Taming Crude Behavior: Understanding production additives – Part 2

ByMark D. Halloran

 

Oil producers in North Dakota are objecting to any new state regulations that would require them to reduce the volatility of crude before it's loaded onto rail cars.

“Incorporating” Options
Oil industry professionals have traditionally had to accept the trade-offs associated with the use of hexane-based additives. This is largely because the few available alternatives, built on naturally-occurring organic chemicals, condensates (diluted bitumen) and a variety of polymers, didn’t offer a universally acceptable cost/performance balance.

More recently, however, chemists have applied new formulation techniques to introduce a class of additives with “anionic and nonionic” properties. Makers of these chemicals say they represent huge performance leaps over hexane solvents and other alternatives, and that they can be purchased at lower costs and used in much lower quantities.

These new additives, broadly classified as “incorporative/non-evaporative,” use a generic base as a vehicle to transport the anionic and nonionic active agents responsible for reducing the kinematic viscosity of the crude oil for fluidification and drag reduction purposes. These agents apply the science of polarity transformation, which allows them to physically act between the molecules in the crude and rearrange the force of attraction between each to achieve better cohesion. This causes the compact mass of the crude oil with a low API degree to become more fluid and capable of flowing through ducts and pipelines with less turbulence and drag.

The viscosity-reducing components of the additive’s active agents are also hydrocarbons, so they don’t affect the physical properties of substances in the processes of refining or refined products. For example, in the distillation towers, the compounds of each fraction are separating depending on their temperature, recovering in each fraction of the distillate the part that corresponds by its evaporation point.

The most notable feature of these new additives is that they don’t evaporate. Their composition allows them to incorporate into the crude oil, assuming its properties while performing the function for which they have been engineered, even as the temperature and pressure of the crude oil declines. Unlike the hexanes, these incorporative additives do not require re-heating or increased pressure in the flow stream. They effectively reduce drag and turbulence, and they are used in very small dosages (0.1% to 0.5% by volume treated as compared with 10% to 20% by volume treated for traditional hexane solvents like naphtha).

In addition, because the new additives incorporate into the crude oil mass, they do not represent a separate environmental threat apart from the crude oil itself, as hexanes do. There is no residual contamination if the additives are released into the environment separate from the crude. And while they are not considered bio-degradable, manufacturers say the additives aren’t harmful to humans or the environment if they are handled in accordance with practices outlined on their MSDS sheets.

Another area in which the new incorporative additives differ from traditional solvents is the unique “building block” method by which they are formulated. This allows users to customize and add features, such as increased fluidification and drag reduction, and even mix in additives to aid in wax/paraffin separation, asphaltene inhibiting, breaking of the crude oil-water emulsion, cleaning, recovery of crude oil, elimination of incrustations and bacteria, foam prevention, sulfhidric acid reduction, crude oil remediation and performance improvement for the end user.

Technology, Applied
Two common oilfield areas that stand to benefit directly from incorporative additive technology are production wells (upstream) and storage tanks (midstream). In the production well, the new additives can help fluidify the crude via molecular dispersion without altering its original composition. This, in turn, can help address the problems associated with clogged or inactive wells, and/or interruptions in production. Results of additive use in such applications can be faster movement of the crude, a reduction in pressure and better pump traction, all without the potential for adverse environmental impact inherent to hexane-based additives.

In storage tank cleaning applications, the incorporative additives can help recuperate a much larger quantity of the crude that would normally be retained in the tank due to viscosity. Since the additives have a high flashpoint (above 170° C in some formulations as compared with around 44° C for naphtha), they can also greatly reduce the risk of explosion due to static electricity.

This article is part 2 in a 3-part series. Part 1 can be found here. Part 3 can be found here.

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