In a successful drilling operation, the optimization of rheological and filtration characteristics is indispensable as they govern suspension and transport of cuttings along with the stability of wellbore. Loss of filtrate is also critical, especially in hydrophilic and swelling-prone formations because uncontrollable fluid invasion can destabilize the integrity of the formation being drilled. The present study experimentally investigates the combined influence of alkaline-earth metal cations; potassium (K+), sodium (Na+) and magnesium (Mg2+), on the rheological and filtration behavior of water-based mud modified with different concentrations of zinc oxide (ZnO) nanoparticles. The performance of ZnO under different cationic environment is observed in this study. Three custom mud systems each with a unique cation and a corresponding weight of 1.0 wt. % of ZnO were made for K+, Na+, and Mg2+ respectively. The rheological properties (yield point, plastic viscosity, apparent viscosity and gel strength) were assessed using a FANN viscometer in the lab and filtration loss was recorded using an API (American Petroleum Institute) low-pressure, low-temperature (LTLP) filter press. Results show that all samples displayed shear-thinning behavior because the dynamic viscosity values decreased with increasing shear rates. Of the three formulations, the potassium-based system possessed the highest viscosity and gel strength of 9 <InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(\frac{lb}{{100ft}^{2}}\)</EquationSource> </InlineEquation>, which also included a large number of aggregated nanoparticles because of the cations K+ having a weak hydration shell that would have facilitated the inter-particle bonding of the nanoparticles. In contrast, sodium-based mud had intermediate flow properties and magnesium mud had relatively less-pronounced Newtonian characteristics because the stronger hydration shells of Mg2+ particles restricted their ability to interact with each other. The potassium-based mud system out-performed the other formulations in the amount of filtrate lost, having the least amount of lost fluid after 30 min (24 mL). The transport index (YP/PV) confirmed that potassium had the largest transport index of 1.125, well above the operational threshold for all the samples, followed by sodium (0.36) and magnesium (0.2). These results clearly show that the differences in cation selection made significant differences to the dispersion, stability, and functional behavior of nanoparticles in the drilling fluids. Thus, the recommendation for using potassium salts in a nanoparticle-based drilling mud systems is viable to learn optimal rheological performance and filtration loss, and to maintain or improve drilling efficiency and wellbore integrity in a range of ionic conditions in the drilling environment.

Cationic influence on ZnO nanoparticles: a comparative study of monovalent and divalent effects

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发表日期：

2026年1月30日

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Abdur Rahman Misbah,
Shaine Mohammadali Lalji,
Syed Imran Ali,
Mohsin Ayubi,
Muhammad Mustafa

摘要

In a successful drilling operation, the optimization of rheological and filtration characteristics is indispensable as they govern suspension and transport of cuttings along with the stability of wellbore. Loss of filtrate is also critical, especially in hydrophilic and swelling-prone formations because uncontrollable fluid invasion can destabilize the integrity of the formation being drilled. The present study experimentally investigates the combined influence of alkaline-earth metal cations; potassium (K⁺), sodium (Na⁺) and magnesium (Mg²⁺), on the rheological and filtration behavior of water-based mud modified with different concentrations of zinc oxide (ZnO) nanoparticles. The performance of ZnO under different cationic environment is observed in this study. Three custom mud systems each with a unique cation and a corresponding weight of 1.0 wt. % of ZnO were made for K⁺, Na⁺, and Mg²⁺ respectively. The rheological properties (yield point, plastic viscosity, apparent viscosity and gel strength) were assessed using a FANN viscometer in the lab and filtration loss was recorded using an API (American Petroleum Institute) low-pressure, low-temperature (LTLP) filter press. Results show that all samples displayed shear-thinning behavior because the dynamic viscosity values decreased with increasing shear rates. Of the three formulations, the potassium-based system possessed the highest viscosity and gel strength of 9 \(\frac{lb}{{100ft}^{2}}\) , which also included a large number of aggregated nanoparticles because of the cations K⁺ having a weak hydration shell that would have facilitated the inter-particle bonding of the nanoparticles. In contrast, sodium-based mud had intermediate flow properties and magnesium mud had relatively less-pronounced Newtonian characteristics because the stronger hydration shells of Mg²⁺ particles restricted their ability to interact with each other. The potassium-based mud system out-performed the other formulations in the amount of filtrate lost, having the least amount of lost fluid after 30 min (24 mL). The transport index (YP/PV) confirmed that potassium had the largest transport index of 1.125, well above the operational threshold for all the samples, followed by sodium (0.36) and magnesium (0.2). These results clearly show that the differences in cation selection made significant differences to the dispersion, stability, and functional behavior of nanoparticles in the drilling fluids. Thus, the recommendation for using potassium salts in a nanoparticle-based drilling mud systems is viable to learn optimal rheological performance and filtration loss, and to maintain or improve drilling efficiency and wellbore integrity in a range of ionic conditions in the drilling environment.