RE:Espana, in spite of seeing a page count of 68 I decided to Goaweigh, Thanks.
Re. Seismic, You're (+ Wildcatter) both right. Seismic can give you indications of gas "flat spots" but that could also be an oil/water, gas/oil or gas/water contact or something not HC related. It can also detect "gas chimneys" which can lead you back to a pool. I'm no seismic expert but TXP is in good hands with Xavier Moonan.
Bottom line is, the more data you get the closer you are to the truth.