The specifications of fully hydraulic rope coring drillings (BQ, NQ, PQ, and HQ) are widely used in the international geological exploration and drilling industry. They represent drill standards of different sizes and design requirements. Each standard is applicable to different geological conditions and drilling depths. The following is a detailed explanation of these standards:
BQ (small diameter drill)
Definition: BQ is the smallest diameter drilling specification. Its inner diameter is about 36.5 mm (1.44 inches) and its outer diameter is about 61.0 mm.
Applicable scenarios: BQ drillings are often used in very shallow geological exploration, especially in formations with softer or more broken rocks. It can provide a relatively small borehole diameter and is suitable for smaller drilling operations.
Application areas: water well exploration, small-scale mineral exploration, environmental investigation, etc.
NQ (Medium Diameter Drill Tool)
Definition: The inner diameter of the NQ drill tool is about 50.6 mm (2 inches) and the outer diameter is about 75.7 mm.
Application: The NQ drill tool is suitable for medium-depth drilling operations, usually in harder or medium-hard rock formations. Compared with BQ, the NQ has a larger borehole diameter, so it is suitable for deeper coring operations.
Application areas: hydrogeological surveys, infrastructure construction, mineral exploration, etc.
HQ (Larger Diameter Drill Tool)
Definition: The inner diameter of the HQ drill tool is about 63.5 mm (2.5 inches) and the outer diameter is about 96.0 mm.
Application scenarios: The HQ drill tool is suitable for medium to deeper drilling tasks, and can handle harder formations and geological conditions that require larger borehole diameters. It provides larger core samples than NQ and is suitable for exploration work that requires larger samples.
Application areas: Mineral resource exploration, geothermal exploration, large water well construction, etc.
PQ (large diameter drill)
Definition: PQ is one of the largest drill specifications, with an inner diameter of 85.0 mm (3.35 inches) and an outer diameter of approximately 127 mm.
Application scenarios: PQ drills are usually used for deep hole drilling and can effectively perform coring operations in soft or broken rock formations. It is suitable for deep drilling or large-diameter drilling operations.
Application areas: deep mineral exploration, geothermal energy development, large-scale groundwater resource exploration, etc.
Main standards:
ISO 8469: This is an international standard for fully hydraulic rope coring drills, covering requirements for drill design, materials, manufacturing processes, dimensional tolerances, etc.
ANSI, API standards: These are standards for drilling tools in the United States and internationally, and include design specifications for various types of drills.
Considerations for selecting standards:
Drilling depth: Generally, the deeper the drilling, the larger the drill specifications required. For example, PQ and HQ are often used for deep hole drilling, while NQ and BQ are suitable for shallower drilling operations.
Geological conditions: In hard rock formations, smaller drill tool specifications (such as NQ, HQ) may be required, while in softer geological formations, PQ drill tools can provide larger hole diameters and higher coring efficiency.
Core sample requirements: Large diameter drill tools such as PQ can obtain larger core samples, which are suitable for in-depth analysis of mineral resources.
