Oil is a fossil fuel that is widely found in various countries. It is formed under the Earth due to the buried remains of dead animals and plants, millions of years ago. These organisms decay over years, and form fossil fuels in the sedimentary layers.
The micro-organisms decompose the decayed plants and animals to form carbon-rich compounds, to form fine-grained granular source rocks, which are then covered with layers of sedimentary rock. These new rocks pressurize the source rock, and due to the intense heat and pressure, the original organic material is converted into crude oil and natural gas.
Process of Drilling for Oil
The foremost thing in the process is to select the site that contains crude oil. This is done by the geologists with the help of gravity meters, magnetometers, GPS tracking devices, and satellite images. Also, there are electronic noses called sniffers to detect the smell of the crude oil.
The next step is to prepare the land for the drilling process. Initially, the company completes all the formalities regarding the lease agreements. After all the formalities are done, the land is leveled evenly. The process requires water, and hence, the presence of a water body nearby the well is very essential.
After the land preparation, the rig must be placed on the site, and holes are dug for this purpose. A large drilling hole is dug, and around this hole, several other pits are also dug.
Cellar is a rectangular hole that is dug near the actual drilling hole, and is used by the workers for keeping the drilling accessories. Later, the oil rig is set-up in the holes, and the drilling process is started.
The next step is to place the drill bit and the drill collar in the main hole. Then, the kelly and turntable are attached, after which the actual process can begin.
Kelly is a 4 - 6 sided pipe used to transfer the rotary motion to the turntable, and a drilling string is attached to the collar and casing. The turntable is used to impart a rotating motion to the kelly with the help of electric motors.
As drilling progresses, new joints to the drilling pipe are attached. Once, the preset depth of the process is reached, the drilling bit and the pipe are removed from the hole.
After this, the casing pipe sections are placed in the main hole. This pipe is cemented to prevent the breakdown of the other pipe sections. The cement is allowed to harden, and the alignment of the pipe is also checked.
The process of drilling is continued, and the casing pipe is placed in the hole, until the oil is not found. Once it is found, the drilling apparatus is removed from the hole.
With the help of various tests, the well pressure can be measured by noting the rock formations, and by checking the characteristics of the reservoir rock. A perforating gun is then lowered into the well. Packer is a device, which runs down outside the casing of the tube.
A multi-valved structure is placed on the tubing with the help of casing, and it controls the flow of oil from the rig. There is a pumping system, which is used to extract the crude oil out of the reservoir.
There are new technologies emerging everyday due to the advancing times. However, fossil fuels are limited on Earth, and must be used with due respect and care.