Coupled flow-geomechanics for prediction of propagation and collapse of wormholes in matrix acidizing

Acidizing is an established technique to stimulate enhanced hydrocarbon recovery from carbonate reservoirs. Injection of acid into carbonate reservoirs entails a series of interactions between the rock and acid solutions that, at certain conditions, lead to generation of desired preferential pathways for hydrocarbon, also known as wormholes. These wormholes serve the role of high conduits of flow, facilitating the production of hydrocarbon fluids from the porous rock. The process of the effective wormhole generation and its stability during the production period is a coupled phenomenon that requires studying the reactive transport and mechanics of the problem alongside each other. During the generation of wormholes, pore fluid pressure withstands the overburden pressure. However, excessive lateral growth of the wormholes and loss of acid solution to rock could generate geomechanical instability. Under this condition, the wormholes become susceptible to collapse and undermine the efficiency of wormholes to transfer fluids to the well. In this line of research, optimizing acid reaction rates, amount, acidity and level of interaction with rock are key factors in obtaining the desired effects on the formation at downhole conditions. Sufficient acidization must be achieved without overtreatment, which could cause the collapse of pore structures, and may reduce well productivity.

Based on rigorous coupling of geomechanics with the acidizing two-phase modelling, the project aims at developing a novel coupled flow-geomechanics code for matrix acidizing. The research will be crucial for wellbore management and maintenance, and enhanced geothermal systems.