Large Pore Spaces Research Articles

Modeling of Evaporation Losses in Sewage Sludge Drying Bed

A model for evaporation losses in sewage sludge drying bed was derived from first principles. This model was developed based on the reasoning that the rate at which evaporation is taking place is directly proportional to the instantaneous quantity of water in the sludge. The aim of this work was to develop a model to assist in the design of drying beds for effective treatment of wastes derived from households’ septic systems. Data generated after evaporation experiment in sewage sludge drying bed over a period of 15 days at 24 hours intervals was used for the modeling. The model was calibrated and regressed using data for days 1 to 8 by employing the Pearson’s correlation coefficient, “ ” was found to be -0.96124, after which verification was done and regressed using data for days 9 to 15 and was found to be 0.9969 that these fits validates the model. Materials balance show that evaporation reduces with increase in seepage losses which can be enhanced with use of conditioners and coarser sands because of their larger pore spaces. It was discovered that evaporation from the sludge follows first order kinetic in agreement with the fundamental concept. The model will help in the prediction of total water losses due to evaporation over a given period which would aid in the design of drying beds. http://dx.doi.org/10.4314/njt.v34i4.31

Relationship between surface soil water content, evaporation rate, and water absorption band depths in SWIR reflectance spectra

Abstract The spectral reflectance of three soil samples – selected to represent a range of particle size distribution, texture, and drying characteristics – was monitored as the samples progressed from fully saturated to air dry. Band depths of prominent water absorption features in the near and shortwave infrared, centered at 970 nm, 1160 nm, 1440 nm, and 1930 nm, were then compared to the surface water content, with the expectation that this metric would be characteristic of the soil moisture content and be largely independent of soil properties. As expected, the band depths at 970 nm and 1160 nm decreased monotonically as the water content decreased. Unfortunately, these bands were only detectable in the sample consisting of large, reflective particles and large pore spaces (quartz sand). That they were not apparent in the darker soils with smaller particles and pore spaces suggests that these water absorption bands will not be generally useful for observing surface soil moisture. In contrast, the band depths of the 1440 nm and 1930 nm absorption features were very responsive to the water content over the entire drying cycle, providing a strong, but more complex signal, with the band depth initially increasing with decreasing water content before reaching a maximum and finally decreasing late in the drying cycle. The change in band depth at 1930 nm was particularly interesting since it reached a maximum coincident with the transition from constant evaporation rate (stage-1 drying) to a much slower evaporation rate (stage-2 drying) for all three soils. A simple mathematical model suggests that the pattern of change in the band depth is related to the near extinction of light at the band center relative to the band shoulders, which can be related to a specific water optical path length. The maximum absorption band depth at 1930 nm (and the associated water optical path length) appears to coincide with a trace amount of water present in the pore spaces for all three soil samples, which is consistent with the transition in drying rates.

Analysis of marrow cavity fillings as a tool to recognise diverse taphonomic histories of fossil reptile bones: Implications for the genesis of the Lower Muschelkalk marine bone-bearing bed (Middle Triassic, Żyglin, S Poland)

Abstract The bone-bearing bed from Żyglin (S Poland), which likely represents the oldest Lower Muschelkalk accumulation of reptile remains in the SE part of the Germanic Basin, has been investigated in order to determine its genesis. The basic methods were supported by petrographic analysis of the marrow cavity and large inter-trabecular pore space fillings of fossil bones, which was used to check its usefulness to identify the environments where the bones were initially deposited and to decipher taphonomic histories of the remains. The bone-bearing bed is a composite deposit, which consists of three distinct layers (from bottom to top): micritic limestone (mudstone, bioturbated autochthonous mud), crinoidal limestone (grainstone to packstone, calcirudite), and shell-rich limestone (packstone to wackstone, calcirudite). The crinoidal limestone layer, the main bone-bearing bed, is recognised as the proximal tempestite deposited in the mid-ramp zone. The petrographic analysis of the fillings reveals the prevalence of minute ostracod carapaces, accompanied by other grains, embedded together with micrite to microspar. Such compositions suggest that these sediments may have been inserted into the bone pore spaces in lagoons and tidal-flat ponds. Features of some bones record their early diagenetic burial and lithification before the final redeposition. The isopachous spar, blocky spar and weathered pyrite document changes in the chemical composition of fluids that flowed into the bone interiors. The burrow found in the marrow cavity of specimen IGUAM-ZOV-7 provides evidence that some remains were inhabited by minute or juvenile invertebrates. All recognised features indicate that both invertebrate and vertebrate bioclasts, included in the tempestite, were initially deposited in various settings of the carbonate ramp and in the end redeposited as a result of a heavy storm or a hurricane. The examined bone-bearing bed represents time-averaged assemblage, which originated due to hydraulic concentration of the vertebrate bioclasts. The petrographic analysis of the fillings is a valuable tool to identify complex taphonomic pathways of vertebrate bioclasts.

