Stimulation results prediction

Predicting results from Acidizing without any analog information is impossible to do with any degree of precision - there are just so many variables and primary/secondary/tertiary chemical reactions that can occur. Sandstones and carbonates also behave very differently due to the fundamental difference of dissolving the damage (sandstone) vs dissolving the matrix (carbonate) as well as radial dominated flow (sandstone) vs wormhole/fractured dominated flow (carbonate). There do exist some commercial and proprietary simulators that attempt to predict treatment performance, but they are not that effective and require DETAILED input of mineralogy and reaction kinetic parameters.

If you want a balllpark (gu)estimate for a well designed sandstone acidizing job, take your formation skin and reduce it by 90% - this will be horribly wrong in many cases though, but may be enough for what you need. For carbonates, take it to zero or perhaps even slightly negative..... again, you really need some analog results to 'tune' . In the case of purely 'synthetic' examples, you can do simple concentric radial permeability models with the inner cylinder damaged (reduced perm) and model volumetric penetration of the live acid and make assumptions of damage reduction (ie 90% of perm recovery in contacted damaged zone).... depends on what you are trying to achieve

Hydraulically fractured well performance though is reasonably well understood by comparison, and as long as you know your fracture wing length (Xf) and the dimensionless conductivity (Fcd), there are type curves available to predict production pressure performance (ref SPE 084287 as a start). You could also try some reservoir simulation with fine scale grid, mimicking the fracture properties, but unless you have a simulator designed fro this sort of work you get into problems with numerical convergence and undefined well connection factors (speaking from experience) - As your block size approaches the wellbore diameter, the Peaceman equation starts breaking down.

Good luck