Understanding Water Injection and its Implication in EOR

As opposed to recovering oil naturally from a producing well, Enhanced Oil Recovery (EOR) refers to the use of additional engineering techniques to improve and increase the amount of recovered oil. Primary EOR methods include chemical injection, gas injection, steam injection, thermal injection, and more. While the use of gas injection accounts for about 60% of EOR method usage, production companies are achieving great results using water injection to recover oil.

Water Injection and How It Works

One of the secondary EOR production processes, water injection, sometimes called waterflooding, is commonly used for onshore and offshore developments. For this injection method, injection wells are drilled into reservoirs and water is introduced into those reservoirs to stimulate oil production. The method is not only used to boost depleted pressure within reservoirs but it can also move the oil as well.

While injecting water helps to increase exhausted pressure inside the reservoir, it also helps to move the oil around. The injected water sweeps any remaining oil from the reservoir to the production wells for recovery whether the injection is used after well production has already been exhausted or prior to reservoir production having been drained.

Waterflood Methods

While the water used for this method can come from a number of sources, most of such water is some form of brine. It’s important that the water used be able to work within the formation. Sometimes it’s necessary for the water to be treated or filtered prior to use so no debris is present to clog the pores of the well and an environment for bacteria growth isn’t created. It’s not uncommon for oxygen to be removed from the water in an effort to minimize the risk of corrosion within the reservoir.

Water-injection wells can be specifically drilled for this method though some elect to simply convert production wells into injection wells. Once the water is pumped into the reservoir, gravity forces the liquid to move within the formation. The method positions water tanks in locations above the well and it’s directed straight to the wellbore.

Improved Oil Recovery Using Injected Water

Oil production without the use of any additional methods like waterflooding usually achieve the recovery of 30 to 35 percent of the available oil. While the effectiveness of any secondary enhanced oil recovery method depends on the individual formation, the injection of water recovery rates range from 5 to 50 percent of any remaining oil which is a significant increase in productivity.

This method is even more productive when there are smaller amounts of primary production. In cases where the water cut reaches a 90 to 99 percent level, it’s no longer an economically viable option. The method can take time. It can take as much as two years of injection to boost production to desired possible levels with some waterfloods. Sometimes the technique isn’t the best option with a given reservoir’s characteristics. There are cases where it can’t be used as in natural gas wells.

Some production teams improve results using heated water in reservoirs, different from steam injection, which helps make the oil itself more fluid, especially in wells with heavier oil. Some treat the water with polymers to increase water viscosity to help promote the movement of oil within the wells.

The Second Most Commonly Used EOR Method

Since water is inexpensive and available in large volumes, it provides an affordable, effective solution to boost oil recovery from production wells. With the right understanding of geological considerations, waterflood can be a successful method of oil recovery in fields of varying sizes and across a wide range of locations.

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The Role of EOR Techniques in Revitalizing Mature Oil Fields

Mature oil fields are fields with production rates that have significantly declined from what they once were. They’ve reached their peak. Many mature fields have old wells and equipment, some with infrastructures that have an above-average risk of environmental or safety issues.

Are these oil fields done? Not necessarily. There are, in fact, many methods and technologies available to revitalize mature fields.

EOR for Revitalizing Mature Oil Fields

There are several ways an aging oil field may be regenerated. It must first be determined what the desired goal of the project is, the target, in order to select the best method to use.

An analysis of the reservoir is a great place to start, evaluating the situation carefully so there are no unknowns pertaining to the project including resources and more. There’s a great variety of software available today to help with the visualization process, modeling, and more to help identify any oil deposits that were previously undiscovered to be your target.

Once your target is designated, you’re ready to choose your recovery method. whether it’s improved oil recovery technology (IOR), enhanced oil recovery (EOR), or a combination of the two. IOR processes include conformance control, gas flooding, horizontal or infill drilling, and waterflooding. EOR processes might include gas injection (hydrocarbons, N2, and CO2), injection of alkali, low salinity materials, polymers, steam injection, surfactants, and thermal technology systems. Some might even elect to makeover their facilities and wells and keep the same production processes.

In using the advanced reservoir-management techniques, however, production companies like Nakasawa Resources can craft rejuvenation plans to greatly boost not only production but reserves as well.

