Using oxygen isotopes to quantitatively assess residual CO2 saturation during the CO2CRC Otway Stage 2B Extension residual saturation test

Residual CO2 trapping is a key mechanism of secure CO2 storage, an essential component of the Carbon Capture and Storage technology. Estimating the amount of CO2 that will be residually trapped in a saline aquifer formation remains a significant challenge. Here, we present the first oxygen isotope ratio (δ18O) measurements from a single-well experiment, the CO2CRC Otway 2B Extension, used to estimate levels of residual trapping of CO2. Following the initiation of the drive to residual saturation in the reservoir, reservoir water δ18O decreased, as predicted from the baseline isotope ratios of water and CO2, over a time span of only a few days. The isotope shift in the near-wellbore reservoir water is the result of isotope equilibrium exchange between residual CO2 and water. For the region further away from the well, the isotopic shift in the reservoir water can also be explained by isotopic exchange with mobile CO2 from ahead of the region driven to residual, or continuous isotopic exchange between water and residual CO2 during its back-production, complicating the interpretation of the change in reservoir water δ18O in terms of residual saturation. A small isotopic distinction of the baseline water and CO2 δ18O, together with issues encountered during the field experiment procedure, further prevents the estimation of residual CO2 saturation levels from oxygen isotope changes without significant uncertainty. The similarity of oxygen isotope-based near-wellbore saturation levels and independent estimates based on pulsed neutron logging indicates the potential of using oxygen isotope as an effective inherent tracer for determining residual saturation on a field scale within a few days

He, Ne and Ar 'snapshot' of the subcontinental lithospheric mantle from CO2 well gases

The subcontinental lithospheric mantle (SCLM) constitutes a significant portion of the upper mantle sourcing magmatic volatiles to the continents above, yet its geochemical signature and evolution remain poorly constrained. Here we present new interpretation of noble gas datasets from two magmatic CO2 fields in the SW US, namely Bravo Dome and Sheep Mountain, which provide a unique insight into the volatile character of the SCLM sourcing the Cenozoic volcanism in the region. We identify that reduction of 3He/4Hemantle ratio within the Sheep Mountain CO2 field can be attributed to radiogenic production within the SCLM. Using a Reduced Chi-Squared minimisation on the variation of derived 4He/21Necrust ratios within samples from the Sheep Mountain field, combined with a radiogenically raised 21Ne/22Nemantle end member, we resolve 3He/4Hemantle ratios of 2.59 ± 0.15 to 3.00 ± 0.18 Ra. These values correspond with a 21Ne/22Nemantle value of 0.136. Using these 3He/4Hemantle end member values with 21Nemantle resolved from Ne three component analysis, we derive the elemental 3He/22Nemantle of 2.80 ± 0.16 and radiogenic 4He/21Ne*mantle range of 1.11 ± 0.11 to 1.30 ± 0.14. A second Reduced Chi-Squared minimisation performed on the variation of 21Ne/40Arcrust ratios has allowed us to also determine both the 4He/40Armantle range of 0.78 to 1.21 and 21Ne/40Armantle of 7.66 ± 1.62 to 7.70 ± 1.54 within the field. Combining these ratios with the known mantle production ranges for 4He/21Ne and 4He/40Ar allows resolution of the radiogenic He/Ne and He/Ar ratios corresponding to the radiogenically lowered 3He/4Hemantle ratios. Comparing these values with those resolved from the Bravo Dome field allows identification of a clear and coherent depletion of He to Ne and He to Ar in both datasets. This depletion can only be explained by partial degassing of small melt fractions of asthenospheric melts that have been emplaced into the SCLM. This is the first time that it has been possible to resolve and account for both the mantle He/Ne and He/Ar ratios within a SCLM source. The data additionally rule out the involvement of a plume component in the mantle source of the two gas fields and hence any plume influence on the Colorado Plateau Uplift event

Tracking CO2 Injection, Migration and Fate at Carbfix2 Using Stable Isotopes

Industrial scale Carbon Capture and Storage (CCS) and Carbon Dioxide Removal (CDR) is required for the world to limit global warming to 1.5-2˚C. Methods that verify CO₂ storage will be necessary for legal accounting and public reassurance. Stable isotopes are inherent tracers readily used throughout the natural sciences as indicators of subsurface reactions and temperatures. The aim of this study is to demonstrate the capabilities of these tracers at the Carbfix2 CO₂ mineral storage site in Iceland. We find that oxygen isotope ratios (δ¹⁸O) of water samples are higher than meteoric water due to water-rock interaction in the geothermal reservoir. Water isotope ratios vary across the dataset due to differing steam-water ratios controlled by hydrothermal phase separation. Carbfix2 monitoring wells are depleted in ¹⁸O and ²H relative to other geothermal production wells and calculated unreacted monitoring well fluids. This is likely because monitoring wells receive background fluids that are isotopically distinct from other geothermal production wells. This work demonstrates the capabilities of stable isotope measurements as tracers of active reactions and processes in CCS reservoirs. Measurements can be used as a direct tracer of injected fluids, while also identifying other important reservoir characteristics such as fluid source and water-rock interaction

