Monitoring casing corrosion of legacy wells using CSEM: implications for large-scale energy and CO2 storage projects in shut-down hydrocarbon fields

Large-scale CO2 and energy storage is a mandatory part of the green shift to reduce CO2 emissions and limit consequences of climate change. Large-scale storage will require the use of shut-down depleted hydrocarbon fields to take advantage of well-characterized reservoirs and cap rocks. Thanks to extensive data from historical hydrocarbon production, the uncertainties related to storage capacity, injectivity, and containment are limited. However, legacy exploration and production infrastructure, and especially legacy wells, are the main threat for possible fluid leakage toward the surface. Such legacy wells are numerous and penetrate the full rock column. In this paper, we describe a workflow to screen and monitor legacy wells in the shut-down Frigg Field in the North Sea. By using numerical modeling of electromagnetic (EM) field propagation in one of the Frigg Field wells, we explore the complex interactions of fields, currents, and well structure in the presence of corrosion. The corrosion is implemented as a change in the electrical conductivity of the innermost steel casing at different depths along the structure. To enhance probing depth, we plug the dipole source (1 km long) into the casing at the seafloor and excite the casing as an antenna. We find that at moderate levels of corrosion, the current distribution is significantly modified with respect to the uncorroded case. This generates a signal that propagates and can be observed at the seafloor in the numerical results. Other elements of the well geometry (e.g., concentric overlapping cement casings) have their own effect on the signal. This leads the possibility of estimating the location of the corroded area within the well geometry. These results suggest that by relaxing some of the model's approximations and implementing realistic transmitters, it will be possible to evaluate and optimize controlled-source EM survey strategies for detecting and monitoring corrosion levels.publishedVersio

Energy Expenditure Performing Hands-Only Cardiopulmonary Resuscitation During Average Emergency Response Times

Early cardiopulmonary resuscitation (CPR) by civilian responders is a critical aspect in the survival of cardiac arrest patients. According to the American Red Cross (ARC), the average response time to a 911 call is 8-12 min. High-quality CPR performed as soon as possible following cardiac arrest considerably increases a person’s chances of survival and recovery. It is possible that fatigue may decrease CPR quality, and to date no data exists on the metabolic cost of preforming hands-only CPR. PURPOSE: To determine the energy expenditure of performing hands-only CPR during the average emergency response time. METHODS: Eight college-aged participants (23.6 ± 4.6 years) with a current CPR certification from the ARC or American Heart Association (AHA) volunteered for the study. Anthropometric measurements were collected, participants were then fitted with a heart rate (HR) monitor. Indirect calorimetry was used to measure oxygen consumption and caloric expenditure during hands-only CPR for the minimum 8-minute response time. Participants were instructed to provide hands-only CPR to a manikin at a rate of 100-120 compressions per minute with a metronome (110 bpm) providing pacing. Descriptive statistics (mean ± SD) were evaluated for peak HR, peak metabolic equivalents (MET), estimated maximal HR, percent of maximal HR and caloric expenditure (kcals). RESULTS: Participants expended 33.3 ± 13.7 kcals when performing hands-only CPR for 8 minutes. Further, participants provided compressions at an intensity of 5.7 ± 1.5 METs. CONCLUSION: Our data suggest that the metabolic cost of performing hands-only CPR for the minimum 8-minute response time is comparable to the energy expenditure of a very brisk walk. One of the common reasons to discontinue CPR is that the responder is too exhausted to continue. The results of our study suggest it is unlikely that cardiorespiratory fatigue is the primary cause of exhaustion. Therefore, future research should aim to measure the energy expenditure of hands-only CPR to volitional exhaustion and identify perceived sources of fatigue

Evaluating the hydrogen storage potential of shut down oil and gas fields along the Norwegian continental shelf

The underground hydrogen storage (UHS) capacities of shut down oil and gas (O&G) fields along the Norwegian continental shelf (NCS) are evaluated based on the publicly available geological and hydrocarbon production data. Thermodynamic equilibrium and geochemical models are used to describe contamination of hydrogen, loss of hydrogen and changes in the mineralogy. The contamination spectrum of black oil fields and retrograde gas fields are remarkably similar. Geochemical models suggest limited reactive mineral phases and meter-scale hydrogen diffusion into the caprock. However, geochemical reactions between residual oil, reservoir brine, host rock and hydrogen are not yet studied in detail. For 23 shut down O&G fields, a theoretical maximum UHS capacity of ca. 642 TWh is estimated. We conclude with Frigg, Nordost Frigg, and Odin as the best-suited shut down fields for UHS, having a maximum UHS capacity of ca. 414 TWh. The estimates require verification by site-specific dynamic reservoir models.publishedVersio

