Identification of sand layers based on key drilling parameters.

Sand layer sampling is important in water conservancy and hydropower exploration, and the accurate identification of sand layers is the premise for foundation design and treatment. In this study, a new method for identifying sand layers based on key drilling parameters was proposed. Simulated formation laboratory experiments using a self-developed measurement-while-drilling system were first conducted to study the relationships between four drilling parameters and sand layers. Quantitative criteria based on key drilling parameters for sand layer identification were then proposed, followed by validation through three engineering projects. The results showed that bit pressure and drilling speed are sensitive to formation changes and can be used for sand layer identification. Specifically, in sand layers, the variation ratio of drilling speed is more than 150% and the variation ratio of bit pressure is less than 200%. Applications of the proposed method in Na water conservancy project, Sancha water conservancy project, and Tuodan reservoir project show satisfying accuracy, indicating that it can be used as an effective tool for sand layer identification in various engineering projects. [ABSTRACT FROM AUTHOR]