Perpustakaan Digital ITB

Conventional carbonate matrix acidizing using hydrochloric acid (HCl) often causes severe corrosion and shallow penetration, thereby necessitating safer alternatives. This study presents a systematic evaluation of commercial bio-lactic acid (88%) as a more environmentally friendly carbonate acidizing fluid, closing two prior gaps: the laboratory-scale kinetic characterization of dissolution under reservoir-like conditions and an integrated procedure to establish the optimum injection rate based on PVbt, pressure-drop (?P) profiles, and wormhole morphology. The research problem is formulated to determine how temperature, stirring speed, and acid concentration govern the dissolution rate and how injection rate controls acidizing efficiency through the formation of a dominant wormhole. Consistent with the objectives, the hypotheses state that dissolution follows pseudo–first-order kinetics with measurable release of (Ca²?) and (Mg²?), and that an intermediate Damköhler regime exists in which a single dominant wormhole forms, PVbt is minimized, and ?P exhibits a clear breakthrough signal. The methodology comprises batch/flocculator tests to obtain the rate constant (k) and activation energy (Ea = 63.8 kJ mol?¹) via Arrhenius analysis with ion concentrations monitored by UV–Vis, and multi-rate core-flooding (0.1, 0.3, 0.5, 0.9 mL/min) at reservoir-like T/P to record ?P–time, compute PVbt, and verify morphology by CT scan and SEM. Results show consistent pseudo–first–order behavior; the rate constant (k) increases with temperature and stirring. In cores, the PVbt–rate relation forms a U-shaped curve: 0.1 mL/min produces face/near-uniform dissolution with high PVbt; 0.5 mL/min yields PVbt = 0.73 accompanied by a sharp ?P drop at breakthrough (dominant wormhole; maximum efficiency); whereas 0.9 mL/min shows a ramified/branching tendency and a renewed rise in PVbt. This synthesis confirms the hypotheses and meets the objectives: bio-lactic acid is practical, quantifiable, and parameterizable (k, Ea); the optimum rate of 0.5 mL/min minimizes acid usage to traverse the core. The Damköhler concept frames engineering implications: to maintain efficiency in hotter reservoirs, the injection rate should be scaled up to remain near the optimal Da. The practical contribution of this work is a kinetic map for bio-lactic acid (k, Ea) and an operational PVbt–?P–CT protocol for setting the optimum rate in carbonate matrix-acidizing design.