Forensic Analysis of PDC Bits at the Sinopec Shengli Oilfield

Abstract

Polycrystalline diamond compact (PDC) bit has occupied more than 90% of the total drilling footage in the world. Forensic analysis of dull PDC bits is an important research field that can investigate multiple factors and then find the main failure cause. The findings of the forensic analysis not only guide the selection and placement of the next bit but also promote the advancement of PDC bits. In this study, the PDC bit pulled out of the hole was photographed, and then a forensic analysis was carried out. Based on the analysis of 45 dull PDC bits, the failure causes of PDC bits were divided into three categories: impact, wear, and erosion, which were further divided into ten sub-categories. The correlation between the failure forms and the position of the cutters on the bit tip profile was also investigated. The result shows that the front impact is the dominant failure cause of PDC bits at the Sinopec Shengli Oilfield, which often occurs at the nose and shoulder of the tip profile, while the failure caused by the tip impact is concentrated at the cutters near the OD (outside diameter) position. The results would assist the selection and deployment of the PDC bit.