Field Evaluation of D.E. and Cartridge Filters for Completion/Workover Fluid Filtration

Abstract

Proper filtration of "clean" brines is an important step in well workover or completion operations. The use of properly filtered brines has resulted in increased oil production in several Conoco wells in the Gulf Coast region. This is a direct result of reduced formation damage. The results of a 3-year field evaluation of D.E. and cartridge filter systems are reported and compared to findings of laboratory core flow tests to determine needed brine "clarity" for minimum formation damage.The evaluations show that even highly contaminated completion/workover fluids can be satisfactorily filtered to contain less than 50 mg/ R. of solids with either diatomaceous earth (D.E.) and/or cartridge filter systems. Both systems removed as much as 96 to 99 percent of influent solids. The D.E. filters, in general, handled a much wider range of solids concentration more efficiently than the "nominal rating" cartridge filters. Laboratory core flow tests have shown that completion/workover fluids with approximately 5 mg/R. of solids do not cause formation damage with limited pore volume injection.