Prevention of CO2 leakage from underground storage reservoirs

The risk of leakage from CO2 storage sites is recognised as one of the challenging aspects of large scale implementation of geologic sequestration of CO2. Uncertainties in characterizing a geologic reservoir and the current lack of a complete understanding of possible interactions between rock and fluids involved in CO2 storage have resulted in concerns over contingent leakages. The debate on the allowable rate of leakage has led to different perspectives among the CCS stakeholders; some believe that, by analogy to natural CO2 reservoirs, risk of having leakage of less than 1 %/year is dispensable and on the other side, some state that “Any non-zero leak-rate from a stored carbon system means that eventually the entire inventory will be released to the atmosphere”. There is also the issue of public acceptance which would be adversely affected by the non-zero potential of leakage of CO2 back to the surface. This negative impact on the members of the public has proved to be very powerful as it has resulted in the delay and even cancellation of some CCS (carbon capture and storage) projects. To the best of our knowledge, no practically viable techniques existed for prevention of CO2 leaks from unknown leakage paths. Our technique is based on in-situ precipitation of an appropriate solute dissolved in the stored super-critical CO2. Supercritical CO2 (SCCO2) has a distinct characteristic that its density changes from gaseous-like to liquid like monotonically and uniformly. This allows SCCO2 to act as manageable solvent for various solid solutes. Thus, once the solution of SCCO2 + solid solutes departs from the equilibrium conditions, the solute will appear in the form of crystallized particles. Based on this unique behaviour of the supercritical solutions, we have developed a novel technique for tackling contingent CO2 leakage from storage sites as a preventive method. The sealing process takes place in-situ at the exact location of the leak without the need for identifying the leak target area and the exact nature of the leak. In this study, an integrated research methodology was designed and employed to comprehend the physics behind our leakage prevention technique and also, to deliver the required package, i.e. suitable solutes and reliable simulator, for larger scale implementation of this technique. It was aimed firstly to demonstrate the performance of our proposed leakage prevention technique at different leakage scenarios and secondly, to put forward a number of solutes efficient in tackling contingent leakages. In order to identify the underlying mechanisms and the pertinent parameters controlling the efficacy of this technique, a good number of direct visualisation experiments were performed where the kinetics behind solute solidification and precipitation were visually investigated. Three different ranges of potential solid solutes were used in visualisation experiments to cover a wide spectrum of solute solubility in supercritical CO2, which would enable us to draw more general and consistent conclusions. The understandings acquired from the direct visualisations were employed to design efficiently a few yet adequate number of coreflood experiments in which the performance of our technique was studied in more realistic reservoir cores. Having attained the adequate information from the experimental part of this investigation, the findings was subsequently utilised to develop an in-house simulator to fundamentally model the kinetics of solid solute precipitation and consequently, the pertinent parameters of the semi-empirical equations were tuned to match and predict the coreflood experiments. In experimental part of this investigation, a series of visualisation experiments using transparent porous media (micromodel) to physically simulate CO2 leakage under conditions typical of geologic storage sites. In these experiments, degree of “supersaturation” was identified as an important parameter behind effectiveness of solute precipitation. In addition to evaluating the behaviour of different solutes, the impacts of resident water existing in storage reservoir and impurities in CO2 stream were taken into account in visualisation experiments. Utilising the findings from the visualisations, 6 coreflood experiments were carried out, which revealed that a strong and durable blockage was formed in the core and the flow (leakage) of CO2 was effectively sealed. Practically speaking, there should not be any premature precipitation as the solution travels inside the storage reservoir; therefore, apart from the performance of this technique in the vicinity of contingent leakages, the integrity of the solution (as it flows in the simulated storage reservoir) was also investigated in visualisation and coreflood experiments. From the findings revealed by the coreflood and micromodel experiments, it was identified that the solution made with solid-solute and SCCO2 may not be responsive in some scenarios. Therefore, the desire to better control the onset of blockage formation has triggered investigation of developing a complementary method to be able to adjust the response of the solution. It was rationalised that adding another solutes (co-solvent) to the solution would enable us to modify the response of the solution. Sandpack, micromodel visualisations, and coreflood experiments were performed to evaluate influence of co-solvent on the response of the solution to various leakage types. On the modelling the precipitation process in the leakage path, it was first demonstrated that conventional reservoir simulators could not adequately capture the physics leading to the blockage formation and the results of lab-scale coreflood experiments could not be correctly simulated. Therefore, there is a need for developing models, which can predict the performance of the LPT at different cases. Based on the experimental information, we have attempted to develop the relevant equations that describe the mechanisms behind particle formation due to pressure drops. After matching one coreflood experiment, the resultant model was used to predict another coreflood experiment performed at similar conditions, which demonstrated an encouraging performance for the developed mathematical model. The results and findings of this study have primarily verified that our leakage prevention technique, which is developed here through extensive experimental and modelling investigation, is well-capable of tackling various contingent leakages. A number of economically feasible solid solute has been found with positive responses to physically simulated leakage paths, which would be considered as the potential solutes for large scale implementation of our technique. Moreover, an in-house simulator was developed based on the finding observed in the different experiments. The simulator can successfully predict the results of coreflood experiments, which implies that it captures the underlying mechanisms adequately. Having developed the necessary equipment, i.e. appropriate solutes and reliable simulator, our proposed leakage prevention technique is ready to be incorporated in demonstration and pilot trials

