Thermo-thickening behavior of LCST-based copolymer viscosifier for water-based drilling fluids

摘要: Abstract Thermo-thickening polymers have gained a strong interest due to its attractive properties and had great potential for making up the deficiency of viscosity low-solid water-based drilling fluid at high temperature. The work in this paper was focused on studying thermo-thickening behavior new class LCST-based (Lower Critical Solution Temperature) polymeric viscosifier fluid. additives, which were obtained our previous work, showed good temperature resistance However, influence molecular composition copolymer thermo-associative still unsettled. Based structure/properties relationships copolymers, aimed investigate thermo-association role thermo-assembling behavior. For that purpose, five copolymers with different NVCL content prepared same synthetic process. Thermo-associating no-solid freshwater base (NSFBF) (LSFBF) investigated by rheometer. Results from rheological tests interesting intimately related content. Only when confined certain range, it would appear obvious phenomenon above critical associative (Tass). And Power-Law Herschel-Bulkley model best fit rheology fluids. In relation macroscopic properties, phase change process monitored Differential scanning calorimetry (DSC) H1-NMR spectroscopy. DSC indicated displayed similar endotherms NSFBF LSFBF. compared LSFBF, transition polymer lower (Tp) higher heats (ΔH). spectroscopy PVCL chains gradually became hydrophobic upon heating resulting association micro-domains led increase viscosity. Furthermore, values Tass Tp analyze application as