HOW HYDROLYZABLE METAL IONS REACT WITH CLAYS TO CONTROL FORMATION WATER SENSITIVITY

Abstract

Principal cause of formation water sensitivity is dispersion and movement of clay particles; dispersion is largely brought about by expansion of tiny cation '%'atmospheres'%' around each clay particle; hydrolyzed metal ions prevent clay dispersion by displacing exchangeable cations and becoming firmly attached to clay surfaces; polyvalent metals hydrolyze through formation of multiple hydroxyl bridges (olation polymerization); soluble compounds of hydrolyzable metals have effectively combated formation water sensitivity both in laboratory and in field tests.