The characteristics of fines migration and clogging of sediments recovered from the gas hydrate deposits from the Ulleng Basin, East sea, Korea [Caractéristiques de la migration des particules fines et du colmatage des sédiments récupérés à partir des gisements d'hydrate de gaz du bassin de l'Ulleng, mer de l'Est, Corée]

Abstract

The gas hydrates is an ice-like crystalline compound mostly composed of water and natural gas. Gas hydrates are widespread, occurring in both permafrost sediments and deep marine sediments on the world’s continental margins. The large amounts of gas hydrate reserves suggest the potential of gas hydrates as an energy resource if economically viable production methods were developed. The fines migration is one of the major issues for managing safe and efficient gas production from unconsolidated gas hydrate deposits. The migrating fines can alter geotechnical properties such as permeability and strength. Formation damage caused by fines migration and clogging reduce the permeability significantly and thus the productivity. Two-dimensional micro model test has been adopted to characterize fine migration and clogging. The varied test conditions include pore throat width, pore-water chemistry and single and multiphase flow. The tested sediments are natural fines extracted from the gas hydrate deposits in the Ulleung Basin, East sea, Korea. The test results show that the characteristics of permeability changes induced from fine migration can vary depending on the pore size distribution host sediments, the characteristics of fines, multiphase flow, and pore-fluid chemistry. Multiphase flow can accelerate the pore throat clogging by concentration and localizing fines at the gas-liquid interfaces. Pore fluid chemistry alters the capacity of certain fines to cluster and thus cluster size relative to the pore-throat width. The interactions can be also assessed with electrical sensitivity of fines.