{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,23]],"date-time":"2026-10-23T16:30:59Z","timestamp":1792773059234,"version":"4.5.0"},"reference-count":48,"publisher":"American Chemical Society (ACS)","license":[{"start":{"date-parts":[[2026,10,23]],"date-time":"2026-10-23T00:00:00Z","timestamp":1792713600000},"content-version":"stm-asf","delay-in-days":0,"URL":"https:\/\/doi.org\/10.15223\/policy-029"},{"start":{"date-parts":[[2026,10,23]],"date-time":"2026-10-23T00:00:00Z","timestamp":1792713600000},"content-version":"stm-asf","delay-in-days":0,"URL":"https:\/\/doi.org\/10.15223\/policy-037"},{"start":{"date-parts":[[2026,10,23]],"date-time":"2026-10-23T00:00:00Z","timestamp":1792713600000},"content-version":"stm-asf","delay-in-days":0,"URL":"https:\/\/doi.org\/10.15223\/policy-045"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>CO2 huff-and-puff has emerged as a promising approach for enhanced oil recovery in unconventional source rock shales, yet the underlying recovery mechanisms remain difficult to isolate and quantify. Here, high-field 1H nuclear magnetic resonance (NMR) spectroscopy was used to investigate in situ CO2\u2013shale interactions in a preserved, intact slim source rock plug. CO2 was stepwise loaded from 0 to 6000 psi and unloaded back to 0 psi at 40 \u00b0C. At each pressure step, 500 MHz 1H spectra were acquired and deconvoluted into two Lorentzian peaks representing pore fluid and one Gaussian peak representing kerogen. Pressure-dependent changes in the integrals and line widths of these peaks were used to investigate hydrocarbon depletion from the rock sample and CO2-induced changes in molecular mobility of kerogen and pore fluids. In control experiments, helium injections up to 2500 psi produced no measurable changes in the NMR spectra. In contrast, CO2 injections caused pronounced, pressure-dependent changes in intensities and line widths of 1H NMR signals, revealing mixing with pore fluids and penetration into the kerogen matrix. Both pore fluid and kerogen spectra changed markedly as CO2 entered the supercritical regime above 1000 psi at 40 \u00b0C, indicating a distinct transition in molecular mobility. Above 4000 psi, substantial light hydrocarbon evaporation from the plug left heavier, less-mobile components in the pores, resulting in broader NMR peaks. Analysis of the complete loading\u2013unloading cycle indicated that approximately 24.5% of the initial pore fluid was produced, dominated by late-stage high-pressure CO2 loading. These results demonstrate that high-field 1H NMR can quantify hydrocarbon recovery while resolving molecular-scale CO2 interactions with different components in source rock shales that are not easily accessible by conventional mass-balance methods.<\/jats:p>","DOI":"10.1021\/acs.energyfuels.6c03407","type":"journal-article","created":{"date-parts":[[2026,10,23]],"date-time":"2026-10-23T14:05:59Z","timestamp":1792764359000},"source":"Crossref","is-referenced-by-count":0,"title":["CO2 Enhanced Hydrocarbon Recovery in Organic-Rich\nShales: Insights from 500 MHz 1H NMR"],"prefix":"10.1021","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-0722-0244","authenticated-orcid":true,"given":"Jin-Hong","family":"Chen","sequence":"first","affiliation":[{"name":"Aramco Americas: Aramco Research Center-Houston , , ,","place":["Houston, Texas, United States, 77084"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"J. David","family":"Broyles","sequence":"additional","affiliation":[{"name":"Aramco Americas: Aramco Research Center-Houston , , ,","place":["Houston, Texas, United States, 77084"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mohammed","family":"Boudjatit","sequence":"additional","affiliation":[{"name":"Saudi Aramco , ,","place":["Dhahran, Saudi Arabia, 31311"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"316","published-online":{"date-parts":[[2026,10,23]]},"reference":[{"key":"2026102310021615800_cit1","unstructured":"EIA.