We investigate the sensitivity of surface controlled-source electromagnetic (CSEM) monitoring for CO2 storage in the Aquistore project (Saskatchewan, Canada), where injection occurs at 3200 m depth. The sensitivity of frequency-domain electric-field responses to CO2 plume evolution was evaluated using six forward modelling scenarios: three assuming homogeneous 90% post-injection CO2 saturation, and three representing heterogeneous CO2 saturation reflecting more realistic resistivity distributions. Detectability is assessed using the scattered electric fields, proportional changes in electric-field magnitudes (anomalous fields), and time-lapse phase variations. For a four-layered model, galvanic connection of the bipole source to a steel-cased injection well enhances scattered electric fields by more than two orders of magnitude at low frequencies. For in-line configurations, sensitivity to plume change is greatest between 0.1-1 Hz, at offsets of 5-10 km. For a realistic 18-layered resistivity structure, the present 10 m-thick CO2 plume produces responses below typical detection thresholds but defines minimum requirements for a viable system: post-processing noise levels of 10(-)& sup1;(5) V/(A.m & sup2;), anomalous field sensitivity of similar to 0.5%, and time-lapse phase resolution of similar to 0.3 degrees. We demonstrate CSEM response depends weakly on plume depth and radius but strongly on thickness, with anomalous magnitude and phase increasing almost proportionally. An 80 m-thick plume from future commercial-scale injection would yield anomalous magnitude changes >5% and phase changes >1.5 degrees. Leakage into shallower carbonate units produces smaller responses than formation of the original plume, with changes dominated by effects of loss from the reservoir. The study also examines areal electric field distribution and effects of transverse anisotropy.

American black bears (Ursus americanus) in the Lower Mississippi Alluvial Valley (LMAV) suffered significant declines in the 20th century from habitat loss and overexploitation. Remnant black bear subpopulations in southeastern Arkansas and eastern Louisiana have recovered and expanded into western Mississippi in the early 2000s. However, the genetic status and origin of subpopulations in Mississippi remain poorly understood. We evaluated genetic diversity, population structure, and connectivity of black bears in the LMAV and compared our results to a previous study. We identified an expanded admixture zone in western Mississippi where black bears dispersing from Arkansas and Louisiana converged and reproduced. The subpopulation in southern Mississippi exhibited the highest allelic richness (AR = 4.50) and elevated expected heterozygosity (HE = 0.61), consistent with recent admixture. Gene flow was greatest from the Tensas River Basin in Louisiana to the Mississippi subpopulations and to the Three Rivers Complex in Louisiana (m = 0.17–0.22), suggesting corridors between Mississippi and Louisiana may be similar in quality to corridors among Louisiana subpopulations. However, dispersal into Arkansas from all subpopulations remained limited, underscoring the genetic isolation of the White River Basin and West Gulf Coastal Plain subpopulations. Our results revealed an undocumented dispersal pathway from Louisiana’s Upper Atchafalaya River Basin into southern Mississippi. Despite these promising findings, genetic diversity in Mississippi and the LMAV remains lower than in many other black bear populations. Continued habitat restoration, improved corridor connectivity, and ongoing genetic monitoring are essential to support black bear recovery in Mississippi and across the LMAV.

Full-waveform inversion (FWI) of seismic data is a powerful method for estimating high-resolution models of the subsurface. An accurate initial model and low-frequency data are necessary to avoid cycle skipping and perform a successful FWI. In the absence of this information, FWI is likely to fail due to convergence in local misfit minima. With the recent advancements in artificial intelligence, studies have shown that absent low-frequency data can be extrapolated using deep learning (DL). These studies have been mostly focused on surface seismic data whose frequency content is different from cross-well data. In this study, we assess the use of DL for low-frequency extrapolation for a cross-well survey that was done at the Aquistore storage site in Saskatchewan. This assessment includes both numerical and field data examples. We extrapolate the low frequencies to increase the bandwidth of the acquired data at the Aquistore site and perform FWI. We evaluate the efficiency of this method by comparing the results with obtained velocity models from the conventional multiscale FWI. Our results for the Aquistore data show that the proposed strategy leads to an accuracy improvement of 39% and 20% in the model and data domains, respectively.

