Small Fields Modelling from Satellite Image to Subsurface: Reducing the Uncertainty on the Position of a Field-Bounding Fault

Madelon Nijman*, Sami Al Nofli, and Karl-Heinz Zelt
PDO
*[email protected]

This field in South Oman was studied in PDO by an integrated team using a multi-disciplinary approach. The modelling effort focussed on capturing the main uncertainties and assessing the impact on the field development. For the field, one of the main uncertainties was the position of the field-bounding fault. The field consists of an half-anticline terminating against a graben fault in the north. This graben fault is the southern fault of a prominent graben. The graben faults are seen on satellite images of the area. The wells start in the graben and drill through the graben fault in the overburden. To constrain the location of the graben fault, all available data was used to construct a mechanically consistent 3-D fault interpretation. The resulting mechanical interpretation was compared to the 3-D seismic interpretation of the fault. The seismic interpretation placed the fault considerably further south. Seismic imaging of the fault was problematic due to the extent of the graben faults all the way to the surface, and strong multiples of the overburden. Multiple 3-D models were created based on both mechanical and seismic interpretations to assess the impact of the fault positioning on field size and development planning. The mechanical interpretation has been driving an attempt to drill the field further north than previous wells, which has resulted in a successful well in 2007. This presentation describes the methodology to quantify the uncertainty around the graben fault position and the impact of the uncertainty on field development planning.

AAPG Search and Discovery Article #90077©2008 GEO 2008 Middle East Conference and Exhibition, Manama, Bahrain