Preinjection Reservoir Fluid Characterization at a CCS Demonstration Site: Illinois Basin – Decatur Project, USA
Bibliographic record
Abstract
The Midwest Geological Sequestration Consortium is conducting the Illinois Basin – Decatur Project (IBDP), a large-scale carbon capture and storage (CCS) project in Decatur, Illinois, USA. An extensive Monitoring, Verification, and Accounting (MVA) program has been implemented, and a deep monitoring well, VW#1, was drilled to a depth of 2,201 m (7,264 ft). The well was perforated in eleven zones ranging in depth from 1,499 to 2,153 m (4917 to 7061 ft.). Fluid samples were collected during three sampling events using two different sampling methods. This paper describes the well construction, well completion, sample collection procedures, and selected preinjection sampling results from VW#1. Prior to sampling, particular care was taken to remove non-native fluids from each of the sampling zones. Density, specific conductance, bromide concentrations, and bromide-chloride ratios have been used as indicators of sample representativeness. Fluid compositional data and formation pressure data have been collected from VW#1. These high-quality, field- based data are essential to establish hydrochemical conditions in and above the storage reservoir prior to CO 2 injection, indicate the response of the reservoir to injection, provide detailed geochemical model inputs, and provide insights for on-going work at the Illinois State Geological Survey about the origin of Illinois Basin brines. Primary brine constituents are chloride, sodium, and calcium with average total dissolved solids concentrations of 190,000 mg/L in the Mt. Simon Sandstone and 65,600 mg/L in Ironton-Galesville Formation (above the injection reservoir).
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".