POLYPAC UL polyanionic cellulose (PAC) is a high‐quality, water‐soluble polymer designed to control fluid loss. Since it is an “ultra‐low” (UL) additive, POLYPAC UL causes a minimal increase in viscosity in water‐base muds.
POLYPAC UL additive controls fluid loss in freshwater, seawater, KCl and salt muds. It forms a thin, resilient, low‐permeability filter cake. This minimizes the risks of differential sticking and the invasion of filtrate and mud solids into permeable formations. POLYPAC UL additive resists bacterial attack and does not require a biocide or preservative.
It is effective in low concentrations, with the normal concentration to control fluid loss ranging from 0.25 to 1 lb/bbl (0.71 to 2.85 kg/m3). In saltwater and PAC‐polymer systems, higher concentrations are required for encapsulation, with normal concentrations ranging from 1 to 3 lb/bbl (2.85 to 8.6 kg/m3).
POLYPAC UL additive is an anionic polymer which attaches to, and encapsulates exposed shales and drill cuttings. This protective polymer ʺenvelopeʺ inhibits the dispersion of shale cuttings and restricts fluid interactions with exposed shales.
POLYPAC UL additive is an ʺultra‐lowʺ additive which generates less viscosity than regular POLYPAC additive.