Vertically averaged equations with variable density for CO2 flow in porous media

Carbon capture and storage has been proposed as a viable option to reduce CO 2 emissions. Geological storage of CO 2 where the gas is injected into geological formations for practically indefinite storage, is an integral part of this strategy. Mathematical models and numerical simulations are important tools to better understand the processes taking place underground during and after injection. Due to the very large spatial and temporal scales involved, commercial 3D-based simulators for the petroleum industry quickly become impractical for answering questions related to the long-term fate of injected CO 2 . There is an interest in developing simplified modeling tools that are effective for this type of problem. One approach investigated in recent years is the use of upscaled models based on the assumption of vertical equilibrium (VE). Under this assumption, the simulation problem is essentially reduced from 3D to 2D, allowing much larger models to be considered at the same computational cost. So far, most work on VE models for CO 2 storage has either assumed incompressible CO 2 or only permitted lateral variations in CO 2 density (semi-compressible). In the present work, we propose a way to fully include variable CO 2 density within the VE framework, making it possible to also model vertical density changes. We derive the fine-scale and upscaled equations involved and investigate the resulting effects. In addition, we compare incompressible, semi-compressible, and fully compressible CO 2 flow for some model scenarios, using an in-house, fully-implicit numerical code based on automatic differentiation, implemented using the MATLAB reservoir simulation toolkit

Oxidatively stable membranes for CO2 separation and H2 purification

CO2-selective facilitated transport membranes are well-known for providing remarkably high CO2/H2 selectivity along with high permeance at high temperatures (100 – 120oC). In some cases, it is desirable to use air as the sweep gas to enhance the driving force and membrane performance, and the membrane should be stable in the presence of oxygen. This work demonstrates the development of a new class of facilitated transport membranes containing quaternaryammonium hydroxide small molecules and quaternaryammonium hydroxide- and fluoride-containing polymers as mobile carriers and fixed-site carriers, respectively, for CO2 separation and H2 purification. The active nature of tetramethylquaternaryammonium hydroxide (TMAOH) as a mobile carrier was successfully demonstrated with the high CO2 permeance obtained by the TMAOH-containing membranes. However, the membrane performance was improved significantly by the incorporation of quaternaryammonium hydroxide- and/or fluoride-containing polymers in the membrane. The resulting hydroxide- and fluoride-containing membranes exhibited CO2 permeance \u3e 100 GPU and CO2/H2 selectivity \u3e 100 at 120oC using humid air as the sweep gas. The membrane composition was optimized, and the transport stability of the membrane was investigated. The membrane showed oxidatively stable during the 145-hour transport measurement at 120oC using air as the sweep gas. Furthermore, the effects of sweep steam content and membrane thickness were investigated. As the sweep steam content was increased (especially for steam content \u3e 50%), both CO2 permeance and CO2/H2 selectivity increased. As the membrane thickness was reduced from 15 µm to 2 µm, a sharp drop in the CO2/H2 selectivity was observed whereas the CO2 permeance did not seem to increase as prominently as the H2 permeance. In addition, the membrane was successfully scaled up using a roll-to-roll continuous membrane fabrication machine, and the scale-up membrane showed similar performance as the lab-scale membrane

Geochemical Endmembers preserved in Gale Crater: A tale of two mudstones and their compositional differences according to ChemCam

Gale crater contains two fine-grained mudstone sedimentary units: The Sheepbed mudstone member, and the Murray formation mud-stones. These mudstones formed as part of an ancient fluviolacustrine system. The NASA Curiosity rover has analysed these mudstone units using the Chemistry and Camera (ChemCam), Alpha Particle X-ray Spectrometer (APXS) and Chemistry and Mineralogy (CheMin) onboard instrument suites. Subsequent mineralogical analyses have uncovered a wide geochemical and mineralogical diversity across and within these two mudstone formations. This study aims to determine the principal cause (alteration or source region) of this geochemical variation through a statistical analysis of the ChemCam dataset up to sol 1482, including the lower to middle Murray formation

A Finite-Volume-Based Module for Unsaturated Poroelasticity

In this chapter, we present fv-unsat, a multipoint finite-volume–based solver for unsaturated flow in deformable and nondeformable porous media. The latter is described using the mixed form of Richards’ equation, whereas the former by the equations of unsaturated poroelasticity. The module aims at flexibility, relying heavily on discrete operators and equations, exploiting the automatic differentiation framework provided by the MATLAB Reservoir Simulation Toolbox (MRST). Our examples cover two numerical convergence tests and two three-dimensional practical applications, including the water infiltration process in a nondeformable soil column and a realistic desiccation process of a deformable clay sample using atmospheric boundary conditions. The resulting convergence rates are in agreement with previously reported rates for single-phase models, and the practical applications capture the physical processes accurately.publishedVersio

