Applications

Challenge

Shell was interested in a thrust-belt play where the main exploration uncertainty was whether the structural trap had retained hydrocarbons

Shallow gas layers in the overburden that reduced the quality of the seismic imaging at the crest of the structure. Seismic data quality improves down-flank from such structures, and indirect hydrocarbon indicators such as flat spots had been observed.

However, flat spots may be remnant features indicating where hydrocarbons have escaped. Shell wanted an independent test to confirm that hydrocarbons remained in the trap.

Application

A seabed-logging survey was performed over a well on the flank of the structure. This well had found only residual hydrocarbons.

Result

After careful processing and depth imaging of the seabed-logging data, a resistive anomaly was identified just up-dip of the original well. A second well was drilled and found to contain the commercial hydrocarbons that EMGS had predicted.

The seabed-logging information reduced the uncertainty about the trap's charge retention. Without this independent verification, the well might not have been drilled.

Apparent resistivity and seismic section showing that a resistive body (red and yellow) lies within the structural trap, which indicates that the trap may contain hydrocarbons. (Image courtesy of Shell)