Genesis 4-D Project Status and Preliminary Lookback

Hudson, Thomas A.¹, B. W. Regel¹, J. E. Bretches¹, P. J. Condon², J. E. Rickett², B. P. Cerney³, P. L. Inderwiesen³, R. T. Ewy² (1) ChevronTexaco North America Upstream, New Orleans, LA (2) ChevronTexaco Energy Technology Company, San Ramon, CA (3) ChevronTexaco Energy Technology Company, Houston, TX

A 4D seismic survey was acquired over Genesis Field, deepwater Gulf of Mexico, in October, 2002 specifically for reservoir monitoring and field management. The acquisition criteria were designed to replicate the pre-production baseline survey. Both baseline and monitor surveys were co-processed to minimize differences except those related to pro­duction. Extensively interpreted reflection seismic volumes and preliminary interpretation of acoustic impedance (AI) volumes indicate that the 4D project will add significant value to the field.

The interpretation of 4D data on the field’s five primary reservoir sands has resulted in:

• Observed production-related time-lapse anomalies including changes in reflection strength due to fluid movement and pressure reduction and an increase in travel time of up to 10 ms at the top of the producing interval due to reservoir compaction and overburden dilation; • Identification of updip potential and/or its risk reduced in three reservoirs; • Resolved con­nectivity uncertainties in several reservoirs leading to better understanding and modeling of reservoir behavior.

Preliminary assessment of the 4D project indicates significant value added by modifying field operations: • One anticipated sidetrack has been eliminated saving over $10 million dol­lars; • The geological risk of one sidetrack was reduced and the estimate of recoverable vol­umes increased; at least two future sidetracks should be affected similarly; • Adjustments to the reservoir simulation should lead to better well placement, improved recovery estimates, and better reservoir management.