Semi-supervised Learning of Pushforwards For Domain Translation & Adaptation

Given two probability densities on related data spaces, we seek a map pushing one density to the other while satisfying application-dependent constraints. For maps to have utility in a broad application space (including domain translation, domain adaptation, and generative modeling), the map must be available to apply on out-of-sample data points and should correspond to a probabilistic model over the two spaces. Unfortunately, existing approaches, which are primarily based on optimal transport, do not address these needs. In this paper, we introduce a novel pushforward map learning algorithm that utilizes normalizing flows to parameterize the map. We first re-formulate the classical optimal transport problem to be map-focused and propose a learning algorithm to select from all possible maps under the constraint that the map minimizes a probability distance and application-specific regularizers; thus, our method can be seen as solving a modified optimal transport problem. Once the map is learned, it can be used to map samples from a source domain to a target domain. In addition, because the map is parameterized as a composition of normalizing flows, it models the empirical distributions over the two data spaces and allows both sampling and likelihood evaluation for both data sets. We compare our method (parOT) to related optimal transport approaches in the context of domain adaptation and domain translation on benchmark data sets. Finally, to illustrate the impact of our work on applied problems, we apply parOT to a real scientific application: spectral calibration for high-dimensional measurements from two vastly different environmentsComment: 19 pages, 7 figure

Upscaled modeling of CO2 injection and migration with coupled thermal processes

A practical modeling approach for CO2 storage over relatively large length and time scales is the vertical-equilibrium model, which solves partially integrated conservation equations for flow in two lateral dimensions. We couple heat transfer within the vertical equilibrium framework for fluid flow, focusing on thermal processes that most impact the CO2 plume. We investigate a simplified representation of heat exchange that also includes transport of heat within the plume. In addition, we explore available CO2 thermodynamic models for reliable prediction of density under different injection pressures and temperatures. The model concept is demonstrated on simplified systems.publishedVersio

Verhinderung und Bekämpfung der Kontaminierung der Umwelt mit Oozysten von <em>Isospora</em> spp. (Apikomplexa, Coccidia) : Wirksamkeit und Verträglichkeit einer neuen kokzidioziden Suspension für Hunde und die Möglichkeit der Desinfektion