Long‐term observation of permeability in sedimentary rocks under high‐temperature and stress conditions and its interpretation mediated by microstructural investigations

AbstractIn this study, a series of long‐term, intermittent permeability experiments utilizing Berea sandstone and Horonobe mudstone samples, with and without a single artificial fracture, is conducted for more than 1000 days to examine the evolution of rock permeability under relatively high‐temperature and confining pressure conditions. Effluent element concentrations are also measured throughout the experiments. Before and after flow‐through experiments, rock samples are prepared for X‐ray diffraction, X‐ray fluorescence, and scanning electron microscopy coupled with energy dispersive X‐ray spectroscopy to examine the mineralogical changes between pre and postexperimental samples, and also for microfocus X‐ray CT to evaluate the alteration of the microstructure. Although there are exceptions, the observed, qualitative evolution of permeability is found to be generally consistent in both the intact and the fractured rock samples—the permeability in the intact rock samples increases with time after experiencing no significant changes in permeability for the first several hundred days, while that in the fractured rock samples decreases with time. An evaluation of the Damkohler number and of the net dissolution, using the measured element concentrations, reveals that the increase in permeability can most likely be attributed to the relative dominance of the mineral dissolution in the pore spaces, while the decrease can most likely be attributed to the mineral dissolution/crushing at the propping asperities within the fracture. Taking supplemental observations by microfocus X‐ray CT and using the intact sandstone samples, a slight increase in relatively large pore spaces is seen. This supports the increase in permeability observed in the flow‐through experiments.

Enhanced foam stability by adding comb polymer gel for in-depth profile control in high temperature reservoirs

Abstract A long-term stability of gel enhanced foam as an in-depth profile control agent in high temperature reservoirs was successfully prepared by adding comb polymer gel. The increased viscosity of gel brings a negative effect on surface tension which reduces the gel enhanced foam volume. In turn, the increased viscosity could enhance the thickness and strength of foam film which increases foam stability and plugging capacity in porous media. The morphology results show that the gel enhanced foam has a thicker bubble film which enhances its foam stability. The effect of injection mode, gas–liquid ratio, gas injection velocity and formation permeability on the plugging capacity was investigated by single sand-pack experiments. When the gas–liquid ratio and gas injection velocity were respectively set at 1:1 and 0.5 ml/min, co-injection of gel enhanced foaming solution and gas could obtain a better plugging capacity in high permeability sand-packs. Parallel sand-pack experiments show that the profile improvement capacity of high formation permeability ratio is much better than that of low formation permeability ratio. The visual simulation experiment was also conducted to illustrate the flowing behavior of gel enhanced foam. By Jiamin effect or Jamin superimposed effect, directly plugging and bridging in the large pore space, the gel enhanced foam can effectively reduce the permeability of porous media in high permeability zones and divert fluid into low permeability zones, thus increases the swept volume. The treatment has been successfully used in Henan oilfield of China which provides a reference to water production control in other similar high temperature oilfields.

