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Introduction

The Carbon Storage Process begins with the initiate stage, during which screening workflows are used to identify suitable regions and sites that can be compared to pinpoint potential opportunities for carbon storage projects (Figure 1). Traditional screening workflows often take months to complete, and the process is further complicated by a lack of data.

CO2 Storage challenges and processes graphic

Figure 1: CO2 Storage challenges and processes.

The DecisionSpace® 365 CO2 Storage Suite provides a series of workflows that can be leveraged across the various stages of the Carbon Storage Process, the first of these workflows in the CO2 Storage Screen.

Initiate: CO2 storage screening workflow

The CO2 Storage Suite offers on-demand, agile play fairway analysis tailored to rapidly identify prospective storage resources, even in areas with limited data control.

The Neftex® global lithostratigraphic framework and the automated workflows allow first past screening to be conducted in a matter of minutes rather than weeks. The stepped approach drives a consistent, repeatable methodology (Figure 2), allowing more time for testing ideas, considering multiple scenarios, and ultimately making more informed decisions.

CO2 Storage Solution screening workflow and inputs graphic

Figure 2: CO2 Storage Solution screening workflow and inputs.

Selecting an area of interest (AOI) (Figure 3) allows the user to provide input on the storage fairway, enabling a holistic overview of reservoir and seal presence and effectiveness, CO2 supercritical state, and operational factors. The result is a Common Chance Risk Mapping map, from which prospective storage resource estimates can be derived, providing theoretical storage capacity for the storage fairway.

Select an area of interest(AOI) anywhere in the world functionality

Figure 3: Users can select an AOI anywhere in the world, regardless of its size.

Reservoir presence and effectiveness

The Neftex® framework and content are used assess the spatial distribution of candidate reservoirs and seals over stratigraphic time Users can adjust screening criteria to assess specific formations, time horizons/intervals, and lithology (Figure 4a). The screening parameters are then further refined to evaluate reservoir effectiveness. A depth grid is selected, allowing users to specify depths at which reservoir effectiveness would be impacted (Figure 4b). When the screening run begins, regional porosity and depth information from Neftex are automatically incorporated to visualize the impact of burial on total porosity and apply necessary cutoffs.

 Reservoir presence screening and reservoir effectiveness calculation

Figure 4: a) Reservoir presence can be screened for a specific formation, time horizon/interval, and lithology; b) Depth parameters can be defined, which will be used to calculate reservoir effectiveness.

Seal presence and effectiveness

Similar to assessing reservoir presence, users can quickly evaluate the spatial distribution of candidate seals and their relationship with underlying reservoir targets. Specific formations, time horizons/intervals, and lithology can all be customized by the user. The seal analysis is automatically refined to incorporate paleotectonic events from the Neftex geodynamic model, which may have impacted seal integrity and effectiveness.

CO2 supercritical state

For effective, safe storage, CO2 should be injected and remain in a supercritical state. This means CO2 has the buoyancy of a liquid but the volumetric characteristics of a gas, allowing for more secure storage. This dependence relies on reservoir conditions exceeding specific pressure and temperature limits. To estimate reservoir pressure, a depth-pressure relationship is applied to generate a pressure grid, and a reservoir temperature grid is calculated using geothermal gradients, surface temperature, and depth data. These pressure and temperature grids are combined to create a supercritical output for the target formation. A user simply selects a depth interval of interest, and reservoir pressure and temperature conditions are predicted to calculate whether CO2 will remain in a supercritical state if injected.

Calculating supercritical state parameters for safe storage

Figure 5: Depth surfaces (a) are used to calculate reservoir pressure (b) and temperature (c) conditions to predict the state of CO2 under such conditions (d)

Operational factors

Operational factors can play a key role in the project’s viability and should be included in the initial screening assessment alongside subsurface considerations. Users can specify specific operational limits (Figure 6) and leverage emitter location and information, combined with reservoir depth and bathymetry, to create an operational apron over the specified fairway.

specify specific operational limits functionality

Figure 6: Operational factors including water depth and distance from certain facilities can be defined to create an operational apron that can provide an additional screening cutoff.

Results

After defining the screening parameters, users can initiate the screening workflow.  A Common Risk Segment map of the geological elements of the carbon storage system (Figure 7a) is generated in minutes. The fairway can then be further constrained by the operational apron (Figure 7b), calculated based on the input parameters. Storage resource estimates are automatically calculated using an inbuilt storage resource calculator. This tool determines the total available pore space within the defined AOI and allows for the recalculation of the AOI and/or reservoir properties are refined (Figure 7c).

The output of running the automated screening workflow

Figure 7: The output of running the automated screening workflow includes a) A CRS map that considers geological criteria for the defined reservoirs and seals, such as reservoir presence and effectiveness, seal presence and effectiveness, and CO2 supercriticality; b) Operational apron that illustrates the specified operational limits; c) Storage resource estimates that can be recalculated on the fly.

Summary

By leveraging the Neftex global framework and content and applying automated workflows, the time required to evaluate opportunities and pass through the first decision gate of the Carbon Storage Process is drastically reduced.

However, identifying and comparing potential storage sites is just the first step in a lengthy process. Prospective resources need to be matured to be effective and ultimately matched in capacity. This refinement will help reduce uncertainty and cost. The maturation process requires additional subsurface data and characterization, resulting in plume migration models and scenarios in map and 3-dimensional model format with applied cut-off criteria, such as pressure data. This is part of the Assess Stage, which we will explore in more detail in the next spotlight in this series that span the Carbon Storage Process.

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