Zinc Status in Febrile Seizure: A Case-Control Study

How to Cite This Article: Salehiomran MR, Mahzari M. Zinc Status in Febrile Seizure: A Case-Control Study. Iran J Child Neurol. 2013 Autumn; 7(4):20-23.ObjectiveFebrile seizure is the most common type of seizure in children. Their incidence is 2-5%. There are different hypotheses about relationship between neurotransmitters and trace elements (such as zinc) and febrile seizure. Zinc, asa major element of some enzymes, plays an important role in the central nervous system (CNS) and can affect some inhibitory mechanisms of CNS. The aim of the present study was to determine whether there were any changes in serumzinc level in children with febrile seizure in comparison with febrile children without seizure.Materials & MethodsThis case-control study was performed on 100 patients aged 6 months to 6 years.This study was conducted between January and August 2012, on 50 children with febrile seizures (case) and 50 febrile children without seizures (control), that were referred to Amirkola Children Hospital (a referral hospital in the northof Iran). Two groups were matched for age and sex. The serum zinc levels in the both groups were determined by atomic absorption spectrophotometry method.ResultsThe mean serum zinc level was 0.585±0.166 mg/L and 0.704±0.179 mg/L in the case group and the control group, respectively (p=0.001). The mean serum zinc level was significantly lower in the febrile seizure group compared to thecontrol groups.  ConclusionOur findings revealed that serum zinc level was significantly lower in children with simple febrile seizure in comparison with febrile children without seizure. It can emphasize the hypothesis that there is a relation between serum zinc level and febrile seizure in children. ReferencesVarma RR. Febrile seizures. Indian J Pediatr 2002; 69(8); 697-700.Talebian A, Vakili Z, Talar SA, Kazemi M, Mousavi GA. Assessment of the relation between serum zinc and magnesium levels in children with febrile convulsion. Iranian j pathol 2009;4(4):157-60.Mollah MA, DEy PR, Tarafdar SA, Akhter S, Ahmed S, Hassan T, et al. Zinc in CSF of patients with febrile convulsion. Indian J Pediatr 2002;69(10):859-61.Auvichayapat P, Auvichayapat N, Jedsrisuparp A, Thinkhamrop B, Sriroj S, Piyakulmala T, et al. Incidence of febrile seizures in thalassemic patients. J Med Assoc Thai 2004;87(8):970-3.Nelson KB, Ellenberg JH. Prenatal and perinatal antecedents of febrile seizures. Ann Neurol 1990;27(2):127-31.Udani V.Pediatric epilepsy - An Indian perspective. Indian J Pediatr 2005; 72(4):309-13.Ehsanipour F, Talebi-Taher M, Harandi N, Kani k. Serum zinc level in children with febrile convulsion and its comparison with that of control group. Iranian J Pediatr 2009;199:65-8.Heydarian F, Ashrafzadeh F, Kam S. Simple febrile seizure: The role of serum sodium levels in prediction of seizure recurrence during the first 24 hours. Iran J Child Neurol 2009;3(2):31-4.Jun-Hwa Lee, Jeong Hyun Kim. Comparison of Serum Zinc Levels Measured by Inductively Coupled Plasma Mass Spectrometry in Preschool Children with Febrile and Afebrile Seizures. Ann Lab Med 2012;32(3):190-3.Heydarian F, Ashrafzadeh F, Ghasemian A. Serum zinc level in patient with simple febrile seizure. Iran J Child Neurol 2010;4(2):41-3.Garty B, Olomucki R, Lerman ST, Nitzan M. Cerebrospinal fluid zinc concentration in febrile convulsion. Arch Dis Child 1995;73(4):338-41.Daoud AS, Batieha A, Abu-Ekteish F, Gharaibeh N, Ajlouni S, HijaziS. Iron status: a possible risk factor for the first febrile seizure. Epilepsia 2002;43(7):740-3.Ganesh R, Janakiraman L, Meenakshi B. Serum zinc levels are low in children with simple febrile seizures compared with those in children with epileptic seizures and controls. Ann Trop Paediatr 2011;31(4):345-9.Cho WJ, Son BH, Kim SW. Levels of Sodium and Zinc concentration in febrile convulsion. Korean Child Neural Soc1999;7(2):214-9.Burtis carl A, Ashwood, Edwhard R; Brun, David E. Tietz fundamentals of clinical chemistry. 6th ed. Philadelphia: Saunders Elsevier; 2008. P. 505-7.Smart TG, Hosie AM, Miller PS. Zn2+ ions: modulators of excitatory and inhibitory synaptic activity. Neuroscientist 2004;10(5):432-4.Mollah MA, Rakshit SC, Anwer KS, Arslan MI, saha N, Ahmeds, et al. Zinc concentration in serum and cerebrospinal fluid simultaneously decrease in children with febrile seizure: Finding from a Prospective study in Bangladesh. Acta pediatr 2008;97(12):1707-11.  

