The goals of treating oil and gas generated water include adhering to discharge rules, reusing treated produced water in oil and gas operations, establishing agricultural water uses, restoring aquifers, providing drinking water for cattle and other animals, and even providing water for people.
The advantages and limitations of current generated water technologies, and their successful uses, can be used to judge their applicability. According to volume, water produced during oil and gas extraction operations is the most significant waste stream in the sector. Some estimates have the annual water production from the oil and gas sector at around 14 billion barrels.
Let’s look at the treatment of wastewater from oil and gas industry sector.
The quantity and quality of the water vary widely, and in some circumstances, the water may even be a usable by-product or a marketable good. The industry is starting to view produced water as a potential source of revenue, even though it is typically regarded as trash.
Produced water, whether it is trash or a commodity, has management expenses that must be handled in accordance with each unique production project and region, or it could negatively impact the well's life and leave a significant amount of recoverable reserves in the ground.
Environmental protection must also be a priority while handling produced water. The composition of produced water, location, volume, and the availability of resources all affect how it is handled.
Problems with produced water in oil and gas industries
The issue with generated water is that as a well matures, its volume grows and its water content may increase to 98%. The severe limits on how produced water may be discharged, are pressuring oil producers to adopt more effective treatment plans.
The following are a few of the alternatives an oil and gas operator may have for managing produced water:
1: Use polymer gels to plug water-contributing fissures or fractures or down-hole water separators, to separate water from oil or gas streams underground and inject it back into the right formations to prevent the generation of water on the surface.
2: Transporting produced water from the point of production to the injection site, entails injecting it into the same formation or another suitable formation. It could be essential to treat the injectate to lessen germs, scaling agents, and fouling agents. While wastewater is produced in this scenario, the waste is buried once more.
3: Produced water should be discharged after being treated to comply with onshore or offshore discharge laws. Sometimes it may not be necessary to treat produced water.
4: Use the produced water again in oil and gas operations by purifying it to the standards needed for drilling, stimulation, and work-over operations. As treated generated water can be used as continuous steam injection, or as purified water, it is also used to make the Polymer solutions to inject into oil wells. This option is particularly advantageous in EOR (Extended Oil Recovery) operations.
5: Consume it for beneficial purposes. In some circumstances, substantial treatment of produced water is necessary to achieve the quality necessary for beneficial purposes, like irrigation, drinking water for personal use, or in public water systems.
When deciding how to handle produced water, operators should keep the following goals in mind:
· De-oiling - Removing hydrocarbons (free and scattered oil and grease) from generated water
· Soluble organics removal
· Disinfection - Elimination of microbes, algae, and other contaminants
· Suspended solids removal - Removal of turbidity, sand, and other suspended materials
· Removal of dissolved gases, such as carbon dioxide, hydrogen sulphide, and other light hydrocarbon gases
· Desalination or demineralization - Elimination of pollutants, scaling agents, dissolved salts, sulphates, and nitrates
· Softening - Removing excessive amounts of water hardness
· Adjusting the sodium adsorption ratio (SAR) which involves adding calcium or magnesium ions, to the generated water to reduce its sodicity before irrigation
· Removal of naturally occurring radioactive materials
De-oiling, the removal of oil and grease
Free oil, dispersed oil (tiny oil droplets), and emulsified oil are all types of oil and grease found in produced water. The best way to remove oil and grease depends on how the water will be used in the end, and how the oil will be removed from the water.
How to treat wastewater in oil and gas industry sector?
Treatment of produced water that works well is oxidation of soluble organics and pollutants (bacteria nitrate, etc.). Strong oxidizers include ozone and hydrogen peroxide. Dissolved carbon dioxide is produced during the oxidation process, and can be eliminated using air stripping.
Additionally, oxidation using ultraviolet (UV) radiation has been utilised to de-ionize water into hydrogen and hydroxyl ions. Strong oxidizers also include hydroxyl ions. In order to purify the water, UV radiation also eliminates germs and other pathogens.
Chemical oxygen demand (COD), biological oxygen demand (BOD), organics, iron, nitrite, manganese, cyanides, hydrogen sulphide, and aromatic hydrocarbons can all be decreased through oxidation. Additionally, helpful for treating both raw generated water and post-treatment water after it has undergone previous treatments is biological decomposition, which involves a combination of oxidation and reduction of produced water in a built wetland.
The most crucial component of water treatment systems is frequently the removal of dissolved solids, salts, or pollutants. The range of TDS in generated water is 2000 ppm to >150,000 ppm. Seawater has a TDS concentration of about 35,000 ppm on average.
The TDS content and the ability of the treatment system to function when additional pollutants are present in the generated water, influence the desalination method selection. TDS is removed from the produced water using a variety of processes, including evaporation, distillation, membrane filtration, electric separation, and chemical treatments (Lime Softening, ion exchange, etc.).
To avoid scaling and water contamination, bacteria, viruses, germs, algae, etc. must be removed from the produced water. Microorganisms can be added during de-oiling processes or can be found naturally in the generated water.
One of the efficient technologies used to eliminate germs is advanced filtration. Other available procedures to disinfect generated water include UV light treatment, chorine or iodine disinfection, and ozone treatment.
Depending on the content of the generated water, produced water treatment may include softening, SAR modifications, and the removal of trace impurities, pollutants, naturally occurring radioactive materials (NORM), etc.
Manufacturer of high-quality wastewater treatment plants!
We at Netsol Water have the knowledge and treatment products, necessary to assist you in managing the water treatment plants and wastewater treatment plants across your facilities.
Furthermore, if you need any advice on water or a wastewater treatment problem, we can guide you towards the best water purification system for your requirements, including RO Plants, water softeners, WTPs, STPs, ETPs, and much more.