International Conference on Gas Hydrates (ICGH) (6th : 2008)

QUALIFICATION OF LOW DOSE HYDRATE INHIBITORS (LDHIS): FIELD CASES STUDIES DEMONSTRATE THE GOOD REPRODUCIBILITY OF THE RESULTS OBTAINED FROM FLOW LOOPS Peytavy, Jean-Louis; Glénat, Philippe; Bourg, Patrick

Abstract

Replacement of the traditional thermodynamic hydrate inhibitors (methanol and glycols) in multiphase applications is highly desirable for Health, Safety & Environment (HSE) considerations and for investment costs savings. Low Dose Hydrate Inhibitors (LDHI) are good candidates to achieve this objective and their interest is growing in the E&P industry. There are two types of LDHI: the Kinetic Hydrate Inhibitors (KHI) and the Anti-Agglomerants (AA) also called dispersant additives. The main challenge with LDHIs is that they require the unprocessed effluents to be produced inside the hydrate stability zone. It is then of the utmost importance to select, qualify and implement properly LDHIs, so that their field deployment is performed with success. But due to the very stochastic nature of the nucleation step, the hydrate crystallisation process leads to very large discrepancies between performances results carried out at lab or pilot scales. In order to overcome this difficulty, we have developed an in-house special protocol which is implemented prior to each qualification tests series. This in-house 15 years old protocol consists in conducting each tests series with a fluids system having previously formed hydrates in a first step but followed by a dissociation step at moderate temperature for a few hours. This paper presents results selected from several field cases studies and obtained from our 80 bara and 165 bara flow loops. They show the very good reproducibility obtained with and without LDHIs. In the case of KHI, where the stochastic nature of the nucleation step is very critical, the results show that the deviation on the “hold time” for a given subcooling is less than 15%. (Revised version of ICGH paper 5499_1)

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