Low-dose hydrate inhibitors present new flow assurance option

A relatively new technology for hydrate mitigation is the family of chemical additives known as low dose hydrate inhibitors.

Gas hydrates with no anti-agglomerants.
Gas hydrates with no anti-agglomerants.
(Courtesy Clariant)

Zachary T. Ward, Nirupam Purkayastha, Felix Hoevelmann, Jonathan J. Wylde, Dirk Leinweber, Clariant

While oil prices have settled down from the volatility seen in recent years, further expectations indicate that the market is in a realignment phase. Within this realignment, new strategies for oil and gas production must be explored to remain competitive in this new environment.

In deepwater production, one of these new strategies is the installation of longer subsea tiebacks to develop remote reservoirs, where no existing host facilities are nearby; and a fixed installation is considered uneconomical. Subsea tiebacks with distances of more than 60 mi (97 km) between the well and host facility are not uncommon, and new technologies continue to push the boundaries of what was previously thought infeasible.

A principal consideration for subsea flow assurance is the prevention of gas hydrates. Formation and agglomeration of gas hydrates in pipelines may result in a plug that terminates oil and gas flow. Remediation costs for a gas hydrate plug are relatively high and the prevention of these plugs is of great importance. A number of mechanical and chemical options exist for the mitigation of gas hydrates. A classic method for hydrate prevention involves the use of antifreeze chemicals like methanol or ethylene glycol to thermodynamically inhibit hydrate formation.

However, oil producers and service providers must innovate to remain competitive. A relatively new technology for hydrate mitigation is the family of chemical additives known as low dose hydrate inhibitors (LDHI). LDHIs consist of two classes of chemicals: kinetic hydrate inhibitors (KHI) and anti-agglomerants (AA). Both classes are successfully used to mitigate gas hydrates in subsea and deepwater applications globally, though neither can be considered a universal solution.
LDHI chemistry provides a significant logistic and operating expense advantage over traditional alcohol treatments, where steep methanol-in-crude penalties have rendered methanol injection uneconomical for many fields. As deepwater production continues to push toward higher pressures, longer tiebacks and increasing water cuts, gas hydrate treatment using LDHIs is approaching the limit of current technology. 

Gas hydrates that have been treated with anti-agglomerants.Gas hydrates that have been treated with anti-agglomerants.

To remain competitive under this new market paradigm, Clariant has developed a high throughput experimentation (HTE) platform to rapidly accelerate new product development. This new platform brings together automation and intelligent analytics to fully automate all aspects of product development, including: test planning, formulation and synthesis, application testing, and results analysis. This platform only requires the chemical and test fluid inputs for testing. When combined with traditional application testing methods, such as the rocking cell, autoclave and/or flow loops, new products can be developed and delivered to market in a fraction of the time.

The typical life cycle of an innovation project is divided into several phases. The initial discovery phase involves extensive searching and application testing of a wide array of available materials to determine a potential solution. This is where the new HTE platform is capable of rapidly accelerating the innovation life cycle in addition to finding more candidates, leading to the determination of a better potential solution. Where traditional rocking cell methods would typically run two experiments per week, the HTE platform will run up to 24 experiments per day.

Once candidates are determined, the product identification phase begins where these candidates are fully tested on traditional methods to verify their performance. Once the ideal product is identified, the HTE platform may be used again to optimize the formulation with more granularity than traditional methods. Resulting in a more efficient product ready for introduction to the market.

This method was used to develop the first product in a suite of next-generation AA-LDHIs capable of reducing current LDHI consumption during production up to 30% as compared to current state of the art technology. These chemicals were developed using the new HTE platform in conjunction with currently established rocking cell and autoclave technology. This technology will enable continued production in fields that are currently reaching LDHI injection capacity due to design constraints.

Looking forward, additional products may be developed that are better tailored for their target application. •

More in Production