94 research outputs found
CO2 interaction with aquifer and seal on geological timescales: the Miller oilfield, UK North Sea
Carbon Capture and Storage (CCS) has been identified as a feasible technology to reduce CO2
emissions whilst permitting the continued use of fossil fuels. Injected CO2 must remain
efficiently isolated from the atmosphere on a timescale of the order of 10000 years and greater.
Natural CO2-rich sites can be investigated to understand the behaviour of CO2 in geological
formations on such a timescale. This thesis examines the reservoir and seal on one such
oilfield. Several hydrocarbon fields in the South Viking Graben of the North Sea naturally
contain CO2, which is thought to have charged from depth along the western boundary fault
of the graben. The Miller oil field which contains ~ 28 mol% CO2, of isotopic composition
δ13C = -8.2‰. The Upper Jurassic Brae Formation reservoir sandstones and the Kimmeridge
Clay Formation (KCF) seal have been exposed to the CO2 accumulation since its
emplacement.
Rock samples from the reservoir sandstone and bottom of the seal mudrock were examined
using multiple techniques, including XRD, SEM, fluid inclusion and carbonate stable isotope
analyses. The sandstones show no features directly attributable to abundant CO2 charge. SEM
analyses reveal significant heterogeneities in diagenesis within the KCF. The silt/sand
lithologies of the KCF have undergone a diagenetic history similar to that of the Brae
Formation sandstones. In contrast, the KCF shales display a distinctly different diagenesis of
dominant dissolution of quartz and feldspar with little evidence of mineral precipitation. In
both the Brae Formation and the KCF, pore-filling kaolinite, illite and carbonates are
relatively late diagenetic events which can be associated with CO2-induced feldspar
dissolution.
Mudrock X-ray diffraction mineralogical data reveal abrupt vertical mineralogical variations
across the reservoir crest in the Miller Field, while such variations are absent in a low-CO2
control well in the same geological settings. This suggests that reactions induced by abundant
CO2 dissolved feldspar and produced kaolinite, carbonates and quartz in the seal, while oil
emplacement inhibited the reactions in the oil leg. However, petrographic evidence and
comparison between different sections argue against CO2 reactions as the sole cause for such
large mineralogical variations, especially for quartz. The vertical mineralogical variations to a
certain extend represent original sedimentary heterogeneity.
Linear variations of carbonate δ13C with depth were discovered in both shale and silt/sand
lithologies of the KCF in a 12m zone immediately above the reservoir. These features are
absent in the low-CO2 control well. These trends are interpreted as dissolution of original
carbonates by CO2 slowly ascending from the reservoir. New carbonates precipitated from a
carbon source with upwards decreasing δ13C due to mixing between three carbon sources with
different C isotopes at systematically varying ratios. The isotopes in the reservoir and the
bottom of the seal suggests initial CO2 charge at about 70-80 Ma. CO2 infiltration rate is
estimated at about 9.8×10-7g·cm-2·y-1. Geochemical modelling was applied to reconstruct the
reservoir fluid evolution by calibrating it to mineralogy, fluid chemistry, diagenesis and fluid
inclusion data. The modelling suggests that CO2 migrated into the reservoir together with a
saline basinal fluid derived from the underlying evaporites at ~ 70 Ma. The CO2 and basinal
water charge imposed an important influence on the mineral reactions and fluid chemistry.
This study suggests that the KCF has formed an excellent CO2 seal, with no substantial
breach since its charge at 70-80 Ma
Assessing risk to fresh water resources from long term CO2 injection- laboratory and field studies
In developing a site for geologic sequestration, one must assess potential consequences of failure to adequately contain
injected carbon dioxide (CO2). Upward migration of CO2 or displacement of saline water because of increased pressure might
impact protected water resources 100s to 1000s of meters above a sequestration interval. Questions posed are: (1) Can changes in chemistry of fresh water aquifers provide evidence of CO2 leakage from deep injection/sequestration reservoirs containing brine and or hydrocarbons? (2) What parameters can we use to assess potential impacts to water quality? (3) If CO2 leakage to
freshwater aquifers occurs, will groundwater quality be degraded and if so, over what time period?
