BY: Tariq Siddiqui
Why Storage Projects?
Anthropogenic carbon-dioxide (CO2) storage projects are key to achieving the Net-zero emissions. They are very similar to hydrocarbon development project with large uncertainties; and a multi-discipline effort, requiring significant capabilities, time and resources to manage them.
Managing Uncertainties
Like most hydrocarbon capital projects, CO2 storage projects have many uncertainties and risks, however, they can be reduced and managed with additional data and information in a stage-gated project management process (See: Title Slide, top).
CO2 Resource Classification System
The CO2 resource classification and assessment is a critical first step towards a successful storage project. "The steps taken in the development of CCUS project are expected to be very similar to oil & gas projects", according to DOE/NETL that has developed best practice guidelines for locating and developing a geologic storage project from initial stages of regional exploration to a point when site can be considered qualified for permitting and significant additional work.
DOE/NETL in developemt of the CO2 Resource Classification System (CO2-RCS) has taken a very similar approach to that of Petroleum Resource Management System (PRMS) in order to technically and commercially mature the CO2 resources, given the range of uncertainty.
Classes/Type of Resources
The CO2 resource classification system is project based, and like PRMS, it is divided into three main classes.
Prospective Storage Resources (Prospective Resources)
Contingent Storage Resources (Contingent Resources)
Proved Storage Capacity (Proved Reserves)
Managing Prospective Resource - First Step
This article focuses on the maturation of ‘Prospective Storage Resources.’ a class that is very similar to hydrocarbon ‘Prospective Resources’ in the hydrocarbon exploration phase. As operators start looking for onshore and offshore prospective opportunities for the CO2 storage projects, a clear understanding of classification of 'Prospective storage Resources,' their identification, selection and quantification is paramount.
The ‘Prospective Storage Resources,’ storage class is further subdivided in sub-classes (See: figure )
Potential Sub Regions (Play) - Site Screening
Selected Areas (Leads) - Site Selection
Qualified Sites (Prospects) - Site Characterization
The objective during ‘Prospective Storage Resource’ stage is to take a broad regional/basin view of the storage resources, manage and reduce uncertainties with additional data and technically and commercially mature ‘Potential Site’ to a ‘Qualified’ site ready for permitting.
Prospective Resource Evaluation - In Three Steps
The ‘Prospective Storage Resource’ evaluation is divided into three discrete steps with significantly increasing data requirements as the technical & commercial maturation progresses:
Site Screening
Site Selection
Site Characterization
The article only highlight summary of the activities and deliverables in each of above steps. In subsequent articles we will discuss the details of each step.
1. Site Screening
In this activity, the integrated team look at much wider area of interest such as basin scale and identify ‘Potential Sub-Regions’ (see: title figure). It uses readily accessible, reliable existing data (seismic, well logs, groundwater, confining formation). The deliverable of this evaluation is ‘List of Selected Areas.’
Key elements and best practices are highlighted in 'CO2 Storage Project: Best Practices For Site Screening.'
2. Site Selection
The purpose of site activity is to further evaluate “Selected Areas.’ The analysis uses the site screening analysis and augment it with new data. Site selection concludes with one or more potential sites being evaluated to the ‘Site Characterization’ Stage
3. Site Characterization
Finally, in the 'Site Characterization,' the multidisciplinary team analyzes the technical and non-technical data. This process has two stages: ‘Initial Characterization’ and ‘Detailed Characterization.’ The purpose of this stage is to scrutinize a ‘Potential Site’ to define its storage-related attributes and determine whether it can be ranked as ‘Qualified Site.’ A ‘Qualified Site,’ resources are classified as ‘Contingent Storage Resource.’ Ready for permitting.
CONCLUSION
As oil & gas companies announce the hub-level CCS infrastructure projects (example : ExxonMobil and CRC) in USA; a clear CO2 resource maturation process and a classification system is a first step towards the identification, selection and characterization of 'Prospective Storage Resources' from 'Potential Regions' at basin level into a robust 'Qualified' specific storage sites.