--> Abstract: Redevelopment of Ekofisk Field, North Sea, Based on Rerservoir Characterization and Innovative Well Design, by C. T. Feazel, H. H. Nielsen, B. Agarwal, and S. C. Key; #90928 (1999).

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FEAZEL, CHARLES T., HARDY H. NIELSEN, BIJAN AGARWAL, and SCOTT C. KEY
Phillips Petroleum Company Norway

Abstract: Redevelopment of Ekofisk Field, North Sea, Based on Rerservoir Characterization and Innovative Well Design

After 26 years of oil and gas production from chalk of Danian and Maastrichtian age, the giant Ekofisk field is only halfway through its economic life. The installation of new surface facilities provides a challenge to teams responsible for planning and drilling up to 50 new wells in a field with a mature waterflood underway. Locations of the new wells are based on a history-matched reservoir flow simulation model derived from a three-dimensional geological model.

Attributes in the 23-million-cell geological model (e.g. permeability, initial fluid saturation facies type, rock composition) are distributed deterministically and geostatistically from a database of well logs, cores, and 3D seismic data inverted for porosity and thickness. An upscaled 39,000-cell flow model is used to predict the movement of injected water, and to optimize the paths of wells varying from near-vertical to long-reach horizontal, and from simple slant-holes to complex multilateral wellbores.

The technology and teamwork applied to reserves optimization in a mature waterflood also lead to various plans for monitoring sweep efficiency in the chalk reservoir, using downhole, seabed, and surface acquisition techniques; and for overcoming such obstacles as (a) a gas-charged overburden which obscures seismic returns, and (b) reservoir compaction resulting in both wellbore collapse and sea-floor subsidence.

AAPG Search and Discovery Article #90928©1999 AAPG Annual Convention, San Antonio, Texas