Best Practices for Shale Core Handling: Transportation, Sampling and Storage for Conduction of Analyses

Drill core shale samples are critical for palaeoenvironmental studies and potential hydrocarbon reservoirs. They need to be preserved carefully to maximise their retention of reservoir condition properties. However, they are susceptible to alteration due to cooling and depressurisation during retrieval to the surface, resulting in volume expansion and formation of desiccation and micro fractures. This leads to inconsistent measurements of different critical attributes, such as porosity and permeability. Best practices for core handling start during retrieval while extracting from the barrel, followed by correct procedures for transportation and storage. Appropriate preservation measures should be adopted depending on the objectives of the scientific investigation and core coherency, with respect to consolidation and weathering. It is particularly desirable to maintain a constant temperature of 1 to 4 °C and a consistent relative humidity of >75% to minimise any micro fracturing and internal moisture movement in the core. While core re-sampling, it should be ensured that there is no further core compaction, especially while using a hand corer

Challenges in Qualification of Thermal Protection Systems in Extreme Entry Environments

Planetary entry vehicles employ ablative TPS materials to shield the aeroshell from entry aeroheating environments. To ensure mission success, it must be demonstrated that the heat shield system, including local features such as seams, does not fail at conditions that are suitably margined beyond those expected in flight. Furthermore, its thermal response must be predictable, with acceptable fidelity, by computational tools used in heat shield design. Mission assurance is accomplished through a combination of ground testing and material response modelling. A material's robustness to failure is verified through arcjet testing while its thermal response is predicted by analytical tools that are verified against experimental data. Due to limitations in flight-like ground testing capability and lack of validated high-fidelity computational models, qualification of heat shield materials is often achieved by piecing together evidence from multiple ground tests and analytical simulations, none of which fully bound the flight conditions and vehicle configuration. Extreme heating environments (>2000 W/sq. cm heat flux and >2 atm pressure), experienced during entries at Venus, Saturn and Ice Giants, further stretch the current testing and modelling capabilities for applicable TPS materials. Fully-dense Carbon Phenolic was the material of choice for these applications; however, since heritage raw materials are no longer available, future uses of re-created Carbon Phenolic will require re-qualification. To address this sustainability challenge, NASA is developing a new dual-layer material based on 3D weaving technology called Heat shield for Extreme Entry Environments (HEEET). Regardless of TPS material, extreme environments pose additional certification challenges beyond what has been typical in recent NASA missions. Scope of this presentation: This presentation will give an overview of challenges faced in verifying TPS performance at extreme heating conditions. Examples include: (1) Bounding aeroheating parameters (heat flux, pressure, shear and enthalpy) in ground facilities. How to certify TPS if environments can't be bounded or aeroheating parameters can't be simultaneously achieved. (2) Higher uncertainties in ground test environments (facility calibration and analytical predictions) at extreme conditions. (3) Testing in flows similar to planetary atmosphere composition (H2/He for Gas and Ice Giants). (4) Test sample size limitations for qualifying seam designs. (5) Lack of computational tools capable of simulating all significant aspects of TPS performance (including initiation and propagation of failures). This presentation will provide recommendations on how the EDL community can address these challenges and mitigate some of the risks involved in flying TPS materials at extreme conditions. Examples include: (1) Dedicated activity to understanding TPS failure modes. Develop computational tools capable of modelling fluid interaction with material's thermostructural response. Validate these tools through failure testing. A better understanding of failure mechanisms may eliminate the need to fully bound all aeroheating parameters in ground testing. (2) Enhancements to current testing facilities to simulate flight-like ablation mechanism (ex. testing in Nitrogen at Ames Interaction Heating Facility to limit oxidation in favor of more sublimation). (3) Improved characterization of test conditions with new diagnostic methods and determination of environment uncertainty through rigorous statistical analysis of available data. (4) Design margin policies that are directly tied to uncertainties in ground test environments and modelling fidelit

