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.
Fluid-fluid interactions can affect any enhanced oil recovery (EOR) method, including nanofluid (NF) brine-water flooding. Flooding with NFs changes wettability and lowers oil-water interfacial tension (IFT). Preparation and modification affect the nanoparticle (NP) performance. Hydroxyapatite (HAP) NPs in EOR are yet to be properly verified. HAP was synthesized in this study using co-precipitation and in situ surface functionalization with sodium dodecyl sulfate in order to investigate its impact on EOR processes at high temperatures and different salinities. The following techniques were employed, in that sequence, to verify its synthesis: transmission electron microscopy, zeta potential, thermogravimetric analysis, Fourier transform infrared spectroscopy, X-ray diffraction, particle size analysis, and energy-dispersive X-ray spectra. The outcomes showed the production of HAP, with the particles being evenly dispersed and stable in aqueous solution. The particles' surface charge increased from -5 to -27 mV when the pH was changed from 1 to 13. The HAP NFs at 0.1 wt % altered the wettability of sandstone core plugs from oil-wet at 111.7 to water-wet at 9.0 contact angles at salinity ranges of 5000 ppm to 30,000 ppm. Additionally, the IFT was reduced to 3 mN/m HAP with an incremental oil recovery of 17.9% of the initial oil in place. The HAP NF thus demonstrated excellent effectiveness in EOR through IFT reduction, wettability change, and oil displacement in both low and high salinity conditions.