The Right Method for a Specific Field

For fields where the remaining saturation is considerable, even in part, fluid properties and the reservoir determine which EOR techniques, like steam injection or thermal technology systems, or IOR processes, like waterflooding, are most appropriate. Fortunately, there are many tools available in the industry for screening wells for these methods. The biggest considerations will be economic viability, field location, well integrity, and resource availability.

Some find nearby analogies very helpful because if another field in close proximity was successfully flooded, there’s a good chance that the same method will work for your mature oil field.

Others find reservoir simulation to be very effective in identifying a method to use as they provide good indications of recoveries and rates that can be expected from such a project. Core flooding and lab tests can be important in estimating the results for a considered project.

The Best Candidates for EOR Techniques

Fields with remaining oil saturation of 35% or more make ideal EOR field candidates. Some mature fields have obvious properties conducive to EOR like accessible locations, easy access to an injectant source (CO2, water, etc.), and have viable infrastructures.

If the field has a high permeability or has already been used successfully for IOR methods like water injection, it may also make for a good candidate. The continuity of the reservoir is also a good determining factor. Even so, reservoirs that seem less ideal shouldn’t be dismissed so quickly. If an EOR method could possibly be used on it, the field could be viable and still make a profit.

Challenging Conventional Thinking to Regenerate Mature Oil Fields

With the constantly developing innovation and technology available today, existing methods of enhancing and improving oil recovery will keep mature fields viable. The revitalization projects can be affordable and even increase the amount of oil recovered by as much as 20% and more. Achieving more with less is a beautiful concept, regardless of the industry or application.

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The Birth of EOR: How CO2 Gas Works to Rise Oil Recovery Rates

The oil industry has devised a method using CO2 gas (Carbon Dioxide) to improve oil recovery rates. Known as Enhanced Oil Recovery (EOR), the practical technique uses CO2 gas and then stores it underground. The method has shown great results when used in improving oil recovery rates and prolonging how long mature oil fields can be utilized. EOR has been effectively used in Canada and Texas where CO2 flooding has not only proven useful but environmentally beneficial as well.

CO2 Used Responsibly

CO2 has been identified by NASA as the largest greenhouse gas contributing to our planet’s climate change because there’s so much of it. Substantial amounts of CO2 are released into the atmosphere each day, mostly from the burning of fossil fuels to generate power. It’s also released into the atmosphere through manufacturing processes like aluminum smelting, the production of petrochemicals and steel. The great need to diminish CO2 emissions has been the focus of scientists in America and Europe wishing to find ways to capture and store CO2 emissions from the underground chimneys of power stations.

Making CO2 A Help Not a Hindrance

The oil industry has made great strides in finding ways to do the same thing, capture and store CO2 emissions underground. Yet, they’ve also found a way to make them useful. Enhanced oil recovery was first used in the 1970s in Texas to try to make mature oil fields last longer and to improve oil recovery rates.

Today, how CO2 gas recovers oil is an improved process involving the injection of compressed CO2 gas into oil-bearing formations by way of injection wells. The CO2 injected flows through and permeates rock structures, swelling and expanding into pore spaces. Oil is pushed out of the rock through fractures in it and up into the production wells. CO2 gas in the oil produced is then separated from the product and recycled so it can be used again for the same process at another time.

The technique results in a 30% to 60% increase in the amount of original oil that can be extracted from the reservoir. It’s an improvement over the 20% to 40% increase achieved with using injections of pressurized water or re-injection of natural gas. EOR is the best choice of method for mature oil fields with more complex geology but that provide heavy oil. How CO2 gas recovers oil is not only a more efficient method but it is also an environmentally responsible use of the gas.

Additional Environmental Benefits

While the recycled use and storage of CO2 gas has obvious benefits for the oil industry, there are additional environmental benefits for people and plant life as well. In the United States, the use of EOR techniques consumes as much as 72 million metric tons of CO2 gas each year. 55 million tons of that originally came from natural sources while 17 million were produced by human activity resulting in pollution.

Since natural gas supplies are limited, EOR becomes an even bigger factor in global CO2 reduction goals. If used by power plants or industrial sites, “next generation” EOR techniques have the potential to capture and contain up to 45 billion metric tons of CO2 which are the equivalent of North America’s total estimated CO2 production from fossil fuel electricity generation for the next two decades.

