Lawrence Berkeley National Laboratory

© 2018 Elsevier Ltd The objective of this study is to quantify, by means of numerical simulation, the response of the complex system of gas hydrate accumulations at Site NGHP-02-09, Krishna-Godavari Basin, Indian Ocean, to different production conditions, and to determine the technical feasibility of gas production through depressurization-induced dissociation. The study assesses the suitability of the site for a long-term production test involving a single vertical well, and the long-term potential of the deposit under full-field production using a system of multiple vertical wells. We simulate gas and water flow, estimate the production performance of the accumulation and separately investigate the corresponding geomechanical response of the system. Results indicate that production from Site NGHP-02-09 under the conditions of a long-term field test involving a single vertical well is technically feasible and can yield high gas production rates. However, an inability to fully isolate the water bearing zones results in production that is largely from dissolved gas rather than hydrate dissociation and is thus burdened by excessive water production. Given the estimated physical properties of the reservoir system, Site NGHP-02-09 does not appear to be a promising location for a single-well field test of gas production, but may be a promising production target for full-field production operations using a multi-well system in which exterior wells can mitigate water inflows to allow interior wells to more effectively depressurize the formation and capture methane from gas hydrate dissociation. Geomechanical issues need to be carefully considered as significant displacements are possible, which can be challenging to well construction and stability.