In dieser Arbeit sollte die Möglichkeit der Verhinderung und Bekämpfung der Kontaminierung der Umwelt mit Isospora-Oozysten diskutiert werden. Dazu wurde die Wirksamkeit und Verträglichkeit einer neuen kokzidioziden Welpensuspension und die Möglichkeit der Desinfektion überprüft. Zunächst wurde ein Infektionsmodell etabliert. Dann wurde die Verträglichkeit verschiedener Suspensionen und schließlich die Wirksamkeit einer Suspension überprüft. Des Weiteren wurde die Möglichkeit der Desinfektion von mit Isospora spp. kontaminierter Umwelt in einem in-vitro-Versuch getestet. Zur Etablierung des Infektionsmodells wurden insgesamt 59 Hunde aus zwei Altersgruppen (vor- oder nach dem Absetzen) mit unterschiedlicher Anzahl an I. ohioensis-Komplex-Oozysten oder I. canis-Oozysten infiziert. Sechs weitere Welpen wurden mit einer Mischkultur infiziert. Die Infektion sollte deutliche, aber nicht zu schwere klinische Symptome hervorrufen und einen typischen Infektionsverlauf mit klarer Präpatenz und Patenz und deutliche Oozystenausscheidung zeigen. Der Infektionserfolg wurde anhand der ausgeschiedenen Oozystenmenge und der Kotkonsistenz überprüft. Die Verträglichkeit der Suspensionen wurde an insgesamt 71 Hunden untersucht. Hierzu wurden die Hunde mit verschiedenen Suspensionen, die auf zwei verschiedenen Lösungsmitteln basierten mit therapeutischer, sowie drei- und fünffacher Überdosierungen behandelt und danach auf das Auftreten von Nebenwirkungen beobachtet. Zur Überprüfung der Wirksamkeit wurden insgesamt 100 Welpen mit I. ohioensis-Komplex-Oozysten oder I. canis-Oozysten oder einer Mischkultur experimentell infiziert. Die Suspension wurde in zwei Dosierungen und zu unterschiedlichen Behandlungszeitpunkten (während der Präpatenz und während der Patenz) einmalig oder alle 2 Wochen verabreicht. Wirksamkeitskriterium war die Oozystenausscheidung der behandelten Gruppen gegenüber einer placebo- oder unbehandelten Kontrollgruppe. Die Wirksamkeit zweier Desinfektionsmittel wurde gegen Isospora-Oozysten in einem in-vitro-Versuch überprüft. Eine Infektionsdosis von 80 000 I. ohioensis-Komplex-Oozysten oder 60 000 I. canis-Oozysten bzw. eine Mischinfektion mit 11 000 I. ohioensis-Komplex-Oozysten und 20 000 I. canis-Oozysten bei Welpen vor dem Absetzen ergab den leicht klinischen Verlauf und eine adäquate Anzahl ausgeschiedener Oozysten. Hunde, denen man nach dem Absetzen Kokzidien inokulierte, entwickelten keinen typischen Infektionsverlauf. Viele Hunde schieden bereits vor Infektion Oozysten aus, was auf eine natürliche Infektion schließen lässt, die bei Welpen vor dem Absetzen den Verlauf der experimentellen Infektion nicht merklich beeinflusste. Bei allen Infektionsversuchen mit I. canis wurden auch Oozysten des I. ohioensis-Komplexes ausgeschieden, was jedoch ebenfalls keinen Einfluss auf den Verlauf der I. canis-Infektion hatte. Die Suspension wurde sehr gut vertragen und von den Tieren gut akzeptiert; das eine getestete Lösungsmittel verursachte Erbrechen und die Suspension auf Basis des anderen Lösungsmittels wurde für die Wirksamkeitsstudien verwendet. Sowohl therapeutisch als auch metaphylaktisch wirkte die Suspension gegen Isospora spp. und reduzierten die Oozystenausscheidung signifikant und somit die Kontaminierung der Umwelt. Außerdem linderten die metaphylaktischen Behandlungen die Symptomatik. Ein Behandlungsschema wie bisher empfohlen über mehrere Tage (ECKERT et al., 2000) war nicht erforderlich und erscheint nicht sinnvoll. Vielmehr sollte in Betrieben mit Kokzidioseproblematik alle 14 Tage nachbehandelt werden. Um die Kontaminierung der Umwelt mit Isospora-Oozysten zu verhindern sollten Welpen am besten während der Präpatenz mit der kokzidioziden Suspension behandelt werden. In Grossbetrieben empfiehlt sich eine Behandlung alle 14 Tage ab den ersten Lebenswochen aller Welpen. Nur so kann sichergestellt werden, dass nur noch wenige Oozysten in die Umgebung gelangen. Werden in einem Grossbetrieb von einigen Hunden bereits Oozysten ausgeschieden müssten sofort die betreffende Tiere und deren Zwingergenossen und sicherheitshalber auch die Tiere der Nachbarzwinger behandelt werden. Außerdem empfiehlt sich eine unmittelbare Desinfektion der Anlage mit den getesteten Desinfektionsmitteln. Jedoch werden diese Maßnahmen nach persönlicher Erfahrung in Großbetrieben die Kokzidien nicht ausrotten, sondern können nur helfen, schwerer Kokzidiose vorzubeugen und den Infektionsdruck gering zu halten. In der kleingewerblichen Hundezucht mit nur ein bis zwei Würfen im Jahr ist die Kokzidioseproblematik erfahrungsgemäß nicht so groß. Zwar ist ein Großteil der Tiere infiziert und scheidet Oozysten aus, jedoch verläuft die Infektion weitgehend subklinisch. Deshalb empfiehlt sich eine Behandlung erst, wenn es Fälle von klinischer Kokzidiose gegeben hat, um eine Infektion der nachfolgenden Generationen zu verhindern. Bei Wildkarnivoren treten kaum Fälle von klinischer Kokzidiose auf und somit ist eine Behandlung nicht erforderlich, obwohl sich die Suspension vermutlich auch als wirksam gegen Isospora-Arten in Wildtieren erweisen würde.Prevention and control of the contamination of the environment with oocysts of Isospora spp. (Apikomplexa, Coccidia) : Efficacy and safety of a new coccidiocide puppy suspension and the potential of disinfection These investigations tested the prospect of prevention and control of contamination of the environment with Isospora oocysts. Firstly an infection model had to be established. Also the safety of different suspensions and the efficacy of one puppy suspension was investigated. Finally the possibility of disinfection with Isospora spp. contaminated environment