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Study Evaluates Hydrate Antiagglomerants

Topics: Flow assurance

A common hydrate-management strategy involves the use of large volumes of thermodynamic inhibitors (THIs) to operate outside the hydrate-stability region. However, this strategy represents significant capital expenditure and operating costs. Low-dosage hydrate inhibitors (LDHIs), in the form of kinetic hydrate inhibitors (KHIs) and antiagglomerants (AAs), present an economical alternative to THIs. In this study, a quantitative micromechanical force (MMF) has been deployed to study the performance of seven industry AAs. The results illustrate that an effective AA is one that lowers the cohesive forces between hydrate particles.

Introduction

AAs prevent hydrate agglomeration of a steady-state hydrate slurry. Hydrate-philic AAs are surfactants that adsorb to the hydrate/oil interface in preference to the water/oil interface. Current operating experience suggests that AAs may be unsuited to the high water cuts that are characteristic of late field life. A successful hydrate AA lowers the cohesive force or surface free energy of hydrate particles to prevent agglomeration. Rocking cells and high-pressure visual autoclaves provide a semiquantitative assessment of hydrate blockage. However, a knowledge gap exists with regard to whether current industry AAs actually lower hydrate interparticle cohesive and surface free energy. Techniques to deconvolute the mechanism of the action of AAs are required to better understand how AAs affect hydrate blockage.

Experimental Procedure

Micromechanical Hydrate Cohesive Force. A third-generation MMF apparatus was used to measure the cyclopentane hydrate interparticle cohesive force. The MMF uses cyclopentane to create Structure II cyclopentane hydrates, the same hydrate structure present in the field. The cohesive-force-measurement technique was adapted from previous research on hydrate cohesion and asphaltene cohesion.

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper OTC 28578, “Quantitative Ranking and Development of Hydrate Antiagglomerants,” by Shane A. Morrissy, Temiloluwa O. Kuteyi, Mike L. Johns, Eric F. May, SPE, and Zachary M. Aman, SPE, University of Western Australia, and Stuart F. McKay, SPE, Woodside Energy, prepared for the 2018 Offshore Technology Conference Asia, Kuala Lumpur, 20–23 March. The paper has not been peer reviewed. Copyright 2018 Offshore Technology Conference. Reproduced by permission.
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Study Evaluates Hydrate Antiagglomerants

01 September 2019

Volume: 71 | Issue: 9

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