Using a Reactive Transport Simulator to Simulate CH4 Production from Bear Island Basin in the Barents Sea Utilizing the Depressurization Method†

Abstract

Abstract:The enormous amount of methane stored in natural gas hydrates (NGHs) worldwide offers a significant potential source of energy. NGHs will be generally unable to reach thermodynamic equilibrium at their in situ reservoir conditions due to the number of active phases involved. Lack of reliable field data makes it difficult to predict the production potential and safety of CH 4 production from NGHs. While the computer simulations will never be able to replace field data, one can apply state-of-the-art modelling techniques to evaluate several possible long-term scenarios. Realistic kinetic models for hydrate dissociation and reformation will be required, as well as analysis of all phase transition routes. This work utilizes our in-house extension of RetrasoCodeBright (RCB), a reactive transport simulator, to perform a gas hydrate production case study of the Bjørnøya (Bear Island) basin, a promising field with very limited geological data reported by available field studies. The use of a reactive transport simulator allowed us to implement non-equilibrium thermodynamics for analysis of CH 4 production from the gas hydrates by treating each phase transition involving hydrates as a pseudo reaction. Our results showed a rapid propagation of the pressure drop through the reservoir following the imposition of pressure drawdown at the well. Consequently, gas hydrate dissociation and CH 4 production began in the early stages of the five-year simulation period.

Influence of Reservoir Stimulation on Marine Gas Hydrate Conversion Efficiency in Different Accumulation Conditions

“…As shown in Table 6, (2,8) , which meant intrinsic permeability k and initial NGH saturation S H0 had a more significant influence on CH 4 cumulative volume. Furthermore, when F 0.01 (2,8) > F N > F 0.05 (2,8) , crack quantity N had a significant influence on CH 4 cumulative volume, which was smaller than that of k and S H0 , and the significance of interaction between k, S H0 , and N were small. The results showed that the impact of intrinsic permeability, initial NGH saturation, and the stimulation effect on NGH conversion efficiency were significant; however, the interaction had no significant effect.…”

“…By comparing F i and F 0.05 (2,8) and F 0.01 (2,8) , the impact of factor i was significant when F i > F 0.05 (2,8) , and had a more significant influence when F i > F 0.01 (2,8) . As shown in Table 6, (2,8) , which meant intrinsic permeability k and initial NGH saturation S H0 had a more significant influence on CH 4 cumulative volume.…”

“…These are also known as "combustible ice" [2]. NGH is an alternate energy resource with great reserves [3], very clean natural gas can be produced from NGH deposits, especially from sandy turbidites, from which conventional hydrocarbons can be produced [4].…”

Simulation Study on the Effect of Fracturing Technology on the Production Efficiency of Natural Gas Hydrate

“…Among them, methane hydrate is the most widely-distributed in nature [1][2][3][4][5]. Marine gas hydrate is mainly developed in hydrate stability zones (HSZ) below a 500-m water depth in the open ocean, where temperatures and pressures are suitable for its spontaneous formation.…”

“…Fracturing technology can be divided into vertical and horizontal fracturing (Figure 2), according to the different characteristics of the formations [35]. Increasing the permeability of the hydrate layer can improve heat and mass transfer efficiency, increase the gas migration channels in the hydrate layer, accelerate the hydrate dissociation and discharge, and increase the gas production rate and the cumulative production of CH4 [4,13,28,30,36].…”