The impact of geologic variability on capacity and cost estimates for storing CO2 in deep-saline aquifers

Abstract

While numerous studies find that deep-saline sandstone aquifers in the United States could store many decades worth of the nation's current annual CO 2 emissions, the likely cost of this storage (i.e. the cost of storage only and not capture and transport costs) has been harder to constrain. We use publicly available data of key reservoir properties to produce geo-referenced rasters of estimated storage capacity and cost for regions within 15 deep-saline sandstone aquifers in the United States. The rasters reveal the reservoir quality of these aquifers to be so variable that the cost estimates for storage span three orders of magnitude and average > $100/tonne CO 2 . However, when the cost and corresponding capacity estimates in the rasters are assembled into a marginal abatement cost curve (MACC), we find that~75% of the estimated storage capacity could be available for b $2/tonne. Furthermore,~80% of the total estimated storage capacity in the rasters is concentrated within just two of the aquifers-the Frio Formation along the Texas Gulf Coast, and the Mt. Simon Formation in the Michigan Basin, which together make up only~20% of the areas analyzed. While our assessment is not comprehensive, the results suggest there should be an abundance of low-cost storage for CO 2 in deep-saline aquifers, but a majority of this storage is likely to be concentrated within specific regions of a smaller number of these aquifers.

Economic evaluation of offshore storage potential in the US Exclusive Economic Zone

“…Our evaluation of the cost for onshore storage capacity in DSAs is essentially identical to that already published in Eccles et al 13 To estimate storage capacity, we use the same digital, geo-referenced grids of reservoir properties we created in Eccles et al 13 for 15 deep-saline sandstone DSAs from data published by the University of Texas at Austin's Bureau of Economic Geology. 18 Th ese grids, which include sand thickness, porosity and permeability, represent the geology of the DSAs underlying ~750 000 km 2 of the 2.1M km 2 that makes up the total surface area of the DSAs.…”

“…18 Th ese grids, which include sand thickness, porosity and permeability, represent the geology of the DSAs underlying ~750 000 km 2 of the 2.1M km 2 that makes up the total surface area of the DSAs. We also estimate storage costs for the DSAs using the same economic model in Eccles et al, 13 with one minor yet important change. In our original publication, we assumed the spacing of injection wells, which aff ects storage costs, to be constant.…”

“…We use data from a previous publication 13 on off shore storage capacity to assess its cost. Th ese data include geo-referenced grids of sea-fl oor depth, and sub-seafl oor sediment thickness and temperature, as well as digitized Deep-Sea Drilling Project and Ocean Drilling Project core data.…”

“…To estimate the cost of off shore storage, we modify the economic model in Eccles et al 13,21 into a version that is appropriate for the ocean environment. In this model, net sand thickness b is critical for calculating both storage capacity and cost.…”

“…13 In applying this model to DSAs distributed about continental USA, we have found that these reservoirs could store at least hundreds of gigatonnes of CO 2 , much of it at relatively low cost. 13 In this paper, we expand upon our onshore economic model to create a similar model for the off shore and use the latter model to estimate the cost of sequestering CO 2 in marine strata, including not only the deep-water self-sealing storage described previously but also off shore storage in non-self-sealing strata assuming the latter possess a caprock seal (Fig. 1).…”