Study on the prediction model of extended-reach limit length in horizontal drilling with dual-channel drillpipe in shale formation

Abstract

Abstract Dual-channel drillpipe drilling is an effective way to elongate the horizontal well's horizontal section length. In order to predict the horizontal well's maximum measured depth, a prediction model of extended-reach limit length with dual-channel drillpipe is established in this paper. Extended-reach limit length of horizontal well with dual-channel drillpipe is analyzed. Compared with the previously established extended-reach limit length model with conventional drillpipe, both the formation factor and the drilling pump's hydraulic factors are considered to investigate the horizontal well's extension ability with dual-channel drillpipe. Through this model, the well's extension limit length of horizontal section and extended-reach limit length can be calculated under different constraint conditions. In the paper, an application example is also analyzed for verification. Results show that the extended-reach limit length of horizontal drilling with dual-channel drillpipe is significantly greater than that with conventional drillpipe, which further proves that well's extension ability can be improved by dual-channel drillpipe. Besides, there is a decrease in the well's extended-reach limit length as the drilling fluid density and flow rate are increased. Meanwhile, when the rated pressure of drilling pump is increased, the constraint limitation of the well's extension ability changes from rated pressure to fracture pressure. Furthermore, the extended-reach limit length with dual-channel drillpipe in shales varies along with the anisotropic formation. This study provides guidance to both the shale gas production and the extension limit theory of horizontal well with dual-channel drillpipe in the shale formation.