david grislis oil


Read on for a step-by-step educational breakdown of the basic process of getting oil into above-ground wells!


Where oil comes from:

We get oil from the remains of small animals and plants that had died in the ancient seas between the times estimated from 10 million to 600 million years ago. The organisms were broken down into carbon-rich compounds with the help of microorganisms because they had no source of oxygen. The sedimentary layers exerted pressure on the source rock that distilled the organic material into natural gas and crude oil. The Earth’s movement trapped the natural gas and oil between the layers of impermeable rock such as granite or marble.

Locating the oil:

Geologists find oil by finding right conditions for oil trap. They measure tiny changes in Earth’s gravitational field that indicates the presence of oil. They use sniffers, sensitive electronic noses, to detect the smell of hydrocarbons. Another method used is called seismology, in which shocks are created and are passed through the rock layers and then these shock waves are interpreted and studied when they are reflected back to the surface. Once the perspective oil strike is found, the location is marked using GPS coordinates on the land or marker buoys on the water.

Land preparations:

The site is then selected and the area is surveyed by the scientists. After the preparation of the land, the crew makes holes for the rig and one main hole. Depending upon the location of the site, it may require bringing equipment by truck, helicopters or barge.

Oil drilling:

Crew sets up the rig and starts drilling operations. They first drill a surface hole down towards a pre-set depth. For drilling the surface hole, they go through 5 major steps. After these steps, when the crew reaches the pre-depth, they run and cement the casing. The casing pipes have spacers around it to keep it centered. The casing pipe is put into the hole and the cement is pumped into it using drill mud many other things. The pressure from the drill mud causes the cement to fill the space between the casing outside and the hole. The cement is the hardened and forms a proper seal.

Testing for oil:

Drilling still continues and final results are tested by the crew. Such as: well-logging, drill-stem testing and core samples. Once the crew has reached the final depth, they lower a perforating gun in the well to allow the oil to flow in it in a controlled manner.

Extraction of oil:

After the removal of the rig, the crew puts a pump on the well head. The reason for this pump is to create a suction that will draw oil out of the Earth, up into the well.

Offshore oil:

Land or shallow waters is not the only accessible place to find oil, it can also be present under the ocean floor. Oil companies use sonic equipment to find the drilling site for oil production. They use a MODU (Or Mobile Offshore Drilling Unit) to dig the initial well. Sometimes the MODU is replaced with: a Submersible MODU, a Jackup, Drill ships, or Semisubmersibles.


After the oil is drilled and held in the well, the process moves to refining the crude oil. Stay tuned for the process of handling the oil once it’s above ground!