Geomechanics and Wellbore Stability Design of an Offshore Horizontal Well, North Sea
Bibliographic record
Abstract
Abstract This paper describes a comprehensive geomechanical assessment of the P2-NE Field in the North Sea. The objective was to review the available core, log, and drilling data to characterize the geomechanical performance of the P2- NE Field in order to explain observed behaviour, and extrapolate this to future drilling, particularly for Well P2-NE- 2 Horizontal. This study focussed on the inclined Well P2- NE-2 Pilot, which was drilled specifically to obtain reservoir data for the subsequent horizontal well. The geomechanical analysis is based upon the general geological setting, deductions made from field data, and geomechanical core tests. Wellbore stability analyses were conducted, using the mechanical properties and regional stresses as input. Geomechanical tests and petrophysical logs were used to obtain realistic profiles of mechanical properties. Anomalously, the reservoir mudstones were of considerable strength, exceeding the strengths of the sandstones. Weak zones were found in the sandstone that would be stable while drilling if an adequate mud weight were used. These zones would likely be sand producers during production. This is because the rock stresses would continue to increase, due to the continued pressure decline during depletion. To obtain stress data, a minifrac test from an adjacent field was analyzed. This provided the breakdown pressure, fracture propagation pressure, the ISIP, and most importantly the fracture closure pressure. The principal horizontal stress orientations were determined from borehole breakout analyses, and compared to residual strain relaxation tests on core. Other observed borehole elongations included wellbore washouts and keyseating. Finally, a stability analysis was conducted for the horizontal well, in order to assess the effect of increasing the mud weight.
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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) | 0.000 | 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".