Title: Numerical Simulation of the Storage of Pure CO2 and CO2-H2S Gas Mixtures in Deep Saline Aquifers
Abstract: Numerical Simulation of the Storage of Pure CO2 and CO2-H2S Gas Mixtures in Deep Saline Aquifers Robin Chandra Ozah; Robin Chandra Ozah Search for other works by this author on: This Site Google Scholar Srivatsan Lakshminarasimhan; Srivatsan Lakshminarasimhan U. of Texas at Austin Search for other works by this author on: This Site Google Scholar Gary Arnold Pope; Gary Arnold Pope U. of Texas at Austin Search for other works by this author on: This Site Google Scholar Kamy Sepehrnoori; Kamy Sepehrnoori U. of Texas at Austin Search for other works by this author on: This Site Google Scholar Steven Lawrence Bryant Steven Lawrence Bryant U. of Texas at Austin Search for other works by this author on: This Site Google Scholar Paper presented at the SPE Annual Technical Conference and Exhibition, Dallas, Texas, October 2005. Paper Number: SPE-97255-MS https://doi.org/10.2118/97255-MS Published: October 09 2005 Connected Content Related to: Numerical Simulation of CO2 and CO2/H2S Storage in Deep Saline Aquifers Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Get Permissions Search Site Citation Ozah, Robin Chandra, Lakshminarasimhan, Srivatsan, Pope, Gary Arnold, Sepehrnoori, Kamy, and Steven Lawrence Bryant. "Numerical Simulation of the Storage of Pure CO2 and CO2-H2S Gas Mixtures in Deep Saline Aquifers." Paper presented at the SPE Annual Technical Conference and Exhibition, Dallas, Texas, October 2005. doi: https://doi.org/10.2118/97255-MS Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex Search Dropdown Menu nav search search input Search input auto suggest search filter All ContentAll ProceedingsSociety of Petroleum Engineers (SPE)SPE Annual Technical Conference and Exhibition Search Advanced Search AbstractWe have studied strategies for maximizing several phenomena beneficial to large-scale subsurface storage of waste gases such as CO2 and H2S. Numerical simulations using a compositional reservoir simulator were carried out for 10,000 years to understand the flow and long-term storage potential of pure CO2 and CO2-H2S mixtures in deep saline aquifers. Hysteresis in the relative permeability curve results in substantial volumes of gas trapping. Aquifer characteristics such as heterogeneity, dip angle and vertical to horizontal permeability ratio were varied to determine their effect on storage potential and injectivity of a CO2-H2S gas mixture. The opportunity for escape of the gases from the aquifer can be minimized by careful design of injection strategies. One such strategy is to use horizontal wells low in the formation so that all of the injected gases are trapped, dissolved or precipitated before they reach geological seals and/or faults. This allows significantly larger volumes of waste gases to be stored in a given aquifer. Preferential solubility of the H2S in brine reduces the distance H2S travels relative to CO2. Simulations with local grid refinement show that fingering due to buoyancy is mitigated by natural heterogeneity in the aquifer petrophysical properties. Thus the amount of gas trapping observed in coarse-grid simulations is likely to be a reasonable estimate of what can be obtained in the field. Three-dimensional simulations of coupled flow and reactive transport showed that the amount of CO2 sequestered as minerals was small relative to gas trapping and dissolution into brine. However, the mineralization further reduces the already small amount of mobile gas over long periods of time.IntroductionGeological sequestration of CO2 and other greenhouse gases is one of the few ways to store such gases in sufficient volumes to mitigate the greenhouse effect.[1,2,3] Several groups have reported numerical simulations of the storage process, usually in order to estimate the volume that can be stored. Most schemes depend on storing CO2 in the supercritical state. In these schemes, buoyancy forces will drive the injected CO2 upward in the aquifer until a geological seal is reached. The permanence of this type of sequestration depends entirely on the integrity of the seal. Assuring such integrity over very long periods of time is very difficult.We have focused on an alternative scheme built on three modes of sequestration that avoid this concern:pore-level trapping of the gas phase within the geologic formation;dissolution into brine in the aquifer; andprecipitation of dissolved gases as minerals. All three modes are well known phenomena among reservoir engineers and others familiar with flow and reaction in permeable media. Each of these modes is permanent for the time frame of interest in sequestration of waste gases. Here "permanent" means the following: gas placed in the aquifer will not reach the surface any sooner than other species or fluids originally present in the formation. The key issues then become 1) maximizing these three highly desirable modes of sequestration so that very large volumes can be permanently stored in aquifers, without the need for ensuring long-term seal integrity and 2) predicting the time needed for injected gas to become immobilized by one or more of these modes of storage.The principal petrophysical parameters influencing storage as an immobile gas phase (in this paper, we use the term "gas" to include "supercritical fluid") are relative permeability, including hysteresis, and the residual gas saturation. Both depend on the rock properties in the aquifer and thus can vary with location. The phase behavior of the gas/brine mixture controls storage in solution, and this depends upon gas compositing brine salinity, temperature and pressure. The geochemical driver accompanying storage is the acidification of the brine resulting from dissociation of dissolved CO2 and H2S. Low pH brine in turn induces several reactions with minerals in the formation. Dissolution reactions can release cations such as Ca++ and Fe++. These cations may form relatively insoluble carbonate precipitates such as siderite and sulfide precipitates such as pyrite. Keywords: storage, gas mixture, base case, percentage co2, enhanced recovery, capillary pressure, vertical slice, co 2, modeling & simulation, reservoir simulation Subjects: Reservoir Characterization, Reservoir Fluid Dynamics, Improved and Enhanced Recovery, Reservoir Simulation, Flow in porous media This content is only available via PDF. 2005. Society of Petroleum Engineers You can access this article if you purchase or spend a download.
Publication Year: 2005
Publication Date: 2005-10-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 4
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