Crude Oil Production Process

Crude oil production process involves operations that bring crude oil to the surface for further processing. Here we will be looking at exploration, extraction and recovering processes involved in crude oil production.  First, let’s look at the exploration process:

Exploration Processes

The first step involved in crude oil production process is exploration where geologists use seismic surveys and other methods to search for geological structures that may form oil reservoirs. As of 2010, no method has proven 100 percent effective in helping geologists locate crude oil deposits. The best, and most profitable, technique oil explorers’ use is seismic exploration.

“Classic” and “passive” methods are used in seismic surveys. The “classic” method includes making an underground explosion nearby and observing the seismic response that provides information about the geological structures under the ground while “passive” method involves extracting information from naturally-occurring seismic waves.

However, in most recent seismic exploration, a satellite or mobile seismic device shoots radio waves at prospective crude oil sites and then sends that data to a supercomputer which creates a digital model of the environment based on that data

Other instruments such as magnetometers and gravimeters are also sometimes used in crude oil exploration.

Extraction Processes

The second step involved in crude oil production process is extraction which normally starts with drilling wells into the underground reservoir. However, while the first drilling technique stuck a pipe straight into the ground, modern drillers now have slant drilling techniques. In general, slant drilling proves much more beneficial than vertical drilling. Slanted pumps are curved, allowing them to rotate 360 degrees and reach several different deposits from the same location.

Oil extraction also occurs at sea using the same methods as land-based oil extraction, but requires special types of platforms because the ocean floor may not support the weight of a normal rig or the size of a solid platform proves to costly to reach ocean depths. Most offshore operations tether a floating platform connected to cables attached to the ocean floor. Those drilling in shallow water or those who have found a large deposit might want to install a permanent structure. Movable rigs, such a ship or a barge, are good for finding oil deposits and gathering oil from several smaller sites.

Generally, when an oil well has been tapped, a geologist will note its presence. The mixtures of oil, gas and water from the well is separated on the surface. The water is disposed of and the oil and gas are treated, measured, and tested.

Recovering Processes

The third and final step involved in crude oil production process is recovering which include bringing the crude oil and associated gas to the surface, maintaining production, and purifying, measuring, and testing. Three stages are involved in crude oil recovering: Primary recovery stage, secondary recovery stage and tertiary recovery stage.

Now, let’s look at each of the recovery stages:

Primary recovery method of crude oil production process

Reservoir drive comes from a number of natural mechanisms during the primary recovery stage. These include: natural water displacing oil downward into the well, expansion of the natural gas at the top of the reservoir, expansion of gas initially dissolved in the crude oil, and gravity drainage resulting from the movement of oil within the reservoir from the upper to the lower parts where the wells are located. Typically, 5-15% recovery factor are achieved during the primary recovery stage.

Secondary recovery method of crude oil production process

With diminishes in natural reservoir drive, secondary recovery methods are applied. They rely on replacing or increasing the natural reservoir drive with an artificial drive by the supply of external energy into the reservoir in the form of form of injecting fluid to increase reservoir pressure. This is achieved by water injection, natural gas reinjection and gas lift, which injects air, carbon dioxide or some other gas into the bottom of an active well, reducing the overall density of fluid in the wellbore. Typically, 35-45 recovery factors are achieved after primary and secondary recovery operations.

Tertiary Recovery method of crude oil production process

When secondary oil recovery isn’t enough for adequate crude oil recovery, tertiary recovery methods are applied, though when cost effective. This involves increase in the mobility of the crude oil in other to increase extraction. Different techniques are used in tertiary recovery methods which include:

·         First is the thermally enhanced oil recovery technique (TEOR). This is a tertiary recovery technique that involves heating the oil, thus reducing its viscosity and making it easier to extract. Steam injection is the most common form of TEOR, and is often done when a gas turbine is used to generate electricity and the waste heat is used to produce steam, which is then injected into the reservoir. In-situ burning is another form of TEOR, but instead of steam, some of the oil is burned to heat the surrounding oil.

·         Another method used to reduce viscosity is through carbon dioxide flooding.

·         Microbial treatments are another tertiary recovery method. Special blends of the microbes are used to treat and break down the hydrocarbon chain in oil thus making the oil easy to recover as well as being more economic versus other conventional methods.

Typically, tertiary recovery allows another 35%-45% of the reservoir’s oil to be recovered.

In essence, crude oil production process involves exploration, extraction and recovering of crude oil.