\n          . U.S. crude oil\nproduction rose in 2025, setting new record DOE United States, 2026. https:\/\/www.eia.gov\/todayinenergy\/detail.php?id=67404."},{"key":"2026102310021615800_cit2","unstructured":"EIA.\n          . U.S. natural\ngas production reached a new record in 2025, 2026. https:\/\/www.eia.gov\/todayinenergy\/detail.php?id=67345."},{"key":"2026102310021615800_cit3","doi-asserted-by":"crossref","unstructured":"Clark, A. J.\n           In  Determination of\nRecovery Factor in the Bakken Formation, Mountrail County, ND, SPE Annual Technical Conference and Exhibition; OnePetro, 2009.","DOI":"10.2118\/133719-STU"},{"key":"2026102310021615800_cit4","doi-asserted-by":"crossref","unstructured":"Fassihi, M. R.; Kovscek, A. In  Pushing Oil Recovery\nTechnical Limits For Liquids-Rich Shales, IOR; European Association of Geoscientists & Engineers, 2021; pp 1\u201321.","DOI":"10.3997\/2214-4609.202133157"},{"issue":"8","key":"2026102310021615800_cit5","doi-asserted-by":"publisher","DOI":"10.1115\/1.4065382","article-title":"Analysis of Ultimate\nGas Recovery in Shale Reservoirs","volume":"146","author":"Zhang","year":"2024","journal-title":"J. Energy\nResour. Technol."},{"issue":"6","key":"2026102310021615800_cit6","doi-asserted-by":"publisher","first-page":"4262","DOI":"10.1016\/j.petsci.2024.07.029","article-title":"Production decline\ncurve analysis of shale oil wells:\nA case study of Bakken, Eagle Ford and Permian","volume":"21","author":"Tang","year":"2024","journal-title":"Pet. Sci."},{"key":"2026102310021615800_cit7","doi-asserted-by":"crossref","unstructured":"Kovscek, A. R.; Tang, G. Q.; Vega, B. In  Experimental\nInvestigation\nof Oil Recovery from Siliceous Shale by CO2 Injection, SPE\nAnnual Technical Conference and Exhibition: OnePetro, 2008.","DOI":"10.2118\/115679-MS"},{"key":"2026102310021615800_cit8","doi-asserted-by":"crossref","unstructured":"Hoffman, B. T.\n           In  Huff-N-Puff Gas\nInjection Pilot Projects in the Eagle Ford, SPE Canada Unconventional\nResources Conference; OnePetro, 2018.","DOI":"10.2118\/189816-MS"},{"key":"2026102310021615800_cit9","unstructured":"Hoffman, B. T.; Evans, J. G. In  Improved Oil Recovery\nIor Pilot Projects in the Bakken Formation, SPE Low Perm\nSymposium; OnePetro, 2016."},{"key":"2026102310021615800_cit10","doi-asserted-by":"publisher","DOI":"10.1016\/j.fuel.2022.125676","article-title":"Experimental\nevaluation of enhanced oil recovery in unconventional reservoirs using\ncyclic hydrocarbon gas injection","volume":"331","author":"Akbarabadi","year":"2023","journal-title":"Fuel"},{"key":"2026102310021615800_cit11","unstructured":"Schmidt, M.; Sekar, B. K.\n          Innovative Unconventional2\nEOR-a Light EOR an Unconventional Tertiary Recovery Approach to an\nUnconventional Bakken Reservoir in Southeast Saskatchewan\n          21st World Petroleum Congress\n          2014; Vol. 12."},{"issue":"06","key":"2026102310021615800_cit12","doi-asserted-by":"publisher","first-page":"695","DOI":"10.2118\/153853-PA","article-title":"Wettability Survey\nin Bakken Shale With Surfactant-Formulation Imbibition","volume":"15","author":"Wang","year":"2012","journal-title":"SPE Reservoir Eval. Eng."},{"key":"2026102310021615800_cit13","doi-asserted-by":"publisher","first-page":"183","DOI":"10.1016\/j.jngse.2018.08.029","article-title":"Electromagnetic\nthermal stimulation\nof shale reservoirs for petroleum production","volume":"59","author":"Chen","year":"2018","journal-title":"J. Nat. Gas Sci. Eng."