Simulation and Field Studies on an Innovative Downhole Machine Designed for Ultrashort-Radius Horizontal Well Drilling Engineering

Ultrashort-Radius Horizontal Well (URHW) drilling engineering plays an important role in increasing the recovery factor of old oilfields. By sidetracking wellbores at a very high build-up rate, URHW can effectively exploit residual oil near wellbores. Currently, main problem faced is reduced torque received by drill bits owing to increased friction between flexible assembly and wellbore as horizontal section extends, which greatly limits production from single trip. To tackle this problem, we proposed innovative machine design, Dynamic Flexible Drill Rod (DFDR), provide extra bit extend URHW. The interior structure working principle DFDR were illustrated. mechanical properties DFDRs critical load-bearing part examined via simulation. pressure loss characteristics analyzed using computational fluid dynamics. Corresponding modifications made optimize with model machines produced accordingly. Field trials carried out based on Chunliang District, Shengli Oilfield. DFDR-based technique extended URHWs area 13.38% average.