Vanja Krsmanovic, "Gas hydrate reservoirs: Detection, simulation and production technologies ", Master Thesis, School of Mineral Resources Engineering, Technical University of Crete, Chania, Greece, 2020
https://doi.org/10.26233/heallink.tuc.90919
Natural gas hydrates are distributed all over the planet, mainly in marine environments and in permafrost regions. If production methods that are developed could be economically profitable, the huge amounts of reserves of natural gas hydrates would be a potential source of energy. In order to develop drilling and production operations in this type of reservoirs, formation and dissociation of hydrates should be investigated. Due to the fact that there are not many production operations conducted in gas hydrate reservoirs, and therefore there is not enough production data available, it is very important to develop numerical simulations in order to predict productions in experimental studies and field production trials. In this thesis, an overview of gas hydrate reservoirs with a focus in reservoirs located in permafrost regions, such as Mallik, Messoyakha and Alaska North Slope, has been made. The Mallik site was drilled in 1998, while the focus was Gas Hydrate Research Well Program applied to Mallik 2002 site, thermal injection and depressurization of in-situ gas hydrate-bearing formation. Three tests were conducted and three zones of hydrate layers were observed. The Messoyakha Gas Field is located in Siberian permafrost, in Russia. It was the first discovered gas hydrate field. This is the only field where long-term production took place in an area of gas hydrate reservoirs. Production of gas reached the maximum in the first years of production until 1982. Evidence for the occurrence of gas hydrates in the Alaska North Slope comes from the analysis of cores and downhole logs from the gas hydrate test wells: The Mount Elbert, and Iġnik Sikumi wells. Mount Elbert Gas hydrate site is located in the Milne Point Field near the Prudhoe Bay oil field. In December 2018, drilling operations finally confirmed the presence of gas hydrates reservoirs. The new method of production was used, injection of CO2, and it is shown to be technically feasible in combination with depressurization. Nankai Trough, example of offshore gas hydrate production, is presented because of the fact that two production tests were conducted in this site. Method used for production was depressurization, and the goal of this study was to prove that production from offshore gas hydrates can be used for commercial purpose.