Core Drilling Rig and Coring Method

Core Drilling Rig and Coring Method

April 20, 2020

Core drilling often grinds away materials when the hole is being drilled to get intact sample via rotary drilling by core drill rigs. Rotary drilling has a rotary action combine with the downward movement/force plus drilling fluid provided by mud pump Diamond core drill rigs perfectly suit for wireline drilling, traditional double tube core barrel exploration drilling as well as single tube core drilling to get samples.

Core Drilling Key Elements

  • Core drilling machine, it includes conventional mechanical rotary core drilling rig and diamond hydraulic core drill rigs
  • Core drilling tools/string
  • Drilling Fluid – Normally take mud as drilling fluid and it is pressurized to drilling string by mud pump

Core Drill Rigs Configuration

  • Undercarriage – two tracks with tramming motor and gears
  • Jack Cylinder – for leveling during drilling
  • Power Pack – Diesel engine, cooler for engine and hydraulic system, air filter, exhaust
  • Hydraulic System – Pump, Motor, Valves and hydraulic hoses
  • Control system
  • Cover
  • Mast Assy. – Top drive(motor and gears), clamp or rod holder, sheaves for rope
  • Winch – for taking out core samples
  • Mud Pump – offer drilling fluid
Core Drilling Rig Configuration

Core Drilling Tools

Core Drill Tools – Wireline/Conventional

Core Drilling Rig Working Principle

  • Whole process of core drilling consist HOLE OPENING -> CORING -> REMOVING CORE SAMPLE -> REPEATING CORING
Core Drilling Procedure
  • Hole Opening
    • For some ground investigation cases, the formation of first layers is soil or mixture of soil and rock which make it hard to get very intact sample. It often uses percussion drilling or auger rigs for previously sampling.
    • Among all the method of hole opening, Tricone bit for rock or drag bit for soil are commonly used
Open Hole Coring Bits
  • Coring Procedure
    • In order to get intact samples of rocks being drilled, it uses rotary coring and advancing the borehole simultaneously
    • The core bit is fitted to core barrel in lower end, which its upper end connecting to drill rod. The drill rod mounted with top drive of coring drills
    • The core bit is rotated and grinds away an annulus of rock. The stick of rock, so called ‘core sample’, in the center of the annulus passes up into the core barrel. When core barrel is full, the core will be removed out and the borehole also formed.
    • For wireline drilling, due to it is double tube core barrel, it only needs to take inner tube of core barrel out of drilling string and keep the wireline drill rod in the hole by clamp or drill rod holder(as shown in picture of “Getting core sample out procedure”)
    • The core barrel is empty after core is taken out and can start repeating coring procedure again

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