A review of formation damage processes encountered during gas hydrate production

Although gas hydrates have not yet been produced commercially, several lab and hlfield-scale trials have demonstrated the feasibility of producing gas from subsurface gas hydrate reservoirs both offshore and on land. However, during field-scale production trials, common formation damage problems such as sand migration and fluid invasion were identified. Therefore, it is crucial to comprehend how the damage arises, how it can be quantified, and what tactics must be used to cope with the effects of the formation damages before commercial production. During production, hydrates dissociate releasing the trapped (methane) gas and yield large volumes of fresh water. The unconsolidated sediments that typically make up gas hydrate reservoirs can lose integrity when hydrate dissociates, and the sediment grains can readily mobilize and subsequently become trapped elsewhere in the porous medium. This entrapment can result in a loss of permeability as the fluid flow paths are blocked. Furthermore, the water released during hydrate dissociation may also freeze due to the low temperatures and the cooling effect from hydrate dissociation, which can further clog the pore space. The hydrate dissociation also changes the geomechanical properties of the formation and causes the sediments to collapse. Water and gas blockage can also occur due to the fluid invasion occurring during drilling and completion operations, and adverse chemical interactions can occur between the rock minerals and the released produced fresh water. Sand control is a relatively mature field in the oil and gas industry, but applying sand control principles to gas hydrate reservoirs remains a challenge and active area of research. Current areas of research in preventing formation damage during methane hydrate production include optimizing the production parameters particularly the solid–liquid velocity and depressurization rate, introducing nanoparticles to stabilize loose grains in the hydration layer, and using the correct additives in the drilling fluid to limit early hydrate dissociation.