Mapping 3-D structure using 2-D seismic

Everyone who’s tried to make a structure map from a 2-D seismic grid knows that you can’t uniquely map a 3-D structure with 2-D seismic. Even if you were perfectly accurate in picking reflection times and converting the times to depth, there would still be many possible reflecting surfaces that could have produced the same set of 2-D picks. This nonuniqueness is commonly treated purely as a sampling issue; you don’t have any coverage between the lines, so you are free to contour these regions in any geologically reasonable way.