Experimental and Numerical Study on Air Flow Behavior for a Novel Retractable Reverse Circulation Drill Bit of Casing-while-Drilling (CwD)

<div>Testing stand of retractable drill bit. 1: borehole wall; 2: retractable drill bit; 3: outer drill pipe; 4: inner drill pipe; 5: outlet pipe; 6: air flow rate; 7: pressure sensor; 8: air flow rate; 9: air compressor; 10: gas inlet pipe.</div>

Geofluids

fig5

Figure 5

Figure 5: Experimental and Numerical Study on Air Flow Behavior for a Novel Retractable Reverse Circulation Drill Bit of Casing-while-Drilling (CwD) 