Characterization of Sand Production for Clayey-Silt Sediments Conditioned to Openhole Gravel-Packing: Experimental Observations
Bibliographic record
Abstract
Summary As one of the geotechnical risks, sanding has been one of the main constraints for safely and sustainably developing marine natural gas hydrate. In this study, a cylindrical vessel that is packed with the clayey-silt sediment collected from the Shenhu area of the northern South China Sea is used to microscopically observe sand detachment, migration within matrix, invasion to gravel packing, and production for openhole gravel packing. More specifically, by injecting water from the vessel boundary, the seepage and stress-strain field for sediment near the wellbore after hydrate dissociation is simulated, and the sand failure characteristics [i.e., the produced sand volume and particle size distributions (PSDs)] are quantified. The sand failure pattern is found to largely differ from that of a sandstone reservoir, whereas fractures, wormholes, and fluidized channels are successively developed along with a large scale of sand production and inlet pressure variation. Followed is a steady flow state with a stable inlet pressure without noticeable sand failure. Correspondingly, the fracture is induced and propagated by the combinational effort of shear and tensile failure, whereas wormholes and fluidized channels are associated with the liquid dragging force. At the end of each test, foraminifera are found to accumulate near the external side of the gravel-packing region, which is beneficial to sand control. In the meantime, a compact mudcake, as an infiltration medium, is observed outside the gravel-packing layer. The 30/50 mesh gravel packing is able to control grain size up to 30.0 µm in diameter with a median of 5.0 µm, whereas the produced grains account for less than 1.0 vol% of the total sediment. By performing sensitivity analysis on sand production, depressurization shall be conducted at a small rate to not only control sand production, but also to induce flow paths at the early stage. Moreover, the sand production rate associated with fracture development is larger than those of wormholes and fluidized channels. This study focuses on the experimental observations on sand failure patterns, and the theoretical formulations and modeling will be presented and explained in a future work.3
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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 | 0.000 | 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) | 0.002 | 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 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".