Three different approaches were used and compared to smooth a density log: binomial filtering, seismic wavelet filtering and discrete wavelet transform (DWT) filtering. Smoothing physical property logs improves correlation at the seismic scale. In general, log data have a resolution of at least two orders of magnitude greater than seismic data. The difference in resolution between well logs and seismic data is a major hurdle faced by seismic interpreters when tying both data sets. If you mess them up and don't find out till later, you will be very sad, but not as sad as your exploration manager.Correlations between physical properties and seismic reflection data are useful to determine the geological nature of seismic reflections and the lateral extent of geological strata. fun) interpretation so they sometimes get brushed aside, left till later, rushed, or otherwise glossed over. Well ties are one of those things that get in the way of 'real' (i.e. Don't create multiple, undocumented, obscurely named copies or almost-copies of well logs and synthetics, unless you want your seismic interpretation project to look like every seismic interpretation project I've ever seen (you don't).
#Seismic well tie tutorial hampson russell how to
Don't tie wells to 2D seismic lines you have not balanced yet, unless you're doing it as part of the process of deciding how to balance the seismic.Get help before trying to load or interpret a VSP unless you really know what you are doing.Do not trust any checkshot data you find in your project - always go back to the original survey (they are almost always loaded incorrectly, mainly because the datums are really confusing).If you go ahead, read your software's manual. Be careful with deviated wells you might want to avoid tying the deviated section entirely and use verticals instead.Capture all the relevant data for every well as you go (screenshot, replacement velocity, cross-correlation coefficient, residual phase, apparent frequency content).Definitely no more than 5 tie points per well, and no closer than a couple of hundred milliseconds.
Don't extract a wavelet till you have a few good ties with a zero-phase wavelet, then extract from several wells and average.Look at the bandwidth of your seismic and make an equivalent zero-phase wavelet.Edit as gently and objectively as possible.Chop any casing velocities or other non-data off the top of your log.Ask people, look at SEGY headers, but don't be satisfied with one data point. And get your datums straight, especially if you are on land: make certain your seismic datum is correct. Use a volume with less filtering if you have it (and you should be asking for it). Keep it to the nears if possible (don't use a full-angle stack unless it's all you have). Rachel Newrick's essays in 52 Things are essential. Next, think about the seismic volume you are trying to tie to. White & Simm (2003) in First Break 21 (10) is excellent. How else can we explain the fact that any reasonably mature exploration project has at least 17 time-depth curves per well, with names like JLS_2002_fstk01_edit_cks_R24Hz_final? My top tipsįirst, read up. I'd go so far as to say that I think tying wells robustly is one of the unsolved problems of subsurface geoscience.