Volume 8 – Mechanical and Electrical Services - Malaysia Geoportal

Chapter 3 GROUND WATER FACILITIES
Often the value of information obtained can be improved considerably by a simple change in
sampling methods. Qualities desired in chip sampling:
- Sampling interval identified accurately and recorded
- Sample free of contamination from material from other depth.
- Sample not contaminated or change by drilling action or fluids.
- Large clean chips
- All chips including fines covered.
More frequently, samples are required to permit positive identification of the rock types penetrated.
3.8 BOREHOLE TEST
3.8.1 Depth measurement
Fig. 3.4 Sampling for Flow
Hole depth is the first measurement for the driller. There are several methods of measuring hole
depth in common use by the driller. These two methods give acceptable accuracy:
- Measurement of the suspended drill string using a tape.
- Measurement counting and totalling the number of precise length drill rods pipe.
Typical hole zero is at the natural surface, at the top of the casing collar, at the top of rotary table,
or at the rock face (underground). Once decided upon, the hole zero becomes the starting points of
all measurements and may be referred to as the ‘collar level’ or ‘drilling datum’.
March 2009 3-5