One company that has made great advances in EOR is Nakasawa Resources. Guided by the founding principle of innovation, the company’s mission is to provide top-level upstream (EOR) solutions for the benefit of all. Established in 2001, they have faithfully served the gas and oil industry, successful in having improved the efficiency of wells in as much as 35% of their production potential. Through the continual development and use of unique engineering, latest technologies, and production maximization efforts, they continue to be a leading upstream technology supplier for the gas and oil industries. 

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How Nanofluids Can be Used With Success In Enhanced Oil Recovery

When it comes to gas and oil production, finding new reservoirs has become increasingly difficult. As a result, the petroleum industry is refocusing its efforts on ways to maximize the production of existing reservoirs. New, more efficient ways of extracting additional hydrocarbons from reservoirs currently in production are being devised. One of the most promising of these is nanofluid use in enhanced oil recovery EOR). Nanofluids and EOR, it’s believed, make a great team in boosting oil production.

What are nanofluids?

Nanoparticles suspended in fluids compose what is known as nanofluids. Nanoparticles are 1 to 100 nanometers (nm), with one nanometer being a billionth of a meter. To put it into an everyday perspective, a millimeter is roughly the diameter of the lead in a wooden pencil and a nanometer is one-millionth of that.

Silica nanoparticles are inexpensive to create, easy to modify to suit the needed parameters, and installation has a modest capital cost. Researchers believe that Silica nanoparticles (SiNPs) have the potential to improve oil production without a negative impact to the environment.

Nanoparticles are suspended in saltwater by researchers in controlled concentrations from 0.01 to 1 weight percent. Alternatively, metal oxide nanoparticles are also suspended in saltwater by the same researchers.

Why Use Nanotechnology Enhanced Oil Recovery?

Seawater aids in producing oil in most existing reservoirs. Injected directly into the reservoirs, seawater aids in propelling the oil into the production wells. After the initial application of seawater reaches the production well, more water is injected and mostly follows the same water path so it doesn’t flush out more oil. The contrast in viscosity between oil and water, aside from the interfacial tension between water and oil phases, is the reason.

Water is thinner in consistency and less viscous so it flows easily through a reservoir. Oil has a thicker viscosity and doesn’t flow well independently. Some oil clings to rock within the reservoir or gets trapped in small remote or porous channels. While the injection of seawater is and has been an effective way of improving oil production, many believe that other methods can be devised and used to further improve oil production.

Here is where nanofluids for enhanced oil recovery is proven. When nanoparticles are added to the injected seawater, it can help flush out remaining oil deposits within the reservoir that might normally remain. The distinctive silica nanoparticles (sand) have proven effective in growing oil recovery when added to seawater injected into oil-saturated sandstone blocks. Like smaller petroleum reservoirs, the blocks when combined with other experiments help researchers comprehend how rock and oil interconnect with the nanoparticles in EOR processes making the use of nanofluids for enhanced oil recovery beneficial.

How can nanofluids maximize oil recovery?

There are several different ways in which nanofluids and EOR work together to boost oil production including, but not limited to, the following:

• By slightly increasing the viscosity of seawater, nanoparticles help push oil through reservoirs.
• By lowering the interfacial tension between seawater and oil to dislodge oil in tiny porous channels can be released from into production wells, nanoparticles push more oil out of reservoirs.
• Nanoparticles can strip oil drops and small deposits from rocky surfaces by forming wedge-films.

Nanoparticles, along with nano-gels, are used to plug up water pathways so water flow can be controlled and directed through oil-filled paths.

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Guide to Ultrafiltration Systems and the Processes Behind Them

Water is our most important resource. With so many industries consuming high volumes of water or producing highly toxic sewage, ultrafiltration is more important than ever. Used in wastewater treatment, ultrafiltration (UF) mechanisms are utilized to reclaim and reuse water that holds practically no physical solids.

The following is a guide to ultrafiltration systems, what they are, and the benefits they offer.

What is Ultrafiltration?