Application of 3D technologies to the wide range of Geosciences knowledge domains is well underway. These have been operationalized in workflows of the hydrocarbon sector for a half-century, and now in mining for over two decades. In Geosciences, algorithms, structured workflows and data integration strategies can support compelling Earth models, however challenges remain to meet the standards of geological plausibility required for most geoscientific studies. There is also missing links in the institutional information infrastructure supporting operational multi-scale 3D data and model development. Canada in 3D (C3D) is a vision and road map for transforming the Geological Survey of Canada's (GSC) work practice by leveraging emerging 3D technologies. Primarily the transformation from 2D geological mapping, to a well-structured 3D modelling practice that is both data-driven and knowledge-driven. It is tempting to imagine that advanced 3D computational methods, coupled with Artificial Intelligence and Big Data tools will automate the bulk of this process. To effectively apply these methods there is a need, however, for data to be in a well-organized, classified, georeferenced (3D) format embedded with key information, such as spatial-temporal relations, and earth process knowledge. Another key challenge for C3D is the relative infancy of 3D geoscience technologies for geological inference and 3D modelling using sparse and heterogeneous regional geoscience information, while preserving the insights and expertise of geoscientists maintaining scientific integrity of digital products. In most geological surveys, there remains considerable educational and operational challenges to achieve this balance of digital automation and expert knowledge. Emerging from the last two decades of research are more efficient workflows, transitioning from cumbersome, explicit (manual) to reproducible implicit semi-automated methods. They are characterized by integrated and iterative, forward and reverse geophysical modelling, coupled with stratigraphic and structural approaches. The full impact of research and development with these 3D tools, geophysical-geological integration and simulation approaches is perhaps unpredictable, but the expectation is that they will produce predictive, instructive models of Canada's geology that will be used to educate, prioritize and influence sustainable policy for stewarding our natural resources. On the horizon are 3D geological modelling methods spanning the gulf between local and frontier or green-fields, as well as deep crustal characterization. These are key components of mineral systems understanding, integrated and coupled hydrological modelling and energy transition applications, e.g. carbon sequestration, in-situ hydrogen mining, and geothermal exploration. Presented are some case study examples at a range of scales from our efforts in C3D.

Fibre-optic sensing technology has recently become popular for oil and gas extraction, mining, geotechnical engineering, and hydrogeology applications. With a successful track record in many applications, distributed acoustic sensing using straight fibre-optic cables has become a method of choice for seismic studies. However, distributed acoustic sensing using straight fibre-optic cables cannot detect off-axial strain at high incident angles (the angle between the ray and normal vector of the surface); hence, a helically wound cable design was introduced to overcome this limitation. The helically wound cable field data at the New Afton deposit in British Columbia, Canada, showed that the quality of the data is highly dependent on the incident angle and surrounding media. A 3D finite element model developed using COMSOL Multiphysics quickly and efficiently assessed the effects of various materials surrounding a helically wound cable for simple geometry for scenarios corresponding to a real deployment of such cable underground at the New Afton mine. The proposed numerical modelling workflow could be applied to more complicated scenarios (e.g., non-linear material constitutive behaviour and the effects of pore fluids). The results of this paper can be used as a guideline for analyzing the impact of surrounding media and incident angle on the response of helically wound cable, optimizing the installation of helically wound cable in various conditions, and validating boundary conditions of 3D numerical models built for analyzing complex scenarios.

This paper focuses on a high accuracy permanent reservoir monitoring system that integrates a permanent seismic source named accurately controlled routinely operated signal system（ACROSS）and a fiber optic sensing technology called distributed acoustic sensing（DAS）. To evaluate the effectiveness and benefits of this system, we have conducted a DAS-VSP data acquisition demonstration test at the Aquistore CO2 storage site in Saskatchewan, Canada. We have acquired four monitoring data sets in this field since 2016 when ACROSS was moved to a location about 750 m away from the observation well. During data acquisition, ACROSS was remotely controlled from Japan to reduce the HSE risk and cost. We constructed an efficient data processing flow including ACROSS signal processing, data matching, VSP data processing and 4D noise suppression. A 4D response evaluation method was established using two different types of repeatability indexes. The data acquisition, processing and evaluation were successful and a high- repeatability seismic section was obtained. In addition, we performed advanced data acquisition using a wireline DAS method and data processing using reverse time migration（RTM）. Lastly, we compared the latest data processing results with 3D seismic monitoring results acquired in the same time and discussed future prospects of reservoir monitoring in a CCUS and EOR field. We think that our monitoring system will be implemented as a useful reservoir monitoring system, so we plan to continue associated research, including the preparation for the new data acquisition in 2022.

