Chapter 8 – Drilling

Drilling in the Earth’s crust is the most effective means of exploration since it provides lithological information and allows collection of samples for various investigations. Different types of drilling may be classified, depending upon the hole-making action and the hole-cleaning method. Selection of right drilling method, drilling fluid, and the pump is described. Various types of bits for specific applications are described. Core drilling yields a solid cylindrical piece of ground at an exact depth which is an intact sample of the underground geology which can be examined for its nature, mineralization, structural details, etc. Continuous coring system is explained. Core logging, core preservation, and high-resolution, hyperspectral core scanning details are explained. Deductions from drill core samples are described along with the use of portable XRF analyzer for on-site analysis. Exploratory drilling methods including the emerging new trends are described. Borehole deviation survey measurements are detailed besides the advantage of directional drilling and planning a drilling campaign.