You may think it’s hard to get all the oil and natural gas out of the sedimentary rock it was formed in…and your right! It takes a lot of teamwork to find the oil and natural gas and to get them out.
First, we have to find the reserves. Back in the day, people used to look for oil reserves on a hunch. They just guessed where oil might be and started digging; these were called “wildcat wells”. Today, we have better technology and we have learned that using sound is a great way to find oil and natural gas reserves. Sound waves travel through solids, liquids and gases at different speeds. They travel the slowest through gases, faster through liquids, and fastest through solids. Scientists can recognize whether there are liquids or gases (or both) under the ground through sound waves. The scientists lay out several lines of sensitive sound receivers called geophones. Then they create explosions or mechanical vibrations on the surface. The geophones record the sound waves reflected back from rock layers at many different depths. Remember how sound, a form of energy, travels fastest through solids? Well, the geophones can quickly receive the reflected sound from the explosion, which tells scientists what type of material it bounced off of. If the material seems like it might contain oil or natural gas, the drilling begins…
Rotary drilling rigs are used to reach oil and natural gas that is far below the earth’s surface. A drill pipe is sunk into the earth and a metal bit from its center turns really fast, making a hole that will be lined with steel pipe called casing that will enable oil to be pumped and gas to flow to the surface.
In recent years, a new technology called directional drilling allows the hole to be drilled straight down and then to curve deep underground. Another technology, called hydraulic fracturing is then used to create small breaks called fissures that allow for oil and gas to flow out of very solid shale rocks. If this explanation sounds a little confusing, don’t worry, there is a short video that shows how it is done. Click on this link to watch the video from the American Petroleum Institute on horizontal drilling and hydraulic fracturing.
A lot of times oil sources are found below the ocean floor. In those cases, a drill and a container to hold the oil are lowered to the bottom of the ocean floor. To anchor the drill and container, a huge platform is constructed in the water.