Thermochemical Removal of Near-Wellbore Paraffin Deposits Using the Activated Aluminum–Water Reaction: A Coupled Multi-Component Multistate Wax Model

Paraffin-rich organic deposits in the near-wellbore zone reduce pore space, increase the skin factor, and impair oil-well productivity, and frequently recur after conventional treatment. This study develops a coupled one-dimensional radial model of thermochemical treatment in which an activated aluminum alloy reacts with formation water in the wellbore, releasing heat that propagates into the formation and melts and dissolves paraffin deposits. The model combines two-phase oil–water flow; heat transfer with latent-heat effects; eight paraffin pseudo-components in dissolved, suspended, and deposited states; temperature-dependent solid–liquid equilibrium; and wax deposition, dissolution, melting, and redistribution coupled to porosity–permeability recovery. Hydrogen is treated as a wellbore reaction byproduct that segregates upward and accumulates below the closed packer, rather than as a mobile reservoir phase, and the reaction kinetics are based on experimental hydrogen-evolution data for three activated aluminum alloys of differing reactivity. Simulations show a rapid skin-factor reduction during the reaction, followed by partial recovery to approximately 80–90% of the initial value during prolonged shut-in because of cooling, recrystallization, and redeposition. Increasing reagent amount or reactivity, initial wax-induced damage, or oil saturation enhances the predicted treatment effect, whereas reservoir type has a comparatively minor influence.