Potential Application of Saponite Clay for Production of Drilling Fluids

Saponite is classified as a trioctahedral mineral of the smectite group.Natural saponite of the Lomonosov deposit (Arkhangelsk region, Russia) is represented as Na- or Ca- forms according to XRD analysis. The interlayer space of the structure contains water molecules. The saponite clay sampled at the deposit is represented by pulp. The clay powder for the research was obtained by the technology of concentrating fine clay material. The crystallochemical formula of saponite was calculated based on the data obtained from XRD, XRF and atomic emission analyses. The purpose of the research was to study the effect of mixed sodium carbonate-sulfate electrolyte (Na2SO4 - 80%; Na2CO3-20%), polyacrylamide (PAA) and low viscosity polyanionic cellulose (PAC L) on the structure, filtration and rheological properties of saponite suspension. The optimum solids content in the water suspension of saponite clay was determined to be in the range of 85-100 g/l. Going out of range leads to deterioration of filtration properties presented by significant increase in filtration loss or increased thickness of the filtration cake. Filtration loss at 85 g/l solids content in the water suspension was 22 cm3/30 min. Addition of mixed sodium carbonate-sulfate electrolyte to the saponite suspension improved rheological properties, but increased filtration loss to 34-36 cm3/30 min. The admixture of polyacrylamide leads rather quickly to flocculation and sedimentation of clay particles; filtration loss was 16-21 cm3/30 min. The presence of polyanionic cellulose in the suspension creates a gel structure, increasing the viscosity of the mud system and significantly reducing filtration loss to 7-9 cm3/30 min.