Transcript for Wrestling with Uncertainty, segment 06 of 16

We know that major accumulations of oil and gas occur in basins like this. Yet finding a new field is still a risky business, and this uncertainty has been part of the petroleum exploration game from the very beginning. It reflects nothing more than our difficulty in deciphering the complex conditions under which oil and gas form. In many ways the Gulf Coast petroleum province may be the best example of the challenges that confront us.

A hundred fifty million years ago the southern part of the Americas broke away from the north creating a sea we call the Gulf of Mexico. Early in its history circulation was restricted. Intensive evaporation formed a vast layer of salt, in some places more than a mile thick. As ocean circulation improved, the waters advanced and retreated, creating a complex layering of tropical limestone, wind-blown sand, river deposits, and organic rich mud. As the pile thickened, its weight caused the salt to flow slowly upward and pierce the sediments, forming irregular masses, some more than three miles high. These salt structures strongly influenced the distribution of oil and gas. At the surface waves and currents sculpted sediments into linear sand barriers that protected quiet lagoons, much as they do now along the Louisiana coast. The organic rich mud that rests in these lagoons may become a primary source material for petroleum.

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