Modeling and reaction experiments plus known occurrences of naturally CO2-charged potable water show that the
common chemical reaction products from dissolution of CO2 into freshwater include rapid buffering of acidity by dissolution of
calcite and slower equilibrium by reaction with clays and feldspars. Results from a series of laboratory batch reactions of CO2
with diverse aquifer rocks show geochemical response within hours to days after introduction of CO2. Results included decreased
pH and increased concentrations of cations in CO2 experimental runs relative to control runs using argon (Ar). Some cation (Ba,
Ca, Fe, Mg, Mn, and Sr) concentrations increased over and an order of magnitude during CO2 runs. Results are aquifer dependant in that experimental vessels containing different aquifer rocks showed different magnitudes of increase in cation concentrations.
Field studies designed to improve understanding of risk to fresh water are underway in the vicinity of (1) SACROC
oilfield in Scurry County, Texas, USA where CO2 has been injected for enhanced oil recovery (EOR) since 1972 and (2) the
Cranfield unit in Adams County, Mississippi, USA where CO2 EOR is currently underway. Both field studies are funded by the
U.S. Department of Energy (DOE) regional carbon sequestration partnership programs and industrial sponsors. Preliminary
results of groundwater monitoring are currently available for the SACROC field study where researchers investigated 68 water
wells and one spring during five field excursions between June 2006 and July 2008. Results to date show no trend of preferential
degradation below drinking water standards in areas of CO2 injection (inside SACROC) as compared to areas outside of the
SACROC oil field.Bureau of Economic Geolog
Laboratory Batch Experiments and Geochemical Modelling of Water-rock-super Critical CO2 Reactions in Gulf of Mexico Miocene Rocks: Implications for Future CCS Projects
AbstractStorage of CO2 in deep saline formations in a super critical liquid state has been proposed as a way to mitigate the effects of increased atmospheric CO2 levels. The ultimate fate of the CO2 after injection requires an understanding of mineral dissolution/precipitation reactions occurring between the target formation minerals and the existing formation brines at formation temperatures and pressures in the presence of supercritical CO2. In this experiment core material taken from a Miocene age Gulf of Mexico core from a depth of 2806 m was reacted with synthetic brine at varied but high temperatures and pressures in the presence of super critical CO2. XRD and SEM analyses were conducted before and after reaction to identify dissolution of existing minerals and precipitation of authigenic mineral phases. Periodic geochemical analysis of the reaction fluid was used to quantify changes in the elemental composition of the reaction fluid which helps identify potential mineral dissolution/precipitation reactions.Reaction brine (140ml) was loaded into a high pressure reaction vessel with 8g of core sample.Experimental temperature was set to 70, 100 or 130°C; pressure was set to 200 or 300bar, and solution chemistry was changed from de-ionized (DI) water to a 1.88M NaCl solution. After the introduction of CO2 the Ca and alkalinity concentrations showed the largest increases, Ca concentrations increased ∼1000ppm, suggesting carbonate dissolution was the dominant geochemical reaction. Final equilibrium Ca concentrations increased with decreasing reaction temperature because of greater CO2 solubility. In addition, the reactions with the NaCl brine produced higher equilibrium Ca concentrations than the DI water experiment, likely due to the decrease in ion activity with higher ionic strength solutions. Pressure change from 200 to 300bar did not significantly alter reaction rates. Unlike Ca, silicate dissolution reactions appear to be positively correlated with reaction temperature. Silicate dissolution rates are 2 orders of magnitude slower than carbonate dissolution rates.In this study, PHREEQC was used to simulate brine-rock-CO2 interactions in batch experiments under high pressure and high temperature. Generally, the geochemical models reproduced concentration of Ca, Mg, K and Si seen in the water rock experiments suggesting that carbonate and K-feldspar dissolution are the dominant geochemical reactions. In addition, geochemical models show that dawsonite precipitates in higher salinity (higher Na+ concentration) experiments
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Impact of CO2 Impurities on Storage Performance and Assurance - Report on Tasks 3 and 4 (Geochemistry) Prepared for: CO2 Capture Project (Phase III)
This document presents the results of Tasks 3 and 4 out of 5 tasks, focusing on the geochemical impacts of impurities in the CO2 stream. Tasks 1 and 2 were dedicated to examining the effects on flow behavior. The impurities primarily consist of N2, O2, and Ar, with several minor reactive species potentially added, including CO, H2, SOx, and other trace gases. The research methodology involved laboratory autoclave experiments combined with geochemical numerical modeling.