Alternative fiber configurations have been tested in an attempt to improve the sensitivity of surface-deployed distributed acoustic sensing (DAS) fiber cables for the purpose of recording steep-angle P-wave reflections. Four alternative fiber configurations were deployed at the Aquistore CO 2 storage site to record 401 dynamite shots during a 3D vertical seismic profiling survey. The test cable comprised horizontal configurations (straight fiber, helixes, and asymmetric helixes) buried in a shallow trench and vertical configurations (straight fiber and helixes) deployed in 3.5 m drillholes. Evaluation focused on deep reflections with two-way traveltimes of 0.8–1.8 s. All of the alternative fiber configurations increased the sensitivity relative to the horizontal straight fiber. Sensitivity was highest for the vertical straight fiber configurations and the asymmetric helixes with sensitivity increases of more than 10 and 5 dB, respectively, and amplitude-variation-with-offset behavior similar to that of a vertical-component geophone for reflections with incidence angles of 0°–15° at the surface and 0°–34° at the reflector. Modeling of the DAS responses explains the general pattern of sensitivity variability among the different configurations, but it does not explain the large range of observed sensitivities.

Geodetic monitoring involves the repeated measurement of the deformation of the Earth. As discussed here, it is a cost-effective approach for inferring reservoir integrity and detecting possible leakage associated with the geological storage of greenhouse gas emissions. Most geodetic methods have favorable temporal sampling, from minutes to months depending upon the technique adopted, and can detect anomalous behavior in a timely fashion. Satellite-based approaches such as Interferometric Synthetic Aperture Radar (InSAR), with their high spatial resolution and broad coverage, are particularly well suited for monitoring industrial-scale storage efforts. Multitemporal analysis, such as permanent scatterer techniques, are improving the accuracy of surface displacement measurements to better than 4 – 5 mm. New satellites, including the recent X-band systems, are allowing for the routine estimation of two components of deformation. Data interpretation and inversion techniques may be used to relate the observed displacements to injection-related volume change at depth. InSAR monitoring was used successfully at a gas storage site at In Salah, Algeria, where it was determined that the flow in the reservoir was influenced by large-scale fault/fracture zones. InSAR observations are also key components of the monitoring programs at the Aquistore CO 2 storage project in Canada, and the Illinois Basis Decatur Project in the United States. Current InSAR data from both sites indicate no major surface deformation that might be attributed to the stored carbon dioxide, suggesting that the injected fluid remains at depth.

Borehole geophysical methods are a key component of subsurface monitoring of geologic CO2storage sites because boreholes form a locus where geophysical measurements can be compared directly with the controlling geology. Borehole seismic methods, including intrawell, crosswell, and surface-to-borehole acquisition, are useful for site characterization, surface seismic calibration, 2D/3D time-lapse imaging, and microseismic monitoring. Here, we review the most common applications of borehole seismic methods in the context of storage monitoring and consider the role that detailed geophysical simulations can play in answering questions that arise when designing monitoring plans. Case study examples are included from the multitude of CO2monitoring projects that have demonstrated the utility of borehole seismic methods for this purpose over the last 20 years.

Background and Aims Nerve injury is a rare but well-known complication of regional anaesthesia and may arise from high pressure administration of local anaesthetic directly into nerve fascicles. Safe injection pressures (< 20psi) 1,2 are subjective to estimate with manual injection, and this task is often delegated to skilled assistants. Pressure-limiting injection devices such as SAFIRA® (Medovate, UK) have been designed to reduce this risk. This study measures injection pressures deemed ‘safe’ by experts and compares them with that of SAFIRA®. Methods Following IRB approval and with consent, ten skilled Operating Department Practitioners (ODPs) and ten Anaesthetists were recruited to inject 0.9% Saline at the ‘highest pressure they thought safe’ using a series of syringes (2.5 ml, 5 ml, 10 ml, 20 ml and 50 ml) attached to a Fluke 700GO6® pressure transducer (Fluke Corp, WA, USA). One hundred measurements were recorded. We then attached the SAFIRA® device (fitted with a 20 ml syringe) to the pressure transducer and measured the machine-limited pressure 100 times for comparison. Results In 21/100 manual injections, estimated ‘safe’ pressure was exceeded, with the highest measured at 44psi. Though the data was skewed by a few individuals, 50% of ODPs and 30% of Anaesthetists injected at pressures ≥20psi at least once (at all syringe sizes). Cut-off pressures from SAFIRA® were consistently below 20psi. Conclusions Practitioners best estimates of safe manual injection pressure is inaccurate. In contrast, a calibrated and engineered solution such as SAFIRA® does not require subjective user estimation.

