JNTU B.Tech II DRILLING AND BLASTING Previous Question Paper (July/August - 2021 - R16)

Proper care and preservation of rock cores are essential to maintain their geological integrity for laboratory testing and analysis. The process involves the following steps:

1. Cleaning and Drying: Cores should be cleaned of drilling mud and debris using water or a soft brush, then air-dried to prevent mineral alteration.
2. Marking and Orientation: Each core piece must be clearly marked with the borehole number, depth interval, and top/bottom orientation using permanent ink or labels.
3. Core Logging: Detailed logging should be performed immediately after recovery to record lithology, fractures, and RQD (Rock Quality Designation) before any degradation occurs.
4. Storage: Cores are stored in sturdy, moisture-resistant core boxes made of wood or plastic, with separators to prevent movement. Fragile or soft cores should be wrapped in plastic film or aluminum foil to prevent moisture loss and oxidation.
5. Environmental Control: Boxes should be kept in a cool, dry, and well-ventilated area to prevent weathering, mold growth, or thermal degradation of sensitive rock types.

While both terms refer to boreholes that do not follow a straight vertical path, they differ in intent and methodology:

In summary, a deviated borehole is an uncontrolled departure from the planned trajectory, often necessitating corrective measures to bring the bit back to the target. A deflected borehole is a planned, purposeful change in direction, commonly employed in directional drilling to bypass obstacles, reach multiple targets from one location, or perform sidetracking operations.