Sound velocity and related properties of seafloor sediments in the Bering Sea and Chukchi Sea

The Bering Sea shelf and Chukchi Sea shelf are believed to hold enormous oil and gas reserves which have attracted a lot of geophysical surveys. For the interpretation of acoustic geophysical survey results, sediment sound velocity is one of the main parameters. On seven sediment cores collected from the Bering Sea and Chukchi Sea during the 5th Chinese National Arctic Research Expedition, sound velocity measurements were made at 35, 50, 100, 135, 150, 174, 200, and 250 kHz using eight separate pairs of ultrasonic transducers. The measured sound velocities range from 1 425.1 m/s to 1 606.4 m/s and are dispersive with the degrees of dispersion from 2.2% to 4.0% over a frequency range of 35–250 kHz. After the sound velocity measurements, the measurements of selected geotechnical properties and the Scanning Electron Microscopic observation of microstructure were also made on the sediment cores. The results show that the seafloor sediments are composed of silty sand, sandy silt, coarse silt, clayey silt, sand-silt-clay and silty clay. Aggregate and diatom debris is found in the seafloor sediments. Through comparative analysis of microphotographs and geotechnical properties, it is assumed that the large pore spaces between aggregates and the intraparticulate porosity of diatom debris increase the porosity of the seafloor sediments, and affect other geotechnical properties. The correlation analysis of sound velocity and geotechnical properties shows that the correlation of sound velocity with porosity and wet bulk density is extreme significant, while the correlation of sound velocity with clay content, mean grain size and organic content is not significant. The regression equations between porosity, wet bulk density and sound velocity based on best-fit polynomial are given.

Lattice Boltzmann simulation of dissolution and precipitation in porous media

In this paper, we simulate numerically the dissolution and precipitation in porous media by using the lattice Boltzmann method (LBM). The fluid flow in porous media is simulated by using a multiple-relaxation-time (MRT) LBM, while a D2Q9 lattice BGK model is used for reactive solute transport. Frst, the code of LBM is tested by simulating the diffusion and reaction at a boundary in an open rectangular domain, and comparing the results with the analytic solution. Then, the effects of the Reynolds number (Re), the Schmidt number (Sc) and the Damkohler number (Da) on the variations of the geometry of the porous media and the concentration field are carefully studied. It can be found that for the dissolution (precipitation), as Re is increased, the porosity of the porous media will be increased (decreased), and the average concentration will be decreased (increased). Besides, at low Damkohler numbers or Schmidt numbers, the dissolution and precipitation will be reaction-controlled and are highly uniform. However, as Da or Sc is high, the dissolution and precipitation will be diffution-controlled, and mainly occur in the upstream and large pore space.

Investigation on the roles of activated carbon particle sizes on methane hydrate formation and dissociation

The presence of porous media such as activated carbon has been known to enhance the hydrate formation rate and the amount of gas consumption for methane storage applications. However, information on the effects of porous media particle size on the formation and dissociation kinetics is very limited or not available. Activated carbons with different particle sizes, 250–420µm, 420–841µm, and 841–1680µm, were used in order to investigate their effects on the methane hydrate formation and dissociation. The methane hydrate formation experiments were conducted at 8MPa and 4°C in a quiescent fixed bed crystallizer. The result showed that the experiment conducted with the 841–1680µm activated carbon showed the highest average water conversion to hydrate, 96.5%, due to its large interstitial pore space between the activated carbon particles, which were observed by the two-step methane consumption. In contrast, the highest average percentage of methane recovery, 98.1%, was achieved in the methane hydrate dissociation experiment conducted with the 250–420µm activated carbon.

