Usage of a Coiled Tubing PWC Tool to Abandon Two Wells with Surface Casing Vent Flow on Onshore Australia
Bibliographic record
Abstract
Abstract The increase in plugging and abandonment (P&A) activities requires innovative solutions that can reduce costs, enhance operational efficiency, and reduce emissions while ensuring that Operators comply with local regulations, maintain environmental responsibility, and achieve P&A objectives. One solution is the introduction of a coiled tubing perf-wash-cement (PWC) tool, which can install cross-sectional cement barriers without rigs. In this paper, we present the basis of PWC via a case study of two wells decommissioned in Australia. The installation of the cross-sectional cement barriers was part of a 20-week P&A campaign to decommission two wells in the Bowen/Surat Basins, onshore Australia. Through zone selection in the P&A design, the objective was to improve cement barrier placement over a 60m interval behind production casing and remediate a surface casing vent flow (SCVF) problem while managing the effective isolation of multiple aquifer units. The solution needed to provide long-term well integrity while overcoming these complex conditions. Another challenge was that the operator could not establish circulation for a traditional perf & squeeze at the desired depths. Considering the location, tool availability, cost targets, and technical challenges, a decision was made to attempt a coiled tubing PWC operation. The tool was deployed successfully in September 2024, placing two cement plugs in each well, four plugs in total. Despite the complexity of the operation, all four plugs were installed within a three-week interval, which contributed to reducing the project timeline, with three out of four plugs each taking only 11 hours to complete. All four plugs were confirmed through tagging and pressure testing, in line with the Code of Practice (CoP), ensuring a good quality barrier was placed between the formation and the casing, capable of remediating any potential leak pathways. The combination of testing and the correct job execution – following the operational parameters set during job design and used previously in other similar PWC operations - was sufficient to successfully execute the four jobs, and to meet compliance with the QLD regulations and the CoP. Later monitoring, which consisted of monthly inspection during 6 months, confirmed that the observed issues of SCVF and SCP were remediated post-job. It can be concluded that the operation was successfully deployed using the coiled tubing PWC tool, achieving all the targets, which included operational efficiency that was set by the operator during the P&A design. This case study highlights the PWC flexibility as a method for annular remediation during plugging and abandonment in combination with coiled tubing and a mechanical perforator. This allowed for safe, environmentally responsible, and cost-effective P&A operations, remediating well integrity issues by permanently sealing potential leak pathways using cement. Such technology has many other well candidates in Australia (and worldwide) that could benefit from the flexibility provided by coiled tubing PWC, saving costs and reducing emissions.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| 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 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".