Huff & Puff CO2 Cleaning for Tight Rocks
Laboratory measurements of porosity, matrix permeability and saturations are essential for accurate petrophysical characterization to aid in log calibration, fluid saturation modeling and resolve reservoir complexities. The core must be cleaned before porosity, permeability and saturations are measured. The objective of the cleaning process is to remove all hydrocarbons, water and any possible invasion of drilling mud during the coring process.
Cleaning intact low permeability rocks in distillation-extraction equipment is time consuming and the process and solvents damage the rock. Crushing tight rocks followed by distillation-extraction cleaning for reducing the cost and time of fluid extraction is a common practice in the industry. However, crushing the rock brings rock fabric damage.
At Metarock Laboratories, we have developed this technology specially designed to clean low to ultra-low permeability intact plug samples. Pressurized CO2 is used to clean intact plug samples and remove the mobile fluids by automated gradual pressure release. This test helps to more accurately measure the absolute matrix permeability of ultra-tight rock, improving the understanding of fundamental petrophysical properties.
Experiment is run at a temperature higher than room temperature to reach and maintain supercritical conditions.
It’s quick (no more than 2 weeks to clean low permeability rocks) and efficient.
The system is equipped with automatic valves for a controlled release of pressure.
The process ends when the weight stabilizes for each sample, indicating removal of fluids.
Recommended Sample Dimensions: