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Non-isothermal effects of a CO2 injection into a geologic reservoir
  • Richard Jayne,
  • Ryan Pollyea,
  • Yingqi Zhang
Richard Jayne
Virginia Polytechnic Institute and State University

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Ryan Pollyea
Virginia Polytechnic Institute and State University
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Yingqi Zhang
Lawrence Berkeley National Lab
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Carbon-capture and sequestration (CCS) in geologic reservoirs is one strategy for reducing anthropogenic CO2 emissions from large-scale point-source emitters. Recent developments have shown that basalt reservoirs are highly effective for permanent mineral trapping on the basis of CO2-water-rock interactions, which result in the formation of carbonate minerals. However, the injection of super-critical CO2 into the subsurface causes a disturbance in the pressure, temperature, and chemical systems within the target reservoir. How the ambient conditions change in response to a CO2 injection ultimately affects the transport and fate of the injected CO2. Understanding the behavior and transport of CO2 within a geologic reservoir is a difficult problem that is only exacerbated by heterogeneities within the reservoir, for example, permeability can be highly heterogeneous and exhibits significant control on the movement of CO2. The non-isothermal effects that accompany a CO2 injection are also affected by heterogeneous reservoir properties. These non-isothermal effects can lead to significant changes in temperature in both the reservoir water and rock, which can also affect the injectivity and movement of the CO2. This study is focused on gaining a better understanding of the non-isothermal effects of a CO2 injection and how the changes in temperature will affect the movement and reactivity of the CO2, as well as investigate the efficacy of using temperature as a proxy for CO2 breakthrough in the subsurface. iTOUGH2 eco2n is utilized to simulate CO2 injections into a 1D radially symmetric domain over a range of permeabilities, porosities, and salinities. Preliminary results indicate that for a modest CO2 injection rate of 31,500 metric tons/year the exothermic dissolution of CO2 can cause a temperature increase of up to 3.6oC at the edges of the CO2 plume and the Joule-Thomson effect can cause a decrease in temperature up to 10oC near the injection well. Additionally, results from this study indicate that the thermal effects of a CO2 injection, namely the heat of dissolution associated with a large-scale CO2 injection may be an effective MMV strategy for monitoring CO2 breakthrough.