HAL-BRGM, les publications scientifiques en libre accès du BRGM
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Repurposing O&G Wells for CO2 Storage: Key Aspects for Safety
No full textInternational audienceThe oil and gas industry has over 50 years of experience in continuously developing CO2 transport and injection for advanced oil recovery (EOR). These efforts have highlighted the need for infrastructure adjustments and concerns regarding maintaining the integrity of the well and the entire operation. The technology and requirements for well barrier elements are similar for both permanent CO2 storage and the reuse of O&G production facilities for CO2 injection. This means that specific equipment and infrastructure investments are necessary, including gas treatment facilities, pipelines, compression equipment for transport, distribution lines, and conversion wells for CO2 injection. The focus of this study is on the latter. This study conducts a systematic literature review to identify the key factors in assessing wells for CO2 injection. The outcome is a flowchart for evaluating active and suspended wells. This flowchart encompasses the qualitative and initial analysis of crucial factors in well assessment, such as cement integrity, corrosion, CO2 flow composition, and material compatibility. If the suggested actions cannot rectify the issues with the well, it should be plugged and abandoned. The findings indicate significant potential for the study, including assessing abandoned wells and converting actives and/or suspended wells into monitoring well
Mapping groundwater recharge potential zones in a semi-arid, anthropogenically modified mountainous basin
No full textInternational audienceMapping groundwater recharge potential zones (GRPZ) is essential for predicting recharge distribution and supporting aquifer management in large basins. However, previous studies have mainly relied on multiparameter approaches without validation using multiple lines of evidence. Stable isotopes, which are effective tracers of recharge sources and altitudes, have rarely been applied in semi-arid anthropized basins. Delineating GRPZ remains challenging in these regions due to limited observational data, spatial heterogeneity of recharge mechanisms, and increasing anthropogenic impacts such as urbanization and irrigation. To address these challenges, this study adopted a multi-factorial approach integrating several factors controlling water sources and infiltration processes. Land Use and Land Cover (LULC) was emphasized as a pivotal recharge factor in (semi)arid anthropized basins, reflecting the effects of urbanization, irrigation, and surface water bodies. GRPZ in the Tensift basin (Morocco) were delineated using remote sensing (Google Earth Engine), GIS, Analytical Hierarchy Process (AHP) and stable isotopes. Six recharge factors were used: rainfall (TerraClimate), LULC, lithology, lineament density, slope, and drainage density. Validation was done using stable isotopes (δ18O and δ2H) for groundwater samples and Local Altitudinal Line (LAL) to determine Altitudes of Groundwater recharge and sources. The findings indicated that mountains and piedmonts represent the most favorable recharge zones, consistent with previous studies. These areas receive high precipitation and seasonal snowfall, while the plains are dominated by moderate recharge potential, with localized high recharge beneath irrigated areas and low recharge beneath urban zones. The study provides a transferable framework for guiding groundwater resources management and Managed Aquifer Recharge MAR in semi-arid regions and contributes to advancing sustainable water use and climate resilience in line with the Sustainable Development Goal
Artisanal mining in Africa. Green for Gold?
No full textInternational audienceThe livelihoods of 130 to 270 million people depend on artisanal mining. Artisanal mining is a labour-intensive, often illegal, extractive activity. We combine geological knowledge and a source of exogenous temporal variation to construct the first proxy for artisanal gold mining in Africa—the main form of artisanal mining. We establish that an increase in the potential value of artisanal mining is a significant driver of deforestation. The historical increase in the gold price accounts for 8% of forest loss across the continent and, within the subset of gold-suitable areas, 28 %. In parallel, artisanal mining increases local economic wealth and may provide an alternative livelihood should a weather shock jeopardise agricultural output. Finally, mining-induced deforestation seems rooted more in the direct clearing of trees for the activity than in indirect deforestation triggered by increased local demand
Stability and flow behavior of polymer-enhanced foams for improved in-situ remediation of hydrocarbons: Effect of polymer-surfactant interactions
No full textInternational audienceConventional in-situ hydrocarbon remediation technologies face challenges associated with high costs and low long-term efficacy. Aqueous foam injection presents a promising approach by enhancing volumetric sweeping efficiency. This study investigates the efficiency of polymer-enhanced foams (PEFs) for in-situ remediation of hydrocarbon-contaminated soil, focusing on the impact of Xanthan Gum (XG) biopolymer on foam stability against antifoaming diesel and the flow behavior in soil matrices. We examined two PEFs: Sodium Dodecyl Sulfate (SDS)-based and a blend of SDS and Cocamidopropyl Hydroxysultane (SDS-CAHS: SC)-based. Bulk foam tests pre-evaluated foam stability, while 1D sandpack experiments assessed PEFs' performance in porous media mimicking contaminated soil remediation. Stability tests showed that XG strengthens the foam by increasing liquid phase viscosity and improving overall foam stability. The findings emphasize the importance of the interactions inside polymer-surfactant complexes, where SDS was more impacted by XG than SC due to repulsive forces and hydrophobic interactions. Foam flow experiments revealed PEFs' higher mobility reduction factors (MRF) and noticable recovery improvement of the free-phase product (>= 95 %) compared to traditional surfactant-based foams. This research provides valuable insights into optimizing PEF compositions, potentially guiding future scale-up applications for hydrocarbon-contaminated sites
