Ultradeep-Field Study: Extreme-Underbalanced HP/HT Coiled-Tubing-Conveyed Perforating
- Chris Carpenter (JPT Technology Editor)
- Document ID
- Society of Petroleum Engineers
- Journal of Petroleum Technology
- Publication Date
- April 2018
- Document Type
- Journal Paper
- 84 - 85
- 2017. Society of Petroleum Engineers
- 1 in the last 30 days
- 35 since 2007
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This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 186948, “Extreme-Underbalanced High-Pressure/High-Temperature Coiled-Tubing-Conveyed Perforating: KN Ultradeep-Field Study,” by Miguel Rosato, Mohd Farris Bakar, and Fadzliana Azmi, Petronas, prepared for the 2017 SPE/IATMI Asia Pacific Oil and Gas Conference and Exhibition, Bali, Indonesia, 17–19 October. The paper has not been peer reviewed.
At an initial stage in a project to carry out the first high-pressure/high-temperature (HP/HT) field development offshore Malaysia, a locally conventional initial design considered the use of coiled-tubing-conveyed perforating (CTCP) to perforate a 7-in. liner and then to complete the well in open hole with overbalanced completion fluid. This solution posed several challenges that would have affected the safety of the completion process and the future integrity of the well architecture. A different approach, in which a fully cased hole well was completed in underbalance and then perforated once the completion was installed and tested, was used by the operator for the first time.
The KN field is located west/northwest of Labuan offshore Sabah. The operator has been tasked to develop the KN ultradeep HP/HT reservoir (pressures exceeding 12,000 psi, temperature exceeding 300°F). The well production-casing envelope consisted of a single 10¾-×10⅛-×9⅞-in. production casing, while the reservoir section was drilled and then covered with a 7-in. production liner. This liner was cemented, secured at the top with a liner hanger, and secured at the bottom with a bridge plug.
Once these barriers were installed, the next operation in the well was to run a wellbore-cleanup assembly with a scraper, brushes, magnets, and an inflow-test packer. After wellbore cleanup, the drillpipe volume was displaced with inhibited fresh water, an initial inflow test was conducted, and, then, after good indication of well integrity, the well was displaced completely to inhibited fresh water. Immediately, an extended inflow test was conducted. At the time of the inflow test, the well was in an underbalanced condition of 6,000 psi at total depth. Fig. 1 shows the results.
The completion philosophy for the ultradeep well was a single completion string to be run in the closed well immediately after the wellbore-cleanup tools were out of the hole. After running the completion, the following operations were performed:
- Setting the tubing hanger
- Setting the production packer
- Pressure testing the production packer from above and below
- Nippling down the blowout preventer (BOP)
- Nippling up the tree
- Function and pressure testing the wellhead system
In the case of this well, these operations were conducted safely and within the allocated time and cost as per the approval for expenditure.
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