Sandstone acidizing simulation based on exponential damage model

A mathematical model of sandstone matrix acidizing radial heterogeneous flow reaction which conforms to reservoir scale, is developed based on Heterogeneous Sandstone Reservoir Generalized Distribution Model and Fine Scale Sandstone Acidizing Model. In order to study the effect of pore and permeability distribution differences of damage zone on acidification simulation, the permeability of damage zone was assumed as exponential distribution. By introducing the model of pore and permeability distribution differences of damage zone and exponential model into radial heterogeneous flow mathematical model respectively, we focused on the influence of different damage zone assumption on acidizing simulation effect. Simulation results show that in the former case the formation porosity along the radial direction is diminishing after acidizing, while in latter case the formation porosity along the radial direction is still increasing after acidizing and porosity undulates more gently along radial direction, indicating that seepage conditions is improved evenly in the damage zone and the result conforms to the real situation. Under the same condition of injection, acidification effect of exponential model calculation is more significant. Compared with the small injection rate, the large one is helpful to increase acid penetration distance, but both of the stimulation ratios are almost same.