},{"key":"2026102310021615800_cit14","doi-asserted-by":"publisher","DOI":"10.1016\/j.fuel.2020.118976","article-title":"Electromagnetic-heating\nenhancement\nof source rock permeability for high recovery","volume":"283","author":"Chen","year":"2021","journal-title":"Fuel"},{"key":"2026102310021615800_cit15","doi-asserted-by":"publisher","first-page":"112","DOI":"10.1016\/j.fuel.2018.04.012","article-title":"Co 2 -EOR\nMechanisms in Huff-N-Puff Operations in Shale\nOil Reservoirs Based on History Matching Results","volume":"226","author":"Alfarge","year":"2018","journal-title":"Fuel"},{"key":"2026102310021615800_cit16","doi-asserted-by":"crossref","unstructured":"Alzobaidi, S.; Kortunov, P.; Chhatre, S.; Chen, A.; Guice, K.; Baier, K.; Messner, M.; Leiphart, J.; Laverick, L.; Longoria, R.; Valenza, J.; Meier, S.; Rainey, J. In  Experimental Evaluation of Huff and Puff EOR Mechanisms in Unconventional\nRock, SPE\/AAPG\/SEG Unconventional Resources Technology Conference, 2022.","DOI":"10.15530\/urtec-2022-3719062"},{"issue":"5","key":"2026102310021615800_cit17","doi-asserted-by":"publisher","first-page":"5331","DOI":"10.1021\/acs.energyfuels.9b03658","article-title":"A Literature Review\nof CO2, Natural Gas, and Water-Based Fluids for Enhanced Oil Recovery\nin Unconventional Reservoirs","volume":"34","author":"Burrows","year":"2020","journal-title":"Energy Fuels"},{"key":"2026102310021615800_cit18","doi-asserted-by":"publisher","DOI":"10.2118\/1017-0034-JPT","article-title":"Shale EOR\nWorks, but Will It Make a Difference?","volume":"69","author":"Rassenfoss","year":"2017","journal-title":"J. Pet.\nTechnol."},{"key":"2026102310021615800_cit19","unstructured":"Occidental-Petroleum-Corp.\n          . Third Quarter Earnings Presentation2025https:\/\/www.oxy.com\/investors\/quarterly-earnings\/."},{"key":"2026102310021615800_cit20","volume-title":"Carbon Dioxide Capture\nand Storage: Special Report of the Intergovernmental Panel on Climate\nChange","author":"Metz","year":"2005"},{"key":"2026102310021615800_cit21","doi-asserted-by":"crossref","first-page":"2225","DOI":"10.1016\/B978-008044704-9\/50306-2","article-title":"Analysis of\nDevonian black shales in kentucky for potential carbon dioxide sequestration\nand enhanced natural gas production","volume-title":"Greenhouse\nGas Control Technologies 7","author":"Nuttal","year":"2005"},{"issue":"5948","key":"2026102310021615800_cit22","doi-asserted-by":"publisher","first-page":"1656","DOI":"10.1126\/science.1175677","article-title":"Onshore\nGeologic Storage of CO2","volume":"325","author":"Orr","year":"2009","journal-title":"Science"},{"issue":"15","key":"2026102310021615800_cit23","doi-asserted-by":"publisher","first-page":"9222","DOI":"10.1021\/acs.est.5b01982","article-title":"A Model\nTo Estimate Carbon Dioxide Injectivity and Storage Capacity for Geological\nSequestration in Shale Gas Wells","volume":"49","author":"Edwards","year":"2015","journal-title":"Environ. Sci.\nTechnol."},{"key":"2026102310021615800_cit24","doi-asserted-by":"crossref","unstructured":"Ribeiro, L.; Thoma, A.; Bryant, J.; Sundararajan, D.; Zurovec, W. In  Lessons Learned from the Large-Scale\nCO2 Stimulation of 11 Unconventional Wells in the Williston Basin:\nA Practical Review of Operations, Logistics, Production Uplift, and\nCO2 Storage, SPE Hydraulic Fracturing Technology Conference\nand Exhibition; OnePetro, 2022.","DOI":"10.2118\/209159-MS"},{"key":"2026102310021615800_cit25","doi-asserted-by":"publisher","DOI":"10.1016\/j.ijggc.2025.104406","article-title":"A review of modeling approaches for\nCO2 injection into depleted gas reservoirs: Coupling transient wellbore\nand reservoir dynamics","volume":"145","author":"Mohammadi","year":"2025","journal-title":"Int. J. Greenhouse Gas\nControl"},{"key":"2026102310021615800_cit26","doi-asserted-by":"crossref","unstructured":"Hoffman, B. T.; Reichhardt, D. In  Quantitative Evaluation\nof Recovery Mechanisms for Huff-N-Puff Gas Injection in Unconventional\nReservoirs; SPE\/AAPG\/SEG Unconventional Resources Technology\nConference, 2019.","DOI":"10.2118\/195223-MS"},{"key":"2026102310021615800_cit27","doi-asserted-by":"publisher","DOI":"10.1016\/j.cej.2025.160098","article-title":"Mechanisms of CO2 huff and puff enhanced oil recovery\nand storage within shale nanopores","volume":"506","author":"Wang","year":"2025","journal-title":"Chem. Eng.