Kinetic hydrate inhibitor removal from produced waters by solvent extraction

Anderson, Ross; Tohidi, Foroogh; Mozaffar, Houra; Tohidi, Bahman

doi:10.1016/j.petrol.2016.06.016

Cited by 13 publications

(12 citation statements)

References 10 publications

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“…The PVCap polymer might partition to this phase and be less active in the water phase where hydrate formation first occurs, thus giving poorer performance. The effect can be considered similar to the addition of medium-size organic carboxylic acids such as pentanoic and hexanoic acid or 1-octanol, which have been found to be effective at displacing KHI polymers such as PVCap from produced water. , This indicates the importance of finding the right concentration in order to not under- or overinhibit the system.…”

Section: Resultsmentioning

confidence: 99%

Further Investigation of Solvent Synergists for Improved Performance of Poly(N-vinylcaprolactam)-Based Kinetic Hydrate Inhibitors

Dirdal

Kelland

2021

Energy Fuels

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Poly(N-vinylcaprolactam) (PVCap) and related copolymers have been used as kinetic hydrate inhibitors (KHIs) to combat gas hydrate formation in oil and gas field production flow lines. It is known that the addition of certain solvents to the KHI polymer can enhance its ability to hinder gas hydrate formation. In an earlier study, a wide range of alcohols, glycol ethers, and ketones were investigated as synergetic solvents with PVCap. In that study, an outstanding synergetic effect was achieved by 4-methyl-1-pentanol (iHexOl). This report builds on that study by investigating iHexOl in more detail as well as some newly synthesized solvents predicted by the first study to have good synergism. Both slow constant cooling (SCC) and isothermal KHI experiments were conducted in high-pressure steel rocking cells using a structure II-forming natural gas mixture. The KHI polymer concentration, solvent concentration, and mixed solvent systems were investigated. The solvent synergist water solubility, also in brines, and partitioning to the liquid hydrocarbon phase are shown to be important factors to consider for optimizing KHI performance. Further, it was observed that the optimal molecular weight distribution for the KHI polymer when used with a solvent synergist is not the same as the optimum distribution when using the polymer alone.

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Section: Resultsmentioning

confidence: 99%

Further Investigation of Solvent Synergists for Improved Performance of Poly(N-vinylcaprolactam)-Based Kinetic Hydrate Inhibitors

Dirdal

Kelland

2021

Energy Fuels

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“…Another method involves solvent extraction by adding a tailor-made special solvent at the processing facilities, possibly with thermal treatment to reach a target temperature for optimizing the partitioning . For example, higher molecular weight carboxylic acids, such as pentanoic acid and higher, i.e., carboxylic acids with a carbon number of five or more, have been found to be effective at displacing KHI polymer from produced water. , A method of precipitation prevention in produced water containing KHIs injected downhole has been claimed . The method involves incorporating a water-immiscible solvent therein having a polarity index greater than about 3.…”

Section: Methods To Avoid Discharge Of Less Biodegradable Khismentioning

confidence: 99%

A Review of Kinetic Hydrate Inhibitors from an Environmental Perspective

Kelland

2018

Energy Fuels

111

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Kinetic hydrate inhibitors (KHIs) have been used in the upstream petroleum industry for about 25 years to prevent plugging of flow lines with gas hydrates. The main ingredients in current commercial KHI formulations are one or more water-soluble polymers which contain both hydrophobic and hydrophilic functionalities. Although the vast majority of KHIs are low in acute toxicity and bioaccumulation, very few commercial products show good biodegradability, and for that reason, there is always some concern of long-term chronic toxicity from partially degraded products if discharged into the environment. This report reviews all efforts to develop more biodegradable KHIs, and outlines the fact that some classes of so-called "green" chemicals are not necessarily readily biodegradable or low in toxicity. The review also covers methodologies to recover or destroy KHIs and reduce their discharge to the environment.

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“…8 Laboratory investigation of this approach demonstrates that, in most cases, almost all of the polymer can be removed from the aqueous phase by introducing a small fraction of an appropriate solvent "treatment chemical" (TC) to the system. 5 From an investigation into the potential of various chemicals for this purpose, fatty alcohols (mainly linear chain normal 1-hexanol to 1-octanol) were found to show the most promising removal effectiveness. Besides being an excellent solvent for various KHI polymers, the main desirable feature of fatty alcohols is their very low aqueous miscibility; some of the most effective for KHI removal are practically immiscible in water.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Besides being an excellent solvent for various KHI polymers, the main desirable feature of fatty alcohols is their very low aqueous miscibility; some of the most effective for KHI removal are practically immiscible in water. 5 Kinetic hydrate inhibitors are generally formulated to prevent gas hydrate formation from liquid water, so it is assumed that this requires themin particular the active polymeric componentto be miscible with the aqueous phase. As a result, commercially available KHI formulations are watermiscible as rule.…”

Section: ■ Introductionmentioning

confidence: 99%

Evaluation of a Novel Water-Immiscible Kinetic Hydrate Inhibitor Formulation

2018

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The application of low dosage kinetic hydrate inhibitors (KHIs) for hydrate mitigation in hydrocarbon production operations can offer considerable practical benefits and cost savings. However, there are still concerns over KHI usage, particularly with respect to fouling problems in produced water handling/disposal. One possible solution to fouling is KHI polymer removal from produced waters by solvent extraction, with fatty alcohols showing particular promise for this purpose, these having a high affinity for common KHI polymers, but very limited miscibility with water. In this study, it is demonstrated that such solvents can also be used to create novel water-immiscible KHI formulations, with these offering potential for KHI recycling/reuse. The fatty alcohol 1-octanol has been successfully used as carrier solvent for PVCap to produce a KHI, which is immiscible with water, yet shows comparable hydrate inhibition performance to aqueous PVCap. Evaluation of this immiscible KHI using a crystal growth inhibition method shows that it can work well in various systems, including for dry/lean gases, with highly saline waters, and even in the presence of liquid hydrocarbons, despite strong dilution by these.

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Kinetic hydrate inhibitor removal from produced waters by solvent extraction

Cited by 13 publications

References 10 publications

Further Investigation of Solvent Synergists for Improved Performance of Poly(N-vinylcaprolactam)-Based Kinetic Hydrate Inhibitors

Further Investigation of Solvent Synergists for Improved Performance of Poly(N-vinylcaprolactam)-Based Kinetic Hydrate Inhibitors

A Review of Kinetic Hydrate Inhibitors from an Environmental Perspective

Evaluation of a Novel Water-Immiscible Kinetic Hydrate Inhibitor Formulation

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