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Resistivity Index by Continuous Oil Injection System was developed to meet the industry
demand for quick accurate Resistivity Index data and is based on the continuous
oil injection techniques developed by Shell Research. The production model is based
on a development system used in our Aberdeen Advanced Technology Center and uses
a modular approach that allows for future expansion by the addition of core holders
and pump modules. The number of cells required should be specified at the time of
The system consists of a bank of Hassler-type 2 electrode core holders mounted on
a support frame; each core holder has a dedicated piston cylinder for oil injection,
a pressure transducer and a double glass pipette to collect the eluted brine (as
a visual cross check on the computer monitored injection volumes). A stepper motor
drives each bank of five piston cylinders capable of controlling injection rate
rates of 0.04 cm3/hour or less. Each core holder/cylinder pair has an independent
valve manifold, with manual valves and a regulator to apply backpressure when saturating
the core. Resistivity is measured sequentially at regular programmable intervals
by a programmable RCL meter linked to the PC based data acquisition software. Confining
pressure is applied to the core holders by an air driven hydraulic pumps module.
The system is contained in a temperature controlled environmental cabinet. The PC
based data acquisition software logs resistance, phase angle, pump displacement,
pressure and temperature as well as pump control.
The RICI-100 offers a number of advantages for the determination of Resistivity
Index as experimental errors are minimized by automation data acquisition, measurements
equivalent reservoir stress and the ability to complete tests in four weeks or less.
In addition the system enables non-liner RI vs Sw function to be accurately defined.
A clean dry evacuated core sample is saturated with simulated formation brine in
a pressurized core holder and then flushed with brine to remove any residual trapped
air. Brine is then displaced from the core by mineral oil at a very low injection
rate. A semi-permeable membrane at the outlet end of the core holder prevents the
mineral oil from leaving the sample. Resistance and pressure drop across the core
sample are measured as a function of the volume of mineral oil injected at constant
monitored temperature is. The experiment is complete when the injection pressure
is equal to the entry pressure for the mineral oil to the semi-permeable membrane.