Ionic Liquid Aqueous Two-Phase Systems for the Enhanced Paper-Based Detection of Transferrin and Escherichia coli

Aqueous two-phase systems (ATPSs) have been widely utilized for liquid-liquid extraction and purification of biomolecules, with some studies also demonstrating their capacity as a biomarker concentration technique for use in diagnostic settings. As the limited polarity range of conventional polymer-based ATPSs can restrict their use, ionic liquid (IL)-based ATPSs have been recently proposed as a promising alternative to polymer-based ATPSs, since ILs are regarded as tunable solvents with excellent solvation capabilities for a variety of natural compounds and proteins. This study demonstrates the first application of IL ATPSs to point-of-care diagnostics. ATPSs consisting of 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4]) and sodium phosphate salt were utilized to quickly concentrate biomarkers prior to detection using the lateral-flow immunoassay (LFA). We found the phase separation speed of the IL ATPS to be very rapid and a significant improvement upon the separation speed of both polymer-salt and micellar ATPSs. This system was successfully applied to both sandwich and competitive LFA formats and enhanced the detection of both Escherichia coli bacteria and the transferrin protein up to 8- and 20-fold, respectively. This system's compatibility with a broad range of biomolecules, rapid phase separation speed, and tunability suggest wide applicability for a large range of different antigens and biomarkers

A Scalable Approach to Modeling on Accelerated Neuromorphic Hardware.

Neuromorphic systems open up opportunities to enlarge the explorative space for computational research. However, it is often challenging to unite efficiency and usability. This work presents the software aspects of this endeavor for the BrainScaleS-2 system, a hybrid accelerated neuromorphic hardware architecture based on physical modeling. We introduce key aspects of the BrainScaleS-2 Operating System: experiment workflow, API layering, software design, and platform operation. We present use cases to discuss and derive requirements for the software and showcase the implementation. The focus lies on novel system and software features such as multi-compartmental neurons, fast re-configuration for hardware-in-the-loop training, applications for the embedded processors, the non-spiking operation mode, interactive platform access, and sustainable hardware/software co-development. Finally, we discuss further developments in terms of hardware scale-up, system usability, and efficiency

Current pretreatment technologies for the development of cellulosic ethanol and biorefineries

Lignocellulosic materials, such as forest, agriculture, and agroindustrial residues, are among the most important resources for biorefineries to provide fuels, chemicals, and materials in such a way to substitute for, at least in part, the role of petrochemistry in modern society. Most of these sustainable biorefinery products can be produced from plant polysaccharides (glucans, hemicelluloses, starch, and pectic materials) and lignin. In this scenario, cellulosic ethanol has been considered for decades as one of the most promising alternatives to mitigate fossil fuel dependence and carbon dioxide accumulation in the atmosphere. However, a pretreatment method is required to overcome the physical and chemical barriers that exist in the lignin–carbohydrate composite and to render most, if not all, of the plant cell wall components easily available for conversion into valuable products, including the fuel ethanol. Hence, pretreatment is a key step for an economically viable biorefinery. Successful pretreatment method must lead to partial or total separation of the lignocellulosic components, increasing the accessibility of holocellulose to enzymatic hydrolysis with the least inhibitory compounds being released for subsequent steps of enzymatic hydrolysis and fermentation. Each pretreatment technology has a different specificity against both carbohydrates and lignin and may or may not be efficient for different types of biomasses. Furthermore, it is also desirable to develop pretreatment methods with chemicals that are greener and effluent streams that have a lower impact on the environment. This paper provides an overview of the most important pretreatment methods available, including those that are based on the use of green solvents (supercritical fluids and ionic liquids)

Rekonstruktion der phanerozoischen tektonischen und thermischen Geschichte Zentral- und Süd- Madagaskars, basierend auf Spaltspurthermochronologie.

