Vegetable oil-based preflush fluid in well cementing

Efficient cement bonding in wellbores provides better zonal insulation, containment of gas migration, prevention of excessive water production, besides affecting their economical performances. Carrying out a properly sized and formulated cleanup process (or pre-flush) is one of the most costly tasks in wellbore preparation. Different chemicals are commonly used both to remove filter cakes and enhance surface water-wetting, such as solvents and surfactants. The search for environmentally-friendly cleanup fluids, in particular, with acceptable wetting properties, has been challenging. This paper describes an experimental study to characterize and prepare a vegetable oil-based microemulsion to work as pre-flush fluid in wellbores. Results obtained from cleaning assays (removal test), wettability testings and fluid compatibility analyses have exhibited excellent performances in filter cake removal. Enhanced water-wetting and suitable rheological compatibility of cement/cleanup fluid/mud systems and good compressive strength were also achieved.