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