Summary A multifluid acid-fracturing design program, ACIDFRAC, was developed for IBM PC and Apple Macintosh computers to assist in the design of acid-fracture stimulations. The simulator compares the results of closed-fracture acidization and conventional acid-fracture stimulation. The program was designed for ease of use, incorporating data input windows, on-line help panels, and user-input checks for validity. The user moves through the program with a navigator window. Data validity is checked by a status window. The program has the ability to handle multiple rates, 15 stages, and up to five different fluid systems, correctly handling the fluid properties of each system. The fracture geometry is obtained from a 2D fracture simulator using a Perkins-Kern-Nordgren1, 2 model. The acid-transport model uses an infinite reaction rate and an empirical correlation to partially account for finite reaction rates. Data is output through multiple resizable graphs with zoom and expand capabilities. A complete report can be displayed or printed, including input and digital output data.