Abstract: Application of 3D Visualization and VSP for Horizontal Well Planning - 9/13a-N1, Nevis Field, UKCS

DICKSON, A.J., G.C. BINGHAM, G.C. STYLIANIDES, and H.W.A. THOMPSON

The Nevis Field, operated by Mobil North Sea Limited, came on stream in September 1996. This was achieved by completion of an existing vertical well in the Triassic and the drilling and completion of a horizontal well in the Middle Jurassic Beryl Formation. Horizontal wells are necessary for the economic development of the field. However these wells are high risk due to the relatively thin and faulted reservoir interval. Consequently a multi-disciplinary team worked concurrently to manage the risk of the crucial first horizontal well.

3D visualisation was used to allow all disciplines the opportunity to understand the structure and difficulties associated with the well. The location of the pilot well was optimized to maximize the chance of penetrating the OWC. A wide range of possible horizontal sections, dependent on the results of the pilot, was constructed interactively in 3D. Using an iterative process, a well path was engineered that catered for the range of outcomes.

An imaging VSP was acquired in the pilot well to help optimize the location of the final horizontal section. Thorough planning resulted in an excellent quality VSP which identified faults not apparent in the 3D dataset. Detailed structure maps were created based on the faults and bed dips interpreted from the VSP and fault trends observed from the 3D seismic data. The well design work in 3D meant that the new horizontal section was achievable. The final horizontal section proved 2000 ft of oil-bearing section which was successfully completed.

AAPG Search and Discovery Article #90942©1997 AAPG International Conference and Exhibition, Vienna, Austria