Sand migration modeling in hydrate-bearing sediments

Abstract:

Establishing a commercially viable extraction technique for methane gas production from hydrate-bearing sediments has been a major challenge. Hydrates, existing as solids in pores, make the host soil stronger, stiffer and more dilatant. Hydrates also occupy pore space, inhibiting fluid flow. Transforming them into gas phase through hydrate dissociation would therefore alter geomechanical as well as hydraulic characteristics of the hydrate-bearing sediments. These changes may cause sand migration, often excessively as has been found in the past field trials, and lead to termination of gas production operations. A better understanding of causes and effects of sand migration during gas production in hydrate-bearing sediments is therefore a vital step towards successful long-term operations.

This abstract presents an overview of the developed thermo-hydro-mechanical sand migration model in hydrate-bearing sediments. The highlights of the developed model include [1] sand (solid) status changes from intact, flowing to settled based on hydraulic gradient; [2] multiphase media for grain flow; [3] pressure and temperature field change due to grain flow; and [4] effective stress reduction induced by grain detachment.