Thermodynamics‐related processes during the migration of acid gases and methane in deep sedimentary formations

Abstract

TMGAS, an equation of state module of TOUGH2 V.2.0 reservoir simulator, was used to model the migration of CO2, H2S, and CH4 in a deep sedimentary formation. The scope is the improvement of the description of non‐condensable gas (NCG) migration within modeling studies of sedimentary basins’ evolution. Different scenarios have been simulated with NCG migration taking place in a large sedimentary formation discretized with a full 3D Voronoi approach by using specifically improved versions of the pre‐ and post‐processing tools for TOUGH2 developed at the University of Bologna. Simulated reference scenarios are related to the migration of CO2, H2S, and CH4 generated at constant rate for 1 × 106 years in a fresh water aquifer. Additional scenarios are simulated with NCG migration taking place in the same formation but saturated with brine. The effects of pressure‐temperature‐composition (PTX) conditions on thermodynamic equilibria, phase composition, phase thermo‐physical properties and, consequently, on the migration features of different NCGs are modeled and discussed. © 2016 Society of Chemical Industry and John Wiley & Sons, Ltd

Reply on RC1

“…This information can then be used as input to quantify scenario uncertainties, by delineating the spatial and temporal extent of CO2 influx. Transport and accumulation of CO2 across the subsurface can then be analyzed through approaches such as those described, e.g., in Battistelli et al (2016). From an operational standpoint, our approach could be applied to enhance our knowledge on the degree of compatibility of CO2 concentrations observed in field scale systems with the occurrence of CCR, as opposed to the action of other processes which might be considered in a large scale transport model of choice.…”

Quantification of CO2 generation in sedimentary basins through carbonate/clays reactions with uncertain thermodynamic parameters

“…We assume that the conceptual model proposed by Cathles and Schoell (2007) still holds when CO2 is in supercritical conditions. Supercritical CO2 is always characterized by lower density when compared to water and buoyancy effects always force the CO2rich separate gas phase to migrate upwards as soon as it is generated (Battistelli et al, 2016;Span and Wagner, 1996;Johnson et al, 1992). For simplicity, we refer in the following to the separate CO2rich phase as gaseous CO2.…”

Probabilistic modeling of field-scale CO<sub>2</sub> generation by carbonate–clay reactions in sedimentary basins

“…This information can then be used as input to quantify scenario uncertainties by delineating the spatial and temporal extent of CO 2 influx. Transport and accumulation of CO 2 across the subsurface can then be analyzed through approaches such as those described, e.g., in Battistelli et al (2017). From an operational standpoint, our approach could be applied to enhance our knowledge of the degree of compatibility of CO 2 concentrations observed in field-scale systems with the occurrence of CCR, as opposed to the action of other processes which might be considered in a large-scale transport model of choice.…”