Where do you extract oil from?

Dec. 06, 2023

Removal of petroleum from the earth

"Oil extraction" redirects here. For the 1907 Azerbaijani film, see Oil Extraction (film)

Petroleum is a fossil fuel that can be drawn from beneath the earth's surface. Reservoirs of petroleum are formed through the mixture of plants, algae, and sediments in shallow seas under high pressure. Petroleum is mostly recovered from oil drilling. Seismic surveys and other methods are used to locate oil reservoirs. Oil rigs and oil platforms are used to drill long holes into the earth to create an oil well and extract petroleum. After extraction, oil is refined to make gasoline and other products such as tires and refrigerators. Extraction of petroleum can be dangerous and have led to oil spills.[1]

Locating the oil field
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Geologists and geophysicists use seismic surveys to search for geological structures that may form oil reservoirs. The "classic" method includes making an underground explosion nearby and observing the seismic response, which provides information about the geological structures underground. However, "passive" methods that extract information from naturally occurring seismic waves are also used.[2]

Other instruments such as gravimeters and magnetometers are also used in the search for petroleum. Extracting crude oil normally starts with drilling wells into an underground reservoir. When an oil well has been tapped, a geologist (known on the rig as the "mudlogger") will note its presence.

Historically in the United States, in some oil fields the oil rose naturally to the surface, but most of these fields have long since been used up, except in parts of Alaska. Often many wells (called multilateral wells) are drilled into the same reservoir, to an economically viable extraction rate. Some wells (secondary wells) may pump water, steam, acids or various gas mixtures into the reservoir to raise or maintain the reservoir pressure and economical extraction

Drilling
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The oil well is created by drilling a long hole into the earth with an oil rig. A steel pipe (casing) is placed in the hole, to provide structural integrity to the newly drilled well bore. Holes are then made in the base of the well to enable oil to pass into the bore. Finally, a collection of valves called a "Christmas tree" is fitted to the top; the valves regulate pressures and control flow. The drilling process comes under "upstream", one of the three main services in the oil industry, along with mid-stream and downstream.

Oil extraction and recovery
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Primary recovery
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During the primary recovery stage, reservoir drive comes from a number of natural mechanisms. These include: natural water displacing oil downward into the well, expansion of the associated petroleum gas at the top of the reservoir, expansion of the associated 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. Recovery factor during the primary recovery stage is typically 5-15%.[3]

While the underground pressure in the oil reservoir is sufficient to force the oil (along with some associated gas) to the surface, all that is necessary is to place a complex arrangement of valves (the Christmas tree) on the well head to connect the well to a pipeline network for storage and processing. Sometimes pumps, such as beam pumps and electrical submersible pumps (ESPs), are used to bring the oil to the surface; these are known as artificial lifting mechanisms.

Secondary recovery
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Over the lifetime of a well, the pressure falls. At some point there is insufficient underground pressure to force the oil to the surface. After natural reservoir drive diminishes, secondary recovery methods are applied. These rely on supplying external energy to the reservoir by injecting fluids to increase reservoir pressure, hence increasing or replacing the natural reservoir drive with an artificial drive. Secondary recovery techniques increase the reservoir's pressure by water injection, gas reinjection and gas lift. Gas reinjection and lift each use associated gas, carbon dioxide or some other inert gas to reduce the density of the oil-gas mixture, and thus improve its mobility. The typical recovery factor from water-flood operations is about 30%, depending on the properties of the oil and the characteristics of the reservoir rock. On average, the recovery factor after primary and secondary oil recovery operations is between 35 and 45%.[3]

Enhanced recovery
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Steam is injected into many oil fields where the oil is thicker and heavier than normal crude oil.

Enhanced, or tertiary oil recovery methods, increase the mobility of the oil in order to increase extraction.

Thermally enhanced oil recovery methods (TEOR) are tertiary recovery techniques that heat the oil, reducing its viscosity and making it easier to extract. Steam injection is the most common form of TEOR, and it is often done with a cogeneration plant. This type of cogeneration plant uses a gas turbine to generate electricity, and the waste heat is used to produce steam, which is then injected into the reservoir. This form of recovery is used extensively to increase oil extraction in the San Joaquin Valley, which yields a very heavy oil, yet accounts for ten percent of the United States' oil extraction.[citation needed] Fire flooding (In-situ burning) is another form of TEOR, but instead of steam, some of the oil is burned to heat the surrounding oil.

Occasionally, surfactants (detergents) are injected to alter the surface tension between the water and the oil in the reservoir, mobilizing oil which would otherwise remain in the reservoir as residual oil.[4]

Another method to reduce viscosity is carbon dioxide flooding.

Tertiary recovery allows another 5% to 15% of the reservoir's oil to be recovered.[3] In some California heavy oil fields, steam injection has doubled or even tripled the oil reserves and ultimate oil recovery.[5] For example, see Midway-Sunset Oil Field, California's largest oilfield.

