Lost Circulation Control for Pump-Injected Reverse Circulation Drilling: Experimental Optimization and Theoretical Analyses

Abstract

The reverse circulation drilling method is now widely accepted as an effective way of exploration and grade control. However, the performance of reverse circulation drilling operations is greatly affected by the filtration effect (lost circulation) and no research has critically addressed this issue. In this study, a simulation experiment was conducted, the filtration effect was quantified as the mass of water loss measured at a flow rate of 4.00 m3/h to 8.00 m3/h for reverse and forward circulation drilling. Then the dynamic filtration effect was analyzed in three ways; first, a filtration versus circulation flow rate curve was obtained for both the forward and reverse circulation process. Second, the positive and negative effect of hydrodynamics on filtration was analyzed through a computational fluid dynamic approach, and finally, via qualitative analyses. The results showed that: (1) An optimal flow rate occurred when the filtration effect was minimum, (2) There is a point where the positive and negative effect of the increase in flow rate on filtration is the same, and (3) filtration monotonously increases with flow rate. This study provides a better understanding of the effect of filtration during the reverse circulation drilling process, a guide to field experts, and a theoretical framework for future research.