A variety of membrane filtration, ultrafiltration processes are similar to reverse osmosis in that they use hydrostatic pressure to blast water through a semi-permeable membrane. UF utilizes a force-driven barrier to filter out bacteria, endotoxins, solids, viruses, and other pathogens to output water that’s very pure. The pore size of the UF membrane averages 103-106 Daltons, resulting in quality water with low silt density. Solids and solutes of substantial molecular weight are held back in the retentate, allowing the water and solutes of low molecular weight to pass the membrane.

Water Filtration Uses

UF is most commonly used for the production of potable water, removing macromolecules and particulates from water in its raw form. The process can be used as a standalone system for regions with increasing populations in isolated areas. It can also be used in place of secondary filtration systems, like coagulation, flocculation, and sedimentation, and tertiary filtration systems, like chlorination and sand filtration, utilized in water-treatment plants. UF can also be part of the process when there are high suspended solids.

UF water filtration is preferred over traditional treatment processes for several reasons:

• Chemical are not used (with the exception of cleaning)
• Consistent output quality
• Can be processed in a smaller facility
• Exceeds water quality standards, often achieving up to 100% pathogen removal.

When more intense purification is necessary, processes often include the use of UF to remove physical solids, capturing them in filters, and discarding them. The water recycled using UF can be used by a variety of industries for purposes like concrete mixing, construction uses, dust control, equipment sterilization, hardstands and vehicles, fire prevention and protection, pH adjustments, processing water for manufacturing production lines, rinse water processing, toilet uses, tower feed water supplementing, and more.

The Benefits of Ultrafiltration Processes

There are a lot of benefits in using UF on top of the production of a dependably, locally maintained supply of water. There are substantial environmental benefits as well.

In producing an extra source of water, recycled water provides ways to minimize the diversion of water from sensitive and vital ecosystems. It guarantees that sufficient water flows to fish habitats, plants, and wildlife that they need to survive and thrive. It also prevents toxic wastewater from being released into the environment to pollute it.

Water that’s recycled saves energy too because as the demand for water increases, more water is taken, treated and sent, sometimes over substantial distances, all of which takes energy to do. More energy is required to tailor water quality for specific uses.

Industries Using Ultrafiltration

 

Industries that use a lot of water or produce toxic discharge are strong candidates for ultrafiltration water processes. Industries centered around chemicals, food and beverage, paper and pulp, pharmaceutical, and plastics benefit greatly from ultrafiltration processes. So do power, water, and wastewater plants.

UF is frequently used to prefiltration for reverse-osmosis processes and often provide an effective means of minimizing silt density in water and eliminating particulates that can soil membranes used in reverse osmosis. It’s also commonly used to pretreat surface water, seawater, the biologically treated municipal water that’s upstream from reverse osmosis units.

 

Ultrafiltration Systems Guidance

The intention of this guide to ultrafiltration systems is to provide answers to common questions about the process. Any company that could potentially benefit from UF or representatives who have further questions can contact the team at Nakasawa.

Nakasawa’s certified, innovative, and responsive technologies are tailored to suit each individual client’s needs, designed to be environmentally responsible, and with the goal of successfully completing meeting each goal.

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Difference Between Traditional and EOR Methods for Oil Extraction

Oil extraction has been evolving for years. The latest method of enhanced oil recovery is taking oil extraction to a new level.

So what makes EOR methods of oil extraction better than traditional methods like drilling?

Enhanced oil recovery techniques remove a much higher percentage of oil from the earth, bringing down cost while increasing efficiency.

Primary and Secondary Oil Recovery

Primary drilling methods either tap oil that naturally rises, or can easily be pumped to the surface.

US Department of Energy studies show that primary drilling methods extract around 10 percent of a well’s oil reserves.

Secondary oil recovery, like fracking, can retrieve up to 30 percent more oil from an existing well by pumping water to push trapped oil to the surface.

What is Enhanced Oil Recovery?

EOR methods to oil extraction include thermal recovery, chemical injection, and gas injection to enable even further yield.

Thermal Injection

Thermal injection, like the use of steam, heats oil within a reservoir to reduce its viscosity and ease the release of oil and make it flow to the surface.

Gas Injection

Gas injection uses carbon dioxide, nitrogen, or natural gas to mix with trapped oil to make it more viscous. The gas also pushes the oil to the surface.

