Boris Bukhanov

The degradation of submarine permafrost and the destruction of hydrates on the shelf of east arctic seas as a potential cause of the “Methane Catastrophe”: some results of integrated studies in 2011

On the basis of the analysis of published data and in the course of the authors’ long-term geochemical and acoustic surveys performed in 1995–2011 on the East Siberian shelf (ESS) and aimed to research the role of the Arctic shelf in the processes of massive methane outbursts into the Earth’s atmosphere, some crucially new results were obtained. A number of hypotheses were proposed concerning the qualitative and quantitative characterization of the scale of this phenomenon. The ESS is a powerful supplier of methane to the atmosphere owing to the continued degradation of the submarine permafrost, which causes the destruction of gas hydrates. The emission of methane in several areas of the ESS is massive to the extent that growth in the methane concentrations in the atmosphere to values capable of causing a considerable and even catastrophic warning on the Earth is possible. The seismic data were compared to those of the drilling from ice performed first by the authors in 2011 in the southeastern part of the Laptev Sea to a depth of 65 m from the ice surface. This made it possible to reveal some new factors explaining the observed massive methane bursts out of the bottom sediments.

CO2 Capture by Injection of Flue Gas or CO2–N2 Mixtures into Hydrate Reservoirs: Dependence of CO2 Capture Efficiency on Gas Hydrate Reservoir Conditions

Injection of flue gas or CO2-N2 mixtures into gas hydrate reservoirs has been considered as a promising option for geological storage of CO2. However, the thermodynamic process in which the CO2 present in flue gas or a CO2-N2 mixture is captured as hydrate has not been well understood. In this work, a series of experiments were conducted to investigate the dependence of CO2 capture efficiency on reservoir conditions. The CO2 capture efficiency was investigated at different injection pressures from 2.6 to 23.8 MPa and hydrate reservoir temperatures from 273.2 to 283.2 K in the presence of two different saturations of methane hydrate. The results showed that more than 60% of the CO2 in the flue gas was captured and stored as CO2 hydrate or CO2-mixed hydrates, while methane-rich gas was produced. The efficiency of CO2 capture depends on the reservoir conditions including temperature, pressure, and hydrate saturation. For a certain reservoir temperature, there is an optimum reservoir pressure at which the maximum amount of CO2 can be captured from the injected flue gas or CO2-N2 mixtures. This finding suggests that it is essential to control the injection pressure to enhance CO2 capture efficiency by flue gas or CO2-N2 mixtures injection.

A novel method for CO2 storage and methane recovery in gas hydrate reservoirs through injection of flue gas from coal-fired power plants

The geological Storage of CO2 together with the recovery of methane gas from methane hydrate reservoirs in permafrost and sub-marine areas is promised a strategy towards overcoming climate change and energy supply. The major challenge in carbon capture and storage (CCS) is the difficulty in removing and capturing CO2 from other components of air mainly nitrogen, covering the main cost in CCS. In this study, a novel economical technique, without CO2 capture process, based on direct injection of flue gas from coal-fired power plants (14 mol% CO2, and 86 mol% N2) into gas hydrate reservoirs was investigated at bulk conditions. Experiments were conducted at different typical hydrate reservoir temperatures (278.2 K, and 283.2 K) and different ratio of flue gas to initiated methane hydrate. The efficiency of both CO2 storage and methane recovery were investigated by measuring the gas composition change during step-wise depressurization of system using gas chromatography. Methane recovery was induced by flue gas injection, shifting the methane hydrate phase boundary due to driving force of changed Vapour phase composition. In addition, injected CO2 was sequestrated as different types of hydrate. Finally, it’s concluded that CO2 storage efficiency is dependent on thermodynamic condition of the experiment.