<p>Conventional rheological models describe how drilling fluids respond to shear but do not explain why their properties emerge from molecular interactions. This study introduces a novel Entropy-Regulated Percolation (ERP) (interpretive) conceptual framework; a first-principles theory linking thermodynamics, microstructure, and drilling fluid behaviour. ERP treats rheology and filtration as outcomes of a single entropy–energy balance that governs reversible bond networks. Two new dimensionless parameters are introduced: the entropy–power ratio (Ψ), capturing the balance between structural reorganization and shear energy input, and the bond-lifetime number (Λ), describing how long mud-network bonds endure relative to the deformation timescale. Together, Ψ and Λ form a universal map that classifies drilling fluids as shear-dominated, balanced, or network-dominated. In addition to the engineering-level quantitative interpretation of the ERP framework, a citric acid:glycerine NADES-based drilling fluid study is re-examined as a conceptual case study showing that its position near the balanced-to-network regime explains its stable viscosity, reversible thixotropy, and low permeability. By connecting bond free energy (ΔG_b), bond lifetime (<i>τ</i>_b), and structural order (Ω) to measurable flow and filtration data, ERP provides a thermodynamic interpretive framework that rationalizes empirical rheological and filtration behaviour. The framework shifts drilling-fluid design toward an interpretive, physics-based approach, unifying chemistry, structure, and performance.</p>