Can seismic detect oil and gas?

Drilling a wildcat exploration well has always been a risky proposition. And even drilling a well within a known oil field involves some level of uncertainty about what is under the ground. But advances in seismic surveying and data processing over the past few decades have refined the identificatio...

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Having analyzed a plenty of wildcat well tests, I’ve realized that sometimes even seismic cannot help to drill a real successive well. But maybe this depends on skills of the interpreter….

nowadays , using spatial analysis and modeling can reduce such uncertainties and increase the exploration potentiality, but for wildcats, u should pray alot :D

the oil and gas exploration depend on some parameters one of them "seismic", the basic idea behind seismic is the discountinuity or simply the change in physical properties of the rocks and its componants, in case of gas there is severe change in physical properties but in case of oil there is negligable change and this is the basic idea behind DHI or direct Hydocarbon Indicators used as main gas exploration technique in All Pliocene Gas discoveries in Mediteeranean
modelling or modern seismic depend mainly on integration between seismic and well data
this means that the density and quality of data (well data and seismic data).
there is onother technique called seismic sequence stratigraphy using the seismic interpretatipon of unconformaties to predict the occurence of HC volumes in traps

generally there are two kinds of hydrocarbon (oil or gas) exploration, direct and indirect
the indirect is the old method developed with the experience of using seismic in hydrocarbon exploration, contain the structure interpretation of seismic and the structure trap recognition plus the seismic sequence stratigraphic analysis as mr. masroumalik said.the world success ratio of structure traps detected by seismic is between 10 to 20% and this ratio decrease very much if we talk about seismic sequence stratigraphy.
the second method is DHI(direct hydrocarbon indicator) which recognize the gas directly and this way give success ratio upto 100% under some conditions
we can talk in more details if you are interested.

May be I can help

[email]y6nb@yahoo.fr[/email]

thank you all for the nice conversation

Seismic Data processing is all about making a picture of the subsurface. This picture is in TIME!

I mean, you send a sound signal into the earth, it hits a reflector or a layer (this layer may not be geological :rolleyes: seismic will SEE anything as a boundary if on top and bottom of it you have different velocities, but this does not mean that you have two different rocks on its top and bottom, just that there are 2 different velocities).This sound comes back to your geophones and you know HOW FAR IN SECONDS YOU HAVE YOUR REFLECTOR

For successfully detecting oil or gas this picture has to be in depth, you have to change drilling angles or azimuths when you reach certain depth not when you reach certain times...

Now you get the time section converted to depth using a checkshot survey or better still a VSP. Both are variants of seismic

Log data especially neutron and sonic will tell you porous zones. These Porosities can be populated in your entire field if you have seismic as your control... You can populate porosity on your seismic data and find out more places where you can drill.

BUT AS SUCH A TEXTBOOK ANWER IS: SEISMIC WILL TELL YOU THE FAVOURABLE """STRUCTURE""" (anticlines, pinchouts) and not exactly the Hydrocarbon....

(This answer is suitable for someone who is in introductory stage to geophysics but not for an expert so please use your discretion.)

[QUOTE=ahmedsisy;34855]generally there are two kinds of hydrocarbon (oil or gas) exploration, direct and indirect
the indirect is the old method developed with the experience of using seismic in hydrocarbon exploration, contain the structure interpretation of seismic and the structure trap recognition plus the seismic sequence stratigraphic analysis as mr. masroumalik said.the world success ratio of structure traps detected by seismic is between 10 to 20% and this ratio decrease very much if we talk about seismic sequence stratigraphy.
the second method is DHI(direct hydrocarbon indicator) which recognize the gas directly and this way give success ratio upto 100% under some conditions
we can talk in more details if you are interested.[/QUOTE]
Gas deposits represent rigid acoustic border, and are usually well shown on a seismic section in the form of strong negative amplitudes. Oil usually is not visible in amplitudes. As you have noted, DHI should allocate successfully oil in spectral area, for example [URL="http://en.rafe.geoscitech.ru"]here[/URL] http://en.rafe.geoscitech.ru, and to help to increase percent of productive wells. Somebody really tried to spend such works?

what methods did you used?it's very interested, i've read some in your websites, did you use friendly seismic processing workflow to maintain low frequency content of seismic data and then using time frequency analysis to decompose your seismic data in frequency domain?

CMIIW

Our programmers and geophysics realised own method of allocation DHI from a seismic sections or source data. We recommend to clients use processing/preparation of the initial data on ours processing center (based on Paradigm software). Typical processing graph excludes procedures of Radon, spectral balancing and migration. Next, we process the total stack sections with method RAFE.

If you have the stacke seismic section received without specified procedures, you can independently process its method RAFE on our site. It is simple and free.

the processing is critical issue in seismic, depend mainly on the understanding of geology and affected by geology, acqusition parameters. and in practical world threre is another parameter (cost)
in general the main issue for seismic interpreter is to obtain explainable seismic section or how to interpret and explain most of things and put them in geological meaning
suggestion:
let us concern our discussion on the following
-------different geological and geohysical indications for oil ----------