Experimental Research on the PDC Bit Wear Model

Optimal parameter drilling has been an effective means to improve drilling efficiency for years now. It is an important theoretical basis to build the rate of penetration (ROP) model and wear model of PDC bits for optimal parameter drilling. However, several authors have focused on the ROP models for PDC bits, only a few researchers have attempted to study PDC bit wear models. Thus, the aim of this research is to establish a quantitative relationship between the PDC cutter wear rate and different influencing factors, and then to determine the overall PDC bit wear model. First, the influence of different factors on the PDC wear rate and the general relationship equation were investigated through a single-variable VTL test. Secondly, a new mathematical model is constructed by fitting multifactor orthogonal experimental data to predict the PDC cutter wear rate by considering the factors of WOB, RPM, rock abrasiveness index and dimensionless cutter wear height. Finally, the PDC bit life model was derived based on the IADC bit dull grade evaluation standard and PDC cutter wear rate equation. And the accuracy of the model was verified by field tests in Changchun, Jilin granite formation, which were drilled with three different PDC bit sizes. The results showed that the PDC bit life obtained by the prediction model was well in agreement with the actual field data obtained in bit records, and the margin of error was within 10%. And the PDC bit life model in this paper has a significant theoretical reference value for PDC bit design and improving drilling efficiency.