Lithofacies characterization of fluvial sandstones from outcrop gamma-ray logs (Loranca Basin, Spain): the influence of provenance

Natural gamma spectral (NGS) log motifs and cluster analysis were used to characterize outcropping sandstone bodies formed in braided and highsinuosity streams of the Tertiary Tórtola fluvial system of the Loranca Basin (Spain). Five coarse-grained lithofacies comprise these deposits and determine distinct NGS log motif. Cross-plots and cluster analysis of NGS log data of the lithofacies suggest three distinct clusters. These clusters reflect distinct values for sandstones with small sets of ripple lamination, cross-stratification, and conglomerates and pebbles. Ripple-laminated sandstones show the most variability in NGS signature, whereas conglomeratic sandstones show the most uniform signature. Such cluster analysis may be used to assign NGS log data points of unknown origin to a specific fluvial lithofacies under conditions of equal rock provenance and diagenetic history. A sedimentaclastic (i.e. sedimentary parent rock) origin of sediments appears to be the main control on detrital composition that, in turn, varies with grain size.Depto. de Mineralogía y PetrologíaFac. de Ciencias GeológicasTRUEpu

New insights on subsurface energy resources in the Southern North Sea Basin area

The Southern North Sea Basin area, stretching from the UK to the Netherlands, has a rich hydrocarbon exploration and production history. The past, present and expected future hydrocarbon and geothermal exploration trends in this area are discussed for eight key lithostratigraphic intervals, ranging from the Lower Carboniferous to Cenozoic. In the period between 2007 and 2017, a total of 95 new hydrocarbon fields were discovered, particularly in Upper Carboniferous, Rotliegend and Triassic reservoirs. Nineteen geothermal systems were discovered in the Netherlands onshore, mainly targeting aquifers in the Rotliegend and Upper Jurassic/Lower Cretaceous formations. Although the Southern North Sea Basin area is mature in terms of hydrocarbon exploration, it is shown that with existing and new geological insights, additional energy resources are still being proven in new plays such as the basal Upper Rotliegend (Ruby discovery) for natural gas and a new Chalk play for oil. It is predicted that hydrocarbon exploration in the Southern North Sea Basin area will probably experience a slight growth in the coming decade before slowing down, as the energy transition further matures. Geothermal exploration is expected to continue growing in the Netherlands onshore as well as gain more momentum in the UK

Global Retinoblastoma Presentation and Analysis by National Income Level

Importance: Early diagnosis of retinoblastoma, the most common intraocular cancer, can save both a child's life and vision. However, anecdotal evidence suggests that many children across the world are diagnosed late. To our knowledge, the clinical presentation of retinoblastoma has never been assessed on a global scale. Objectives: To report the retinoblastoma stage at diagnosis in patients across the world during a single year, to investigate associations between clinical variables and national income level, and to investigate risk factors for advanced disease at diagnosis. Design, Setting, and Participants: A total of 278 retinoblastoma treatment centers were recruited from June 2017 through December 2018 to participate in a cross-sectional analysis of treatment-naive patients with retinoblastoma who were diagnosed in 2017. Main Outcomes and Measures: Age at presentation, proportion of familial history of retinoblastoma, and tumor stage and metastasis. Results: The cohort included 4351 new patients from 153 countries; the median age at diagnosis was 30.5 (interquartile range, 18.3-45.9) months, and 1976 patients (45.4) were female. Most patients (n = 3685 84.7%) were from low-and middle-income countries (LMICs). Globally, the most common indication for referral was leukocoria (n = 2638 62.8%), followed by strabismus (n = 429 10.2%) and proptosis (n = 309 7.4%). Patients from high-income countries (HICs) were diagnosed at a median age of 14.1 months, with 656 of 666 (98.5%) patients having intraocular retinoblastoma and 2 (0.3%) having metastasis. Patients from low-income countries were diagnosed at a median age of 30.5 months, with 256 of 521 (49.1%) having extraocular retinoblastoma and 94 of 498 (18.9%) having metastasis. Lower national income level was associated with older presentation age, higher proportion of locally advanced disease and distant metastasis, and smaller proportion of familial history of retinoblastoma. Advanced disease at diagnosis was more common in LMICs even after adjusting for age (odds ratio for low-income countries vs upper-middle-income countries and HICs, 17.92 95% CI, 12.94-24.80, and for lower-middle-income countries vs upper-middle-income countries and HICs, 5.74 95% CI, 4.30-7.68). Conclusions and Relevance: This study is estimated to have included more than half of all new retinoblastoma cases worldwide in 2017. Children from LMICs, where the main global retinoblastoma burden lies, presented at an older age with more advanced disease and demonstrated a smaller proportion of familial history of retinoblastoma, likely because many do not reach a childbearing age. Given that retinoblastoma is curable, these data are concerning and mandate intervention at national and international levels. Further studies are needed to investigate factors, other than age at presentation, that may be associated with advanced disease in LMICs. © 2020 American Medical Association. All rights reserved