We present a summary of physical rock properties and vertical seismic profiling (VSP) results acquired with distributed acoustic sensing (DAS) in boreholes that intersect the main mineralized zone and alteration halo at the New Afton Cu-Au porphyry deposit, British Columbia. We used an advanced DAS system that achieves signal-to-noise ratio of conventional geophones but offers high-density sensing of the entire fibre-optic cable. Straight and helically wound fibre-optic cables specifically engineered for the advanced DAS system were installed in two boreholes and compared with conventional fibre-optic cables with similar configurations connected to a standard DAS interrogator. Comparison of raw field data and processed data of both systems demonstrates a significantly higher signal-to-noise ratio for the new DAS system. Processed VSP data show several reflections with shallow dips that are mostly explained by faults and fractures observed in wireline logs and intersecting the surveyed boreholes.

Summary Over the past decade, geological storage of CO2, mostly in deep saline aquifers, has demonstrated a practical short-to-medium term means to partially meet the ambitious global commitments to climate change mitigation and net-zero carbon emission policies. As a key element of CO2 Plume Geothermal (CPG) systems, we examine the feasibility of running a CO2 circulation test utilizing an existing underground CO2 plume for synergistic utilization of the Aquistore site for both subsurface CO2 storage and geothermal power generation. In this work, we appraised the most probable realizations of CO2 plume extent from history matched numerical simulations and time-lapse seismic monitoring. We extracted and re-built a high-resolution sector model from a developed full geological model to represent the geology near the existing injection and observation wells. Given the extensive field evidence of CO2 arrival at the observation well, we performed uncertainty assessment of a CO2 circulation pilot test between the injector and the producer (i.e. observation well), followed by assessment of the resulting flow regimes during CO2/brine co-production. The findings of this paper assist in identifying the potential and limitations associated with conducting a CO2 circulation test and ultimately CPG operations at geologic CO2 storage sites such as Aquistore.

ABSTRACTWireline logs and vertical seismic profile data were acquired in two boreholes intersecting the main mineralized zone at the Cu–Au New Afton porphyry deposit, Canada, with the objectives of imaging lithological contacts, fault zones that may have acted as conduits that channelled the mineralization, and alteration zones. Log data provide physical rock properties for the main lithologies and alteration zones. Calliper logs reveal many faults and caved‐in zones generally indicating rocks with low integrity at the borehole wall. The preponderance of these zones, as indicated by the logs, suggests that their response may dominate the seismic‐reflection wavefield. Outside fault zones, compressional and shear‐wave velocities exhibit significant variability due to porosity, the heterogeneity of volcanic fragmental rocks and alteration. Distributed acoustic sensing was used to acquire vertical seismic profiling data in the two boreholes surveyed with wireline logs. Straight and helically wound fibre‐optic cables housed standard fibres and a fibre engineered to increase the intensity of backscattering at the distributed acoustic sensing interrogator. Standard and engineered optical fibres placed in the two boreholes were daisy‐chained together to form two 5‐km‐long continuous fibres that were interrogated at once with two interrogators. A new generation of interrogator connected to the engineered fibres provided field data with lower noise level and higher signal‐to‐noise ratio. These data with higher signal‐to‐noise ratio from straight fibre‐optic cable were processed and used for depth imaging. Depth images benefitted from new migration weights that account for the directional sensitivity of the straight fibre‐optic cable and limit the extent of migration artefacts. Migration results show several reflectors with shallow dips to the northwest, some explained by faults intersecting the surveyed boreholes. The main sub‐vertical lithological and alteration contacts at New Afton generated downgoing reflections that were not considered in the migration.

ABSTRACTChronic-wasting disease (CWD) is a prion-derived fatal neurodegenerative disease that has affected wild cervid populations on a global scale. Susceptibility has been linked unambiguously to several amino acid variants within the prion protein gene (PRNP). Quantifying their distribution across landscapes can provide critical information for agencies attempting to adaptively manage CWD. Here we attempt to further define management implications ofPRNPpolymorphism by quantifying the contemporary geographic distribution (i.e., phylogeography) ofPRNPvariants in hunter-harvested white-tailed deer (WTD;Odocoileus virginianus, N=1433) distributed across Arkansas (USA), including a focal spot for CWD since detection of the disease in February 2016. Of these,PRNPvariants associated with the well-characterized 96S non-synonymous substitution showed a significant increase in relative frequency among older CWD-positive cohorts. We interpreted this pattern as reflective of a longer life expectancy for 96S genotypes in a CWD-endemic region, suggesting either decreased probabilities of infection or reduced disease progression. Other variants showing statistical signatures of potential increased susceptibility, however, seemingly do so as an artefact of population structure. We also showed marked heterogeneity across the landscape in the prevalence of ‘reduced susceptibility’ genotypes. This may indicate, in turn, that differences in disease susceptibility among WTD in Arkansas are an innate, population-level characteristic that is detectable through phylogeographic analysis.