Role of Geophysics in CCUS project

Satyesh Bhandari

CCUS, Carbon Capture, Utilization, and Storage, refers to a set of technologies and processes aimed to reduce carbon dioxide (CO?) emissions to atmosphere from industrial sources and helping to mitigate climate change. ?Carbon Capture involves the process of trapping CO? emissions at their source, such as power plants, industrial facilities, or other large emitters. Carbon Storage involves the long-term sequestration of CO? in geological formations deep underground such as Depleted Oil and Gas Fields, Deep Saline Aquifers and Basalt Formations. The Carbon Utilization refers to the Utilization in useful manner or the process of converting captured CO? into useful products.

By capturing and storing CO? that would otherwise be released into the atmosphere, CCUS aims to reduce the concentration of greenhouse gases and mitigate global warming and Supporting Net-Zero Goals. CCUS is seen as a critical technology for industries that are difficult to decarbonize.

Geophysics plays a crucial role in Carbon Capture, Utilization, and Storage (CCUS) projects by providing essential tools and techniques for the successful identification, monitoring, and management of storage sites.

Geophysics holds a crucial position in advancing initiatives related to CCUS. Seismic data are indispensable tools in these endeavors, playing a vital role in characterizing reservoir properties and structures, as well as estimating potential storage capacities.

1.????? Site Selection and Characterization

?Geophysical technologies such as seismic and Gravity - Magnetic helps in identifying suitable geological formations for CO? storage. This could be depleted oil and gas fields or deep saline aquifers. Seismic data provide detailed images of subsurface structures, helping to assess the integrity, porosity, and permeability of the potential storage reservoir.

analysis of Seismic data provides a detailed representation of the features,?enabling geoscientists to identify geological formations suitable for Carbon Capture, Utilization, and Storage (CCUS), such as deep saline aquifers or depleted oil and gas reservoirs. The reprocessing of legacy seismic data using modern depth migration techniques and interpreting that ensures the success of Carbon Capture, Utilization, and Storage (CCUS) projects.

It is crucial to ensure the integrity of the storage reservoirs in CCUS projects. The geophysical methods help in understanding the broader geological context and in identifying the structural features of the subsurface, such as faults and fractures, which could influence CO? storage and migration.

Electromagnetic (EM) techniques help in mapping the electrical conductivity of the subsurface, which delineate the extent of saline aquifers and to detect the presence of hydrocarbons.

2.????? Injection Monitoring

After CO? injection for a reasonable period, time-lapse seismic surveys (4D Seismic Surveys) are used to monitor the movement and distribution of CO? within the reservoir. By comparing seismic data acquired before and after injection, geophysicists can track the CO? plume and detect any potential leaks or unintended migration.

Micro-seismic technique detects small-scale seismic events induced by CO? injection by continuous monitoring, which can provide information on the stress state and the integrity of the reservoir and surrounding rock.

Controlled Source EM (CSEM) data are used to monitor changes in the electrical properties of the subsurface, which can indicate the presence and distribution of CO? over time.

3.????? Long-term Monitoring and Verification

Periodic seismic surveys are conducted to ensure the CO? remains securely stored within the designated reservoir over time and does not leak to the atmosphere.

satellite-based geophysical technique, Interferometric Synthetic Aperture Radar (InSAR) measures ground surface deformation, which can to an extent indicate changes in subsurface pressure due to CO? injection and storage.

Downhole tools provide continuous data on the subsurface conditions around the injection well, which help to monitor reservoir behavior and detect any potential leakage pathways.

4.????? Risk Assessment and Mitigation

Geophysical data such as seismic data is used to map and analyze faults and fractures that could act as potential pathways for CO? leakage. Understanding these features are critical for risk assessment and for designing appropriate mitigation strategies.

Geophysical data are used for preparing reservoir models that on simulation predict how CO? will behave over time. These models are essential for assessing the long-term stability of the storage site and for planning monitoring activities.

5.????? Regulatory Compliance and Reporting

Geophysical monitoring data is often required by regulatory agencies to demonstrate that CO? is being stored safely and effectively. Geophysical methods provide the evidence needed for reporting and for ensuring compliance with environmental regulations.

Importance of Seismic in CCUS

A lot of tax credits and environmental concerns have encouraged investor’s interest in CCUS. However, success of any CCUS project is based on ensuring reservoir’s storage integrity. Induced seismicity from activating faults during injection is a critical concern.

The people involved in CCUS projects generally are not familiar with current seismic imaging techniques. Legacy seismic data available for purchase are often from decades-old processing algorithms. Even minor velocity variations above the reservoir can distort the seismic image, introducing false indications of faults.? The interpretation of legacy data without reprocessing with modern migration methods may be misleading resulting in abandonment of CCUS project. Seismic data analysis plays a crucial role in identifying traps and seals, essential components like porosity and permeability for securely containing and trapping injected CO2.

Geophysics and specially the seismic plays a crucial position in advancing initiatives related to Carbon Capture, Utilization, and Storage (CCUS). Geophysics also plays a pivotal role in the monitoring of CCUS process.

In the field of geophysics, various challenges complicate subsurface interpretation. The high cost of equipment and advanced technology required for geophysical surveys can be a barrier, especially for smaller CCUS projects. The complexity of interpreting geophysical data demands expertise, and misinterpretation can lead to inaccurate conclusions about subsurface conditions.

Seismic data acquisition over the depleted fields were done more than a few decades back. The old coverage and poor resolution of old surveys conducted for specific purposes may not be good enough for new applications or research objectives. The use of outdated technology in some existing surveys may may not provide desired quality of results, necessitating reacquisition or reprocessing.

Geophysics is integral to the success of CCUS projects, providing the necessary data for site selection, monitoring CO? injection, ensuring long-term storage security, and helping to meet regulatory requirements.

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