The autoclave utilized in the experiments is a 250-ml reactor capable of withstanding temperatures up to 150°C and pressures up to 400 bars, simulating conditions observed in reservoirs at depths of up to 12,000 ft. Pressure and temperature were automatically controlled by a computer, and the system allowed for water sampling during the experiments. Typically, 10 to 15 samples of the solution were collected during each experiment, which lasted 5 to 10 days.
Rock samples were exposed to either a supercritical mixture of CO2 and O2 (generally 3.5% molar) or pure supercritical CO2, filling approximately half of the reactor cell. The other half of the cell contained a single core fragment or several large fragments (~8g total) submerged in approximately 140 ml of synthetic brine (~1.88 mol NaCl, corresponding to a TDS of 100,000-110,000 mg/L).
The study analyzed three types of clastic rock samples:
1. A "dirty sandstone" of Miocene age obtained from a deep well in the shallow offshore region off the Texas coast.
2. A relatively clean sandstone from the Cretaceous-age Cardium Formation in Alberta.
3. A chlorite-rich sandstone from the Tuscaloosa Formation in Mississippi, sourced from the Cranfield site, which has been extensively studied by BEG for several years.Bureau of Economic Geolog
Screening and simulation of offshore CO2-EOR and storage:A case study for the HZ21-1 oilfield in the Pearl River Mouth Basin, Northern South China Sea
CO2-enhanced oil recovery (CO2-EOR) and storage is currently the most effective and economic technology for reducing CO2 emissions from burning fossil fuels in large scale. This paper is the first effort of proposing a modelling assessment of CO2-EOR and storage in the HZ2-1 oilfield in the Pearl River Mouth Basin in northern South China Sea offshore Guangdong Province. We attempt to couple the multi-parameter dimensionless quick screening model and reservoir compositional simulation for optimization of site screen and injection simulation. Through the quick screening, the reservoirs are ranked by FOR dimensionless recovery R-D, and by CO2 storage in pore volume SCO2. Our results indicate that SCO2 is highly pressure dependent and not directly related to R-D. Of these reservoirs, CO2-EOR and storage potential of the M10 was estimated through a compositional simulation as a case study based on a 3D geological model. Nine scenarios of CO2 injection operations have been simulated for 20 years with different well patterns and injection pressures. The simulation results represent an obvious improvement in oil production by CO2 flooding over No - CO2 production. The best operation for M10 is miscible CO2 flooding, which led to the higher recovery factors of 52%(similar to)58% and CO 2 stored masses of 8.1 x 10(6 similar to)10.8 x 10(6)t The optimum operation for CO2 injection should be set well pattern in region of injector I1 and high injection pressure for miscible flooding. In a whole, the HZ21-1 field can be used as a candidate geological site for GDCCUS project. We are fully aware of the limitation in the primary modelling including reservoir and fluid properties and production history matching, and regard this study as a general and hypothetic proposal
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Impact of CO2 Impurities on Storage Performance and Assurance -Report on Task 5 (Integration of Flow and Geochemistry) and Final Report Prepared for: CO2 Capture Project (Phase III)
A key impediment to carbon capture and storage is the cost of CO2 capture, particularly for conventional power plants whose flue gas is dominated by gases other than CO2. Waste gas streams from power plants that use novel technologies (such as oxyfuel, the focus of this work) can circumvent the capture step thanks to their CO2-rich composition (CO2 > 90%), but at the expense of CO2 stream purity. In addition to CO2, two non-reactive gases make up the bulk of impurities: N2 and Ar. O2 is the most commonly cited reactive gas, with molar concentrations ranging from 5%. Other minor species may also be present.
Relatively high purity levels must be achieved to avoid compression and complications in pipeline transportation (two-phase flow) and, potentially, subsurface impacts. This work investigates the latter, which, in turn, informs techno-economic assessments of capture and transportation economics. Subsurface impacts of an impure CO2 stream could be twofold: (1) complicate flow behavior and reduce static capacity due to density and viscosity differences and (2) undermine reservoir and top seal integrity due to reactions with reactive species (O2, CO, SOx).
