Improved interpretation gets to the root of salt

Improved interpretation gets to the root of salt

An article published 2 September in Hart Energy’s E&P discussed how 3D CSEM (controlled-source electromagnetic) data can be used to map salt bodies; and improve velocity models and seismic imaging in a traditionally difficult environment.

3D CSEM inversion overlain with 3D seismic. Two, black lines show the salt interpretation from seismic. Note how the 3D CSEM inversion results reveal a salt root not previously mapped.

The article “Coming to terms with subsalt” has implications for exploration in areas of the world which have seen subsalt discoveries, like offshore Brazil, the Gulf of Mexico and Africa.

The article’s author, Peyman Moghaddam, explained that electromagnetic methods are well-suited to image the base of salt and subsalt sediment structures.

Changing prospectivity of the salt flank

The following illustration shows results from a deepwater, 3D CSEM survey performed by EMGS in the Gulf of Mexico.

The black, threadlike lines show the seismic interpretation, while the red to white colors from 3D CSEM below, map a deeper salt structure. Moreover, CSEM shows that the overhang of the salt is actually larger than what was thought.

The survey targeted a salt diaper with potential hydrocarbon reservoirs at the flanks. Seismic data already established the approximate location of the salt diapirs. However, there was a need to identify AVO responses and improve the interpretation of the salt flank and the base of salt

Read how these results and others in the article demonstrate how CSEM data enhances interpretation in complex, salt prone areas.