The 4th in a series of short monthly essays
by
Mike Mackenzie 3-D SEISMIC SURVEYS There is not a single way of researching the subsurface for oil and gas about which you can say "This, above all else, is it!" Everything ought to be taken into account: Information from pre-existing wells, seismic data, the presence or absence of oil field
analogies in the general area, the probable timing of hydrocarbon migration compared to the formation of reservoir trapping…and more. This being said, the use of 3-D seismic data, if
it exists in the area of interest, is very high on the list of "must sees". This is because of two principal reasons - technical and practical. Technically, 3-D surveys can be good indicators of subsurface structure, of lithologies and even, sometimes, of natural gas. The surveys consist of a dense network of source and receiver
lines laid out on the surface – over land or water. Because of the density of received data, more of the subsurface can be "seen" than had been the case previously when perhaps only a few widely spaced seismic lines were acquired in a given area. And better modern processing of the 3-D data increases the confidence levels of interpreters. Practically, even if some surface or subsurface conditions exist
which lower the quality of the 3-D data at certain critical depths, the survey really ought to be reviewed. The current marketplace insists on it. If you invest in a proposed well or in a producing property your partner investors will surely insist on it. 3-D is what people outside the oil patch hear about. 3-D seismic data is expensive. Most licensors of non-exclusive
surveys require a minimum purchase of five square miles at costs ranging from $20,000 - $50,000 per square. Different deals can be negotiated. If you're thinking about investing in proposed wells, many of the submittors will bring corroborating 3-D interpretations. This is not to say that prospects are without value unless they have
this modern geophysical coverage. But, if they don't, it's harder to sell them to your prospective partners. Let me know what you'd like to hear about
Mike Mackenzie | 
