Recent studies have examined uncertainty analysis of geomechanical responses of the Enping reservoir to carbon storage, basalt-CO2 interactions, and more.
Geologic sequestration of carbon dioxide in subsurface formations was pioneered by the petroleum industry, as carbon dioxide has long been used for enhanced oil recovery. Nevertheless, massive CO2 injection and storage requires establishing best practices. Let’s look at some recent studies on this topic.
Rasoul Sorkhabi
Editor, Core Elements
China’s First Offshore Carbon Storage Project
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In 2023, China National Offshore Oil Corp. launched the country’s first offshore carbon storage project at Enping 15-1 oil field in the Peral River Mouth Basin. Now, a new study in Fuel discusses uncertainty analysis of geomechanical responses of the Enping reservoir to carbon storage.
About the project:
The Enping 15-1 field consists of syn-rift Eocene and post-rift Oligocene sandstone and shale sitting atop pre-rift Cretaceous basement rocks.
The field naturally contains high levels of carbon dioxide and is considered an excellent saline aquifer formation for carbon storage.
What researchers did:
The researchers conducted thermos-hydraulic-mechanical-chemical coupling modelling for cap rock, reservoir rock, and base rock.
They used Monto Carlo sampling technology to create 616 cases.
Sensitivity analyses were made for 13 parameters, including reservoir parameters (porosity, permeability, water saturation, temperature, pressure, and compressibility) and compressibility and geomechanical parameters (stresses, Biot’s coefficient, Young’s modulus, Poisson’s ratio, cohesion, and internal friction angle).
What they found:
Model results show that 90 percent of cases in the uncertainty analysis have a maximum surface uplift of less than 8 millimeters.
When reservoir permeability is very low (1 millidarcy), surface uplift may be more than 100 millimeters, and rock failure is more likely.
Permeability, Young’s modulus, vertical/horizontal stress ratio, cap cohesion, and well length have the most impact on surface uplift.
Permeability, reservoir cohesion, and vertical/horizontal stress ratio have the most impact on rock failure and reservoir safety.
Join us for a discussion on Argentina's Vaca Muerta shale and how we can apply its key principles to enhance domestic production. We will explore strategies for a more productive energy future.
One of the geological mechanisms for carbon capture and storage is mineral trapping, or geological storage in basalt and other mafic rocks. In this process, carbon dioxide is dissolved in water and injected into mafic rocks, which results in mineral carbonation.
A recent study in SPE Journal tested basalt-CO2 interaction.
What they did:
Researchers used a sample of an alkaline olivine basalt from the Fuquan Mountain in China’s Yangtze River Basin.
They used SEM, EDS, XRD, and ICP-MS techniques to characterize the solid and liquid phases before and after the experiment. This allowed them to measure the degree carbonation reaction.
What they found: After comparing mineral characteristics with those of untreated samples, results show:
There was significant reduction in silicate minerals and an increase in carbonate minerals in the treated basalt sample.
The CO2 consumption rate in the basalt has a time threshold: After 180 days of reaction, the rate tends to stabilize under all reaction conditions.
The percentage of CO2 consumed under high-pressure conditions was much greater than the CO2 consumed under low-pressure conditions.
Go deeper: Read the article by Ye and colleagues here.
Carbon Dioxide Storage in the Appalachian Basin
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Researchers at The Pennsylvania State University have published two studies on carbon dioxide in Pennsylvania and other parts of the Appalachian Basin in Geoenergy Science and Engineering.
Geology of the location: The Appalachian Basin is a Paleozoic foreland basin that extends from New York to Alabama.
Study #1: One study reviewed methodologies adopted by various organizations for assessment of geological CO2 storage in the United States, including:
Saline formations, including Cambrian Conasauga, Potsdam and Rose Run sandstones; Silurian Medina sandstone, and Devonian Oriskany sandstone.
Saline formations are estimated to store 765 gigatons of CO2. Roughly seventeen gigatons are in Pennsylvania.
Depleted oil and gas reservoirs, including Silurian Medina and Devonian-age Oriskany and Venango sandstones.
Depleted reservoirs may store up to 8 gigatons total, of which up to 2.45 gigatons are technically feasible and accessible.
Coal-bearing formations, including Pennsylvanian-age Pottsville, Allegheny, Conemaugh, and Monongahela groups of rocks.
Coal-bearing formation may store 0.8 gigatons of CO2, of which up to 0.27 gigatons are technically feasible and accessible.
Organic-rich shales of Utica (Ordovician age) and Marcellus (Devonian).
Marcellus in Pennsylvania is estimated to store up to 104 gigatons of CO2 in total, while its technically feasible and accessible storage may be seven to 10 gigatons.
Study #2: In a second study, the same researchers independently assessed CO2 storage in the Marcellus Shale.
What they did: The research team fed data—reservoir volume, porosity, temperature and pressure gradients of the reservoir, and density of free, adsorbed, and absorbed CO2—into a basin-scale geological model constructed by Petrel software. This was meant to simulate CO2 storage.
What they found: The researchers estimate that the Marcellus Shale can store up to 289 gigatons of CO2 in total and up to 32 gigatons in technically accessible wells.
Best practices: The researchers list four criteria for ideal geological storage for CO2:
Depths greater than 2,000 feet to provide enough pressure for supercritical CO2 phase
Impermeable and thick cap rock atop the storage (reservoir) formation
Sufficient porosity, permeability, and volume for reservoir formation
Water salinity of over 10,000 parts per million in the storage formation for protection of groundwater
Go deeper: Read the new studies by Yildrim and colleagues published in Geoenergy Science and Engineering (Article 1 and Article 2).
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