Completion fluid is a specially formulated brine composed of chlorides and bromides. After drilling and well completion, the completion fluid circulates through the wellbore to remove residual solids during completion operations and prepare the well for production. Solids and particulate matter present in the completion fluid will reduce its cleaning efficiency inside the oil well. In addition, completion fluid may migrate into the formation. For well safety, completion fluid features a high density. If the fluid becomes unbalanced or overly heavy, it may flow into the formation during recirculation and result in loss of oil production.
For standard oil well cleaning and overbalanced flow conditions, thorough filtration is required to remove contaminants from the fluid. This prevents formation plugging and ensures the long-term productivity and operational reliability of the oil well.
Clean completion fluid is required throughout multiple completion stages, including initial fluid displacement, perforation flushing (during and after operations), gravel packing, cement reaming and drilling, fluid circulation, tripping operations, pill treatment and pill volume control, as well as the application of new brine blends.

Purpose of Filtration
Filtration is implemented to prevent downhole formation contamination. Formation particle contamination tends to occur during wellbore cleaning, perforation, fracturing, acidizing, workover, water injection and gravel packing operations.
A daul vessel cartridge filter traps impurities in the fluid and allows the treated clean fluid to flow back into the oil well.
Completion fluid contaminants vary greatly in size and form. Drilling operations generate cuttings, rust, scale, pipe coatings, paraffin wax, undissolved polymers and other debris on casings and tubing. All these substances contribute to the total solid content of the fluid.
Issues Causing Producing Zone Failures
All fluids that come into contact with the producing zone, including drilling fluid, borehole fluid, completion fluid, workover fluid and reaming fluid, must be filtered and purified. Fine contaminants entering the producing zone will decrease the permeability of wellbores, which in turn lowers oil well productivity.
Completion Fluid Filtration
To avoid damage to the producing zone, both completion fluid and workover fluid must be filtered.
Ideally, completion fluid should be completely free of solid contaminants. In practical applications, removing particles of 5 microns and smaller is the most cost-effective solution.
Stable and reliable filtration of well fluids maintains high oil output and extends the service life of oil wells.