Research On Minimum Gas Injection Rate In Gas Drilling Horizontal Or Highly-deviated Wells

Air and gas drilling is a kind of key technology for oilfield development, its advantage isincomparable to conventional drilling. Gas injection rate as the key data of gas drilling isalways concerned by researchers. But most of the researches were care about the situation ofvertical wells, the researches for horizontal wells and highly deviated wells were sparse. Thispaper is mainly about making one gas injection model for horizontal wells and highlydeviated wells specially.Based on the cuttings movement analysis this paper get the starting velocity model ofcutting particles in different deviation angles, and use this velocity as the minimum velocityof gas to calculate the minimum gas injection rate. The analysis made this model suitable forhighly deviated wells. Through the research of annular velocity distribution, make thevelocity calculate model in annular. The compare to numerical simulation make sure thismodel is reliable. The combined of starting velocity model and velocity calculate model inannular make minimum gas injection rate more accurate. At last, through the numericalsimulation to discuss the influence rule of annular eccentricity degree to cuttings transport,and illustrate the prevention of drilling tool eccentricity is necessary.