Effect of confined boundary and mud-layers on depressurization-based gas recovery and land subsidence in hydrate reservoirs. Issue 1 (2nd January 2022)

• Record Type: Journal Article
• Authors: Singh, Raghvendra Pratap; Yadav, Rahul; Muralidhar, Krishnamurthy; Das, Malay K.
• Is Part Of: Marine georesources & geotechnology. Volume 40:Issue 1(2022)
• Page Start: 78
• Page End: 95
• Publication Date: 2022-01-02
• Subjects: Hydrate reservoirs -- mud-layers -- depressurization -- subsidence; Marine mineral resources -- Periodicals; 551.46
• DOI: 10.1080/1064119X.2020.1870181
• Languages: English
• ISSNs: 1064-119X

Abstract

Abstract: Hydrate reservoirs present numerous challenges due to their occurrence in ultra-deep regions, presence of mud-layers, unconfined boundaries, and complex morphological heterogeneities. Individual effect of some of these reservoir settings on overall production is known, however, a systematic assessment of their mutual impact on gas production and land subsidence is essential from production outcome point of view. In the present study, we address the mutual effect of confined boundaries and mud-layers, and their subsequent impact on depressurization induced gas recovery and land subsidence in hydrate reservoirs. Reservoir conditions are considered to be representative of Indian hydrate reservoirs. A numerical study is performed using a multiphase, multicomponent hydrate reservoir simulator externally coupled with a semianalytical subsidence model. Results indicate that the gas production vary by a large margin depending on whether the reservoir is confined or unconfined. Presence of mud-layers affects the overall gas production significantly, where, for an unconfined reservoir, hydrate dissociation is higher in reservoirs with thin mud-layers. Properly sealed reservoirs are more vulnerable to depressurization induced subsidence than poorly sealed reservoirs. Subsidence possibility for the reservoir with a higher number of mud-layers is lower and is the greatest for a reservoir with no mud-layers.