13 September 2017
In March 2017, the ninth and final well of the development of Tyra Southeast Field was handed over to production. This completes a successful development project.
Tyra Southeast is located between the Tyra Field and the Halfdan Field in the southern part of the Danish area of the North Sea. The field is one of DUC’s 15 producing fields. The Tyra Southeast accumulation contains free gas overlying an oil zone, and both oil and gas is produced from the accumulation. The field has been developed as a satellite to the Tyra Field with one unmanned platform and first oil was produced in 2002. In 2012 a further development of the field was approved, which includes production of both oil and gas from two different geological formations - Ekofisk and Tor.
The further development consists of a new platform with capacity for a total of 16 wells and installation of gas lift in the existing wells. When using gas lift, well productivity is maintained by injecting gas into the well. In July 2014, the new platform was installed and connected with a bridge to the existing Tyra Southeast platform. After installation, drilling of the first out of nine new wells began and first oil from the development was produced in March 2015. Production from Tyra Southeast is expected to provide some 50 million barrels of oil equivalent over the coming decades.
New drilling rig saves time
The last eight wells were drilled with the drilling rig "Noble Sam Turner", which has a larger capacity than the original rented rig.
This played a role in the wells being drilled significantly faster than estimated combined with campaign drilling where lessons learned are quickly implemented. Due to the saved time and thus less cost, it was possible to perform an extra well within the original budget.
New technologies implemented
During the drilling campaign, the operator Mærsk Oil has tested several new technologies, which has yielded valuable knowledge and experiences to future projects.
In the drilling campaign, oil-based mud has been successfully replaced by a special type of water based mud when drilling through clay layers. Mud is used while drilling to ensure borehole stability. The use of water-based mud has reduced the technical challenges and is also an environmental improvement. Furthermore, new types of tools have been used to optimize the well trajectory in the thin reservoir sections during drilling operations. In addition, the operator has developed a simplified well design.
Overall, these optimizations have resulted in a decrease in drilling days for each well with a record of only 52 drilling days, including completion and stimulation of a 5 km horizontal well. Overall, the drilling campaign was completed more than 20 per cent faster than expected.
Assessment of the potential
The nine new wells have been put on production, and overall the production for the entire project is somewhat above expected.
The hydrocarbons are located in a structure of chalk layers at approx. 2 km depth. The structure is part of the major uplift zone that also comprises Roar, Tyra and parts
of the Halfdan Field. One of the new wells has been drilled towards the Halfdan field to appraise the reservoir and content of oil and gas, see map.
Production data from the wells will now be obtained, and along with data from the drilling campaign the potential will now be evaluated. The evaluation may indicate an additional potential for production of oil and gas in the area.
Facts about Tyra Southeast:
Licence: Sole Concession
Operator: Mærsk Olie og Gas A / S
Year on stream: 2002
Shell Oil and Gas Extraction Denmark B.V. Holland, Danish Branch 36.8 %
A.P. Møller-Mærsk A / S (Concessionaires) 31.2 %
Nordsøfonden 20.0 %
Chevron Denmark 12.0 %