Impact of Temperature on the Solution Conformation and Performance of AMPS (R)- and AHPS-based Fluid Loss Polymers in Oil Well Cement

摘要

A copolymer composed of 2-acrylamido-2-methyl propane sulfonic acid (AMPS (R)) and N,N-dimethylacrylamide (NNDMA) as well as a forpolymer based on AMPS, NNDMA, 1-allyloxy-2-hydroxy propane sulfonic acid (AHPS) and acrylic acid (AA) were synthesized and tested for their temperature stability. Both polymers were dissolved and aged in cement pore solution at temperatures between 100 and 220 degrees C and 35 bar pressure, simulating conditions in actual well cementing. The influence of this high-temperature treatment on the fluid loss performance was assessed via high-pressure filtration tests. Water retention capacity and adsorption of AMPS (R)-co-NNDMA was found to decrease as a result of temperature-induced shrinkage of the stiff, linear polymer chain, as evidenced by dynamic light scattering (DLS) measurement of its hydrodynamic radius. Oppositely, the AHPS-based fluid loss additive did not exhibit coiling under high-temperature conditions. Therefore, its adsorption remained unaffected, and a stable fluid loss performance was observed.