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Sodium hydroxymethyl lignosulfonate (NaHLS) was prepared by hydroxymethylation of sodium lignosulfonate (NaLS) and formaldehyde to enhance the performance as drilling fluids additive. The performances of the modified drilling fluid with NaLS and NaHLS, such as rheology behavior, filtration reducer and inhibitive ability were evaluated. The results indicate that the NaHLS can enhance the viscosity at low temperature, reduce the viscosity after ageing under 180 °C, which is more effective than that of NaLS. And NaHLS reduces the filtration, as the thickness of the modified fluid mud-cake is much thinner than that of NaLS. Besides, the inhibitive ability of NaHLS for clay hydrous disintegration is more effective than that of NaLS. The properties make NaHLS a potentially effective drilling mud additive.

Nitration-oxidation lignosulfonate (NOLS) was prepared using lignosulfonate (LS) as raw material. The product was characterized by Fourier Transform Infrared spectroscopy (FT-IR). The performance as a drilling fluid additive was evaluated with regard to rhology, filtration and temperature resistance. The results showed that NOLS can improve the viscosity under room temperature, decrease the viscosity under high temperature and reduce the filtration more effectively than that of lignosulfonate, which display its good temperature resistance. So NOLS may be used as sustained release nitrogen fertilizer in agriculture as it was abandoned after the drilling process.