Geologic Storage Formation Classifications: Understanding Its Importance and Impacts on CCS Opportunities in the United States

摘要

A need exists for further research on carbon storage technologies to capture and store carbon dioxide (CO2) from stationary sources that would otherwise be emitted to the atmosphere. Carbon capture and storage (CCS) technologies have the potential to be a key technology for reducing CO2 emissions and mitigating global climate change. Deploying these technologies on a commercial-scale will require geologic storage formations capable of: (1) storing large volumes of CO2; (2) receiving CO2 at an efficient and economic rate of injection; and (3) safely retaining CO2 over extended periods. Eleven major types of depositional environments, each having their own unique opportunities and challenges, are being considered by the U.S. Department of Energy (DOE) for CO2 storage. The different classes of reservoirs reviewed in this study include: deltaic, coal/shale, fluvial, alluvial, strandplain, turbidite, eolian, lacustrine, clastic shelf, carbonate shallow shelf, and reef. Basaltic interflow zones are also being considered as potential reservoirs. DOE has recently completed this study which investigated the geology, geologic reservoir properties and confining units, and geologic depositional systems of potential reservoirs and how enhanced oil recovery (EOR) and coalbed methane (CBM) are currently utilizing CO2. The study looked at the classes of geologic formations, and their potential to serve as CO2 reservoirs, distribution, and potential volumes. This study discussed the efforts that DOE is supporting to characterize and test small- and large-scale CO2 injection into these different classes for reservoirs. These tests are important to better understand the directional tendencies imposed by the depositional environment that may influence how fluids flow within these systems today, and how CO2 in geologic storage would be anticipated to flow in the future. Although diagenesis has modified fluid flow paths during the intervening millions of years since they were deposited, the basic architectural framework created during deposition remains. Geologic processes that are working today also existed when the sediments were initially deposited. Analysis of modern day depositional analogs and evaluation of core, outcrops, and well logs from ancient subsurface formations give an indication of how formations were deposited and how fluid flow within the formation is anticipated to flow.