\nJ."},{"issue":"3","key":"2026102310021615800_cit28","doi-asserted-by":"publisher","first-page":"1814","DOI":"10.1016\/j.petsci.2024.02.006","article-title":"A multi-mechanism\nnumerical simulation model for CO2-EOR\nand storage in fractured shale oil reservoirs","volume":"21","author":"Wang","year":"2024","journal-title":"Pet. Sci."},{"issue":"12","key":"2026102310021615800_cit29","doi-asserted-by":"publisher","first-page":"848","DOI":"10.2110\/jsr.2009.092","article-title":"Morphology,\nGenesis,\nand Distribution of Nanometer-Scale Pores in Siliceous Mudstones of\nthe Mississippian Barnett Shale","volume":"79","author":"Loucks","year":"2009","journal-title":"J. Sediment.\nRes."},{"issue":"6","key":"2026102310021615800_cit30","doi-asserted-by":"publisher","first-page":"1071","DOI":"10.1306\/08171111061","article-title":"Spectrum of pore types\nand networks in mudrocks and a descriptive classification for matrix-related\nmudrock pores","volume":"96","author":"Loucks","year":"2012","journal-title":"AAPG Bull."},{"issue":"23","key":"2026102310021615800_cit31","doi-asserted-by":"publisher","first-page":"23025","DOI":"10.1021\/acs.energyfuels.4c04525","article-title":"Quantification of\nCO2 Uptake Capacity in Source Rock Shales for Geologic Carbon Sequestration:\nA 13C Nuclear Magnetic Resonance Spectroscopy Method","volume":"38","author":"Chen","year":"2024","journal-title":"Energy Fuels"},{"key":"2026102310021615800_cit32","doi-asserted-by":"crossref","first-page":"403","DOI":"10.1016\/B978-0-12-818571-1.00011-X","article-title":"11 - Analytical pyrolysis of several organic geopolymers","volume-title":"Analytical Pyrolysis of Natural Organic Polymers","author":"Moldoveanu","year":"2021","edition":"2"},{"issue":"1","key":"2026102310021615800_cit33","doi-asserted-by":"publisher","first-page":"72","DOI":"10.1021\/ef00001a013","article-title":"Effect\nof pressure on carbon dioxide induced coal swelling","volume":"1","author":"Reucroft","year":"1987","journal-title":"Energy Fuels"},{"issue":"5","key":"2026102310021615800_cit34","doi-asserted-by":"publisher","first-page":"719","DOI":"10.1016\/0016-2361(88)90305-5","article-title":"A direct measurement\nof expansion in coals and macerais induced by carbon dioxide and methanol","volume":"67","author":"Walker","year":"1988","journal-title":"Fuel"},{"issue":"6","key":"2026102310021615800_cit35","doi-asserted-by":"publisher","first-page":"1595","DOI":"10.1021\/ef0301349","article-title":"Heterogeneous\nSorption and Swelling in a Confined and Stressed Coal during CO 2\nInjection","volume":"17","author":"Karacan","year":"2003","journal-title":"Energy Fuels"},{"issue":"4","key":"2026102310021615800_cit36","doi-asserted-by":"publisher","first-page":"229","DOI":"10.1016\/j.coal.2006.06.004","article-title":"Measurement and interpretation\nof supercritical CO2 sorption on various\ncoals","volume":"69","author":"Siemons","year":"2007","journal-title":"Int. J. Coal Geol."},{"key":"2026102310021615800_cit37","doi-asserted-by":"crossref","unstructured":"Alharthy, N.; Teklu, T.; Kazemi, H.; Graves, R.; Hawthorne, S.; Braunberger, J.; Kurtoglu, B. In  Enhanced\nOil Recovery in Liquid-Rich\nShale Reservoirs: Laboratory to Field, SPE Annual Technical\nConference and Exhibition; OnePetro, 2015.","DOI":"10.2118\/175034-MS"},{"key":"2026102310021615800_cit38","doi-asserted-by":"crossref","unstructured":"Jin, L.; Hawthorne, S.; Sorensen, J.; Pekot, L.; Bosshart, N.; Gorecki, C.; Steadman, E.; Harju, J. In  Utilization of Produced Gas for Improved\nOil Recovery and Reduced Emissions from the Bakken Formation, SPE Health, Safety, Security, Environment, & Social Responsibility\nConference; OnePetro, 2017.","DOI":"10.2118\/184414-MS"},{"key":"2026102310021615800_cit39","doi-asserted-by":"crossref","unstructured":"Hawthorne, S. B.; Sorensen, J.; Miller, D. J.; Gorecki, C.; Harju, J.; Pospisil, G. In  Laboratory\nStudies of Rich Gas\nInteractions with Bakken Crude Oil to Support Enhanced Oil Recovery, SPE\/AAPG\/SEG Unconventional Resources Technology Conference, 2019.","DOI":"10.15530\/urtec-2019-961"},{"key":"2026102310021615800_cit40","doi-asserted-by":"publisher","first-page":"1149","DOI":"10.1016\/j.jngse.2016.04.009","article-title":"Characterization\nof carbonate mudrocks of the Jurassic Tuwaiq Mountain Formation, Jafurah\nbasin, Saudi Arabia: Implications for unconventional reservoir potential\nevaluation","volume":"33","author":"Hakami","year":"2016","journal-title":"J. Nat. Gas Sci. Eng."