A good seismic image is inadequate for an expedition or area growth analysis. Excellent ties and trusted depth conversion are also needed. The writers have found that rock hounds and geophysicists have a tendency to approach the deepness conversion procedure fairly in a different way. The rock hound claims, “If I do not have wells, how can I do depth?” Often not aware that seismically-derived speeds exist. The geophysicist states, “I have all these rates from my seismic,” and also requires to be warned that these imaging velocities are not right for true deepness conversion.
We have likewise seen that there is sometimes complication regarding what the deliverables of a depth conversion job are. These can be:
- seismic data volume or SEG-Y extensive rather than time
- maps and/or computer grids of depth from the seismic and wells
- a rate version in the kind of a 2D account or 3D cube information quantity or SEG-Y
- another possible deliverable is an uncertainty evaluation on the last ideal result.
Recently, we have likewise seen complications over the definitions of “deepness migration” as well as “deepness conversion,” which are two different processes. Migrations are imaging concerns; conversions are calibration issues, but a few obscuring of the lines did take place just recently with the introduction of anisotropic, pre-stack deepness movement, or APSDM. The differences are gone over later in this article.
There are different approaches to carry out depth conversion, consisting of just how much refinement is needed for various objectives. We will review accounting genuine geologic structure and stratigraphy, correct calibration of seismic speeds, proper honoring of useful information versus seismic information, as well as viability to fulfill time and also price constraints.
Why depth
One thing there is no confusion about is that subsurface rocks exist detailed. Seismic representation data portray this subsurface in recorded two-way time. Many seismic interpretations are made in the moment domain name, which fasts as well as serves for several situations. Stratigraphic interpretation, while the domain name is generally excellent for seismic facies as well as analyze sequence stratigraphy as their analysis stays greatly the same with transforming framework. Architectural interpretation in the time domain name is a riskier business. They are translating framework while domain indicates accepting the risk of assuming a constant rate version, or that the interpreter can catch all feasible rate aberrations. Better, as well as simple geology can create false highs or can obscure true highs, a “speed abnormality” is not required in order to have a time structure. A thick zone of high-velocity material can masquerade while domain name as an equally transferred layer of rock overlying an architectural high. Several good interpreters have actually come under this timeless challenge!
Likewise, structures can be hidden by the overburden, as well as a great depth conversion will be able to show structures on places where it is thought they are impossible to exist, disclosing potentially bypassed reserves.
