A new method for determining the minimum gas injection rate required for hole cleaning in horizontal gas drilling

Horizontal gas drilling has been considered as an innovative technique for tight gas reservoir development. Given currently there are few effective models to determine the exact minimum required gas injection rate in a wide range of ROP of horizontal gas drilling, in this work a new method for determining the minimum required gas injection rate for hole cleaning in horizontal gas drilling is developed, meanwhile a new terminal velocity model and a new required minimum gas velocity model are developed in the “build” section of horizontal well based on the widely used Grayʹs model to extend the minimum velocity criteria to be applied in horizontal gas drilling. Analysis using field data in the published article demonstrates that the new method can accurately determine the minimum required gas injection rate of horizontal gas drilling in a wide range of ROP (or cuttings size) and provides drilling engineers a practical tool for designing the appropriate gas injection rate in horizontal gas drilling.