Reservoir quality evaluation as a measure to forecast hydrocarbon and CO2 storage prospects in Irati and Rio Bonito Formations, Paraná Basin

Enhanced hydrocarbon recovery processes coupled with CO2 storage are, by far, the cheapest carbon capture and storage (CCS) options in geological structures. However, reservoirs are also being explored for CO2 storage in regions without producing/depleted hydrocarbon reservoirs, such as the Irati and Rio Bonito Formations in the southwestern part of São Paulo. Therefore, the study involves petrophysics-based flow unit factors to predict the reservoirs’ quality, primarily focusing on hydrocarbon viability with CO2 storage possibilities based on the shale, carbonate, sandstone and siltstone rock units. The methodology involving the models for the research objective is uncommon for the Irati and Rio Bonito Formations. The porosity range is 0.02 to 0.15 in shales, 0.028 to 0.18 in siltstones, 0.03 to 0.21 in carbonates, and 0.10 to 0.31 in sandstones based on the sonic-density porosity (ФS-D) approach. Permeability (k) is 0.00005mD to 36.6mD in shales, 0.0008mD to 132mD in siltstones, 0.025mD to 786mD in carbonates and 8mD to 10000mD in sandstones. The results show more significant fluid transmission indices for the sandstone based on Ф, k, free fluid index-FFI, reservoir quality index-RQI, and flow zone indicator-FZI. Also, the parameters are considerably significant for carbonates in some instances, less effective for siltstone and comparatively insignificant for shale. However, shales` total organic content (TOC) values are up to 10.5%, suggesting their hydrocarbon generation potentials. Significant values (e.g., Ф ≥25% and FFI ≥20%) in sandstones indicate reservoirs with the potential for hydrocarbon accumulation. Considerable physical qualities, as presented for the sandstone, suggest reservoir rock units with reasonable fluid (e.g., gas) recovery and CO2 injection rates. Therefore, based on the research results, the Irati Formation shales are viable hydrocarbon source rocks, and the Rio Bonito Formation sandstones are potential hydrocarbon reservoirs. Subsequently, future hydrocarbon production events will enhance CO2 storage options in the region. Futhermore, the research results may serve as input data in related hydrocarbon exploration studies. However, if further research indicates non-commercially viable hydrocarbon reserves, the findings will also aid in delineating dedicated geological reservoirs for CO2 storage when needed

Hydrocarbon indication in Rio Bonito Formation sandstone: Implication for CO2 storage in São Paulo, Brazil

São Paulo State has witnessed CO2 storage-based investigations considering the availability of suitable geologic structures and proximity to primary CO2 source sinks related to bioenergy and carbon capture and storage (BECCS) activities. The current study presents the hydrocarbon viability evaluations and CO2 storage prospects, focusing on the sandstone units of the Rio Bonito Formation. The objective is to apply petrophysical evaluations with geochemical inputs in predicting future hydrocarbon (gas) production to boost CO2 storage within the study location. The study used data from eleven wells with associated wire-line logs (gamma ray, resistivity, density, neutron, and sonic) to predict potential hydrocarbon accumulation and fluid mobility in the investigated area. Rock samples (shale and carbonate) obtained from depths >200 m within the study location have shown bitumen presence. Organic geochemistry data of the Rio Bonito Formation shale beds suggest they are potential hydrocarbon source rocks and could have contributed to the gas accumulations within the sandstone units. Some drilled well data, e.g., CB-1-SP and TI-1-SP, show hydrocarbon (gas) presence based on the typical resistivity and the combined neutron-density responses at depths up to 3400 m, indicating the possibility of other hydrocarbon members apart from the heavy oil (bitumen) observed from the near-surface rocks samples. From the three-dimensional (3-D) model, the free fluid indicator (FFI) is more significant towards the southwest and southeast of the area with deeper depths of occurrence, indicating portions with reasonable hydrocarbon recovery rates and good prospects for CO2 injection, circulation and permanent storage. However, future studies based on contemporary datasets are required to establish the hydrocarbon viability further, foster gas production events, and enhance CO2 storage possibilities within the region

The paleoenvironmental and thermal histories of the permian Irati formation shale in the Paraná Basin, Brazil: an integrated approach based on mineralogical and organic imprints

Mineralogical assemblages and organofacies are important sources of information to recover the paleoenvir-onmental and thermal histories of shale deposits. In this study, a detailed qualitative and quantitative charac-terization of the Permian Irati Formation (Assistencia Member) shale is based on mineralogical (XRD and SEM -EDS) and organic components (TOC, Rock-Eval pyrolysis, organofacies, TAI, fluorescence and vitrinite reflec-tance measurements) and provides integrated data about sediment provenance, depositional environment, diagenesis, and thermal history, while supporting interpretations on the Paran & PRIME;a Basin (PB), Brazil, paleogeog-raphy and its correlation to the southwest Gondwana. The results revealed a prevailing type I/II kerogen, with type III kerogen being also present but mainly confined along the paleoshoreline of the PB. The dominance of fluorescent amorphous organic matter (AOM) combined with framboidal pyrite suggests microbial activity in an anoxic-dysoxic neritic-marine paleoenvironment. Additionally, common to abundant well-preserved phytoclasts, as well as the occurrence of Botryococcus braunii, indicates freshwater influx in a brackish marine depositional setting. Immature to early-oil window thermal maturities prevail across the PB, according to the organic maturation indicators. The combined analysis between the organic matter evolution with clay mineralogy, such as the occurrence of interstratified clays (e.g., I/S) and its positive correlation with depth suggest that burial diagenesis reached the transition to early catagenesis on the north, southeast, and south of the basin, attributing a shale oil potential for the Irati Formation on a regional scale. Local scale imprints of the Early Cretaceous Paran & PRIME;a-Etendeka Large Igneous Province (LIP), and its thermal effect in the Irati Formation shale components, are recorded as clay authigenesis (e.g., smectite webby texture and clay coating development), crystallization of minerals by low to high-grade of thermal alteration (e.g., corrensite, talc, lizardite and diopside), and by local scale gas-window maturities. Such thermal alteration, identified in the proximity to intruded sills and dykes, led to a heterogeneous organic maturation pattern with implications on shale gas and shale oil potential of the Irati Formation shale, demonstrating that these subjects in the Paran & PRIME;a Basin should be assessed locally.info:eu-repo/semantics/publishedVersio

Increased interregional virus exchange and nucleotide diversity outline the expansion of chikungunya virus in Brazil

Abstract The emergence and reemergence of mosquito-borne diseases in Brazil such as yellow fever, zika, chikungunya, and dengue have had serious impacts on public health. Concerns have been raised due to the rapid dissemination of the chikungunya virus across the country since its first detection in 2014 in Northeast Brazil. In this work, we carried out on-site training activities in genomic surveillance in partnership with the National Network of Public Health Laboratories that have led to the generation of 422 chikungunya virus genomes from 12 Brazilian states over the past two years (2021–2022), a period that has seen more than 312 thousand chikungunya fever cases reported in the country. These genomes increased the amount of available data and allowed a more comprehensive characterization of the dispersal dynamics of the chikungunya virus East-Central-South-African lineage in Brazil. Tree branching patterns revealed the emergence and expansion of two distinct subclades. Phylogeographic analysis indicated that the northeast region has been the leading hub of virus spread towards other regions. Increased frequency of C > T transitions among the new genomes suggested that host restriction factors from the immune system such as ADAR and AID/APOBEC deaminases might be driving the genetic diversity of the chikungunya virus in Brazil