5th WCSET-2016 at Vietnam
Technical Session - 2
Title:
Uncertainty in Reservoir rock Permeability Measurement
due to instability in equipment design parameters
Authors:
Thomas Adebayo
Abstract:
Permeability is important reservoir parameters that
determine the success of field exploration and
production. The decision to produce a field does not
only depends on the volume of oil in place but equally
on the reservoir permeability. Hence, there is need to
obtain accurate permeability value in order to make
correct decision on oil well production. Various
laboratory experiments being used have repeatability
problem. Various experiments were performed over a
period of two months to determine the permeability for a
sandstone using water as flowing fluid in the Formation
Damage System (formation evaluation) equipment and
Helium gas as the fluid in the unsteady state
Porosimeter-Permeameter. There is so much variation in
the values of the permeability obtained and this was
discovered to be due to various factors such as the
temperature, confining pressure, pore pressure, fluid
flowrate and the stability criteria used that have
direct impact on measured permeability. It was also
discovered that the confining pressure was never stable
but changes with the unstable temperature. Maintaining
constant temperature was also a problem due to slow heat
transfer between the equipment core holder and the
flowing or the confining fluid. It was concluded that
all these factors that affects permeability need to be
accounted for in the permeability measurement and this
is only possible if the equipment manufacturers redesign
the computer macros used in these computerized
permeability systems such that the effect of changing
temperature on the confining pressure and the
corresponding permeability is corrected. Also considered
were the effects of stability criteria and flowrate on
the measured permeability values. Correlations were
obtained as presented below in the result and discussion
section and these are required to be incorporated into
the Excel macro used by the equipment manufacturers. For
the PorosimeterPermeameter, a relationship between the
absolute permeability, confining pressure, pore
pressure, slip velocity and temperature was obtained.
For the Formation Damage System, the permeability
equation to be used is a little more complex and Macros
need to be written based on the different possible
flowrates usable with the equipment. Moreover, there is
need to have continuous measurement of the confining
pressure as it was never constant during the period of
experiments.
Keywords: Permeability, Confining
Pressure, Stability Criteria, Permeability Experiment,
Equipment repeatability
Pages:
141-148