Forties Infill Drilling: A Case History Documenting an Extensive Infill Drilling Campaign Driven by 4-D Seismic Technology
Rose, Philip T. S.,
Stephen Adiletta, David
Allard, Alistair Gray, Donald Keir, Apache North Sea
Ltd,
Apache North Sea Ltd embarked on a 30 well infill drilling
campaign beginning in 2004 in the Forties Field after nearly 30 years and 2.5
billion barrels of oil production. Bypassed oil has been identified by
interpretation of lithology, fluid and fluid difference seismic inversions
derived from 3D seismic surveys, acquired in 1988, 1996 and 2000. Drilling
targets were defined after integrating the seismic interpretations with
individual well production / injection profiles and data acquired during the
previous BP operated Forties infill drilling campaign of 1992 to 2001.
In this presentation the seismic processing methodology is
briefly described and the calibration to discovered hydrocarbon columns is
illustrated. The seismic lithology volume, integrated with the well data, is
used to define the key elements of the Forties Field reservoir architecture.
This reservoir model is integrated with the 4D seismic fluid volumes, well log
and production data to develop a model for the distribution of remaining
hydrocarbons within the Forties Field.
To end 2004, 17 wells have been drilled and with 12 wells
completed and on production. Approximately 25,000 BOPD production has been
added to the field. The best well results (all with initial production rates
between 3 and 6000 BOPD) were defined by strong oil anomalies on the 4D data
and indications of a lack of sweep on the 4D difference volume.