Lignosulfonate-based deflocculant and its derivatives for water-based drilling mud: A review

Chromium-based lignosulfonate (CrLS) deflocculants that are commonly used in water-based drilling muds (WBDMs) to deflocculate bentonites under high temperature (HT), high-pressure (HP), and high-salinity (HS) oil well drilling conditions have been found to contain heavy metals such as chromium, which is toxic and degrades rapidly. However, different ways of addressing this issue have been proffered, including the use of natural polymers such as starch, cellulose, or anionic inorganic agents such as sodium polyphosphates with little or no impact. Other lignosulfonate (LS)-based deflocculants, like sodium-based LS and bio-based LS, have shown a number of benefits, such as being better for the environment, more soluble and evenly distributed in WBDMs, more resistant to salt contamination, easily biodegradable, safe, and able to go through different chemical changes. This is due to its abundant functional groups, which make it a suitable alternative to chrome-based deflocculants. This review discusses LS-based deflocculants as possible additives to WBDMs in comparison with some non-LS-based deflocculants under HTHP and HS conditions. This could address the need for safer alternatives to natural polymers or inorganic agents. Based on recently reviewed studies, the advantages, uses, research obstacles, green synthesis, and potential of incorporating nanotechnology-based modification for LS-based deflocculants improvement in WBDMs under HTHP and HS drilling conditions are discussed.