Particle Size Distribution Selection of CaCO3 in Drill-In Fluids: Theory and Applications

Abstract

Abstract Bridging agents are used in Drill-In fluids to prevent problems of massive loss circulation to the formation and formation damage through fine solids migration that invade the hydraulic flow channels of the reservoir rock. Also, thick cake build up that induces a differential sticking problem, as well as torque and drag of the drill string are avoided. The first step when selecting the particle size distribution of bridging agents (specifically CaCO3) in Drill-In fluids is the petrophysical characterization and pore geometry determination of the rock. In consolidated sands, the criterion of selection of particle size of bridging agents is: 1/7 Dpore throat<Dparticle<1/3 Dpore throat. CaCO3 from different sources were selected with a particle size distribution within the described interval, determined by using a particle size distribution analyzer through LASER dispersion technique. In order to prove experimentally the effectiveness of the formed cake, dynamic filtration tests were conducted in aloxite synthetic cores previously characterized. Determination of the pore and pore throat diameters were performed through S.E.M imaging technique. Verification of the particle size distribution of the CaCO3 to be used was carried out through LASER dispersion technique. Results of the dynamic filtration tests are reported.