Using analogs to identify critical elements
Many people looking for oil and gas do not have a mental image of what they are searching for. How can one recognize something if they do not know what it looks like? A hunter would not have much luck finding rabbits if he had very little idea of the appearance of a rabbit. He also would not have much luck finding rabbits if he did not understand their habits—where they live or what and when they eat. In the same way, we learn about oil and gas fields by studying their habitat.
Visualizing the trap
Visualizing an accumulation is the key to exploring for any type of trap. The explorer must have a mental image constantly before him to maximize his chances of success. Keeping visually focused on what you are looking for (the critical elements derived from analogs) helps define exploration methods, wellbore location, and penetration direction. This is known as the analog method of exploration.
The analog method is the most effective method, in the author's opinion. It closely follows the scientific method: establishing the critical factors of the known and then looking for the same critical factor in an unknown area. In essence, if you can visualize it, you can find it.
Finding analogs
Oil and gas accumulations fall into broad categories, i.e., structural and stratigraphic traps, but there are hundreds of variations of these trap types. The explorer must carefully study the many ways in which oil and gas accumulate. Many local and international geological societies publish field studies that can serve as analogs. AAPG's 11-volume Treatise of Petroleum Geology, Atlas of Oil and Gas Fields is an excellent example of where to find analogs.
Critical elements
These excellent descriptions and analyses provide the explorer with mental images of various trap types, which are essential in recognizing certain critical elements of traps. Usually, at least three to five critical factors must be present for a particular type of trap to work. When we study local analog fields within a region or basin, or perhaps in a similar productive setting in another part of the world, we can develop the critical elements of a specific play, which in turn lead to discovery.