Critical Condition of the Depth Limit of Oil Accumulation of Carbonate Reservoirs and Its Exploration Significance in the Lower Ordovician of the Tazhong Area in the Tarim Basin
Bibliographic record
Abstract
Carbonate rocks typically constitute porous media, making the study of hydrocarbon accumulation in carbonate reservoirs an essential area of research. In the Tazhong area of the Tarim Basin, specifically within the Lower Ordovician stratum exceeding 7000 m, effective reservoirs and industrial liquid hydrocarbon accumulations persist. However, the existence of a depth limit of oil accumulation (DLOA) for oil accumulation in carbonate reservoirs remains unclear, posing a challenge for explorers. This study quantitatively characterizes the critical condition of DLOA in deep carbonate reservoirs from the perspective of hydrocarbon accumulation dynamics. Through comprehensive experimental analysis, statistical assessments, and numerical simulations, it also forecasts the potential for deep oil exploration. Based on the results of mercury injection experiments on 350 carbonate rock cores collected from 19 drilling wells in the deep Lower Ordovician, it was found that the reservoir is compact and exhibits significant heterogeneity. The driving force for oil accumulation is the capillary pressure difference between the surrounding rock and the reservoir. A greater capillary pressure difference indicates improved oil-bearing properties within the reservoir. When the capillary pressure difference between the reservoir and surrounding rock reaches zero, oil accumulation cannot occur, marking the critical condition of DLOA. The critical pore throat radius for DLOA in the deep Lower Ordovician carbonate rocks in the Tazhong area of the Tarim Basin is determined to be 0.01 μm, and the DLOA is estimated at 9000 m. This study confirms that the maximum depth for the embedded Lower Ordovician carbonate reservoir in the Tazhong area does not surpass this limit. Consequently, oil exploration in deep carbonate rocks within this stratum is both feasible and promising. The findings from this study hold significant importance in scientifically predicting favorable areas for oil exploitation in deep layers and offer valuable insights into understanding the oil flow in carbonate rocks.
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How this classification was reachedexpand
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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.002 |
| 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) | 0.000 | 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 teacher head, 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".