 microns, while the multiphase desander can separate down to 15-20 microns.
  • The WSF has a 50-60 liter solids hold-up volume before backflush, while the multiphase desander has 150-300 liter solids accumulation volume.
  • The WSF requires 2 x 100% layout to allow flushing of one unit while the other is in operation. The multiphase desander stays online at all times during operation, even during solids flushing.
  • For the multiphase desander fluid viscosity has a directly proportional relationship with separation size, while the WSF maintains separation performance at all fluid viscosities. However, both units show increase pressure drop with increasing viscosity.


  1. Rawlins, C.H., “Separating Solids First – Design and Operation of the Multiphase Desander”, paper 185658-MS presented at the SPE Western Regional Meeting, Bakersfield, CA, 23-27 April, 2017. https://doi.org/10.2118/185658-MS

Next week I will cover general design and operation of the WSF.

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