Simulation and Analysis of Wormhole Propagation in Carbonates Through the Use of Models with Different Dimensions

Abstract

A 3D continuum simulation model of carbonate matrix acidizing is introduced to study the effect of different dimensions on the dynamic wormhole propagation process. The results obtained show that the wormhole propagation process passes through four stages – competition, dominant wormhole, wormhole breakthrough, and wormhole extension (injection pressure ratio dropping to 1%). In previous studies, the wormhole breakthrough stage was reported to occur when the injection pressure ratio had fallen to 3% instead of 1%. Wormhole simulation using 3D and 2D models at different injection rates indicate that the injection rate and breakthrough volume are optimal in both dimensions, the values of both parameters being higher in 2D than in 3D simulation. This trend is expected, since previous studies also show that the optimal rate and breakthrough volume are lower in 1D than in 2D simulation. CT scanning of limestone cores after acidizing show that the corresponding optimal breakthrough volume for a dominant wormhole is less than 3.1 pour volume (PV). The obtained data closely match the 3D simulation data (2.7 PV) and differ greatly from the 2D simulation data (10 PV). Based on the study, a higher-dimension model should be selected for simulating wormhole propagation and optimizing matrix acidizing as this can help improve the accuracy and efficiency of carbonate reservoir acidizing simulation.