Repurposing matrine for the treatment of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is a manifestation of metabolic syndrome in the liver. It is the most common chronic liver disease with fast-growing prevalence worldwide that parallels the obesity epidemic and type 2 diabetes (T2D). NAFLD ranges from simple hepatosteatosis to non-alcoholic steatohepatitis (NASH) and may finally leads to liver cirrhosis and failure. NASH is the critical stage in the progression from reversible and asymptomatic hepatosteatosis towards irreversible liver disease with significantly worsen prognosis. However, there is no effective drug for treatment of NASH. Matrine (Mtr) is a small molecule (MW: 248) originally isolated from plants and it has been used as a hepatoprotective drug in humans with few reported adverse effects. Several lines of evidence suggest that Mtr may be repurposed for the treatment of NASH, including a previous study of this laboratory showing its ability to reduce hepatosteatosis in high fat diet (HFD)-fed mice. However, a single HFD rodent model only replicates simple hepatosteatosis due to increased exogenous lipid overload. Therefore, the overall aim of this thesis was to characterise the therapeutic properties of Mtr for NASH treatment and investigate the underlying mechanism/s. The hypothesis addressed in this study was that Mtr has therapeutic properties for the treatment of NASH by ameliorating hepatic steatosis and inflammation as well as associated metabolic risk factors. These therapeutic effects were examined in three mouse models mimicking different characteristics of NASH. The first aim was to examine the therapeutic effects of Mtr on hepatosteatosis and glucose intolerance induced by an over consumption of carbohydrates. This was assessed in high fructose (HFru) fed mice, a well-characterised model of hepatosteatosis causing an increased in hepatic de novo lipogenesis (DNL) pathway. This study (Chapter 3) showed that treatment with Mtr markedly ameliorates hepatosteatosis (reduced triglyceride content) and glucose intolerance in HFru-fed mice. Further studies revealed that the reduced hepatosteatosis by Mtr is due to its inhibition of hepatic DNL involving the blocking of the endoplasmic reticulum (ER) stress pathway. These effects are associated with an upregulation of heat shock protein 72 (HSP72), the chaperone protein which is known to be protective against metabolic diseases and inflammation. A separate aim was to evaluate the potential efficacy of Mtr in the treatment for hyperglycaemia as hepatosteatosis is an important contributor to hepatic insulin resistance leading to hyperglycaemia. In this study, the antisteatotic effects of Mtr on hyperglycaemia were investigated in a mouse model where type 2 diabetes is induced by HFD in combination with low doses of streptozotocin (HFD-STZ). The results showed that oral administration of Mtr to HFD-STZ mice reverses hyperglycaemia and hepatosteatosis. These findings support the use of Mtr to treat hepatosteatosis and associated disorders in glucose homeostasis. The second aim of this thesis (Chapter 4) was to examine the therapeutic efficacy of Mtr for hepatic inflammation and fibrosis. This was investigated in mice fed a methionine choline-deficient (MCD) diet, a well-established mouse model which shares pathologic features of severe NASH in humans, in particular hepatic inflammation and fibrosis. The study showed that Mtr treatment suppresses the increases in TNFα, CD68, MCP-1, NLRP3, and hepatic fibrosis markers (TGFβ and Smad3) induced by MCD diet. Along with these effects, Mtr inhibits mTOR activation and upregulates HSP72 expression, suggesting a likely role of mTOR-HSP72 pathway in coordinating the therapeutic effects of Mtr for