Lost Circulation Assessment and Planning Program: Evolving Strategy to Control Severe Losses in Deepwater Projects
Bibliographic record
Abstract
Abstract There was a time when simply dumping some mica or nut hulls down a wellbore was a standard procedure for stopping mud losses. Certainly, these materials still work – for some applications. But, many of today's drilling operations bear little resemblance to that not-so-distant past. The industry is accelerating its activities in deepwater and depleted zones, both of which present narrow operating limits, young sedimentary formations, and high degree of depletion overbalanced drilling. All of these now-common conditions are ideal for fracturing and lost circulation. Drilling through and below salt formations presents a host of technical challenges as well. The thief zone at the base of the salt can introduce severe lost circulation and well control problems, often resulting in loss of the interval or the entire well. Controlling losses in this zone has proven to be extremely difficult. Very few lost circulation remedies have been successful, especially when using invert emulsion drilling fluids. The lost time treating severe sub-salt losses can last for several weeks, with obvious cost implications, especially for deepwater drilling operations. This paper reviews the methods applied to avoid lost circulation in the sub-salt thief zone, as well as in the subsequent intervals for a Gulf of Mexico deepwater project and discusses the time and cost savings obtained. For maximum success in these situations, emphasis has been placed on assessment and planning rather than individual lost circulation products. The authors will detail the Lost Circulation Assessment and Planning process that has been employed to explore and evaluate specific lost circulation problems and link them to existing products, systems and services. The integrative pre-planning process analyzes offset histories and formation data not only to identify risk zones but also to gather information on the exact fracture and pore size as well as fracture density. Afterward, detailed interval-specific decision-tree charts are developed for stopping losses encountered while drilling or tripping in. In addition to discussing the application of this Assessment and Planning process, the authors will outline the lessons learned on the deepwater project, featuring pre-planning issues geared toward ensuring circulation is maintained throughout the wellbore.
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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".