f Structure, stratigraphy, fluid content and field procedures for seismic and EM

This paper looks at the problem of joint inversion of seismic and electromagnetic data and points to ways in which the acquisition of data in both methods should be improved. The sonic and resistivity logs from the same well often show a marked resemblance. Rocks with high compressional wave velocities, such as carbonates, are often very resistive. Porous permeable rocks with a large fluid content are often very conductive and have lower compressional wave velocities. The conductivity can vary enormously within a porous medium depending on the fluid content. Salt water is much more conductive than gas, for example . This suggests that electromagnetic methods should be used to determine fluid content within a reservoir and thus locate the reserves. The problem with electromagnetic methods is that they have poor resolution when used on their own .