摘要：Maintaining reasonable rheology is of vital importance in high temperature and high pressure drilling.In this study,a polyamidoamine low molecular weight polymer was synthesized with (Octadecadi-enoic acid) dipolymer,diethanolamine and triethyl-enetetramine and employed as rheology modifier in oil-based drilling fluid.The synthesized rheology modifier was characterized with Fourier Infrared (FTIR) spectra,gel permeation chromatography (GPC) and hydrogen nuclear magnetic resonance (:H-NMR) spectra.The effect of the rheology modifier on the rheological properties of organic clay suspension and typical oil-based drilling fluid was investigated.The underlying mechanism of the rheology modifier to improve the rheological properties under high temperatures was probed with X-ray diffraction (XRD) analysis and microscope observation.The results indicated that the rheology modifier is a low molecular weight polymer with multi-functional groups.The oil-based drilling fluid formulated with the novel rheology modifier exhibited optimal rheology and low high temperature and high pressure filtration loss after thermal aging at 180 °C.The rheology modifier accelerates the dispersion of organic clay particles and increases the interlayer spacing of organic clay even after high temperature treatment,which provides a high probability for the organic clay particles to form networks for desirable rheology.The synthesized rheology modifier shows promise in application in oil-based drilling fluid especially for high temperature and high pressure drilling.
