Michael Asks PERM:
I have 2 questions:
- I have chosen to quarry and core my rock samples to a dimension of 10inches in length and 1.5inches in diameter for my flow experiment. But many research workers have used dimensions smaller than mine most frequently they have used 6inches in length and 1.5inches in diameter. I am using sandstone core samples and I considered that the core needed to be of larger dimension in order to gain more visualization of the rock – fluid interaction. Please what is your advice ?
- Please kindly advised on the best flow rate to use for this my core dimension.
Dr. Jonathan Bryan from PERM Answers:
For #1: Going longer/bigger is never a bad thing. Often researchers use 6” length for the sake of time/convenience – shorter cores mean smaller pore volumes and faster tests. If you have equipment that can take the longer core, and you don’t mind the longer test, then go for it! In fact, a larger system has a bigger pore volume, which will also improve the accuracy of your material balance, since any errors in dead volumes are normalized over the larger volume.
ONE NOTE: when you say “visualization of the rock-fluid interaction”, we assume that you mean understanding your recovery process and mechanisms better. If you meant direct visualization through something like CT scanning, then note that each cross-section will still have just the same amount of information, since the diameter of your core is the same as others.
For #2: The required flow rate depends completely on what type of process is being studied. Are you running something like a waterflood or chemical flood? In that case, consider what types of pressure gradients are present in the field. If you are running a test on an oil sand, flowing too quickly will lead to viscous fingering. If you are running a test on a tight (low permeability) rock, you will find that pressure drop is higher for you than for others with shorter cores. So select what flow rates make sense for your system. Sorry that this still sounds vague – the answer really depends on what you are studying and in what type of reservoir.
Dr. Jonathan Bryan