Mostafa Yavari, - MSc student in petroleum engineering, Employed in the National Iranian Drilling Company- Air Drilling department
Mohammad Eidan, - MSc in Petroleum Engineering, Drilling Orientation, Employed in the National Iranian Drilling Company- drilling stem testing Unit and. Special Tools
Shahram Shamipor - Master of Executive Management, Employed in the National Iranian Drilling Company- Technical Services Manager

The goal of any drilling operation is to drill in a short time or at a lower cost with safety in operation. The optimal design and planning for drilling each well and gas well requires a comprehensive knowledge of the well hydraulics. The techniques and formulas provided for well hydraulics related to drilling with oil wells and water-based mud are available, but less knowledge is available for drilling wells with air drilling. Hydraulic well drilling with air has completely different problems than drilling with oil mud and water base. There is basically no systematic and comprehensive study of the problems caused by this flow. In this research, an attempt is made to address this issue using a multiphase flow model. This analysis is intended as a broad tool to confirm the approach of this model. The proposed model is clearly able to predict the pressure drop in the anus and the speed of drilling stumps caused by drilling wells, an essential component in the optimal design of air drilling. The results of this study show the model's ability to predict a number of phenomena, including the lifting of drilling cuttings during air drilling operations, and these results can be tested on a larger scale. All the results wereobtained using MATLAB software and data matrix.

air drilling, Hydraulic well, MATLAB software, mud drilling, Boundary conditions,ROP