Downhole motor pneumatic

Air (or Gas) Downhole Motors. Some positive displacement mud motors can be operated on unstable foam. In general, these mud motors must be low-torque, high-rotalional-speed motors. Such motors have found limited use in air and gas drilling operations where directional boreholes are required. Recently a downhole turbine motor has been developed specifically for air and gas drilling operations. This downhole pneumatic turbine motor is a high-torque, low-rotational-speed motor. 

In the 1980s in the United States an effort was initiated to develop a downhole turbine motor that was activated by compressed air. This motor was provided with a gear reducer transmission. This downhole pneumatic turbine has been successfully field tested [82]. 

Figure 4-214. Downhole pneumatic turbine motor design. (Courtesy Pneumatic Turbine Partnership.)...

Air drilling operations can also be utilized for directional drilling and MWD/ LWD technologies. Due to the absence of reliable downhole pneumatic motors, this technology is not yet fully developed. 

Lyons, W. C., et al., Field testing of a downhole pneumatic turbine motor , Geothermal Energy Symposium, ASME/GRC, January 10-13, 1988. Magner, N. J., Air motor drill, The Petroleum Engineer, October 1960. Downs, H. F., Application and evaluation of air-hammer drilling in the Permian Basin, API Drilling and Production Practices, 1960. 

---