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SYNOPSISSulfomethylated phenolic resin (SMP) is a drilling mud additive having good fluid loss and dispersion characters and may be resistant to the action of high temperature and high salt frequently encountered in well drilling, especially in deep wells. SMP is one kind of polyelectrolyte. There are dissociable groups ( -CH2SO;Na+) along the chain of SMP. The conformations and properties of SMP in solution are affected greatly due to electrostatic attraction and repulsion. From the experimental results of viscosities and fluorescence spectra of polyelectrolyte SMP in pure water and aqueous solutions containing added salt, the effects of added salt on molecular conformations of SMP in aqueous solution and properties of reducing fluid loss of water base drilling mud are discussed.

The pitting corrosion behavior of 7150 aluminum alloy was studied by electrochemical impedance spectroscopy (EIS) in the sodium chloride and hydrochloric acid solution. Based on EIS features and corrosion morphologies as well as corrosion potential, the process of pitting corrosion could be clearly divided into four stages: at the first stage, the Nyquist diagram was composed of two overlapping capacitive loops at the high-medial frequency and one inductive loop at the low frequency. At the second stage (metastable pits developing stage), there existed one small capacitive loop at the high frequency and one big capacitive loop at the medial frequency. At the third stage (stable pits developing stage), two time constants were more clearly distinguished, corresponding to two obvious capacitive loops. At the fourth stage, there appeared one capacitive loop, attributing to uniform corrosion. An equivalent circuit was designed to fit EIS, and the experimental results and the fitted results had good correspondence.