1. n. [Drilling Fluids]
Linear, anionic polymer made from the monomer acrylic acid, CH2=CHCOO– H+. The acrylic acid groups are evenly spaced along the chain. Acrylic acid polymer neutralized with NaOH is sodium polyacrylate (SPA). Polyacrylates are best utilized in soft water with low salinity to achieve the best dispersion and full chain elongation. Even low concentrations of hardness ions, for example, Ca+2, precipitate polyacrylates. Low molecular-weight polyacrylates are used as clay deflocculants. High molecular weight polymers are used for fluid-loss control and as a clay extender. As an extender, SPA is added to bentonite at the grinding plant. It is also used at the rig in low-solids mud. Divalent cations can negate its benefits as a clay extender. SPA is highly efficient when used to flocculate colloids in native-solids muds, clear-water muds and wastewater cleanup. The polymer chain links together colloidal solids that can be removed by gravity settling in shallow pits or by applying hydrocyclone, centrifuge or filtration techniques.
See: acrylamide polymer, acrylamide acrylate polymer, anion, calcium contamination, clear-water drilling, deflocculant, deflocculated mud, flocculant, hardness ion, low-solids, nondispersed mud, native-solids mud, PHPA mud, sodium bicarbonate, sodium carbonate, sodium polyacrylate, soft water, water clarification