Geologic Time

Petroleum End Product = [Raw Material+Accumulation+Transformation+Migration] + Geologic Time

This chapter has dealt with the types of petroleum, its nature and its origin. We have discussed in detail various aspects because in order to understand what it is, a renewable resource (albeit very slowly), and where it's found, we must first understand how it got where it is. The one element that is very important in this chapter is that of time; geologic time. We are talking about centuries, millennia. Years as a unit of measurement in earth history is synonymous to measuring a persons lifetime in terms of milli-seconds. Much of Louisiana hydrocarbons were formed during the Jurassic (54 - 59 million years in duration) and Cretaceous (71 million years in duration) Periods, or about 100 million years ago. Younger hydrocarbons developed during the Tertiary Period which began about 65 million years ago. The time frame in which to acquire the organic matter, accumulate it [on the sea floor], transform it into hydrocarbons, expel it from the source rock, and move it into a reservoir rock could be very long indeed, on the order of millions of years. So it is important that we understand that this process is exceedingly slow by human standards, but relatively rapid in terms of earth history. Since the beginning of earth history, oceans have risen and fallen, mountains and land masses have developed and been leveled by erosion, and countless millions of live forms, both plant and animal, have come and gone. It is the natural order of things.

NORTH, F. K., 1985, Petroleum Geology: Allen & Unwin, Inc., Winchester, MA.