Search

Monitoring of intraoperative core temperature is strongly recommended to reduce the risk of perioperative thermic imbalance and related complications. The zero-heat-flux sensor (3M Bair Hugger Temperature monitoring system, ZHF), measures core temperature in a non-invasive manner. This study was aimed at comparing accuracy and precision of the ZHF sensor compared to the esophageal thermometer. Patients scheduled for major elective abdominal or urologic surgery were considered eligible for enrollment. Core body temperature was measured using both an esophageal probe (TESO) and a ZHF sensor (TZHF) every 15 min from induction until the end of general anaesthesia. A Bland–Altman plot for repeated measures was performed. The proportion of measurements within ± 0.5 °C was estimated; from a clinical point of view, a proportion greater than 90% was considered sufficiently accurate. Lin’s concordance correlation coefficient (CCC) for repeated measures were calculated. To evaluate association between the two methods, a generalized estimating equation (GEE) simple linear regression model, was elaborated. A GEE multiple regression model was also performed in order to adjust the estimate of the association between measurements from surgical and patient’s features. Ninety-nine patients were enrolled. Bland–Altman plot bias was 0.005 °C with upper and lower limits of agreement for repeated measures of 0.50 °C and − 0.49 °C. The percentage of measurements within 0.5 °C of the reference value was 97.98% (95% confidence interval 92.89–99.75%), indicating a clinically sufficient agreement between the two methods. This was also confirmed by a CCC for repeated measures of 0.89 (95% CI 0.80 to 0.94). The GEE simple regression model (slope value of 0.77) was not significantly influenced by any patient or surgical variables. According to GEE multiple regression model results, the explored patient- and surgery-related variables did not influence the association between methods. ZHF sensor has shown a clinically acceptable accuracy and precision for body core temperature monitoring during elective major surgery. Clinical trial number: NCT03820232.

As demonstrated by the huge number of publications in the last decade, there is a growing interest in delirium in intensive care. This is a common acute brain dysfunction in the critically ill and is associated with unfavorable outcomes, such as longer hospital stay, increased morbidity, and mortality. Nevertheless, it remains largely underdiagnosed. Its etiology is surely multifactorial and many different mechanisms can be implicated in its development, but its pathogenesis is poorly understood. The use of appropriate diagnostic tools, as specific scoring scales, helps in the diagnosis of delirium, which is not always straightforward, particularly in its hypoactive and subsyndromal forms. Individuation of risk factors and non-pharmacological strategies is a fundamental tool in prevention and treatment of delirium. This chapter outlines epidemiology of delirium, its pathophysiology, and the appropriate measures for diagnosis, prevention, and treatment.

The case study here presented supports the on-going EOR development project of a low net-to-gross fluvial system producing viscous oil form a thick sedimentary column in San Jorge Gulf Basin, Argentina. The selected strategy consists in combining dynamic modeling, analytic tools and field measurements to assess field potential and to model uncertainty through different yet plausible deterministic scenarios. The selected area is Los Perales field in Southern Argentina, with 2880 wells producing from more than 1000 m thick column of thin fluvial sandstone bodies and tuffaceous shale floodplain intercalations. This is a mature field extensively drilled, although single sand extension is likely to be below well spacing. Sands are captured by well logs but have no seismic representation, making connectivity prediction in between wells critical for any IOR or EOR project. For this reason, sand lateral connectivity is estimated by statistical tools, and then several plausible 3D connectivity scenarios are used to model geological uncertainty. Simple analytical tools support simulation results on the identification of key dynamic factors affecting polymer flood incremental volumes. Nevertheless, different modeling approaches are here combined to build deterministic scenarios such as fine scale 2D section models and different resolution 3D sector models for different purposes. We estimate that, given the adverse mobility ratio, when 45% water saturation is reached in the reservoir water sweep efficiency becomes so dramatically low that almost no oil is pushed and water cut raises over 95% as historical production data shows during the 25-year water-flood history in the field. The resulting low recovery factor presents a huge opportunity for polymer flood not only in the already swept areas and heterogeneous regions but also in some unproduced layers with water forecast on swabbing tests. A zone-ranking based on a vertical proportion curve for reservoir and non-reservoir intervals allows us to narrow the development to lower risk confined regions. Further investigation and detail modelling in these regions permit us to assess uncertainty and estimate incremental volumes as up to 3 times those recovered by water-flooding. Production logging confirmed the relevance of targeted intervals in well production, hence supporting polymer business case. This methodology is used to forecast, rank and select the best areas for polymer flood. This integrated approach combines geology, petrophysics and engineering using several laboratory tests, multiple deterministic scenarios and statistical tools to analyze polymer flood opportunities in a large field producing from a low net-to-gross thick sedimentary column.

