A multifunctional polymer for optimization of the cement spacers: oil-based drilling fluid removal and rheology regulation.

A multifunctional polymer (HAMP) for performance optimization of the spacers is presented based on 2-acrylamido-2-methyl propane sulfonic acid (AMPS), maleic anhydride (MA), acrylic acid (AA), and surfactant monomer. Specifically, HAMP was endowed with amphiphilic properties and thermo-associate behavior by introducing surfactant monomer and hydrophobic groups, respectively. Thus, HAMP has the potential for synergies with surfactant due to their amphiphilic properties and exhibits thermo-thickening behavior due to the thermo-associate behavior. These two properties are applied to the removal of oil-based drilling fluids and to increase the stability of spacers. Tests shows that: HAMP can synergize with ionic/non-ionic surfactant to increase the interface activity of surfactant/HAMP mixture; HAMP solution exhibits continuous thermo-thickening behavior at temperature above 70 °C when its concentration is higher than 0.3%, which can mitigate the consistency reduction of spacers at high temperature; the surfactant/HAMP mixture has higher removal efficiency and better temperature and salt resistance than the single surfactant solution; rheological property changes little in the range from 25to 90 ℃, and 0.3% HAMP can prevent the sedimentation of weighted spacer. Series of mechanism experiments indicate that more association forms a denser micronetwork at higher temperature, which leads to the thermo-thickening behavior of HAMP; the groups with different charges and hydrophobic groups in HAMP can make it better adsorbed on the surface and the components the oil-based filter cake, resulting in wetting modification of the surface and stabilizing oil-base components, which are conducive to the removal of the oil-based drilling fluid. It is hoped that the multifunctional polymer proposed in this paper can be applied in various fields. [ABSTRACT FROM AUTHOR]