Temperature impact on linear and radial wormhole propagation in limestone, dolomite, and mixed mineralogy

Abstract

The temperature has a significant impact on acid stimulation efficiency in carbonate reservoirs. To fully understand its effect, this study utilizes a two-scale continuum model coupled with heat transfer. The study investigated the importance of the heat of reaction, injected acid temperature, and reservoir temperature on wormhole propagation and treatment efficiency. This research's novelty stems from its application to limestone, dolomite, and combined mineralogy in radial and linear flow patterns. It also investigated the role of vugs on acidizing efficiency in dolomite formations, showing that vugs improve wormhole penetration distance. The model reproduced the outcomes from the literature, showing that the heat of reaction has a negligible effect on wormhole propagation. On the contrary, increasing the injected acid temperature reduced the wormhole radius in limestone but improved its efficiency in dolomite. The acid could not create efficient wormholes at low acid temperatures in dolomite formation. It diverted itself towards the limestone in sequence mineralogy cases. Nevertheless, it equally stimulated the limestone and dolomite sections at elevated acid temperatures. The reservoir temperature was less critical than the acid temperature in determining the wormhole size and treatment efficiency. The model can be used to select the optimum temperature at which the most efficient wormhole is created.