Flow Assurance is a term used to describe the ability of fluid to flow from reservoir to sales point in an oil and gas system. On that path, there are several different equipment and processes embedded in the system. The image below, provided by Hart Energy, helps paint the picture.

Source: Hart Energy and Expro

Given the multiphase nature of oil and gas, plus the byproducts that get produced, there can be many different issues that arise causing oil not to easily flow. Below we will summarize.

Solids Production: The Main Suspects

Paraffin, sometimes known as petroleum wax, is organic deposit that can build up and cause disruptions in flow lines, pipes, tubing and well itself.

Asphaltenes are dissolved solids of crude oil, that dissolve in toulene, but don’t dissolve in pentane or heptane solutions. It’s the main ingredient in asphalt for roads/construction. These are oftentimes mixed in with paraffins and tricky to treat.

Scale is a deposit or coating found on surfaces sometimes found as calcium carbonate, calcium sulfate or barium sulfate. It’s also what you may find in your bathroom shower wall if you have hard water. Scale can affect completion equipment, tubulars, valves and more. Usually where water passes, because of the dissolved salts, scale has a higher likelihood of occurring. The tricky part about scale is that is that you have to understand what kind of scale you are dealing with to effectively remove.

Hydrates are ice-like solids that form when free water and natural gas combine at high pressure and low temperature. Hydrates are more common in cold climates and can form on gas pipelines, gathering facilities and compressor facilities.

Sand becomes an issue of concern when too much is produced due to formation damage occurring and when frac fluid production occurs. This is an issue in high volume scenarios such as with ESP production. It can affect equipment such as separators and the actual downhole pump.

Status Quo

Oftentimes, oilfield techs tend to generalize issues into broad categories such as wax or fouling. The issue with using “wax” as a terminology is that it usually encompasses paraffin, scale and asphaltenes. This makes it difficult to clearly diagnose which is the true problem, which will help in finding an applicable solution. Fouling is another term common in industry – this is basically any sort of living or non-living organisms that accumulate on surface areas. This can also encompass scale and paraffin if it’s sticking to equipment (aka surface areas). These generalizations are what have paved the way for more generic treatment paths such as hot oiling or hot watering, but an increased understanding of solids, but also general flow assurance and chemistry, has allowed the industry to improve their mechanisms.

Further Innovations

A technology category that has also helped operators better understand flow assurance is instrumentation devices and flow meters. By relying on devices that can better measure and estimate oil, water, and gas, combining this with mass balance approach, operators can deduce where issues are occurring in the production system. Sensors have also been developed to help pinpoint deposition location; an example of a Darcy Presenter is Rocsole.

New technology such as chemical solvents and dispersants, better microbial management, coatings, and ultrasonic cleaning, has been created over the last few years to help solve flow assurance problems.

Innovator Spotlight:

Most recently, anti-fouling technology such as Aculon's omniphobic nanocoatings, covalently bonds to substrates like stainless steel and other metals to functionalize the surface, repelling both organic and inorganic deposition. This technology can be applied to membranes in oil and gas, oil booms and other equipment that experiences fouling such as tubulars and coriolis meters.

Another interesting technology is Altum's software guided ultrasonic cleaning technology which can remediate fouling without having to stop production. This allows operators to clean equipment with the presence of fouling, such as heat exchangers, while in operation. Altum is also developing an anti-fouling version of their product to prevent fouling from occurring.

If this is a topic you care about, get in touch with our research team so we can explore further!

References

• https://www.slb.com/-/media/files/oilfield-review/p41-53
• https://petrowiki.spe.org/PetroWiki
• https://glossary.slb.com/
• https://darcypartners.com/research/production-report-flow-assurance-2020