Oil sludge is not only a by-product of the production process, but also one of the important challenges of environmental protection and sustainable development. From oil field drilling to refinery, each type of oil sludge reflects the complex production environment and waste management necessity of the oil industry. The following will discuss in detail the classification of various oil sludges and recycling methods.
Oil Sludge from Oilfield Drilling
Oil-based Cuttings
Oil-based cuttings refers to a type of solid waste generated during the oil drilling process. During the drilling process, the drill bit breaks up the rock cuttings from the underground rock and brings them to the wellhead by rotating and drilling. The drilling fluid mixes these rock cuttings to form solid waste known as cuttings. When the drilling fluid is petroleum-based, it generates oil-based cuttings. These solid wastes mainly consist of petroleum-based drilling fluid mixed with formation cuttings and contain a high oil content. Thermal desorption unit for drill cuttings is the mainstream recovery method.
Waste Oil-based Mud
This waste originates from petroleum-based drilling mud. This is a complex mixture that usually includes petroleum (or similar liquids), additives (such as polymers, colloids, drilling fluid additives, etc.) and solid fillers (such as drilling fluid saturated cuttings and cuttings). During the drilling process, operators use petroleum-based drilling mud to lubricate and cool the drill bit. Thereby, it controls the pressure of the wellbore and transports the cuttings from the bottom of the well to the wellhead. The used mud will carry oil, suspended solids and other additives, so it becomes waste oil-based mud.
Oil sludge from Oil Transportation & Storage
Oil-contaminated Soil
Oil-contaminated soil refers to soil contaminated by leakage, spillage or accidental release of petroleum or its derivatives. This pollution usually occurs during the production, storage, transportation or use of oil, such as oil fields, refineries, pipeline leaks, tanker accidents, etc. Oil-contaminated soil mainly consists of petroleum hydrocarbons, heavy metals, organic solvents and additives, and oxidation products. Usually, oil products penetrate the soil, affecting the physical, chemical and biological properties of the soil, resulting in a decrease in soil quality.
Tank Bottom Oil Sludge
Tank bottom oil sludge accumulates as solid waste at the bottom of oil storage tanks. This sludge mainly consists of oil, water, sediment, and solid impurities (such as rust, soil, etc.), typically forming at the junction of the tank’s bottom and side walls. The formation of tank bottom oil sludge is mainly due to the precipitation and decomposition of petroleum products, and the contact between the oil in the tank and the air, water and metal impurities. Long-term accumulated sludge may contain a variety of chemical components, including heavy metals, hydrocarbon compounds and other pollutants.
Oil Sludge from Crude Oil Refining
Oil-water Separator Sludge
In oil refining, oil-water separators are usually used to separate and recover the oil and water. Oil-water separator sludge refers to the sediment produced by the oil-water separator during the oil refining process. Oil-water separator sludge mainly consists of oil, water, suspended solids and other sediments, which come from the oil and water mixture during the processing process. The oil can be a light petroleum product or an oil component containing heavy metals and other contaminants. Water is a by-product of the processing and treatment of petroleum products.
Air Flotation Tank Sludge
During the air flotation process, injecting air or other gases into the liquid forms tiny bubbles. These bubbles use buoyancy to lift suspended solid particles to the surface, creating scum or froth. The solid waste separated and collected from these scums is called air flotation tank sludge. It mainly consists of oil, chemical additives, solid particles (such as soil, minerals, metal oxides, etc.) and water from the oil refining process. These wastes usually contain various chemical components and need to be properly treated and managed to reduce the impact on the environment.
Activated Oil Sludge
Oil refining wastewater usually contains residues and pollutants of various petroleum products. In order to effectively treat these wastewaters, biological treatment technology is usually used. Activated sludge is one of the main treatment media. In the biological treatment process, activated sludge degrades organic matter and petroleum substances in the water into relatively stable products. At the same time, this forms a mixture containing microorganisms, residual grease and other solid wastes, namely activated oil sludge.
Oil Sludge Pyrolysis Technology Achieves Sustainable Recycling
Faced with today’s increasingly severe environmental challenges, oil sludge treatment and recycling have become a vital task. As an advanced treatment method, pyrolysis technology has shown significant potential and advantages. Oil sludge pyrolysis plant can efficiently separate and recover oil components from solid wastes such as oil-based chips, waste oil-based sludge, and oil sludge at the bottom of the tank. This technology can not only effectively reduce the amount of solid waste, but also safely treat oil residues. This recycling method that reduces the risk of environmental pollution meets the requirements of modern industry for sustainable development.
