Modeling PDC cutter-rock interactions using finite discrete element method for geothermal drilling applications

Erin Heilman , Bryan Euser, Luke Frash, Meng Meng, Wenfeng Li, Zhou Lei, Ryan Rhodes, Allison Kimbrough, Esteban Rougier

Polycrystalline diamond compact (PDC) cutters are used in geothermal energy drilling operations as they are exceptionally effective due to their strength and resistance to abrasion. It is important to understand the effect of downhole conditions to accurately model rock-cutter-rock interactions, as well as wear on the bit and drilling efficiency. Cutting efficiency is determined through the weight on the bit, rotational speeds, and other cutter and rock parameters in drilling, here we can comment on cutting efficiency through the cutting force. The ultimate goal of this research is to numerically model the PDC cutter–rock interaction in 3-D to find an optimal arrangement of parameters for efficient geothermal drilling. Using the combined finite discrete element method (FDEM), we model rock fracture and fragmentation for a single PDC cutter for both atmospheric and realistic well pressure conditions. We present the numerical analysis progression of PDC cutter-rock interaction in 2-D and 3-D for a range of cutting speeds, depth of cuts, and pressures using sandstone and granite as our rock materials. These parameters are varied to understand the optimal configuration to increase drilling performance as determined by cutting force, damage style, and fracture energy. Our models successfully reproduce laboratory values, which increases our understanding of rock fracture at downhole conditions.