To address the first issue, we conducted a desktop study using a numerical modeling tool and performed laboratory experiments to determine the actual viscosity and density of the mixtures. Information on the solubility of these various mixture components in the aqueous phase under various pressure, temperature, and salinity conditions was also collected.
An important observation controlling all study results was that the viscosity and density of the mixtures considered are lower than those of pure CO2 at the same temperatures and pressures. It follows that a plume of CO2 with impurities, moving updip with no barrier, will migrate farther from the point of injection but will be trapped through residual saturation sooner than a plume of pure CO2, possibly enhancing dissolution primarily because it is exposed to more rock/brine volume. However, a larger plume means that a larger area must be defined and monitored for leakage pathways, such as faults and wells, but the faster trapping translates into a shorter monitoring period. Equally important is that contrasts of viscosity and density between pure CO2 and a CO2 mixture decrease with depth, suggesting that differences in flow behavior and storage capacity are proportionally reduced with depth.Bureau of Economic Geolog
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Geochemical characterization of shallow groundwater at the Cranfield aquifer and numerical simulation: Can pH and carbonate parameters be used to detect potential CO2 leakage at geological CO2 sequestration sites?
Bureau of Economic Geolog
Membrane chromatographic method for the rapid purification of vitellogenin from fish plasma
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Class I histone deacetylases (HDAC1-3) are histone lysine delactylases
Lysine L-lactylation [K(L-la)] is a newly discovered histone mark stimulated under conditions of high glycolysis, such as the Warburg effect. K(L-la) is associated with functions that are different from the widely studied histone acetylation. While K(L-la) can be introduced by the acetyltransferase p300, histone delactylases enzymes remained unknown. Here, we report the systematic evaluation of zinc- and nicotinamide adenine dinucleotide-dependent histone deacetylases (HDACs) for their ability to cleave ε-N-L-lactyllysine marks. Our screens identified HDAC1-3 and SIRT1-3 as delactylases in vitro. HDAC1-3 show robust activity toward not only K(L-la) but also K(D-la) and diverse short-chain acyl modifications. We further confirmed the de-L-lactylase activity of HDACs 1 and 3 in cells. Together, these data suggest that histone lactylation is installed and removed by regulatory enzymes as opposed to spontaneous chemical reactivity. Our results therefore represent an important step toward full characterization of this pathway's regulatory elements
Decreased Leptin Is Associated with Alterations in Thyroid-Stimulating Hormone Levels after Roux-en-Y Gastric Bypass Surgery in Obese Euthyroid Patients with Type 2 Diabetes
Background: Leptin has been shown to stimulate the hypothalamus-pituitary-thyroid (HPT) axis in vivo and vitro. Its role in thyroid axis regulation after weight loss induced by bariatric surgery is still unknown. The aim of this study was to evaluate the influence of leptin on weight loss and thyroid function variation induced by Roux-en-Y gastric bypass (RYGB) surgery in euthyroid individuals with obesity and type 2 diabetes mellitus (T2DM). Methods: 65 Chinese individuals with obesity and T2DM who underwent RYGB, and 27 healthy volunteers were enrolled in this retrospective study. Participants were evaluated for changes in anthropometric parameters, metabolic indexes, thyroid function, and leptin levels before and 12 months after surgery. Results: After RYGB, all of these patients experienced significant weight reduction and improved glucose control. Metabolic parameters were significantly ameliorated after surgery compared with baseline. Thyroid hormones including free triiodothyronine (FT3), free thyroxine (FT4), and thyroid-stimulating hormone (TSH) declined in parallel. Median (IQR) plasma leptin levels decreased from 33.7 ng/mL (17.9–63.1) to 10.3 ng/mL (4.0–18.5). Pearson correlation analysis showed that TSH was significantly positively correlated with body mass index, C-reactive protein (CRP), and leptin. Multiple stepwise linear regression indicated that leptin and CRP were independent factors affecting TSH. The β coefficients were 0.38 (p = 0.001) and 0.32 (p = 0.004), respectively. There was a significant positive correlation between ΔTSH and Δleptin (r = 0.33, p = 0.01). Conclusion: Decreased or normalized TSH levels after weight loss induced by RYGB might be mediated by the decline in leptin. There could be cross talk between adipose tissue and the HPT axis
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