gyp mud | Oilfield Glossary
1. n. [Drilling Fluids] A calciumbased water mud system containing mud can be used for drilling shales, but it is also wellsuited for drilling gypsum, anhydrite and salt stringers. An advantage of gyp over lime muds is that the pH of gyp mud need not be so high because it contains more soluble Ca +2 to inhibit shale swelling. Gypsum, CaSO 4 #183;2H 2 O, content is measured by an API