The subject of seismic anisotropy has a long history, but only recently has it come to be seen as a central feature of geophysics as applied to the exploration for hydrocarbons, and to their exploitation. The reason for the long neglect of anisotropy is, of course, that isotropy is simpler. The equations are simpler, and the application of one’s intuition is more direct. And, perhaps, because of their simplicity, these basic, isotropic ideas have enabled the discovery of most of the world’s known hydrocarbons.
I am told, even, that hydrocarbons were found at one time by using the ideas of acoustic wave propagation! Improbable as it sounds, this myth does explain how very useful simple ideas can be, and what a strong hold they have upon the imagination.
However, in those ancient days, exploration geophysics was much less effective than it is today. Wildcat success-rates were as low as 10% in the 1950s, growing slowly to 25% by the 1970s, before exceeding 50% today. There are three basic reasons for our increased success-rates in the modern era: