Air reverse circulation (RC) drilling is becoming an increasingly popular technique in engineering fields. It can be used in geological exploration, water well drilling and infrastructure construction and so on. RC bit is the key accessory in this technique. Its structural parameters directly influence cutting transportation during reverse circulation drilling. In order to explain the formation mechanism of reverse circulation, established mathematical models and physics model of the RC bit and studied drilling fluids transportation under the bottom hole. Conducded numerical simulation about velocity field and pressure field of bottom hole flow field using software FLUENT with different parameters of the RC bit, including the size and position of nozzles, the angle of inner nozzle and so on. The result of simulation and experiment show that increase of the effective turbulence zone can improve efficiency of RC transportation. Inner nozzles can produce stable negative pressure region in the central channel, and ensure cutting transportation as RC methods. The data and results are helpful to optimize the structure and size of the RC bit. It can shorten the research period, decrease costs and improve the design ability.
Proposal of Guidelines for field description and classification of porous sediments from water well drilling - in situ fast procedure - ver 1.0
