MODELING HYDROCHLORIC ACID STIMULATION IN CARBONATE RESERVOIRS BY ACCOUNTING FOR NEAR-WELLBORE GEOLOGICAL HETEROGENEITY

Abstract

Carbonate reservoirs often show uneven response to hydrochloric acid (HCl) stimulation because the near-wellbore zone is geologically heterogeneous and contains permeability streaks, fractures, vugs, and mineralogical contrasts that redirect flow and concentrate dissolution. Such preferential flow can trigger early dominant wormholes in high-conductivity sub-volumes while leaving other intervals under-stimulated. This paper presents a practical reactive-transport modeling workflow that explicitly integrates near-wellbore heterogeneity into matrix acidizing design. The workflow couples single-phase flow, acid transport, and mineral dissolution with dynamic updates of porosity and permeability, and uses dimensionless groups (Damkyuler and Pekle numbers) alongside pore volumes to breakthrough (PVBT) as efficiency metrics; PVBT is widely used as an indicator of acid volume required to achieve a conductive dissolution path. The approach supports scenario screening (layered vs fractured vs vuggy near-wellbore structures), sensitivity analysis, and optimization of injection rate and acid schedule to improve volumetric coverage and skin reduction.