Simulation of Wormhole in Carbonate Acidizing Using a New Diffusion Limited Aggregation Model

Wormholes are the main characteristic shapes resulting from the carbonate reservoir acidizing. Understanding wormhole patterns can determine the success of acidizing to a large extent. Due to various influences, such as the reaction rate between the acid and rock, and anisotropy of formation, the shapes of wormholes are quite complex and stochastic. So simulating the wormholes by traditional methods cannot be accurate. A Diffusion Limited Aggregation (for short “DLA”) model of wormholes in dual medium is presented after modifying the traditional DLA model. After discussing the relationship between simulation parameters and wormholes´ fractal dimension, it is revealed that the bigger injected acid volume and porosity, the longer wormholes can be formed. When the natural fractures patterns are complicated(even fractal), it is necessary to connect natural fractures and pores in the formation and get bigger fractal dimensions of wormholes, which may lead to a successful acidizing treatment.