Background Continuous veno-venous hemodialysis with high cut-off membranes (HCO-CVVHD) removes inflammatory mediators involved in organ dysfunction during sepsis. The aim of the present study was to assess the variations in SOFA score and identify early predictors of short-term mortality in a cohort of patients with septic shock, treated with HCO-CVVHD for acute kidney injury (AKI). Methods An observational prospective multicenter cohort study was conducted in four mixed medical-surgical ICUs. Thirty-eight patients with septic shock and AKI (KDIGO stage≥1) treated with HCO-CVVHD have been included in this study. Patients were divided into Survivors and non-Survivors according to mortality observed at 72nd hr of treatment. The variation of SOFA scores and clinical/biochemical parameters were described over time for the entire population and specifically for Survivors and non-Survivors. Similarly, circulating inflammatory mediators (as IL-6, TNF-a and IL-10) were described over time. A logistic regression analysis was used to identify the baseline clinical and biochemical parameters associated with 72 hrs-ICU mortality. Results Overall, the mean SOFA score was 12±3 at baseline, 10.9±3 at 6hrs, 9.8±3 at 12hrs, 8.9±3.3 at 24 hrs, and 8±3.5 at 48 hrs after HCO-CVVHD initiation; and 6.5±2.7 at 24 hrs and 6.6±3 at 48 hrs after HCO-CVVHD discontinuation. In the multivariate regression analysis, baseline serum lactate levels and AKI stage independently correlated with short-term mortality during HCO-CVVHD. A significant reduction was observed in circulating levels of TNFα and IL-6 among Survivors. Conclusions SOFA score significantly decreased early after initiation of HCO-CVVHD in patients with septic AKI. Baseline lactate levels and the AKI stage resulted to be associated to 72 hrs-ICU-mortality.

A group of mature oil fields in Argentina, that share the same sandstone reservoirs, were declining rapidly when applying established methodologies. New wells drilled away from the exploited areas, generally encountered a water column, while infill wells saw either low pressures or injected water. To revitalize these fields, a new approach to both field management and identification of new opportunities was required. This paper discusses the methodologies applied as part of the revitalizing approach, along with the newly identified opportunities. The first of these field studied comprised multiple stacked reservoirs all producing oil through comingled wells; oil production and allocation to date was uncertain. An integrated modelling effort showed unexpectedly that reservoirs containing lighter oil were exhausted; however, the shallower, viscous oil-bearing reservoir (Rayoso Formation) was virtually untouched. To improve the efficiency of the project, one dedicated multidisciplinary team was assigned to identify opportunities over the entire extent of the formation containing viscous oil (~ 860 km2). The key question was where to find the remaining oil within and across the fields. This work enabled reservoir understanding, developed over a long period of time, during the first study, to be rapidly applied to subsequent ones. Frequent iterations between the static and dynamic models were used to test hypothetical scenarios, to speed up the modelling process and to reduced uncertainty. Use of analogues across the sandstone reservoirs reduced the uncertainty associated with commingled production by comparison with fields where injection and production was reservoir specific. Through analogues we also determined that water was not injected in secondary sands and that this reservoir was being bypassed due to the presence of similar petrophysical properties but lower viscosity oil in underlying reservoirs. This combined fields study resulted in significant new volumes being identified with less effort and time required in respect to studying each field separately, this reducing history matching times (from two years to a number of weeks). As a result of this study, gravity forces and different PVT properties between reservoirs were found to adversely affect production in Rayoso, in addition to the high mobility ratio. A polymer pilot is currently being implemented, with another one currently being planned as the future outlook for these previously rapidly declining fields has now significantly improved.