Facies architecture of heterolithic tidal deposits: The Holocene Holland Tidal Basin

The size, shape and spatial position of lithofacies types (or facies architecture) in a tidal estuarine basin are complex and therefore difficult to model. The tidal currents in the basin concentrate sand-sized sediment in a branching pattern of tidal channels and fringing tidal flats. Away from the sandy tidal flats the sediment gradually changes to mud-dominated heterolithic deposits and clay. In this paper the facies analysis of a tidal estuarine basin, the Holocene Holland Tidal Basin (HHTB) is presented based on core data and Cone Penetration Tests (CPT). Four lithofacies associations are recognized: (1) tidal channel sand, (2) sand-dominated heterolithic inter-tidal flat, (3) mud-dominated heterolithic inter-channel, and (4) fresh-water peat. The high data density allowed for the construction of a detailed facies architecture model in which the size, shape and spatial position of the tidal estuarine facies elements were established. The results can be used to improve the reservoir modelling in highly heterogeneous estuarine reservoir settingsCivil Engineering and Geoscience

Reservoir modelling of heterolithic tidal deposits: Sensitivity analysis of an object-based stochastic model

Object-based stochastic modelling techniques are routinely employed to generate multiple realisations of the spatial distribution of sediment properties in settings where data density is insufficient to construct a unique deterministic facies architecture model. Challenge is to limit the wide range of possible outcomes of the stochastic model. Ideally, this is done by direct validation with the ‘real-world’ sediment distribution. In a reservoir setting this is impossible because of the limited data density in the wide-spaced wells. In this paper this uncertainty is overcome by using size, shape and facies distributions of tidal channel and tidal flat sand bodies in a highly data-constrained lithofacies architecture model as input for the object-based stochastic model. The lithofacies architecture model was constructed from a densely perforated (Cone Penetration Tests and cored boreholes) tidal estuarine succession of the Holocene Holland Tidal Basin in the Netherlands. The sensitivity of the stochastic model to the input parameters was analysed with the use of varying tidal channel width and thickness values and calculating the connected sand volume per well for the different scenarios. The results indicated that for a small well drainage radius the difference in drainable volumes between the narrowest and the widest channel scenarios is large, and that for a large well drainage radius the tidal channel width hardly influenced the drainable volume. The sensitivity analysis highlighted the importance of sand-dominated tidal flats in improving lateral connectivityCivil Engineering and Geoscience

Field scale geomechanical modeling for prediction of fault stability during underground gas storage operations in a depleted gas field in the Netherlands

A geomechanical modeling study was conducted to investigate stability of major faults during past gas production and future underground gas storage operations in a depleted gas field in the Netherlands. The field experienced induced seismicity during gas production, which was most likely caused by the reactivation of an internal Central fault separating the two major reservoir blocks. A 3D field scale geomechanical finite element model of the gas field was developed with realistic representation of the structural geology and juxtaposition of various lithologies across the Central fault. The model was calibrated to match the subsidence data and the approximate location of the critically stressed, reactivated part of the fault in agreement with the seismological localization of the hypocenters of the past major seismic events. The model predicted a maximum shear slip of up to 2 cm associated with gas production. Additional, but a smaller, fault slip of up to 0.5 cm could be expected during the subsequent phase of cushion gas injection. During annual cycles of gas injection and production, the Central fault is not critically stressed and the predicted stress changes lie in the elastic region. Although the fault slip is unlikely, continuous monitoring of induced seismicity is essential