A Challenging Workover in an Offshore Fixed Platform - Accessing Bypassed Hydrocarbons
Bibliographic record
Abstract
Abstract This paper presents the planning, execution, and lessons learned of a challenging workover focused on accessing bypassed hydrocarbons for production increase. The workover goal was to add two-bypassed zones, a high quality upper carbonate zone and a thin bed of sandstone, both above the production casing shoe, to the openhole carbonate production of a horizontal well in a fixed offshore platform. Polvo is a brown or mature field in shallow waters of Campos Basin, Brazil. Among the typical problems of mature fields, Polvo shows only pressure drop, declining oil rate, and high water influx, with 80% average water cut. To extend the economic life of Polvo, a huge challenge in the current downturn, its independent operator is rejuvenating existing producing wells, optimizing flow, and identifying, quantifying and accessing bypassed hydrocarbons. The original well was completed in a lower carbonate zone in a 604 m openhole lateral section with sand control screens. After reviewing reservoir and well data, the operator team found the two mentioned bypassed zones. In order to access these zones, it was necessary to perforate them, to control sand production in the sandstone, and to deploy an intermediate completion. Because of internal diameter restriction in the lower completion, hydrajetting replaced casing gun operations in both zones. Sand control in the high angle sandstone interval was a challenge. A specific fracturing/gravel operation followed, successfully, a failed sandstone consolidation trial. Among the main challenges this workover faced budget and time limitations, once the rig operated on a temporary contract, and material, equipment, and footprint restrictions, not mentioning lack of relevant information about the bypassed sandstone zone.
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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 | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.003 | 0.001 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.006 | 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 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".