Tertiary recovery begins when secondary oil recovery is not enough to continue adequate extraction, but only when the oil can still be extracted profitably. This depends on the cost of the extraction method and the current price of crude oil. When prices are high, previously unprofitable wells are brought back into use, and when they are low, extraction is curtailed.

The use of microbial treatments is another tertiary recovery method. Special blends of the microbes are used to treat and break down the hydrocarbon chain in oil, making the oil easy to recover. It is also more economical versus other conventional methods. In some states such as Texas, there are tax incentives for using these microbes in what is called a secondary tertiary recovery. Very few companies supply these.[quantify]

Recovery rates
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The amount of oil that is recoverable is determined by a number of factors, including the permeability of the rock, the strength of natural drives (the associated gas present, pressure from adjacent water or gravity), porosity of the reservoir rock, i.e. the rock storage capacity, and the viscosity of the oil. When the reservoir rocks are "tight", as in shale, oil generally cannot flow through, but when they are permeable, as in sandstone, oil flows freely.

Estimated ultimate recovery
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Although recovery of a well cannot be known with certainty until the well ceases production, petroleum engineers often determine an estimated ultimate recovery (EUR) based on decline rate projections years into the future. Various models, mathematical techniques, and approximations are used.

Shale gas EUR is difficult to predict, and it is possible to choose recovery methods that tend to underestimate decline of the well beyond that which is reasonable.

Health and safety
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The oil and gas extraction workforce faces unique health and safety challenges and is recognized by the National Institute for Occupational Safety and Health (NIOSH) as a priority industry sector in the National Occupational Research Agenda (NORA) to identify and provide intervention strategies regarding occupational health and safety issues.[6][7] During 2003–2013, the annual rate of occupational fatalities significantly decreased 36.3%; however, the number of work-related fatalities in the U.S. oil and gas extraction industry increased 27.6%, with a total of 1,189 deaths because the size of the workforce grew during this period. Two-thirds of all worker fatalities were attributed to transportation incidents and contact with objects or equipment. More than 50% of persons fatally injured were employed by companies that service wells. Hazard controls include land transportation safety policies and engineering controls such as automated technologies.[8]

In 2023, the CDC published that 470 workers had died from 2014–2019.[9]

References
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Essential oils are hydrophobic, hydrocarbon liquids extracted from plant material that are valued for their aromatic, flavoring, medicinal, antiseptic, antiviral, anti-inflammatory, and many other properties.

Custom extraction services from a toll processing partner puts botanical and herbal processing expertise in the hands of companies looking for the best ways to extract essential oils from fresh or dried plant biomass and create product formulations that deliver many benefits to their end users.

Essential oils, especially their volatile components, are the substances that give aromatic plants their characteristic scents and flavors. (Volatile oils evaporate readily at room temperature, while non-volatile oils have a slower rate of evaporation.)

Major industries that use essential oils include pharmaceuticals and nutraceuticals, food and beverage, personal care, cosmetics, home care, and even industrial and agricultural chemicals. Markets for these products are expected to grow as research into their benefits and applications continue, and with increasing consumer preferences for natural products.

High-value essential oils, concretes, and absolutes can be made up of more than 200 volatile and non-volatile constituent components. They are extracted from biomass that can include any or all of the parts of a plant, including:

Roots
Flowers
Fruits
Leaves
Stems
Seeds
Bark

A few examples of popular and useful essential oils and extracts include:

Lavender
Peppermint
Hemp extract
Vanilla
Citronella
Pine
And many more

There are several extraction methods commonly used to obtain the beneficial oils from plants. What’s the best extraction method? The answer to this question depends on the plant, the volume of biomass and production scale, the intended end use of the product, and more. This can be a critical question, especially in the context of hemp processing services.

In this article, we’ll review the top four ways to extract essential oils from plants, and how a toll processor can help you optimize essential oil extraction for cost-effectiveness and efficiency.

Conventional and Advanced Extraction Methods

Humans have been developing and refining extraction methods for essential oils for thousands of years. The ancient Egyptians, Chinese, Indian, and Greek cultures all have records of using aromatic oils for perfume and/or medicine.

These oils have long been used for pharmacological properties that can include anti-inflammatory, antioxidant, and anticarcinogenic effects. Antimicrobial properties can include antibacterial, antifungal, and antiviral activity. Of course, many essential oils are also used to impart pleasant scents or flavors to foods, drinks, and other products, and can have relaxing or calming effects on users, as in aromatherapy.

The most common extraction methods include conventional and also newer, more advanced technologies. Conventional methods include cold pressing (or expression), distillation, and solvent extraction.

Supercritical and subcritical carbon dioxide (CO2) extraction methods are more advanced and especially useful for the growing hemp processing industry.

1. Distillation

Simple distillation involves boiling water to vapor and allowing the steam to flow through biomass before condensing in a collection vessel. Because simple distillation subjects products to high temperatures, it can be a poor choice for heat-sensitive products — which includes volatile oils.

