Over time the oil and gas industry has developed practices that have reduced the generation of waste, improved the economics of drilling and production operations, and led to safer operations. Below are various oil and gas operations with a brief description next to each operation. Click on the process titles to view the wastes associated with each process. In addition, you will view the pollution prevention alternatives for each operation.

Drill Site Preparation Alternatives -- Drill site construction and rigging up are conducted in preparation for drilling activities. Drill site construction includes clearing and leveling land; building access roads; digging and lining the drilling mud reserve pit.

Drilling Rig Operations Alternatives -- Drilling activities include the operation of the drill rig and string to drill a surface hole and a drilling mud system. Drill rig operation uses numerous systems and various types of machinery.

Well Completion Alternatives -- Flowing wells consist of a wellhead assembly and associated equipment used for well treatment. When pressures in the oil reservoir are not sufficient to produce naturally, some method of artificial lift must be used. Artificial lift is accomplished by use of beam, gas lift, or submersible pumps. Flare pits collect unburned materials from the flare.

Separation and Treatment of Well Fluids Alternatives-- Well fluids often consist of a mixture of oil, gas, and water, which must be separated into components, measured, and treated. A few major considerations during this phase of production include vapor recovery, evaporation control, and fire hazard communication and control.

Storage and Transportation Alternatives-- Flow lines (gathering systems) are used to move produced oil to treatment and storage facilities (commonly referred to as ?tank batteries?). Tank batteries consist of separation and treatment equipment and stock tanks. The number and size of stock tanks vary depending on the daily production of the well(s) and frequency of pipeline runs. Stock tanks are used to store treated crude oil and produced water. Most stock tanks are constructed of steel and equipped with a bottom drain outlet for draining basic sediment and water. The tanks require periodic cleaning to remove basic sediment and water. Crude oil custody transfer is typically accomplished by moving the oil onto tank trucks via a loading line or into a pipeline.

Pipeline Alternatives -- Transportation of oil and gas includes the equipment and facilities used to move products through pipelines.

Liquid Hydrocarbon Separation Alternatives -- Oil absorption plants remove hydrocarbon products from natural gas.
Oil absorption plants include the following:
Stage separators (economizers)
Gas chillers
Rich oil flash tanks
Presaturators
Accumulators
Rich oil demethanizers

Dehydration Alternatives -- Hydrocarbon fluids may retain water. Hydrates form when a gas or liquid containing free water is cooled below its hydrate temperature. A dehydration process is used to avoid free-water problems that cause the formation of hydrates. Dehydration is the removal of water from the produced natural gas and is accomplished by various methods.

Recovery of Natural Gas Liquids Alternatives -- Natural gas liquids (e.g., propane) are used as refrigerants and fuels. Recovery of natural gas liquids is sometimes conducted at the gas plant. Cryogenics may be used to remove natural gas liquids. Filters are used in the gas preparation process (gas that is free of impurities is required). Electrostatic precipitators are sometimes used. Filtered substances include iron sulfide, crude oil, wax, and lube oil. Absorption may also be used to remove natural gas liquids. An absorption oil removes the heavier compounds from the process stream.

Amine Absorption Alternatives -- Amine adsorption is accomplished by passing the gas through the amine liquid where the impurity is dissolved or captured by chemical reaction. The amine can be regenerated. The most common systems use monoethanolamine (MEA) or diethanolamine (DEA). Lean amine is filtered. The reclaimer removes solids and heat-stable salts (amine degraded in the presence of air) and other MEA/DEA degradation products. Charcoal filters may be used to remove liquid contaminants when foaming is a problem. Defoamers may also be added to control foaming. The largest amine losses are usually due to carry-over from contactor due to foaming; continuous small leaks in piping, pump packing, and other fugitive emission points; and sulfur compounds. Charcoal filter beds are used to remove corrosion inhibitors, amines, absorber oils, glycol, and other sieve contaminants.

Dry Bed Absorption -- Dry bed adsorption uses one of a variety of absorbent materials (iron sponge is commonly used) to selectively remove sulfur compounds and CO2. Sulfur is removed from the H2S recovered from the produced gas. The Claus process is typically used to remove elemental sulfur from the H2S (acid gas). Tail-gas cleanup systems remove remaining sulfur from the exhaust.

Well Servicing and Workover Alternatives -- Well servicing operations include activities related to artificial lift installations, tubing string repairs, and work on other malfunctioning downhole equipment. A workover consists of more extensive repairs to increase or maintain production of a producing well.

Well Treatment Alternatives -- Well treatment and stimulation use various chemicals and products to improve the producing characteristics of a well.

Oil Recovery Alternatives -- Enhanced oil recovery operations typically involve the injection of water into a producing formation, as well as injection of certain chemicals. Thermally enhanced oil recovery operations use injected steam for enhanced recovery of crude oil. Steam generators are fueled by crude oil, fuel oil, or natural gas. Feed water is conditioned (softened) to prevent scaling.

Rig Maintenance Alternatives -- Rig maintenance activities include cleaning and lubricating rotating equipment, cleaning walking surfaces, painting to reduce rust, and replacing parts (e.g., valves). Periodic rig inspections may find structural weaknesses that require repair or replacement of rig structure.

Hydrate Inhibition and Separation Alternatives -- Wellhead treatment activities include use of corrosion and hydration inhibitors, and management of produced sand and water. Corrosion damage caused by acidic waters and gases, carbon dioxide, or oxygen is costly because it deteriorates or destroys oil well casing, tubing, and other metal parts. Corrosion inhibitors are chemicals used to counter the reaction between the acid in the gas and the iron of the tubing or other equipment. Usually it is accomplished at the wellhead, either by batch treatments or continuous injection. Many different chemicals can be used, depending on the cause of the corrosion. Because the formation of hydrates can cause restriction or stoppage of product in separation and treatment process, hydrate inhibitors are used. Hydrate inhibition at the wellhead is accomplished by injecting glycol, ammonia, methanol, or brine, or the use of indirect heaters that use bath solutions containing calcium chloride or glycol.

Truck Transportation Alternatives -- Service industry trucks haul a variety of things including but not limited to chemicals, fuel, lubricant, oil, produced water and equipment. Transportation of liquids involves tanker trucks connecting and disconnecting hoses and lines with the possibility of a worn or faulty line, valve, or connection leaking. Routine equipment inspections and replacements can be made to limit the possibility of leaks and spills thus limiting the environmental cleanup costs. Trucks can carry drip pans to place under connection points to catch any accidental release.

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