CO₂injectivity in saline aquifers: The impact of non-Darcy flow, phase miscibility, and gas compressibility

Abstract

A key aspect of CO 2 storage is the injection rate into the subsurface, which is limited by the pressure at which formation starts to fracture. Hence, it is vital to assess all of the relevant processes that may contribute to the pressure increase in the aquifer during CO 2 injection. Building on an existing analytical solution for immiscible and spatially varying non-Darcy flow, this paper presents a mathematical model that accounts for combined effects of non-Darcy flow, phase miscibility, and gas compressibility in radial two-phase displacements. Results show that in low-permeability formations when CO 2 is injected at high rates, non-Darcy simulations forecast better displacement efficiency compared to flow under Darcy conditions. This will have a positive effect on the formation CO 2 storage capacity. This, however, comes at the cost of increased well pressures. More favorable estimations of the pressure buildup are obtained when CO 2 compressibility is taken into account because reservoir pressures are reduced due to the change in the gas phase properties. Also, non-Darcy flow results in a significant reduction in halite precipitation in the nearwell region, with a positive effect on CO 2 injectivity. In the examples shown, non-Darcy flow conditions may lead to significantly different pressure and saturation distributions in the near-well region, with potentially important implications for CO 2 injectivity.

Effects Of Gravity On Flow Behaviour Of Supercritical CO2 During Enhanced Gas Recovery (EGR) By CO2 Injection And Sequestration

“…Furthermore, D'Arcy equation, after Henry D'Arcy (1856), will be used to relate the pressure differential with time to simplify the flow behavioural depiction. The model is valid in for low injection rate, in our case, given that the inertial effect may not be significant to render the Darcy law assumption invalid (Mijic et al 2014). It can adequately describe the flow in the experiment.…”

A screening framework study to evaluate CO2storage performance in single and stacked caprock–reservoir systems of the Northern Appalachian Basin

“…18,19 The process of screening and selecting sites for CO 2 sequestration might also be performed by evaluating pressure buildup. 20,21 The results of experimental, analytical, and numerical studies show the importance of capillary entry pressure, the presence of a fractured zone, 15 and the permeability of caprock and reservoir 22 on CO 2 leakage through the caprock. Sensitivity analysis on the geomechanical response of injection using a 2D single reservoir-caprock system shows the significant effect of permeability and porosity of the system in the isothermal models, 23,24 temperature in the non-isothermal cases, 25 as well as reservoir confinement.…”

Coupled hydro-thermal-mechanical analysis for cold CO2 injection into a deep saline aquifer

“…The long-term sequestration of CO 2 in the reservoir is safeguarded by the sealing efficiency of overlying caprocks. The behavior of CO 2 flow in the storage reservoirs is the first step to the success of CO 2 sequestration [4]. Current analysis for the first step usually assumes a constant temperature of reservoir (called isothermal process later).…”