Ancient porosity preserved in ordinary chondrites: Examining shock and compaction on young asteroids

AbstractWe use a combination of 2D and 3D petrographic examination and 40Ar‐39Ar analyses to examine the impact histories of a suite of seven ordinary chondrites (Baszkówka, Miller, NWA 2380, Mount Tazerzait, Sahara 98034, Tjerebon, and MIL 99301) that partially preserve their ancient, but postaccretionary, porosity ranging from 10 to 20%. We examine whether materials that seem to be only mildly processed (as their large intergranular pore spaces suggest) may have more complex shock histories. The ages determined for most of the seven OCs studied here indicate closure of the 40Ar‐39Ar system after primary accretion, but during (Baszkówka) or shortly after (others) thermal metamorphism, with little subsequent heating. Exceptions include Sahara 98034 and MIL 99301, which were heated to some degree at later stages, but retain some evidence for the timing of thermal metamorphism in the 40Ar‐39Ar system. Although each of these chondrites has olivine grains with sharp optical extinction (signaling an apparent shock stage of S1), normally indicative of an extremely mild impact history, all of the samples contain relict shock indicators. Given the high porosity and relatively low degree of compaction coupled with signs of shock and thermal annealing, it seems plausible that impacts into materials that were already hot may have produced the relict shock indicators. Initial heating could have resulted from prior collisions, the decay of 26Al, or both processes.

THE LUNAR THERMAL ICE PUMP

It has long been suggested that water ice can exist in extremely cold regions near the lunar poles, where sublimation loss is negligible. The geographic distribution of H-bearing regolith shows only a partial or ambiguous correlation with permanently shadowed areas, thus suggesting that another mechanism may contribute to locally enhancing water concentrations. We show that under suitable conditions, water molecules can be pumped down into the regolith by day-night temperature cycles, leading to an enrichment of H2O in excess of the surface concentration. Ideal conditions for pumping are estimated and found to occur where the mean surface temperature is below 105 K and the peak surface temperature is above 120 K. These conditions complement those of the classical cold traps that are roughly defined by peak temperatures lower than 120 K. On the present-day Moon, an estimated 0.8% of the global surface area experiences such temperature variations. Typically, pumping occurs on pole-facing slopes in small areas, but within a few degrees of each pole the equator-facing slopes are preferred. Although pumping of water molecules is expected over cumulatively large areas, the absolute yield of this pump is low; at best, a few percent of the H2O delivered to the surface could have accumulated in the near-surface layer in this way. The amount of ice increases with vapor diffusivity and is thus higher in the regolith with large pore spaces.

Opportunities for selective catalysis within discrete portions of zeolites: The case for SSZ-57LP

We describe a new zeolite catalyst where we develop only a portion of the structure for strong acid sites. This is achieved using zeolite SSZ-57 in boron lattice substitution (weak acid sites) and then replacing the boron sites in the large pore segments of this novel zeolite, while the intermediate pores (with MEL topology) remain unchanged. We can achieve the creation of such a novel catalyst system due to the inherent structure of SSZ-57 (repeat domains of MEL topology, periodically interrupted by a short segment of large pores) because the re-insertion of aluminum for boron requires that the pores be large to effect substitution. In this work, we describe the preparation and characterization of the novel material designated as SSZ-57LP. We use three model compound reactions to demonstrate the unique behavior for this novel large pore (but short path) zeolite and contrast it with intermediate pore zeolite Al-ZSM-11 (MEL topology) and the Al-SSZ-57 where the strong acid sites are in both intermediate and large pore regions (from direct zeolite synthesis with aluminum in the gel). The reactions studied are the Constraint Index probing reactant selectivity for cracking n-hexane and 3-methylpentane, the hydroisomerization of n-hexane where the formation of dimethylbutanes is examined for large pore space within a zeolite, and then finally, the isomerization and disproportionation of 1,3-diethylbenzene, again as a probe for large enough transition state selectivity within a given zeolite.

Microstructure Distribution of Soft Clay under Conditions of Stratigraphic Profiling Variation

Base on the microscopic structure is characterized by anisotropy of microstructure that inherent in the process of saturated soft clay with sedimentary primary anisotropy or external force caused by induced anisotropy, biological changes along with the trend of the minimum potential energy. By studying the spindle rotation stress characteristics of the soil of the microscopic distribution, the pore characteristics of saturated clay sourced from microstructure pictures in Pearl River Delta region of south China is analyzed considering the microstructure in different stress conditions. Microstructure distribution of soft clay under conditions of section profiling variation including the anisotropy ratio law of pore characteristics are focused to study saturated clay. It is found that major-minor axis status induced the directional property of saturated soil in the process of consolidation by vacuum preloading. And porosity shapes factors which are small indicate directional property would be probability entropy which is able to calculating the chaos of overall arrangement, and it will be a lower value because of directional property. It is apparently inconsistent with the pore distribution of saturated clay which results from the cut section of different point of angle. And horizontal joint and large pore space constitute one of the saturated clay structure characteristic, which related to different pressures.

