The process of matrix acidizing, while aiming at enhancing near-wellbore flow conditions, can result in damaging effects when acid-oil emulsions form. Understanding the behavior of these emulsions, especially when it comes to its stability and viscosity, is an essential step in the design of acid jobs that can lead to successful well productivity enhancement. In this study, we investigate the time-dependent nature of these emulsions using bottle tests and coreflooding experiments. The results of the work provide new insights into the formation of in situ emulsion. This has direct impact on the design of acid jobs in well stimulation treatments.