Global Sensitivity Analysis to Assess Salt Precipitation for CO₂ Geological Storage in Deep Saline Aquifers

Abstract

Salt precipitation is generated near the injection well when dry supercritical carbon dioxide (scCO 2 ) is injected into saline aquifers, and it can seriously impair the CO 2 injectivity of the well. We used solid saturation ( ) to map CO 2 injectivity. was used as the response variable for the sensitivity analysis, and the input variables included the CO 2 injection rate ( CO 2 ), salinity of the aquifer ( NaCl ), empirical parameter , air entry pressure ( 0 ), maximum capillary pressure ( max ), and liquid residual saturation ( plr and clr ). Global sensitivity analysis methods, namely, the Morris method and Sobol method, were used. A significant increase in was observed near the injection well, and the results of the two methods were similar: NaCl had the greatest effect on ; the effect of 0 and max on was negligible. On the other hand, with these two methods, CO 2 had various effects on : CO 2 had a large effect on in the Morris method, but it had little effect on in the Sobol method. We also found that a low CO 2 had a profound effect on but that a high CO 2 had almost no effect on the value.

A numerical simulation of a dry‐out process for CO2 sequestration in heterogeneous deep saline aquifers

“…In the results of Ott et al ., the decreases in k a and the increase in k e are attributed to an increase in k rg . Salinity ( X NaCl ) is the most critical parameter in the parameter sensitivity analysis that affects the value of solid saturation . For different cores, the time of injection and the size of the core also make the amount of salt precipitation different, mainly due to the influence of the dry‐out time and relative amount between water and salt.…”

“…In site‐scale simulations, almost all research on dry‐out problems is based on homogeneous systems, or considers the saline aquifer as a layered structure, and establishes a simplified heterogeneous system model (inter‐layer structural model) . Indoor core‐scale experiments have revealed the influence of the heterogeneous and the low water content on the salt precipitation formed.…”

“…These simplifications are reasonable for the qualitative study of the effects of salt precipitation. However, for site‐scale simulation, and especially the quantitative evaluation of the effects of the dry‐out problem (such as solid saturation and injection well pressure), the accumulation of salt precipitation will be significantly underestimated using traditional equations and an homogeneous system model …”

Morris Sensitivity Analysis for Hydrothermal Coupling Parameters of Embankment Dam: A Case Study

“…Local methods are based on linear models and if a nonlinear term appears in the model, or if the uncertainty of an input variable affects the output at different orders of magnitude, then the local sensitivity analysis method might lead to incorrect results. In contrast, global sensitivity analysis methods can be used to test the interaction of parameters, and also the simultaneous effects of multiple parameters on the response variable [12]. The multivariate regression method [13], the Sobol sensitivity test method [7], the Fourier amplitude sensitivity test (FAST) [14], and the Morris sensitivity method [15] are some examples of these methods.…”

“…King and Perera [17] performed a case study on the Barwon urban water supply system in Australia and applied the Morris method to investigate the importance of input variables used to estimate the yield of urban water supply systems. Wang et al [12] used the Morris method to analyze the sensitivity of a salt precipitation model to its input parameters and obtained the main influencing factors in the salt precipitation problem. The Morris method was also used by Garcia Sanchez et al [18] to analyze and illustrate the potential usefulness of combining first-and second-order sensitivity analyses.…”