Oil extraction is one of the most complex industrial processes in the world and, at the same time, one of the most essential for the functioning of the global economy. But, ultimately, how does it work? oil is found, drilled and extracted How does it get to the refineries? And what technologies make it possible to operate in such extreme environments as the Brazilian pre-salt layer, located more than 7 meters deep?
See also: What is onshore and offshore in oil?
How is oil extracted?
The extraction stage is what brings crude oil from underground formations to the surface. It begins long before the first drop appears: it depends on geological studies, engineering decisions, and equipment designed to work under high pressure, high temperatures, and in harsh environments.
Drilling is the starting point. On land, the process uses platforms equipped with towers and pumping systems. That's where the "mechanical tractor" comes in, perhaps the most recognizable piece of equipment in the sector. It moves up and down when natural pressure is no longer sufficient to push the oil to the surface. In some countries, it has even become a symbol of the producing regions.
After the well is drilled, the production stages begin, which vary according to the amount of pressure present in the reservoir.
1 – Primary extractionIn the early stages of a well's life, the natural pressure of the reservoir pushes the oil towards the surface. During this period, the well can produce oil without the aid of additional equipment. When this internal force decreases, pumps are installed to maintain the flow.
2 – Secondary extractionAfter a certain time, the reservoir loses enough energy to keep the oil moving. To prolong production, water or gas is injected into the field. This boost pressurizes the reservoir again and pushes additional volumes of oil into the well. It is a crucial step to increase the efficiency of the area and prevent large quantities of oil from becoming trapped in the rocks.
3 – Advanced recoveryThe tertiary phase includes even more sophisticated methods. It is used when there is remaining oil that natural pressure and water injection have failed to recover. The idea is to alter the behavior of the oil within the rock to make it more fluid. The techniques involve:
- steam injection to heat the oil and reduce its viscosity;
- Injection of CO₂ or other gases, which improve mobility;
- The use of surfactants or polymers, capable of reducing the tension between fluids and facilitating the movement of oil.
These methods significantly increase the cost of the operation, but they prevent still-productive fields from being abandoned.
4 – Hydraulic fracturing (fracking)This technique, which became known for the growth in shale gas and oil production, consists of injecting fluids at high pressure into the rock to create microfractures. With these fissures, the oil can enter the well more easily.
5 – Offshore drillingOffshore extraction is one of the most complex areas of the industry. It reaches reservoirs located kilometers from the coast and at depths that can exceed 3 meters of water. Drilling is done from fixed platforms, semi-submersibles, or drillships. It is an operation that demands robustness, redundancy, and constant attention, since factors such as strong winds, high waves, and climatic variations can interfere with the process. The production is usually processed and stored in FPSOs, floating production, storage and offloading vessels capable of operating for long periods.
3 steps for oil exploration
Oil and gas production operates within a value chain that includes three stages: exploration and production, transportation and storage, and refining and distribution.
- Exploration: This is the initial phase of the exploration and production process. It involves identifying potential oil and gas reserves using various geological and geophysical methods, including seismic surveys and satellite imagery. The goal is to find reservoirs containing economically viable volumes of oil or gas.
- Drilling: After successful exploration, the drilling phase begins. Specialized drilling platforms drill wells in identified reservoirs to access the oil or gas trapped underground. This process can occur onshore or offshore, depending on the location of the reserves.
- Extraction: The final stage of the upstream process is extraction. In this phase, oil or gas is brought to the surface from the well. In some cases, secondary recovery methods, such as injecting water or gas into the well, may be employed to maximize extraction.
- Transition through midstream operations.
Oil and gas processing and storage operations (midstream) form the link between the extraction of raw materials and the delivery of usable products. It is a bridge that involves the processing, storage, and transportation of oil and gas.
- Processing: The crude product of extraction usually contains impurities and various hydrocarbons that need to be separated. This is done in the processing phase, where the oil or gas is treated to meet market specifications.
- Storage: After processing, oil and gas are stored in specially designed tanks or facilities. Storage ensures that these resources are kept safe until they are ready to be transported to various refining locations.
- Transportation: This phase involves moving oil and gas from extraction sites to refineries and processing units. Depending on the distance and available infrastructure, transportation can be done via pipelines, trucks, or tankers.
The oil and gas refining and distribution stage is where oil and gas are transformed into finished products for industrial and consumer use. This stage also involves the sale and distribution of these products.
- Refining: In this phase, crude oil is transformed into a wide variety of products. These include gasoline, diesel, aviation kerosene, fuel oil, and asphalt. Natural gas, in turn, is processed to produce products such as ethane, propane, and butane.
- Distribution: The final stage in the oil and gas production process is distribution. This phase involves the sale and delivery of products to consumers, businesses, and industries. It includes gas stations, residential heating suppliers, power plants, and petrochemical companies, among others.
How is oil extracted from the seabed?
When oil is located on the seabed, operations depend on specialized platforms and vessels, as well as constant monitoring and a higher level of safety. In shallow waters, jack-up platforms are used, which rest their legs on the seabed. In deeper waters, semi-submersible platforms and drillships, capable of drilling thousands of meters deep, come into operation.
