Flow Assurance

Asphaltene Inhibitors/Dispersants

When asphaltene molecules – which are present in most oils and condensate liquids – become destabilized, asphaltene control is needed. Asphaltenes are usually present as a stabilized suspension in hydrocarbon liquids, and the molecules are destabilized by changes in conditions such as pH, electrical charges caused by movement in the reservoir and system, production operations (i.e., acidizing, CO₂ flooding, mixing production fluids, etc.), and pressure and temperature changes.

When asphaltenes are destabilized, the asphaltene molecules precipitate and form hard and brittle deposits. Like the damage caused by paraffin and mineral scale, these deposits can plug pore spaces in the reservoir and near wellbore area, form downhole blockages and emulsions, cause pump failures and tubing blockages, separation issues, and tank bottoms.

Asphaltene deposition is expensive to remove due to labor, equipment and chemicals; causes safety and environmental concerns; results in system downtime and lost production revenue; and at times, causes water treatment issues. Asphaltene is valuable in solution, so the key is to minimize your cost and lost production by keeping the asphaltene in solution from the reservoir to the refinery.

Asphaltene Control Features and Benefits

• Stabilizes asphaltene molecules in hydrocarbon liquids, reducing precipitation and deposition
• Reduces failure risks and provides additional asset integrity and system reliability, especially in subsea or deepwater production systems
• Maximizes hydrocarbon production and revenue by maintaining optimal production levels and getting the asphaltene to the refinery
• Minimizes separation issues and interface pad stabilizes by asphaltene molecules
• Eliminates downhole “rigid film” emulsion
• Reverses skin-damage caused by acids jobs
• Maximizes flow through separation and sales systems

Paraffin/Wax Inhibitors

Paraffin (wax) is a valuable component of hydrocarbon production. It may be present in trace amounts or constitute more than 50% of total hydrocarbon production in some oil fields. It is of critical importance to prevent paraffin from precipitating in the production system, as it is transported from the reservoir to the refinery.

Paraffin naturally crystalizes, precipitates and forms deposits with changes in pressure and temperature. All system locations are at risk of paraffin deposition once the oil cools to its wax appearance temperature (WAT). The WAT could be downhole (i.e., reservoir and near wellbore, perfs, tubing, pumps), or on the surface (i.e., flow lines, valves, headers, separation equipment, tanks, etc.).

When wax deposits form, they attract more wax crystals and grow, eventually blocking the flow channels. In some instances, wax co-precipitates with mineral scale and asphaltene, increasing the complexity of removal and disposal processes.

Veolia has formulated specialized ProSolv* Paraffin Control solutions to address paraffin issues consisting of inhibitors, dispersants and solvents. The key is to analyze the fluids and deposits and assess system operating parameters. With this knowledge, an effective paraffin control program can be designed to minimize operating issues and maximize hydrocarbon production and revenue.

ProSolv Paraffin Control Features and Benefits

• Minimizes deposition and production throughput
• Minimizes remediation and intervention to remove paraffin deposits
• Improves safety and reduced the environmental risks due to paraffin
• Fit for use in most oilfield situations
• Can be applied in several ways, including batch and continuous

Scale Inhibitors

Oilfield brines present many challenges, from the reservoir to the disposal wells. In addition to corrosive properties, these brines often contain scale-forming ions which can precipitate and form deposits throughout the system as changes in equilibrium occur. These changes may be related to temperature and pressure, the release of gases, pH, the mixing of incompatible brines and more. Scale inhibitors for oil and gas applications can help reduce the problem.

When scale forms, problems often occur such as: channels in the reservoir and well perforations become plugged; pumps load with the scale, overheat and fail; tubing and production lines become constricted and plug off; valves coat with scale and fail to function; equipment and heat exchangers become scale coated, losing efficiency and requiring costly remedial action; and salt water injection and disposal wells plug off with mineral scale, forcing the pumps to work harder thereby increasing energy cost and eventually failing, requiring equipment replacement and injection well and reservoir remediation.

Veolia realizes that mineral scale-forming tendencies are unique in each case. To control the many combinations of scale that may occur, a variety of fit-for-use ProSolv Scale Control products are required, to both control scaling tendencies and to remove deposits which may have formed.

ProSolv Scale Control Features and Benefits

• Mitigates issues unique to the mineral scale species present in a given system
• Ability to be applied via batch or squeeze, or continuously, to prevent formation of scale
• Effectively removes deposits of mineral scale
• Compatible with other chemicals applied in the system
• Optimizes flow through production and injection or disposal lines
• Ensures operations are running safely and efficiently

Hydrate Inhibitors

Since the early days of deep water oil & gas production, many flow assurance issues were caused by clathrates or gas hydrates. Hydrates are solids developed when water molecules form a cage-like structure around a gas molecule under high pressure conditions. Once hydrates begin to form, they grow rapidly and often plug off flow lines almost instantaneously.

Hydrate plugs are difficult and, in some cases, impossible to remove. The removal usually involves applying heat or chemicals (if possible) and it’s difficult, especially in subsea deep water, to get the treatment to the location of the plug. The industry agrees that it is far better to prevent hydrate deposition from occurring in the first place.

To form, hydrates must have three components: gas (organic or H2S, CO2), water and oil or condensate. For each system, predictive modeling software is used to identify hydrate threats. To control hydrates, removing or modifying one of the three components can prevent hydrate formation, or changing temperature and pressure conditions to put the system outside the hydrate zone will do the same. In many cases, this isn’t an option and the use of chemical additives to control hydrates is required.

If chemistry is the preferred control method, Veolia’s ProSolv Hydrate Inhibitors are available to mitigate the risk: Thermal Dynamic Inhibitors and Low Dosage Hydrate Inhibitors (Kinetic Hydrate Inhibitors, and Anti-agglomerants).

ProSolv Hydrate Inhibitor Features & Benefits

• Prevents hydrate formation in oil and gas production and transportation systems
• Provides effective control while the system is in the hydrate formation zone
• Controls hydrates and does not interfere with separation systems and water quality
• Maximizes flow through the lines and minimize hydrate control costs
• Fit for use in deep water system
• Compatible with polymers, plastics and metal in umbilical injection systems

Flow Improvers

In subsea lines, it is important to maximize production flow to allow for optimum production amounts. Many times, the formation of regular oil-in-water emulsions increases fluid viscosity, putting undue stress on pumps which leads to higher energy costs and premature failure.

Replacing subsea equipment is very costly and requires extensive logistical planning. In addition, factor in timing to ensure weather and sea conditions are just right, and the risk of safety and environmental issues that could occur.

To ensure maximum flow and minimized viscosity due to emulsified fluids, Veolia deep water certified ProSolv DW Emulsion Breakers are prescribed. These products will reduce emulsion formations, facilitating flow and operating separation process.

ProSolv Flow Improvers Feature and Benefits

• Improves flow through subsea flow lines
• Minimizes fluid viscosity and maximizes pump life
• Reduced energy requirements to pump fluids
• Fit for use in deep water system
• Stable under all conditions of subsea production
• Fully compatible with polymers, plastics, metallurgy in the umbilical injection system