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Ultradeep-Field Study: Extreme-Underbalanced HP/HT Coiled-Tubing-Conveyed Perforating

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.

Introduction

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.

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 The paper has not been peer reviewed.
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Ultradeep-Field Study: Extreme-Underbalanced HP/HT Coiled-Tubing-Conveyed Perforating

01 April 2018

Volume: 70 | Issue: 4

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