NASH. The final aim further investigated cellular mechanisms underlying the effects of Mtr on the inflammatory pathway. This was conducted using cultured J774A cells, a macrophage cell line rused here as a model for Kupffer cells believed to be a major source of inflammatory cytokines in the liver. Incubation of J774A cells with LPS stimulated the production of TNFα and increased NLRP3, CD68 and TGFβ expression. Treatment with Mtr also upregulated HSP72, inhibiting inflammation and fibrosis induced by LPS (Chapter 5). Additionally, Mtr suppressed the level of mTOR. These results provide further evidence that Mtr may exert its effect against NASH through the mTOR-HSP72 pathway. In summary, this thesis employed three different animal models to characterise a wide range of therapeutic effects of Mtr on NASH. Findings from these studies led to the following conclusions. Firstly, Mtr is a promising therapy for hepatosteatosis and associated glucose disorders. Secondly, Mtr can attenuate NASH-associated inflammation and fibrosis. Finally, mTOR-HSP72 may play an important role in mediating the therapeutic effects of Mtr on NASH. Overall, these findings provide strong pre-clinical evidence to support the repurposing of Mtr as a promising new drug for the treatment of NAFLD, particularly on the progression towards NASH

An improved understanding about CO2 EOR and CO2 storage in liquid-rich shale reservoirs

During the past decade, enhanced oil recovery (EOR) by CO2 in shale oils has received substantial attention. In shale oil reservoirs, CO2 diffusion into the resident oil has been considered as the dominant interaction between the CO2 in fractures and the oil in the matrices. CO2 diffusion will lead to oil swelling and improvement in oil viscosity. However, despite two-way mass transfer during CO2 EOR in conventional oil reservoirs, one-way mass transfer into shale oils saturated with live oils is controlled by an additional transport mechanism, which is the liberation of light oil components in the form of a gaseous new-phase. This in-situ gas formation could generate considerable swelling, which could improve the oil recovery significantly. This mechanism has been largely overlooked in the past. This study is aimed to better understand the role of this evolving gas phase in improving hydrocarbon recovery. Taking account of Bakken shale oil reservoir data, numerical simulations were performed to identify efficiencies of EOR by CO2 at the laboratory and field scales. Equation of state parameters between CO2 and oil components were adjusted to optimize the calculations and a sensitivity analysis was performed to identify the role of gas formation and consequent EOR efficiencies. At the laboratory scale, in-situ gas formation can increase oil recovery by 20% depending on the amount of gas saturation. Also, the CO2 storage capacity of the shale matrix can be enhanced by 25%, due to CO2 trapping in the gas phase. At the field scale, an additional oil recovery of 9.1% could be attained, which is notably higher than previous studies where this gas evolution mechanism was ignored. Furthermore, the results suggest that a six-weeks huff period would be sufficient to achieve substantial EOR if this new mechanism is incorporated. On the other hand, the produced fluid in the early period was primarily composed of CO2, which would make it available for subsequent cycles. The produced gas of the well under CO2 EOR was used in an adjacent well, which resulted in similar additional oil recovery and hence, impurities in CO2 injection stream would not undermine efficiency of this EOR method. The results of this study, therefore, could potentially be used to substantially improve the evaluations of CO2 EOR in liquid-rich shale reservoirs