Mesurer la contribution de l’écopâturage au cadre de vie
No full textInternational audienceMethods for assessing the social and environmental performance of agricultural systems often overlook their impacts on the living environment. Based on the case study of the Nantaise Cow’s local chain and on interviews with local stakeholders, we develop a set of indicators that integrates social and landscape amenities generated by urban pasture practices. This framework broadens impact assessment to include territorial socio-environmental sustainability.Les méthodes d’évaluation sociale et environnementale des systèmes agricoles négligent souvent leurs impacts sur le cadre de vie. En nous appuyant sur le cas de la filière locale de la Vache Nantaise et à partir d’enquêtes auprès d’acteurs du territoire, nous construisons un tableau de bord intégrant les aménités sociales et paysagères issues de l’écopâturage. Ce cadre permet d’élargir l’analyse des impacts à la durabilité socio-environnementale du territoire
Innovation in assessing property-level flood risk adaptation measures: insights from a coupled hydraulic-economic model at the building scale
No full textThe ex-ante evaluation of the effectiveness of Property-level flood risk adaptation (PLFRA) measures proposed remains underdeveloped. Consequently, professionals carrying out vulnerability assessments lack the tools to validate their recommendations of PLFRA measures and costumers should invest in them without estimations of avoided material damage or safety improvements. Furthermore, from an institutional point of view, the evaluation of the effectiveness of PLFRA measures could call into question the validity of programmes designed based on broad principles but applied to specific areas. This paper proposes an innovative, process-based, 3D, building-level model that combines hydraulic and economic modules, as well as a danger index. This tool can successfully evaluate the effectiveness of PLFRA measures in real buildings and, when installation costs are available, enable cost-benefit and efficiency analyses. Additionally, the tool can estimate the dangerousness of a given path to a shelter as well as the time available to reach it
Optimizing the total oxidizable precursor (TOP) assay: enhanced PFAS quantification and analytical gap bridging in complex environmental matrices
No full textInternational audienceThe Total Oxidizable Precursor (TOP) assay was optimized to overcome the limitations of targeted analyses in detecting diverse PFAS compounds. This study evaluated key factors influencing the assay’s effectiveness, including temperature, sorption, oxidation, and reagent-to-organic compound ratios, using both spiked solutions and real environmental matrices. The efficiency of solid-phase extraction (SPE) was assessed before and after the assay, revealing that post-oxidation SPE improved sensitivity, particularly at low PFAS concentrations. The modified TOP Assay quantified 56 PFAS and their oxidizable precursors, resulting in up to a 1000% increase in perfluoroalkyl carboxylic acids (PFCA), indicating the presence of unidentified compounds. PFAS precursors oxidation ranged from 78 to 100% in liquid samples and 64 to 100% in solid samples (wastewater, sewage sludge, compost, struvite), confirming the assay’s efficacy under optimized conditions (K₂S₂O₈: 240 mM; NaOH: 600 mM; 2.5 mL reaction volume). Optimal conditions were determined based on PFCA formation, precursor transformation rates, and inter-test consistency. This adaptable and versatile protocol enhances PFAS detection across a variety of environmental matrices. Future applications to solid samples could further improve estimates of PFAS contamination in the environmen
Triassic Intracontinental Crustal Reworking of the Eastern Tianshan: New Insights From Late Triassic Adakitic and Low‐Sr/Y Granitoids in the Bogda Range
No full textInternational audienceAbstract Continental intraplate magmatism remains a fundamental challenge in Plate Tectonics. Triassic magmatism represents a critical phase in the evolution of the Central Asian Orogenic Belt and continues to provoke debate about its tectonic setting. This study presents an integrated analysis of field, petrographic, geochronologic, geochemical, and isotopic data from two newly identified Triassic granitoids in the Bogda Range: an adakitic porphyry and a low‐Sr/Y granite porphyry. Zircon U‐Pb dating yields nearly coeval crystallization ages of 221–220 Ma and 219–217 Ma, respectively. Both granitoids are characterized by high SiO 2 and K 2 O content, low MgO (Mg # ) and Ni content, and elevated K 2 O/Na 2 O and Th/Nb ratios. They have also depleted whole‐rock Sr‐Nd and zircon Hf isotopic compositions, indicative of juvenile crustal sources. The adakitic porphyry exhibits high Sr/Y and (La/Yb) N ratios, low Rb/Sr ratios, and weak Eu anomalies, suggesting derivation from garnet‐stable mafic lower crust. In contrast, the granite porphyry displays low Sr/Y and (La/Yb) N ratios, consistent with a plagioclase‐stable source. By integrating these results with regional data, we propose that the diversity of Triassic magmatism in the Eastern Tianshan is due to the reworking of juvenile and ancient crust at different depths and temperatures, resulting in arc‐like geochemical signatures. This process was associated with transcurrent tectonics and variable mantle contributions in a continental intraplate setting