Steam distillation is the most common extraction technique for essential oils. In a still, pressurized steam is passed through the biomass, where it ruptures the plant structures that hold the essential oils, releasing constituent volatile and non-volatile compounds.

The resulting liquid is condensed and naturally separates into two layers: essential oil and hydrosol. Examples of familiar hydrosols include rosewater and orange flower water.

In steam distillation, care must be taken to control pressure and temperature to avoid degrading the essential oils in the process of extracting them. Depending on the plant, steam distillation can take anywhere from a few hours to several days to fully distill oils from the biomass.

2. Cold Pressing (also called Expression)

Cold pressing is a traditional method that’s used for many oils that degrade when exposed to heat, such as lemon, orange, and grapefruit. This very simple extraction technique involves scraping or pricking the biomass, usually fruit peels, before pressing and rinsing the oils away using water. The water and oils are then separated.

Cold-pressed oils retain natural flavors, colors, sterols, and vitamins. But not all plant biomass is suitable for cold pressing, many constituents can be left behind within the biomass, and it is not efficient for high-volume extraction.

3. Solvent Extraction

Solvent-based extraction can use ethanol, methanol, or any of several petroleum-based hydrocarbon solvents, including:

Hexane
Pentane
Acetone

The solvent, selected for its affinity with the desired plant compounds, flows through the prepared biomass to penetrate the plant structures and release the essential oils. The resulting mixture of solvent, plant oils, and botanical solids is typically filtered and vacuum distilled to remove as much solvent as possible, especially when petroleum-based hydrocarbons are used. A small percentage of chemical solvent residue can remain in the final product.

Vanilla extract is an example of a commonly used solvent extraction. The essential oils from the plant remain in alcohol, which was used to extract the desirable aromatic compounds from the structures of the vanilla bean pods.

4. Supercritical and Subcritical CO2 Extraction

The use of carbon dioxide as a solvent is in high demand, especially industrial hemp extraction services, to produce high-quality full-spectrum and broad-spectrum CBD extracts. In CO2 extraction, the carbon dioxide is subjected to specific temperature and pressure conditions to achieve specific effects.

Whether supercritical or subcritical, CO2 works as a highly “tunable” solvent. This means that variables can be adjusted to most effectively extract targeted compounds, leaving behind the undesirable constituents in the biomass.

What is the difference between supercritical and subcritical CO2? In short, the difference is in pressure and temperature. Above critical temperature and pressure, CO2 becomes a supercritical fluid, which means it has properties of both a liquid and a gas. These properties enable the CO2 to penetrate raw hemp biomass and break down the plant structures to release important compounds, including cannabinoids and terpenes.

Subcritical CO2 extraction works similarly, though it can be a slower, less efficient process that results in lower overall yields. However, subcritical CO2 is gentler on some of the more delicate active constituents of the hemp plant. For producers of full-spectrum and broad-spectrum cannabis extracts, this is crucial for producing a whole-plant extract that delivers the “entourage effect.” Depending on the targeted compounds and the desired final product, subcritical CO2 may be the preferred extraction technique.

In both methods, after extraction, pressure and temperature are allowed to return to ambient levels and the CO2 evaporates, leaving no solvent residue, for a pure, unadulterated final product. Unlike other solvents, CO2 is environmentally friendly, nonflammable, and nonhazardous.

CO2 extraction processes are more efficient, less energy intensive, and even less costly than some of the other methods. They’re also suited to scale up to high-volume production.

Creating Finished Herbal Extract Products

Most products of the botanical extraction process are liquids: oils, hydrosols, or tinctures in a base of alcohol or glycerin. But they may also be waxy extracts that are solid at room temperature.

After your toll processor has finished your extraction project, you may need additional steps to create fully commercialized products for your end users — so it’s worth having the conversation with your tolling partner about their capabilities to help transform botanical extracts into finished products. These services can include:

Product formulation R&D
Testing and analysis
Liquid blending
Emulsifying
And more

Bottling and Repackaging Herbal Extracts

Minimizing time to shelf, freight, logistics, and other costs can be key to success in nutraceuticals, cosmetics, food, and beverage. So if your toll manufacturer can help you take your final, blended products from bulk formats to consumer or end-user packaging, the savings you realize in time, efficiency, and cost can make a real difference to your bottom line.

Be sure to ask whether your tolling partner can also offer fully automated, high-speed, cGMP-certified bottling of your liquid and liquefiable herbal extract products. Herbal and botanical extracts can end up in broad range of value-added products and formulations, including:

Extracts and tinctures in dropper bottles
Lip balms and salves
Lotions and creams
Body oils
Herb-infused drinks
And more

A toll processor that you can trust to achieve top-quality extracts, formulate in-demand products, and bottle and repackage for your end-user can help you deliver on your own brand promise of quality.

Learn more about herbal and botanical extraction and processing, and what to look for in a toll processing partner, when you download our eBook, Biomass to Bottle: CO2 Extraction, Blending, Bottling & More. Just click the link below to get your copy.

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