New core and equipment reveal reservoir properties of the Cypress Sandstone

Dmytro Lukhtai, an undergraduate in the Department of Engineering at the University of Illinois at Urbana-Champaign, has been using a new porosimeter and permeameter and Dean-Stark extractors to collect data on recently acquired core samples. Lukhtai is a part of an Illinois State Geological Survey (ISGS) project to investigate the potential of the thick Cypress Sandstone for geologic carbon storage and enhanced oil recovery.

Geologists use the new equipment to quantify the porosity and permeability of oil reservoirs in the Cypress, a geologic formation in the Illinois Basin. “This new equipment makes us more efficient and allows us to see results of experiments in real time and compare them to other data sources,” said Nathan Webb, assistant petroleum geologist at the ISGS and principal investigator of the project.


Dmytro Lukhtai examines measurements produced by the porosimeter for a sample of the Cypress Sandstone. The availability of new laboratory equipment and core provided an opportunity for Lukhtai to gain experience preparing samples and conducting laboratory procedures. The porosimeter measures porosity using the core holder attached to the metal baseplate at the bottom left of the gray box and the permeameter measures permeability using the core holder attached to the center of the gray box.

The Dean-Stark extractors are part of a procedure to measure residual oil saturation, which is completed before the porosimeter and permeameter are used to measure porosity and permeability, respectively.

Two of the new Dean-Stark extractors during the process to measure the residual oil of core samples. Samples are weighed before they undergo the extraction process, which removes soluble liquids. The samples are weighed again afterwards, and the difference in the weight indicates how much oil was in the sample. The extraction process can take 12–24 hours to complete depending on the amount of residual oil and porosity and permeability of the sample.

Geologists combine the porosity and permeability data from core with qualitative assessments of outcrops and subsurface mapping to generate three-dimensional models of an oil reservoir in the Cypress. Reservoir engineers use these models to estimate the amount of carbon dioxide that can be stored in, as well as the amount of additional oil that can be produced from, the reservoir.

Accurate porosity and permeability data from new equipment allows geologists to populate the model with realistic reservoir parameters that represent the Cypress—and increases confidence that estimates of carbon dioxide storage and oil production potential are accurate, too.

“Having in-house analytical abilities allows us to more quickly evaluate reservoir properties and identify potential problems with samples,” said Webb. “These abilities give us a better understanding of what we’re finding by providing the flexibility to change the parameters of the experiments, if needed. The results might take weeks or months to get back if we had to send our samples to an external lab.”

The project is sponsored by the Carbon Storage Program under the US Department of Energy.

More information about this project can be found on its website at

Contact: Nathan Webb

by Dan Klen

Photo credits: Dan Klen (ISGS).