Performance Evaluation of MnCuAl-Layered Triple Hydroxide as an H2S Scavenger in Water-Based Drilling Fluids with Preserved Rheological and Filtration Properties

The presence of hydrogen sulfide (H 2 S) during drilling operations poses serious health, safety, and operational hazards, necessitating effective scavenging solutions that do not compromise drilling fluid performance. While various H 2 S scavengers have been developed, the application of layered triple hydroxides (LTHs), particularly MnCuAl-based systems, in drilling fluids remains unexplored. In this study, the core objective is to evaluate the feasibility of incorporating a novel manganese–copper–aluminum layered triple hydroxide (MnCuAl-LTH) as an H 2 S scavenger in water-based drilling fluids while preserving their rheological and filtration properties. To the best of our knowledge, this is the first report on the integration and evaluation of MnCuAl-LTH in drilling fluid systems. The MnCuAl-LTH was synthesized via a hydrothermal co-precipitation method and characterized using FTIR, XRD, nitrogen adsorption–desorption analyses, and SEM confirming its mesoporous structure, surface functional groups, morphology, and brucite-like layered architecture. The synthesized MnCuAl-LTH was incorporated into a water-based mud formulation at concentrations up to 1.0 wt.% and evaluated for H 2 S scavenging performance. Dynamic breakthrough experiments demonstrated a breakthrough capacity of 180.4 mg H 2 S/g MnCuAl-LTH, corresponding to more than a 36-fold improvement over the base mud formulation. Rheological evaluation revealed that the inclusion of MnCuAl-LTH caused only minor, non-disruptive variations in plastic viscosity (PV), yield point (YP), apparent viscosity (AV), and gel strength. Additionally, API filtration tests showed that both fluid loss and filter cake thickness remained within acceptable limits, despite slight increases upon MnCuAl-LTH incorporation. These findings demonstrate that MnCuAl-LTH introduces a critical H 2 S scavenging functionality without compromising the essential rheological and filtration properties of the drilling fluid. This balance between functional enhancement (i.e., H 2 S scavenging) and performance preservation represents the key practical contribution of this work and highlights the potential of LTH materials as next-generation additives for drilling fluid systems in sour gas environments.