Analysis of the Relationship Between Core Recovery Rate and Coring Tools and Formation Lithology in International Scientific Ocean Drilling

Over the past 50 years, the International Scientific Ocean Drilling has carried out more than 400 expeditions, collecting over 400,000 m of core samples and obtaining a large amount of observational data. However, the coring tools used, the core samples collected, and the core recovery rates are scattered across different expedition reports, making it difficult to achieve efficient utilization and provide experience for subsequent expeditions. This paper summarizes the coring tools currently used in ocean drilling and collects the drilling and coring data from some expeditions. It also categorizes the lithology of the strata in each expedition and analyzes the influence of coring tools and strata lithology on core recovery rates. The results show that as the core density increases, the core recovery rate of the coring tool generally shows a downward trend. When coring in the same type of formation, the core recovery rates of different coring tools and the changes in the density of the collected cores also vary. Due to the working principle of the coring tools, even if the core density is not much different in the same formation, there are still significant differences in the core recovery rates when coring. At the same time, this paper also discusses the selection of coring tools when drilling in different types of formations and proposes corresponding improvement suggestions.