},{"issue":"06","key":"2026102310021615800_cit41","doi-asserted-by":"publisher","first-page":"982","DOI":"10.30632\/PJV66N6-2025a5","article-title":"Measurement of CO2\nUptake Capacity in Source Rock Shales for GCS","volume":"66","author":"Chen","year":"2025","journal-title":"Petrophysics"},{"key":"2026102310021615800_cit42","volume-title":"The Principles of Nuclear\nMagnetism","author":"Abragam","year":"1961"},{"issue":"3","key":"2026102310021615800_cit43","doi-asserted-by":"publisher","first-page":"755","DOI":"10.1021\/acs.macromol.8b01836","article-title":"Modeling and\nSimulations of Polymers:\nA Roadmap","volume":"52","author":"Gartner","year":"2019","journal-title":"Macromolecules"},{"key":"2026102310021615800_cit44","doi-asserted-by":"crossref","first-page":"80","DOI":"10.1017\/CBO9780511623189.004","article-title":"The vibrational\nmodes of polymers","volume-title":"The Vibrational Spectroscopy\nof Polymers","author":"Bower","year":"1989"},{"issue":"22","key":"2026102310021615800_cit45","doi-asserted-by":"publisher","DOI":"10.3390\/ijms20225708","article-title":"Fast Vibrational Modes and Slow Heterogeneous\nDynamics in Polymers and Viscous Liquids","volume":"20","author":"Puosi","year":"2019","journal-title":"Int.\nJ. Mol. Sci."},{"issue":"12","key":"2026102310021615800_cit46","doi-asserted-by":"publisher","first-page":"1147","DOI":"10.1016\/j.progpolymsci.2005.08.001","article-title":"Neutron scattering investigations\non methyl group dynamics in polymers","volume":"30","author":"Colmenero","year":"2005","journal-title":"Prog.\nPolym. Sci."},{"issue":"48","key":"2026102310021615800_cit47","doi-asserted-by":"publisher","first-page":"14046","DOI":"10.1021\/jp203659r","article-title":"Scaling between Relaxation,\nTransport, and Caged Dynamics\nin Polymers: From Cage Restructuring to Diffusion","volume":"115","author":"Puosi","year":"2011","journal-title":"J. Phys. Chem. B"},{"issue":"10","key":"2026102310021615800_cit48","doi-asserted-by":"publisher","first-page":"12354","DOI":"10.1021\/acs.energyfuels.0c02268","article-title":"Structural\nProperties of Kerogens\nwith Different Maturities","volume":"34","author":"Chiang","year":"2020","journal-title":"Energy Fuels"}],"container-title":["Energy &amp; Fuels"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/pubs.acs.org\/doi\/pdf\/10.1021\/acs.energyfuels.6c03407","content-type":"application\/pdf","content-version":"vor","intended-application":"unspecified"},{"URL":"https:\/\/pubs.acs.org\/enfuem\/article-pdf\/doi\/10.1021\/acs.energyfuels.6c03407\/68965753\/acs.energyfuels.6c03407.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"syndication"},{"URL":"https:\/\/pubs.acs.org\/enfuem\/article-pdf\/doi\/10.1021\/acs.energyfuels.6c03407\/68965753\/acs.energyfuels.6c03407.pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,10,23]],"date-time":"2026-10-23T14:10:29Z","timestamp":1792764629000},"score":1,"resource":{"primary":{"URL":"https:\/\/pubs.acs.org\/enfuem\/article\/doi\/10.1021\/acs.energyfuels.6c03407\/5457367\/CO2-Enhanced-Hydrocarbon-Recovery-in-Organic-Rich"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,10,23]]},"references-count":48,"URL":"https:\/\/doi.org\/10.1021\/acs.energyfuels.6c03407","relation":{},"ISSN":["0887-0624","1520-5029"],"issn-type":[{"value":"0887-0624","type":"print"},{"value":"1520-5029","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,10,23]]}}}