Horizontal wells are widely used to increase reservoir development efficiency. The most important factor of successful use of such wells is their capability to preserve reservoir properties in the vicinity of horizontal well. Acid treatment leads to dissolution of rock matrix and rock particles, which can plug flow channels. Therefore it is often used to recover permeability and intensify oil production. Acidizing of horizontal wells requires a special approach. The efficiency of stimulation depends on reagent distribution along the borehole, depth of acid penetration and reaction kinetics. To evaluate these characteristics it is necessary to work with adequate mathematical models giving the possibility to plan the acid treatments. These models should take into account the specific character of fluid flow close to horizontal well, pressure loss along the well, influence of gravity and heterogeneity of reservoir properties. The modeling of rock matrix dissolution should be carried out. Mathematical two-phase multicomponent model describing the flow of acid solution close to horizontal well is presented. The effects related to chemical reactions and fluid flow in well are taken into account. Calculation results for different cases are presented.
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