Cementing technique without drilling fluid in wellbore

For air drilling, drilling fluid need changing after well completion, to start cementing. But changing drilling fluid could not just waste material, but also cause problems, such as wellbore stability, circulation loss prevention, casing collapse, poor annular cementing quality, etc. By optimizing cement slurry properties, normal and reverse pumping cementing technology was taken to realize directly cementing operation after air drilling completion. After transforming drilling fluid for RIH with casing cementing operation, 100% cement slurry filling was realized. It not only saved cement but also secured safe operation and quality and shortened the well completion period. According 9 wells applications with maximum well depth of 3000 m, once cementing successful rate reached 100% and cementing quality rate was also 100%.