A modeling study was undertaken to optimize the subsurface development of a giant offshore oil field in the UAE, using the concept of artificial islands. The new development plan capitalized on many advantages of artificial island in terms of surface and subsurface flexibility [Ref.1].
The main objective of this paper is to present the dramatic changes in a field development plan (FDP) which have been achieved by incorporating the concept of Maximum Reservoir Contact (MRC) wells and Geologic Drainage Area (GDA) for development of reservoir G. This revised FDP was the result of evaluating various development options for reservoir G and incorporating learning from sector model through a workflow which was established for this purpose.
In this paper, we describe multiple field development options which have been evaluated for reservoir G through full field modeling and sector model sensitivity studies. Recommendations are made for the optimal development plan. The recommended development plan (referred to as the Island Option) is tailored to the geologic description of the reservoir and uses 3 km maximum reservoir contact (MRC) wells in addition to shorter MRC wells, enabled by drilling wells from islands instead of conventional drilling and production towers ("WHPTs"). Key elements of the island development plan are that it:
Is based on a variably spaced, line drive pattern flood
Honors the reservoir geology and current oil saturation distribution
Uses ~3 km MRC wells with closer spacing (~0.5 to 1 km) in place of the current 500 m to 1 km WHPT wells in areas of the reservoir with low permeability
Uses ~1 km MRC wells with larger spacing (~1 to 1.5 km) in areas of the reservoir with high permeability
Performs better than the predecessor development plan (referred to as WHPT Option) in terms of plateau duration and ultimate recovery
The recommended plan for reservoir G is the Island Option, which calls for drilling 79 new wells compared to the WHPT Option which would have required 140 new wells. The new wells in the island development plan are a mix of 3 km MRC wells, 1 km horizontal wells and vertical wells. The MRC wells are oriented in a northwest-southeast direction to be aligned with the predominant fault direction in the field, reducing the risk of poor areal sweep because of water breakthrough resulting from wells intersecting faults.