core is a core obtained with sealed pressurized core barrels which,
after the core is separated from the bottom hole, can provide sealing
of the core receiver both in the bottom and top (if necessary). In
this way, hydrodynamic communication between the core receiver cavity
filled with the core and the well bore is eliminated, and bottomhole
pressure is retained. Due to this, when the pressurized core barrel
is pulled out to the surface, formation fluid saturation will be retained
in the pore space of the core.
is obvious that pressurized core can provide much more information
compared to low invasion core obtained with KIM core barrels, as in
addition to preserving the residual water saturation in pressurized
core it is possible to preserve oil and gas saturation, and also temperature
in case of thermostatic control of the core receiver, due to which
the following becomes possible:
determine formation and current values of oil and gas saturation
directly from core;
preserve fluid phase composition, this is especially important
when coring in gas hydrate pools.
coring involves the following:
with a pressurized core barrel equipped with special instruments
to record thermo-baric parameters in the barrel cavity;
of the core receiver tightness on the surface;
degassing of the core receiver, measuring gas rate and taking
gas samples for its future analysis;
of the core receiver and core extraction;
of the measuring instruments data, their computer processing and
treatment, express-analysis, preparation and preservation of samples.
The oriented core removal process
The core with the cuts made over the core height
interest shown to the oriented coring can be explained by the possibility
to obtain valuable information, to determine formation dip, direction
of its angle, reservoir characteristics spatial distribution, tendencies
for porosity and permeability changing. This will help to verify the
pool’s geological model, to estimate potential oil production, field
development plan, etc.
is oriented with the help of a special shoe installed below the core
catcher; this shoe makes three incisions on the core. One incision
will provide the identification; two others are shifted 135° from
the first one along the circumference of the core cross-section.
orientation of the core recovered at the surface can be determined
by the results of its paleomagnetic analysis and location of the incisions
in relation to the cardinal points (North-South).
Plugs of the oriented core with the North indication