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and their complementary next generation Production Enhancement technologies.
PROPPANT CONDUCTIVITY EVALUATION SYSTEM is designed, through the cooperation of
various Business Units of Core Laboratories, to produce data, which allows the engineer
to evaluate and model the performance of proppants used in fracture enhancement
projects. Using the system; proppants can be evaluated at various closure pressures
and temperatures and the resultant conductivity determined at various flow rates
and pressure differentials.
The standard system uses a 100 short ton press to apply up to 20,000-psi closure
pressure on one custom designed cell that can be heated up to 350 °F (177 °C). All
of the wetted parts are constructed in 316 stainless steel, with optional materials
available on request.
Conductivity Cell: 316 stainless steel API configured cell for
the testing proppant conductivities at closure pressures of up to 20,000 psi, flowing
fluid pressures up to 1,000 psi standard. The cell contains standard, shaped, Ohio
sandstone slabs and proppant during the conductivity test with three side ports
allowing high accuracy differential pressure transducers to monitor the pressure
drop across the proppant during fluid flow. The cell is supplied complete with width
slats, o-rings, stainless steel platens and Ohio sandstone slabs. Fracture width
determined using PC linked Laser LVDT’s (2 per cell) with an accuracy of +/- 0.001
Laboratory Press: custom 4-post design, allows an even and constant
force to be applied to the conductivity cell. A 100 short ton model press capable
of delivering up to 20,000 psi closure pressure controlled by a precision syringe
pump is integrated with PC based control software to allow automated ramping and
constant pressure cycles. The press provides the capability to perform crush tests
as described in API RP 56 and 58, in addition to long-term conductivity tests on
proppants. A load cell, of compatible range for the press, is supplied to enable
the precise calibration of the applied pressure.
Fluid System: Provides for the constant pressure, or constant rate flow of de-gassed
brine through the proppant system. The upstream component consists of a nitrogen
blanketed sparging system to remove dissolved air from brines and two 1 liter accumulators
for fluid storage. Oxygen removal is essential to avoid the formation of metal oxides
during long-term tests. The accumulators are pressurized, up to 1,000 psi, using
an Isco or Quizix pump at either constant pressure or constant rate to flow brine
through the Conductivity Cell. The brine passes through a pre-heater and then through
a silica-saturating column. The column is packed with 100-mesh sand and proppant
to avoid leaching the Ohio sandstone and the proppant under the test. Downstream
a back pressure regulator controls the Conductivity Cell pressure and the effluent
brine is collected in a receiving vessel mounted on a PC linked digital balance.