First, do no harm: managing the metabolic impacts of androgen deprivation in men with advanced prostate cancer

Androgen deprivation therapy (ADT) is a standard systemic treatment for men with prostate cancer. Men on ADT may be elderly and have comorbidities that are exacerbated by ADT, such as cardiovascular disease, diabetes, obesity, sedentary lifestyle and osteoporosis. Studies on managing the impacts of ADT have focused on men with non-metastatic disease, where ADT is given for a limited duration. However, some men with advanced or metastatic prostate cancer will achieve long-term survival with palliative ADT and therefore also risk morbidity from prolonged ADT. Furthermore, ADT is continued during the use of other survival-prolonging therapies for men with advanced disease, and there is a general trend to use ADT earlier in the disease course. As survival improves, management of the metabolic effects of ADT becomes important for maintaining both quality and quantity of life. This review will outline the current data, offer perspectives for management of ADT complications in men with advanced prostate cancer and discuss avenues for further research

geochemical data from UK and US produced water batch experiments

<p>Geochemical data set from batch experiments of UK and US shale gas produced water</p

UK shale gas air and water quality data

<p>Datasets for UK coal bed methane compositions (Airth field), shale gas composition from Bowland shale operations and produced water composition from UK Airth field.</p

The noble gas geochemistry of natural CO2 gas reservoirs from the Colorado Plateau and Rocky Mountain provinces, USA

Identification of the source of CO2 in natural reservoirs and development of physical models to account for the migration and interaction of this CO2 with the groundwater is essential for developing a quantitative understanding of the long term storage potential of CO2 in the subsurface. We present the results of 57 noble gas determinations in CO2 rich fields (>82%) from three natural reservoirs to the east of the Colorado Plateau uplift province, USA (Bravo Dome, NM., Sheep Mountain, CO. and McCallum Dome, CO.), and from two reservoirs from within the uplift area (St. John’s Dome, AZ., and McElmo Dome, CO.). We demonstrate that all fields have CO2/3He ratios consistent with a dominantly magmatic source. The most recent volcanics in the province date from 8 to 10 ka and are associated with the Bravo Dome field. The oldest magmatic activity dates from 42 to 70 Ma and is associated with the McElmo Dome field, located in the tectonically stable centre of the Colorado Plateau: CO2 can be stored within the subsurface on a millennia timescale. The manner and extent of contact of the CO2 phase with the groundwater system is a critical parameter in using these systems as natural analogues for geological storage of anthropogenic CO2. We show that coherent fractionation of groundwater 20Ne/36Ar with crustal radiogenic noble gases (4He, 21Ne, 40Ar) is explained by a two stage re-dissolution model: Stage 1: Magmatic CO2 injection into the groundwater system strips dissolved air-derived noble gases (ASW) and accumulated crustal/radiogenic noble gas by CO2/water phase partitioning. The CO2 containing the groundwater stripped gases provides the first reservoir fluid charge. Subsequent charges of CO2 provide no more ASW or crustal noble gases, and serve only to dilute the original ASW and crustal noble gas rich CO2. Reservoir scale preservation of concentration gradients in ASW-derived noble gases thus provide CO2 filling direction. This is seen in the Bravo Dome and St. John’s Dome fields. Stage 2: The noble gases re-dissolve into any available gas stripped groundwater. This is modeled as a Rayleigh distillation process and enables us to quantify for each sample: (1) the volume of groundwater originally ‘stripped’ on reservoir filling; and (2) the volume of groundwater involved in subsequent interaction. The original water volume that is gas stripped varies from as low as 0.0005 cm3 groundwater/cm3 gas (STP) in one Bravo Dome sample, to 2.56 cm3 groundwater/cm3 gas (STP) in a St. John’s Dome sample. Subsequent gas/groundwater equilibration varies within all fields, each showing a similar range, from zero to ∼100 cm3 water/cm3 gas (at reservoir pressure and temperature)