The effect of gas production from deeper conventional gas reservoirs on shallower gas hydrate layer stability: A case study in the conditions of the Sakarya gas field, Western Black Sea


Aydin H., Merey S.

Journal of Natural Gas Science and Engineering, vol.94, 2021 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 94
  • Publication Date: 2021
  • Doi Number: 10.1016/j.jngse.2021.104103
  • Title of Journal : Journal of Natural Gas Science and Engineering
  • Keywords: Gas hydrate, Methane, Hydrate dissociation, Wellbore stability, Black sea, NUMERICAL-SIMULATION, HORIZONTAL WELL, METHANE HYDRATE, DEPRESSURIZATION

Abstract

© 2021 Elsevier B.V.Gas hydrate deposits are generally found in the shallow deepwater regions and permafrost regions. The presence of water, methane, and thermodynamic conditions (low temperature and high pressure) is critical for gas hydrate accumulation. Disturbing thermodynamic conditions such as depressurizing and thermal treatment are the primary processes for gas hydrate dissociation. In this study, we investigate the stability of a shallow depth gas hydrate layer in the conditions of conventional gas production from a newly discovered deep gas field, Sakarya gas field, Western Black Sea. The study focuses on thermal conduction generated by conventional gas production across the wellbore profile along the gas hydrate section. The study includes wellbore simulations using the academic version of PIPESIM to obtain temperature and pressure profiles across the wellbore and numerical simulations for thermal transition for various cases in the hydrate zone using TOUGH + HYDRATE v.1.5 (T + H). The temperature elevation in the hydrate zone was found to change between 19 K and 25 K. The critical temperature elevation for hydrate dissociation and hydrate dissociation front were determined using the simulations, which might cause wellbore stability problems in the long term. We increase the impact of the study by suggesting appropriate solutions to minimize the adverse effects of production from the hot and deep conventional gas on gas hydrate stability found at shallower depths.