Abstract: Improved Seismic Technology for Field Development in the UK North Sea (Central Sector)

DAVIES, D.J., J.BUITING and M.E.MINNNING

Improvements in seismic technology over the past two years, have resulted in better sub-surface imaging of a number of fields in the UK Central Sector of the North Sea. These technology improvements have include denser sampling in acquisition followed by pre-stack time migration (PSTM), stochastic inversion and, more recently, pre-stack depth migration (PSDM). In the light of the subsequent wells drilled, it is possible to quantify the cost effectiveness of these techniques, and indicate in what direction new technology trends may bring greatest benefits.

Examples will be shown from several fields including Guillemot A and Gannet C. The total expectation of reserves in the Shell/Esso fields in the Gannet/Guillemot area is 220MMbbls oil and 156 Bcf gas with an uncertainty range of 33%.

In each case we will show that the improved seismic data has led to:
- A revision of the subsurface model for each field, with a
reduced uncertainty in the reserve estimates.
- Revised drilling locations and a higher drilling success
rate.
- Better defintion of direct hydrocarbon indicators.
- Improved seismic/well ties and more accurate reservoir
parameter prediction.

Specific cost analysis indicates that improved seismic has led to drilling cost savings (benefiting from reducing the sidetrack-rate) of five times the seismic cost. Additional reserves and reduced uncertainties in reserves contribute to improve the cost/saving ratio to 1:10.

AAPG Search and Discovery Article #90942©1997 AAPG International Conference and Exhibition, Vienna, Austria