By: Tariq Siddiqui
Maturation of ‘Prospective Storage Resources’ requires review a large amount of data and analysis with subsequent increasing details from ‘Site Screening,’ to ‘Site Selection’ and finally ‘Site Characterization’ leading to ‘Qualified sites’ ready for permitting.
CO2 resource management is a critical first step towards successful storage project. The data required at each of three stages ; screening, selection and characterization is broadly divided into four data categories;
Geological Data
Site Data
Social Data
Regulatory data
This article highlights some tips & best practices and insights for site screening phase:
SITE SCREENING
The purpose of site screening is to evaluate regions (called Potential Sub-Regions) within a much larger area of interest, such as the entire sedimentary basin.
I. Geological Data
Geological data analysis is divided in three broad categories; Subsurface Analysis, Model Development and Detailed characterization. At the site screening stage only Subsurface Analysis is required. Following is the summary of subsurface analysis required in each of the four sub-categories:
Storage Formation Properties: Must have adequate reservoir characteristics; porosity, permeability, pore pressures and salinity (> 10,000 ppm).
Sufficient Pore Volume: Can accept the planned CO2 injection within acceptable pressures. Initial site screening can help estimate formation capacity to accept project volume (click Storage calculator)
Depth: Adequate depth of storage (> 800m) to maintain CO2 injection at supercritical state.
Confining Zone: Adequate Cap rack and seal to prevent injected CO2 leakage into underground water sources or escape to atmosphere.
Reservoir modeling and detailed reservoir characterization is not required at this stage.
II. Site Data
Four key areas of analysis are required for regional proximity analysis at this stage
Protected & Sensitive Areas : This includes Wetlands, Source Water Protection Areas, Protected Areas, Species Protection
Population Centers: Not a reason to reject a site, but need to review permissions for site characterization. Right to pore spaces, access to right of Ways (ROW). Therefore site away from population center is preferable.
Existing Resource Development: Proximity to existing hydrocarbon development will give valuable information about storage potential with minimal investment. More mature the field, more the availability of data. But each well-bore also poses leakages risk and well bore integrity needs to be examined.
Pipeline Right of Ways (ROW): Must be evaluated at site screening. A new pipeline is capital intensive. Existing CO2 pipeline network must be reviewed for size, capacity and age. IF no pipeline storage close to site, then site must be located close to the emission source.
The detailed, site suitability analysis is not required at site screening stage, as its a detail attended in Site selection phase.
III. Social Data
In social context analysis; objective is to develop a general sense of the communities in the sub-region. Three key areas of analysis are required:
Demographic Trends: This provides social context across the region. The data is available in US from U.S. Census database. This gives a preliminary understanding of the communities in the sub-region where a project might be located and the socio-economic issues they face
Social Context Data: Data that influence public perception of CO2 storage project. Data and research at this stage should be limited readily accessible resources.
Land Use and Environmental History: Is land Industrial, commercial agricultural? Any history of prior oil & gas development means population is accustomed to seeing drilling operations. Dat can be collected easily from industrial activity databases.
Public outreach assessment is not done at site screening or site selection stages. It's a detail done at the site characterization stage.
IV. Regulatory Data
The regulatory issues analysis and data analysis are not required at site screening stage. Injectivity assessment and UIC well classes for the permitting are done later, at the site selection and site characterization stages respectively.
2. DELIVERABLE
The Site Screening process results in the identification of Selected Areas that meet; geologic screening, proximity, and social context criteria, as well as suitability for injection based on criteria established during Project Definition. The highest-ranked Selected Areas will be evaluated further during Site Selection.