Exploration—the Search for Petroleum

Earth scientists in the petroleum industry—including geologists, geophysicists, geochemists and paleontologists—study what has happened to rocks that may be buried thousands of metres below the surface, how those rocks were formed and affected by events stretching back millions of years, and how to identify traps where oil and gas have accumulated within rock formations.

An explorationist may have a well-developed theory or intuition why an area should contain oil and gas. A first-hand look at outcrop geology and surface features sometimes helps to confirm the basic requirements—that there must be sedimentary rocks, potential reservoirs and hydrocarbon-bearing source rocks in a sedimentary basin.

Within a basin, the explorer's first step is to examine all the information already known about the area. This might include academic papers, surface geology observations, any wells drilled, data from agencies, such as the Geological Survey of Canada or provincial government departments, and previous exploration results from nearby or similar areas. In Canada, government regulations ensure that much of the information obtained during exploration is recorded and eventually released publicly. This is often not the case in the United States and elsewhere around the world.

Geophysicists can identify the structure, configuration, thickness and depth of new sedimentary basins by measuring slight variations in the Earth's gravitational and magnetic fields, and by measuring the time taken for seismic energy waves to pass through and be reflected from sedimentary layers.

Petroleum Communication Foundation. Our Petroleum Challenge — Exploring Canada's Oil and Gas Industry, Sixth Edition. Calgary: Petroleum Communication Foundation, 1999. With permission from the Centre for Energy.