Origin and Natural Accumulation of Oil and Gas

Oil and gas deposits are basically hydrocarbons which get into buried rocks and minerals. To better understand and visualize these deposits, one must picture an ancient sea teeming with an immense variety of living organisms. The ancient body of water which these organisms resided would have covered most of the American West, including Texas, Oklahoma, Wyoming, Utah, and Colorado. Some of the creatures in this sea were large fish and other swimming beasts, but the majority of living things consisted of vast amounts of microscopic organisms. Scientists believe that it is these tiny plankton-like creatures that gave rise to today’s oil and gas.

These miniature life-forms died millions of years ago, and their remains settle to the bottom of the sea. Over time, these very small remains build up to enormous quantities of organic sediment. Built up in thick deposits on the seafloor, the organic material mixes up with sand and mud from the bottom. Eventually, the many layers of sediments built up until they became hundreds or even thousands of feet thick. The weight of the overlying layers created great pressure and heat in these bottom layers. The pressure and the heat changed the layers of sediment into rock. Meanwhile, heat, pressure, other natural forces turned the dead organic material within the layers into hydrocarbons. Hydrocarbons are the basis for gas and oil.

At the same period of time that dead organisms are being changed into hydrocarbons, geological forces are influencing the Earth’s crust. Cracks, otherwise known as faults, are created and crust movement created folds in the sediment layers previously discussed. Molten rock is thrust upwards, altering the formation of surrounding beds. Wind and water erode formations and disturbances in the earth moved large amounts of rock. All of these alterations in the layers of our curst are very important because they can trap and store hydrocarbon deposits under the right circumstances.

Over centuries, the weight of the overlying rocks continued to push downward, forcing hydrocarbons out of their source rocks. They seep through the cracks and fissures, oozing upwards until they become trapped by some kind of geological surface. When they are trapped and stored in a subsurface rock, they become our modern day oil and gas deposits. Today, the oil and gas industry is seeking out these petroleum deposits formed and stored millions of years ago.

In order to better seek out and find these oil deposits, geologists started to apply the earth sciences to narrow down the search. Since most petroleum deposits are buried deep underground, there are usually no surface hints as to their locations. Also, most of the world’s gas and oil probably lies under ocean floors. However, scientists have developed effective seismological methods to view the subsurface. Seismology uses sound waves which bounce off of buried rock layers. These sound waves paint a clear picture of the underlying rock surfaces and petroleum deposits. This scientific method ensures that companies will find oil before they spend the money to drill.

The history of our geology and all of the new science available at our disposal leads us to understand that there are very large oil and gas deposits right here in North America. With deposits in Wyoming, Utah, and Colorado being substantial, companies like Heartland Energy in Colorado are taking advantage of domestic oil deposits. Especially in Colorado, there are large shale oil reserves which scientists are researching in order to effectively extract the oil. Heartland Energy is among the leading developers of oil and gas in Colorado trying to capitalize on these deposits left by the ancient sea that once covered the Colorado plateau. Heartland Energy is developing new strategies and is on the cutting edge of Colorado Energy.

(source: A Primer of Oilwell Drilling, 6^th ed. By Ron Baker)