was explored in an in-vitro study. For the establishment of the infection model a total of 59 dogs of two different age groups (before and after weaning) were infected with different numbers of I. ohioensis-complex or I. canis oocysts. Six other puppies were infected with a mixed culture. The infection was to cause definite but not severe clinical symptoms and a typical course of infection with clear prepatency and patency and an obvious oocyst excretion. The success of infection was identified using the number of excreted oocysts and the consistency of faeces. The side effects were observed on 71 dogs. The dogs were given separate suspensions with different solvents as part of a therapeutic as well as three- and five-fold overdosing treatment. After treatment the dogs were observed for possible side effects. The efficacy was observed by infecting 100 puppies with I. ohioensis-complex or I. canis or both. The suspension was given to the puppies in two different doses and at different points of time during the course of infection (at the prepatency or patency). Some puppies received a fortnightly follow-up treatment. Criterion of efficacy was the oocyst excretion of the treated group compared with the placebo or untreated control group. The efficacy of two disinfectants was tested in-vitro against Isospora oocysts. An infection dose of 80 000 I. ohioensis-complex oocysts or 60 000 I. canis oocysts and a mixed dose of 10 000 I. ohioensis-complex oocysts and 20 000 I. canis oocysts respectively of puppies before weaning caused slight clinical symptoms and an adequate oocyst excretion. Dogs infected after weaning did not develop a typical course of infection. Many dogs were naturally infected and excreted oocysts before the infection which did not notably alter the course of the experimental infection in puppies before weaning. All dogs experimentally infected with I. canis also excreted oocysts of I. ohioensis-complex, which also did not alter the course of the I. canis infection. One suspension was tolerated well and no adverse effects were observed. The other suspensions (based on a different dissolver) caused vomiting in the dogs. The therapeutic as well as the metaphylactic treatment with the suspension reduced the oocyst excretion significantly and thus reduced contamination of the environment. Further the metaphylactical treatment reduced the clinical symptoms. A treatment course over several days as formerly recommended (ECKERT et al., 2000) was not necessary and does not seem sensible. In populations with coccidiosis problems dogs should be treated fortnightly. To prevent contamination of the environment with Isospora oocysts puppies should be treated during the prepatency with the suspension. In large commercial kennels all puppies should be treated in their first weeks of life and should receive a follow-up treatment fortnightly. This is the only way to ensure that only a small amount of oocysts end up in the environment. If some dogs in a commercial dog breeding kennel already excrete oocysts these dogs, their penmates and as a precaution also the dogs of the adjacent pens should be treated immediately. Furthermore an immediate disinfection of the facilities with the tested disinfectants is advisable. However, according to personal experience these measures will not completely eradicate the coccidia in commercial kennels, but can only help to prevent severe coccidiosis and keep the threat of infection low. Smaller dog breeders with one or two litters a year rarely have as severe problems with coccidiosis. The majority of the dogs is infected and excretes oocysts but the infection usually takes a subclinical course, therefore treatment should be performed only when the first cases of clinical coccidiosis occur to protect further generations from the infection. In wild carnivores seldom cases of clinical coccidiosis occur and treatment is not necessary. However the suspension presumably would be also effective against Ispospora species from wild animals

Wellbore Permeability Estimates from Vertical Interference Testing of Existing Wells

AbstractWellbore integrity is considered an important risk factor for leakage of CO2 and formation fluids out of geological CO2 storage sites. Quantifying the effective hydraulic parameters that control vertical migration of fluids along the wellbore involves data collection through numerous field and laboratory experiments. The vertical interference test (VIT) is a downhole test designed to measure hydraulic communication of the outside-of-casing wellbore barrier system over a selected well section. Results from these tests can be analyzed numerically to determine the average permeability of the section. Several field surveys of existing wells have resulted in 9 VIT datasets, of which three are presented here. The effective permeability estimates for the three tests span two orders of magnitude, from approximately 1 mD to more than 100 mD. When compared with companion sidewall core analyses of the cement matrix that have permeabilities in the microD range, the VIT data suggest that interfaces or defects in the cement sheath are responsible for flow. Initial analysis of the remaining 6 datasets suggests an even larger range in effective permeability values, as low as microD to more than 1 D, indicating that well permeability can be highly variable from well to well and that high values of permeability are possible. These data provide important insights into realistic wellbore integrity of typical wells in N. America, and help us constrain models for understanding and mitigating risk of leakage during CO2 storage operations