In the Fahud field of Oman, the integration between hierarchies of sequence stratigraphic units and fracture systems has proven to be crucial to explain the distribution of flow and mechanical units. The study focused on the Upper Cretaceous, Albian to Lower Cenomanian Natih e unit (Natih Formation, Wasia Group), a 170-mthick carbonate sequence/reservoir, which exhibits heterogeneities in both facies and reservoir quality. Based on a core-derived high-resolution sequence stratigraphic analysis, the Natih e reservoir can be subdivided into four orders of depositional cycles (from 6th- to 3rd-order). Each cycle consists of a transgressive and regressive hemicycle with characteristic facies and rock properties. The facies and diagenetic overprint of the higher-order cycles vary according to their position within the 3rd-order sequences. Analysis of core, borehole images, seismic, tracer and production data indicate a hierarchy of fractures and faults that seems to follow the stratigraphic subdivisions. A relationship between depositional and diagenetic architecture of the cycles, and the aforementioned data, led to the identification of mechanical layering and stratigraphy within the reservoir. This finding was validated and supported by the successful history match of the three-phase production data within the dynamic model of the reservoir. The combination of sequence and mechanical stratigraphy provides a framework for the correlation of facies and mechanical units across the field. Furthermore, the facies and mechanical units are related to reservoir quality and fracture distribution for consistent upscaling into large-scale reservoir models. Through close co-operation between geologists and reservoir engineers utilising dynamic data, it was possible to determine the most appropriate scale for flow and ensure that such a scale was then used as input for dynamic modelling and for planning of the future exploitation of the Fahud field. As a result of this study, Petroleum Development Oman (PDO) has evaluated a 20% increase in risked reserves, and a 25% reduction of well costs.

The causes and duration of the early Toarcian anoxic event are controversial. Integration of data from calcareous and organic phytoplankton provides a biochronological framework that allows precise correlations across the western Tethys. In particular, the Carinolithus superbus nannofossil Zone can be used to correlate the levels enriched in organic matter and the related δ 13 C negative excursion. Although a variable duration is given in the literature for this negative excursion, it is likely that it lasted between 520 and 650 ka. Increased atmospheric p CO 2 , related to excess volcanic emissions (magmatic activity in the Karoo and Ferrar Provinces), had an impact on climate and ocean chemistry, and marked the inception of a biotic crisis affecting many organisms. The beginning of the crisis within shallow carbonate platforms, documented at southern latitudes, predates the levels enriched in organic matter. Dinoflagellate cysts experienced a decrease in abundance in the C. superbus Zone, until they temporarily disappeared. The nannoplankton crisis was twofold: a decrease in size and low calcified specimens are observed in addition to a drastic decrease in absolute abundance. The increased atmospheric p CO 2 , as a result of the magmatic activity and temporarily amplified by transient methane release, could have been the trigger for the biocalcification crisis, which first affected the probably more reactive neritic system, and eventually the nannoplankton community.

In contrast to the majority of recently published hypotheses, we believe that the main trigger for early Toarcian anoxia is neither increased primary productivity during the Tenuicostatum and Falciferum Zones nor sudden methane hydrate degassing close to the transition between these two zones. In our opinion, this peculiar paleoceanographic episode is linked to a major, though short-lived, regression at the end of Upper Domerian. Sea-level fall resulted from sudden cooling due to increased volcanic activity. This generated global thermal insulation and subsequent glaciation. The regression is responsible for a major hiatus over NW-European epicontinental seas and is later followed by the well-known Lower Toarcian transgression. The interval corresponding to this hiatus allowed vegetation to colonise vast newly emerged surfaces. The leaching and drowning of the accumulated organohumic matter then triggered the anoxic cycle at the transgressive maximum, concomitant with a global warming.