Chemical Injection

Chemical injections lower the oil’s surface tension, letting it flow from trapped pockets and is then brought to the surface by water flooding. Chemical injection is the least favored method due to the need for secondary water pumping to push oil to the surface.

Why Enhanced Oil Recovery is More Efficient for Oil Recovery

Enhanced oil recovery employs methods to alter the state of trapped oil in order to extract it, instead of just trying to force it out the ground by water pressure.

Current EOR methods to oil extraction can recover up to 60 percent of the oil left in a reservoir after traditional extraction methods have been employed. This extra source of fuel is bolstering global oil reserves while reducing expenditure.

Enhanced oil recovery techniques can extract millions of more barrels of oil from wells that have already been through the primary and secondary recovery methods.

The cost to bring the first barrel of oil from a new field is astronomical, especially with locations that are difficult to reach like deep sea reserves. The ability to use enhanced oil recovery on already tapped wells is more environmentally friendly and reduces cost.

The Future of Domestic Oil Production

As the earth’s oil reserves continue to become depleted, the need for extensive research and development into improved EOR methods will increase.

Oil recovery companies, like Nakasawa, incorporate engineering and investment in new enhanced oil recovery technologies that are increasing the yield of new and existing oil fields while cutting overall costs.

Energy companies understand the importance of gaining full recovery from existing oil reserve fields, in order to maintain sufficient oil levels to sustain global demand.

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An Overview of Steam Injection Processes and its Uses for EOR

Different industries have solely relied on oil to drive the wheels of the various machinery. The demand for oil has increased. In 2018, the daily consumption of oil has reached 99 million barrels. So how can oil producers meet the increasing demand?

Oil production process consists of three phases: primary, secondary, and tertiary phases. But even after the last phase, a lot of oil still remains in the well (about 60%-80%). That’s where enhanced oil recovery comes to play. The process generates an additional 30%-40% of the original oil in place.

So, what is enhanced oil recovery? This is a thermal process that increases the quantity of crude oil extracted from a reservoir by the addition of substances that were previously not found in the well.

Understanding Thermal EOR

The thermal recovery process is when the well is heated at controlled temperatures to reduce crude-oil viscosity. It is an effective method in oil production, accounting for over half of the total EOR production. Thermal EOR can be done through the following processes:

· Steam injection

The injection of heated steam to an oil well during the formation stage to lower its viscosity while vaporizing some of it to boost the mobility. It is commonly used in shallow oil reservoirs.

· In-Situ combustion

Injecting a stream of gas containing oxygen into an oil well. The process utilizes a special heater that causes ignition in the reservoir, thus creating fire. As the fire continues it produces a mixture of hot gases that reduce viscosity, causing the oil to flow toward a production well.

The Steam Injection Process

Steam injection processes have been used by oil production companies since the 60s and effective when used in shallow reservoirs. The injected steam not only helps in increasing the mobility of oil but also creates the perfect permeability conditions and enables the oil to seep through the well and into a collection well. The vaporized gas produces oil with better quality once it has condensed in a collection reservoir.

Steam injection can be done through cyclic thermal recovery or steam flooding. During the cyclic oil recovery method, steam is introduced in a well and then used again in production. Initially, a stream of hot moisture is pushed into the well. The process then enters the soak phaser the oil is allowed to soak in steam for a few days. Lastly, the resulting oil is produced in the exact well.

In steam flooding, heated steam produced at ground level is injected in an oil reservoir using special shafts, evenly distributed across the well. The steam then causes the heavy oil to loosen causing it to flow easily. The process also results in the vaporization of oil, which separates from light components. The gaseous oil then collects in an oil bank as cleaner oil.

The Role of Carbon Dioxide (CO2) in Enhanced Oil Recovery

Originally, oil flows naturally from a newly discovered oil reservoir. But as time elapses, the pressure gradient lowers, and the oil hardly makes it to the subsurface. CO2 is then injected as an EOR agent to increase pressure and push the oil toward the surface.

The CO2 along with other agents mix partially with the oil, causing some expansion, which significantly reduces viscosity. It is an alternative EOR method in impermeable wells where water flooding is economically inviable. Besides, using carbon dioxide to recover more hydrocarbons can significantly reduce C02 levels in the environment.

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