In already drilled wells, subsea equipment is installed. Subsea Christmas trees control the well's flow on the seabed; flexible risers connect to the platform; and umbilicals provide power and controls for valves and sensors. Production is mostly carried out on FPSOs, floating production, storage and offloading vessels that process and store the oil.
The cost also changes. Offshore drilling is more expensive and slower because it depends on complex logistics, favorable weather, and equipment that can function even in extreme conditions. It's a model that only works when there are reserves large enough to offset the investment, like Brazil's pre-salt reserves.
The environmental risks are also different. On land, spills tend to be contained more quickly. At sea, a leak can spread for kilometers and take days to control.
In onshore production, the work is done in land areas. This type of operation uses classic industry equipment, such as the land drilling rig, responsible for opening the well. After the natural pressure decreases, pumping systems come into play, mainly the pump truck, the unit that goes up and down pulling the oil. Oil and gas separators, hydraulic pumps, and storage tanks are also common.
And how does oil extraction work in the pre-salt layer?
Oil extraction in the pre-salt layer only takes place offshore and in ultra-deep waters. The reservoirs are located more than 7 meters deep, beneath a thick layer of salt. Therefore, everything needs to be robust, precise, and automated.
According to information from the ANP (National Agency of Petroleum, Natural Gas and Biofuels), the oil is trapped in porous rocks that lie beneath the salt. To reach it, companies drill into the ocean floor, through the water, the layers of sediment and, finally, the salt. Only after this does the drilling reach the reservoir.
Drilling begins with a piece of equipment installed on the seabed called a submerged Christmas tree, which acts as a "control tower" for the well. It opens, closes, and regulates production.
The well is drilled by drillships or semi-submersible platforms, which are enormous units capable of operating where the ocean reaches depths of 2 to 3 meters.
These platforms use:
- Drill string: a long pipe that reaches the seabed.
- BOP (Blowout Preventer): an essential safety device that shuts off the well if there is a sudden increase in pressure.
- Dynamic positioning systems, which hold the ship in the same spot without an anchor.
Once the well is completed, FPSOs (Floating Production Storage and Offloading vessels) come into play. These are the platform ships that produce, process, store, and send the oil to tanker ships. They receive the oil through risers, flexible pipelines that connect the seabed to the platform.
Equipment used in oil extraction
The oil extraction process involves various equipment and technologies to efficiently extract oil from the ground. Understanding this equipment is crucial to grasping the complexities of oil extraction methods.
Drilling rigsDrilling platforms are fundamental to the oil extraction process. They are used to drill wells underground to access oil reservoirs. These platforms can be land-based or offshore, depending on the location of the oil deposits. Advanced drilling platforms are equipped with modern technologies to minimize environmental impact and maximize extraction efficiency.
BrocasDrill bits are attached to the end of the drilling rig and are crucial for penetrating the Earth's layers. There are several types of drill bits, including roller cone bits, fixed-cut bits, and diamond-impregnated bits, each designed for specific rock formations and oil extraction techniques.
Oil pumpsAfter a well is drilled, oil pumps are used to bring the crude oil to the surface. There are different types of pumps, such as beam pumps (commonly known as suction pumps), electric submersible pumps (ESPs), and progressive cavity pumps (PCPs). The choice of pump depends on factors such as well depth and oil viscosity.
Thermocouple: the thermocouples They are used in oil extraction, both in onshore and offshore operations. They are part of the temperature measurement and control system at various stages of the production process.
SeparatorsConsidered vital in the oil extraction process, they separate the extracted mixture of oil, gas, and water into its individual components. These separators can operate using gravity or centrifugal force and increase the efficiency of subsequent refining processes.
Storage TanksAfter separation, crude oil is stored in large tanks before being transported to refineries. These storage tanks are designed to handle large volumes of oil and ensure safe containment, preventing leaks and environmental contamination.
Pipeline infrastructurePipelines are the most efficient way to transport crude oil from extraction sites to refineries. This infrastructure is crucial for maintaining a constant flow of oil and ensuring the stable supply needed to meet global energy demand. Advanced pipeline monitoring systems help detect leaks and ensure the integrity of the oil extraction process.
Alutal products for the oil industry.
Alutal brings together a consistent portfolio of equipment geared towards the oil sector, combining precision, robustness, and technology developed to withstand the most severe conditions of oil and gas extraction, processing, and transportation operations. In the market, the company is recognized for the reliability of the instruments it produces, key components for enhancing facility safety, increasing energy efficiency, reducing unexpected downtime, and ensuring compliance with international industry standards.
The company has a renowned line of instruments used in the sector, focusing on precision and robustness, essential in environments such as offshore and onshore platforms and processing units. Key features include:
- Thermocouples and resistance thermometers (PT100), including mineral-insulated, multipoint, and anti-vibration models.
- Transmitters temperature for integration with industrial systems.
- Ultrasonic level switches and transmitters, and guided wave radars, used in tanks and separators.
- Thermal flux meters from the Thermatel line (TA2, TD1/TD2 and TG1/TG2).
- Metrix vibration sensors, such as the SA6200 and the 5550 switch, for the protection of pumps and compressors.
The brand positions itself as a strategic supplier of instrumentation for the entire oil supply chain.
