CNOOC Built a Well at the Enping 21-4 Field with a Record Deviation from the Vertical for China
At the Enping 21-4 field in the Pearl River estuary basin, CNOOC commissioned a well with a record-breaking reach-out for China. CNOOC reported this on April 13, 2024.
Record well
According to CNOOC:
- well A1H in the Enping 21-4 oil field is China’s first independently designed and constructed extended reach well,
- the well was constructed from the Enping 20-5 unmanned platform, located 8 km from Enping 21-4,
- the length of the wellbore was 9508 m,
- the deviation from the vertical was 8689 m, after testing, the oil flow rate was more than 700 tons/day,
- the well was successfully put into operation,
- this indicates that China has successfully overcome the technical difficulties associated with drilling wells up to 10 thousand meters in length and using long-reach vertical drilling technologies on the shelf, reaching the forefront in the world.
The Enping 21-4 field is small in terms of reserves, which makes its development using traditional methods – through the construction of new offshore production platforms or subsea production complexes (SPC) – economically unfeasible. Therefore, for the development of the field, a technology was chosen with the construction of wells with extended reach from the vertical (Extended-Reach Drilling, ERD) with a nearby offshore platform.
The use of ERD wells allows for economical and efficient development of oil and gas reserves in low-yield oil fields.
The deviation coefficient (ERD) of well A1H in the Enping 21-4 field reaches 4.43, which is equivalent to moving forward nearly 4.5 m for every 1 m depth step. This is not a record figure on a global scale, but for China it is a very important achievement, since the design and construction of the well was carried out in-house using equipment of its own production.
To implement the project, new technological solutions and materials were developed:
- environmentally friendly petroleum-based drilling fluids and continuous circulation systems,
- intelligent control while drilling,
- collection of downhole parameters in real time,
- rotating and floating casing.
The level of localization of materials and equipment used has reached 95%.
Enping 21-4 Field
CNOOC discovered the Enping 21-4 oil field in the South China Sea in 2020. The field is located in the sea approximately 200 km southwest of Shenzhen, the average sea depth at the field is about 86 m. It is part of the Enping group of deposits.
Production at the Enping 23-1 field has been ongoing since 2017. In December 2022, CNOOC put into operation the first fields of the project developed using unmanned MTs – Enping 15-1/10-2/15-2/20-4.
In October 2023, the Enping 18-6 field was launched.
The Enping 15-1 field launched China’s first offshore carbon dioxide capture demonstration project in June 2023.
CNOOC plans to reach peak production at the project in 2024 of 35.5 thousand barrels per day of oil. Incl. Hydrocarbon production from the Enping 21-4 field is expected to be 5.3 thousand boe/d.
