Rock
Centrifuge Automation
The
results of rock-fluid centrifuge tests can be used to calculate capillary
pressure and relative permeability relationships for the reservoir sample tested.
The data collection process of existing Beckman rock-fluid centrifuges can be
automated with the addition of a computer controlled video camera and strobe
light. The additional equipment
includes a line video camera, special strobe light, synchronization encoding,
electronic interfacing and a PC computer to control the test and take the
data. This data collection system is
modeled after the published work of Shell Development Corporation, Houston
Texas USA.
The
integrity of the Model 721 Automated Rock-Fluid Centrifuge is not
compromised as the existing openings in the tub are used and no radical
modification is required. The
additional equipment should not interfere with maintenance contracts or
warranties. Both Beckman J-6 and Ultra
centrifuges can be modified.
The
maximum data rate is one reading per revolution up to 600 RPM and then 10
readings per second. Core holders are
read sequentially, 1 through 6. Centrifuge tests are normally conducted during
speed ramp up, so the transient data is required.
The measured data reported are:
1) the rotor
speed during the previous revolution,
2) the core
holder number,
3) elapsed
time, and
4) the number
of camera pixels from the vial bottom to the interface enhancement. The video camera has 2048 pixels to view the
vial, so that .05 mm resolution of the meniscus position is practical. The meniscus position is enhancement with a
floating a black plastic washer.
Calibration
of the vial volume and meniscus shape variation with speed are measured during
a procedure, covering the speed range, before the sample test is conducted.
Go to Harbert Engineering Homepage