Direct gas-in-place measurements prove much higher production potential than expected for shale formations

Shale gas exploitation has been the game-changer in energy development of the past decade. However, the existing methods of estimating gas in place in deep formations suffer from large uncertainties. Here, we demonstrate, by using novel high-pressure experimental techniques, that the gas in place within deep shale gas reservoirs can be up to five times higher than that estimated by implementing industry standard approaches. We show that the error between our laboratory approach and the standard desorption test is higher for gases with heavier compositions, which are of strongest commercial interests. The proposed instrumentation is reliable for deep formations and, provides quick assessment of the potential for the gas in place, which could be useful for assessing hydrocarbon reservoirs, and the potential for geological carbon sequestration of a given formation

Hexavalent Chromium Induced Oxidative Stress and Toxicity on isolated human lymphocytes

Introduction: The most toxic form of chromium (Cr) in the environment is the oxyanion chromate (Cr (VI)). In this form it is soluble and is transported into the cells. Chromate structurally resemble phosphate and sulfate, and can be transported into cells by the anion carrier.  Methods and Results: In this study, toxicity effects of Cr (VI) on isolated human lymphocytes was studied using accelerated cytotoxicity mechanisms screening (ACMS) technique. Human lymphocytes were isolated from blood of healthy persons using Ficoll-paque PLUS standard method. The trypan blue dye was used to cytotoxicity assay. The mechanistic parameters including reactive oxygen species (ROS), lysosomal membrane destabilization, mitochondrial membrane potential (MMP) collapse, lipid peroxidation, GSH and GSSG levels were assessed after 1, 2 and 3 hrs in potassium dichromate treated lymphocytes. The results indicate that toxicity of Cr (VI) was concentration dependent in human lymphocytes. Cr (VI) significantly (p<0.05) induced ROS production, MMP reduction, lysosomal membrane destabilization and lipid peroxidation in human lymphocytes. There was also a decrease in intracellular GSH and raise in extracellular GSSG levels in Cr (VI) treated lymphocytes.  Conclusion: OOur findings revealed that ROS formation with subsequent cellular damages is the molecular mechanism for Cr (VI) induced human blood lymphocyte toxicity

Sizing and Margin Methodology for Dual-Layer Thermal Protection Systems

This presentation introduces a new sizing and margin methodology for dual-layer Thermal Protection Systems (TPS). The methodology has been tailored for application to a dual-layer 3D-woven TPS called Heat-shield for Extreme Entry Environments Technology (HEEET). Sizing is performed for a reference Saturn probe mission to show how uncertainties in trajectory, aerothermal modelling and TPS response impact the sizing of each layer

Radiative Heating for MSL Entry: Verification of Simulations from Ground Test to Flight Data

The heat shield of the Mars Science Laboratory (MSL) was equipped with thermocouplestacks to measure in-depth heating of the thermal protection system during atmosphericentry. The heat load derived from the thermocouples in the stagnation region was found tobe 33 lower than corresponding post-flight predictions of convective heating alone. It washypothesized that this difference could be attributed to radiation from the shock-heated gas,a mechanism not considered in post-flight analyses of flow fields. In order to test thehypothesis and quantify the contribution of shock-layer radiation to total surface heating,ground tests and simulations (both flow and radiation) were performed at several pointsalong the best-estimated entry trajectory of MSL. The present paper provides anassessment of the quality of the radiation model and its impact to stagnation point heating.Although the impact of radiative heating is shown to be significant, it only accounts for 43of the discrepancy. Additional factors behind the remaining discrepancy are discussed