Hydrocarbon Potential of the Mississippian Carbonate Platform, Bechar Basin, Algerian Sahara
Why this work is in the frame
A frame that forgets how it found something cannot be audited. These are the routes that admitted this work.
Bibliographic record
Abstract
Abstract The western Bechar basin contains a 1500-2000-m-thick Mississippian succession of carbonates consisting of superposed shoaling-upward sequences, whose porosity or diagenesis have never been investigated to establish the reservoir potential of these carbonates. In this paper, we present a diagenetic and porosity evolution of the Visean part of the Mississippian carbonate platform that may lead to the development of new exploration fairways in the region. A diagenetic model is proposed in which ooid and crinoid grainstones may have a reservoir potential if hydrocarbon migration occurred before the end of the Serpukhovian, prior to complete occlusion of porosity. The two facies investigated are Waulsortian-type buildups and overlying ooid and crinoid grainstones that form regularly alternating packages in the thick upper Visean succession. The diagenetic sequence contains five calcite cement phases (C1-C5) that were investigated for isotope geochemistry and fluid inclusion microthermometry. The isotopic signatures of calcite cements range from marine for C1 to deeper burial environments for the 18O-depleted C3 and C4. Fluid inclusion data indicate that C3 and C4 (60-80% of the total cement) precipitated from hot, saline basinal fluids, whereas a meteoric-phreatic origin is suggested for C5. Temperatures of cementation, inferred from stable oxygen isotopes and homogenization temperatures of fluid inclusions, indicate that most pores within the buildups (shelter, stromatactoid, moldic, breccia, and vuggy) were occluded after only a few hundred meters of burial. In contrast, pores in the ooid and crinoid grainstones (mainly interparticle) stayed open after thousands of meters (900-2500 m) of burial. We hypothesize that these grainstones may have served as a regional conduit for hydrocarbon migration from the basin to the carbonate platform. Basin subsidence rate ranged from 220 m/m.y. during the Visean to 40 m/m.y. during the Serpukhovian-Bashkirian, which suggests that 20 m.y. was needed to fill most porosity. As a result, the western Bechar limestones can be considered a good target for petroleum exploration if the hydrocarbon migration occurred before the end of the Serpukhovian. This conclusion has important implications because the Mississippian limestones lie directly above potential Upper Devonian source rock in the Bechar basin.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.033 | 0.001 |
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 it