An extensive core-based sedimentological and high-resolution sequence stratigraphic study has been carried out on two Upper Lekhwair (Thamama Group, Barremian) Reservoir Units (ULRU1 and ULRU2) of a giant oil field onshore Abu Dhabi, with the aim of improving our understanding of the reservoir architecture. ULRU1 and ULRU2 are part of the highstand systems tract (HST) of a third-order depositional sequence, and are interpreted to represent two fourth-order parasequence sets built by eight fifth-order parasequences. ULRU1 and the underlying dense zone consists of burrowed, organic-rich, stylolitized, wispy laminated, packstones with echinoderms, shallowing-upward into wackestones, packstones and grainstones with rare rudists, foraminifera, peloids, and intraclasts. ULRU1 together with the underlying dense zone forms one parasequence set built by four parasequences. ULRU2 and the underlying dense zone consists of burrowed, organic-rich, stylolitized, wispy laminated skeletal wackestones and packstones, coarsening-upwards to grain-dominated, rudist-rich packstones, grainstones, floatstones, and rudstones. Like ULRU1, the reservoir facies of ULRU2 together with the underlying dense zone forms one parasequence set built by four parasequences. Best reservoir quality is developed in ULRU2 (permeability exceeds 1.0 Darcy), corresponding to rudist-rich, grain-dominated lithofacies representing laterally discontinuous shoals. Porosity and permeability trends follow the established high-frequency sequence stratigraphic framework. Our newly developed sequence stratigraphy-based geological (static) model improves prediction of flow behavior in ULRU1 and ULRU2.

A new sequence stratigraphy-keyed geological model has been built for the upper Thamama (Lower Cretaceous) Kharaib and Shu’aiba formations. The Kharaib Formation contains two reservoir units (Lower and Upper Kharaib Reservoir Units) with 80 and 170 ft thickness, respectively, separated and encased by three low porosity and permeability dense zones. The overlying Shu’aiba Formation is separated from the Kharaib Formation by the Upper Dense Zone (Hawar) and contains two reservoir units, only partly separated by dense intervals. The thickness of the Lower and Upper Shu’aiba Reservoir Units is approximately 55 and 90 ft, respectively. Core and well-log data of a giant onshore oil field in Abu Dhabi, as well as outcrop data from Wadi Rahabah (Ras Al-Khaimah) were used to establish a lithofacies scheme and a sequence stratigraphic framework. The scheme is applicable to all four reservoir units and the three dense zones. The Lower and Upper Kharaib Reservoir Units, as well as the Upper Dense Zone, are part of the late transgressive systems tract (TST) of a second-order supersequence, built by two third-order composite sequences. The overlying Lower and Upper Shu’aiba Reservoir Units belong to the late TST and highstand systems tract (HST) of this secondorder supersequence built by four third-order composite sequences. The six third-order composite sequences are composed of twenty-six fourth-order parasequence sets that form the basic building blocks of a new generation static model. On the basis of faunal content, texture, sedimentary structures, and lithologic composition, fourteen reservoir lithofacies and ten non-reservoir (dense) lithofacies are identified from core. Reservoir units range from lower ramp to shoal crest to near back shoal open platform environments.

The carbon isotopic signature of carbonates depends on secular variations of organic carbon and carbonate carbon production/burial rates. A decrease in carbonate productivity makes the organic/carbonate carbon ratio unstable up to the point that even minor variations in the organic carbon reservoirs can provoke carbon isotopic shifts. The δ13C positive shifts of the middle Carixian (early Pliensbachian) and the early Bajocian recorded in the Umbria–Marche–Sabina domain represent a good example of this mechanism. Both sedimentology and lithostratigraphy of pelagic platform–basin carbonate systems in this area show that important changes in the source of carbonates correspond to the observed isotopic shifts. The middle Carixian event is in fact well correlatable to the drastic reduction of benthic carbonate production on rift-related intrabasinal highs, which then became pelagic carbonate platforms. The early Bajocian event is concomitant with the beginning of a long hiatus on the pelagic carbonate platforms and with a drop of the biodiversity of calcareous organisms followed by the onset of biosiliceous sedimentation in basins.