Page 156 - Hydrocarbon
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Reservoir Description 143
Figure 6.32 Coring assembly and core bit (courtesy of Security DBS and Corepro).
about 90 ft long. However, in favourable hole/formation conditions longer sections
may be achievable.
If a conventional core has been cut, it will be retrieved from the barrel on the rig
floor, cut into sections and crated. A lithologic description can be done at this stage.
To avoid drying out of core samples and the escape of light hydrocarbons some
sections will be immediately sealed in a coating of hot wax and foil.
Commonly, a fibre glass or aluminium sleeve is inserted into the steel inner core
barrel and the core is retrieved within the sleeve. At the surface the gap (annulus)
between the inner sleeve and core is injected with an inert stabilizing material which
‘sets’ to hold the core in place. The core is cut into sections (typically 1 m) and
shipped to the laboratory. Core handling is a delicate procedure and it is important to
minimise any alteration or damage to the cored sample or the contained fluids. Any