Titanite and apatite fission track (FT) thermochronology on 127 basement and 18 sedimentary rock samples from central and southern Madagascar record a complex cooling and denudation history since the Early Palaeozoic. Titanite FT analyses gave ages ranging between 483 Ma and 266 Ma. Apatite FT ages vary between 460 Ma and 79 Ma. Samples from Late Carboniferous to Jurassic sediments from the Morondava basin gave apatite FT ages ranging between 462 Ma and 184 Ma. FT data argues for reactivation of several Late Neoproterozoic/Early Cambrian ductile shear zones pre-dating the initial opening of the Morondava basin during the Late Carboniferous. Apatite FT data indicate that the subsequent Mesozoic rift evolution was accompanied with an eastward migration of areas of fast cooling. During Mesozoic times the Morondava basin had a greater eastward extension. Detrital apatite FT data derived from the outcropping Sakoa Group imply that after the Late Carboniferous deposition these rocks were covered by 2-4 km of sedimentary rocks. The final separation of Madagascar and East Africa during the Jurassic influenced mainly samples in southwest Madagascar, where basement regions and also former basin regions were exhumed. Combined Titanite FT and structural data argue for a minor tectono-thermal influence of the Marion hot spot during the Madagascar-India separation. However, apatite FT ages and modelled cooling paths indicate that the break-up during the Cretaceous was associated with a denudation amount of ~4 km crustal section along a narrow stripe parallel to the present eastern continental margin

Reconstruction of the Phanerozoic tectono-thermal history of central and southern Madagascar, based on fission track thermochronology

Titanite and apatite fission track (FT) thermochronology on 127 basement and 18 sedimentary rock samples from central and southern Madagascar record a complex cooling and denudation history since the Early Palaeozoic. Titanite FT analyses gave ages ranging between 483 Ma and 266 Ma. Apatite FT ages vary between 460 Ma and 79 Ma. Samples from Late Carboniferous to Jurassic sediments from the Morondava basin gave apatite FT ages ranging between 462 Ma and 184 Ma. FT data argues for reactivation of several Late Neoproterozoic/Early Cambrian ductile shear zones pre-dating the initial opening of the Morondava basin during the Late Carboniferous. Apatite FT data indicate that the subsequent Mesozoic rift evolution was accompanied with an eastward migration of areas of fast cooling. During Mesozoic times the Morondava basin had a greater eastward extension. Detrital apatite FT data derived from the outcropping Sakoa Group imply that after the Late Carboniferous deposition these rocks were covered by 2-4 km of sedimentary rocks. The final separation of Madagascar and East Africa during the Jurassic influenced mainly samples in southwest Madagascar, where basement regions and also former basin regions were exhumed. Combined Titanite FT and structural data argue for a minor tectono-thermal influence of the Marion hot spot during the Madagascar-India separation. However, apatite FT ages and modelled cooling paths indicate that the break-up during the Cretaceous was associated with a denudation amount of ~4 km crustal section along a narrow stripe parallel to the present eastern continental margin

Electrochemically Enhanced Deposition of Scale from Chosen Formation Waters from the Norwegian Continental Shelf

Reservoir formation waters typically contain scaling ions which can precipitate and form mineral deposits. Such mineral deposition can be accelerated electrochemically, whereby the application of potential between two electrodes results in oxygen reduction and water electrolysis. Both processes change the local pH near the electrodes and affect the surface deposition of pH-sensitive minerals. In the context of the plugging and abandonment of wells, electrochemically enhanced deposition could offer a cost-effective alternative to the established methods that rely on setting cement plugs. In this paper, we tested the scale electro-deposition ability of six different formation waters from selected reservoirs along the Norwegian continental shelf using two experimental setups, one containing CO2 and one without CO2. As the electrochemical deposition of scaling minerals relies on local pH changes near the cathode, geochemical modelling was performed to predict oversaturation with respect to the different mineral phases at different pH values. In a CO2-free environment, the formation waters are mainly oversaturated with portlandite at pH > 12. When CO2 was introduced to the system, the formation waters were oversaturated with calcite. The presence of mineral phases was confirmed by powder X-ray diffraction (XRD) analyses of the mineral deposits obtained in the laboratory experiments. The geochemical-modelling results indicate several oversaturated Mg-bearing minerals (e.g., brucite, dolomite, aragonite) in the formation waters but these, according to XRD results, were absent in the deposits, which is likely due to the significant domination of calcium-scaling ions in the solution. The amount of deposit was found to be proportional to the concentration of calcium present in the formation waters. Formation waters with a high concentration of Ca ions and a high conductivity yielded more precipitate