Technology Of Air Drilling And Its Application In The Northeast Area Of Sichuan

Gas drilling is a kind of underbalanced drilling technology using the compressed air or other gas( such as nitrogen, nature gas, gas mixture etc.) as the cycle medium to bring bit-cuttings. Because of its unmatched advantage in many respects, such as raising penetration rate, saving drilling cost, protecting pay zones and so on, gas drilling technology is now rapidly developed.Based on the previous studies and with the field practice in the northeast of Sichuan, the current research status at home and abroad, technology process, associated equipment overview and field construction procedure of gas drilling are analyzed. After these work, combining the theoretical analysis and field practice, the feasibility study of gas drilling and theory study of cycle parameters are discussed. A feasibility analysis method of gas drilling is proposed, which is mainly based on borehole stability analysis and comprehensively considers formation characteristics. Water zone prediction is accomplished through identification of formation fluid, interpretation of formation physical property and pore pressure and calculation of water production. The formula of pressure distribution along the wellbore is obtained, and the settling velocity and the transporting velocity of cuttings in the annular are calculated. Through a case study, the calculation results of minimum kinetic energy standard and minimum speed standard are compared and indicate that the Angel model using minimum kinetic energy standard is more suitable to the field practice at key points. This study can provide theoretical guarantees and technical support for the pre-drilling feasibility analysis and calculation of main parameters of fluid dynamics.