The Maldives, a giant isolated carbonate platform dominated by bottom currents

The Maldives, a 900 km north-south trending paired chain of atolls that surround a ca. 100 km wide central basin (the Inner Sea) represent a giant isolated carbonate platform in the Indian Ocean. New reflection seismic, multibeam and acoustic Doppler current profiler data show that its development exhibits a distinct change from sea-level to mainly bottom current-controlled sedimentation at the end of the Middle Miocene. The post-Middle Miocene intra-basinal fill consists of 9 mega units that have been formed and shaped by strong bottom currents, entering the Inner Sea between the inter-atoll passages.At the end of the Middle Miocene the Maldives represent a rimmed platform with the Inner Sea forming an empty bucket. A connection to the Indian Ocean existed only in the northeastern part of the platform, namely the Kardiva Channel. Probably concomitant with the onset of the Indian Monsoon, the current pattern around the Maldives changed significantly resulting in the formation of channels in the rimmed platform margin. The latter process was encouraged by local drowning of large platform parts and additionally, by bottom current forced submarine erosion that widened the channels to passages disintegrating the platform into separated atolls of different sizes. The reworked material was dumped into the Inner Sea where it formed large contourite fans. Along-slope bottom currents entering the Inner Sea from the north further redistributed the material leading to a southward shift of these sedimentary bodies. In this way the Inner Sea was filled from west to east (mega units 1–5). Starting with mega unit 6 the opening of a southern gateway introduced a prominent northward flow of bottom waters in the Inner Sea. It leads to the deposition of giant elongated drifts at the eastern flank of the basin, filling it from east to west. Because the current swept away most of the material around the atolls, the system was not able to prograde and the steady subsidence was compensated by aggradation. Accordingly, a fundamental characteristic of a current-controlled carbonate system is that aggradation occurs irrespective of platform sediment export or differently worded the rate of change in accommodation is always positive and greater than the rate of sediment supply.ADCP measurements in the winter monsoon season show two water masses in the Inner Sea, one at the surface 0–150 m and a second below it that reaches its sea-floor. By the use of the grain size distribution of ODP leg 716 located in the Inner Sea as proxy for the flow intensity of the bottom water, we recognized an inverse proportional relationship to the monsoon strength from late Upper Miocene to present.Some of the current-controlled deposits form sigmoidal prograding clinoforms, preferably at the edges of the atolls adjacent to the passages, where the velocity of the current entering the Inner Sea is high. The anatomy of these prograding wedges is similar to sea-level controlled clinoforms described for large isolated carbonate platforms in the sequence stratigraphic concept; however our results document, that they are not influenced by sea-level fluctuations. Because of the high current velocities involved in their deposition, they predominately consist of coarse sand sized carbonate fragments exhibiting large pore space and high permeability. Therefore these drift deposits comprise a possible exploration target.

Characterization of oil shale pore structure before and after pyrolysis by using X-ray micro CT

The pyrolysis of oil shale to produce transportation fuels is a complex process. The organic matter in the oil shale is tightly bound with a heterogeneous mineral matrix. Several physical changes occur during the thermal conversion of kerogen in oil shale to produce hydrocarbon products. The creation of pore space during pyrolysis is an important physical process which determines the flow behavior of the pyrolysis products and the ultimate recovery. In this paper, we report the effect of temperature (350–500°C) on oil shale pyrolysis and creation of pore volume during thermal treatment. One inch diameter oil shale cores from different depths of a single drill hole in the Uinta Basin were used. Increase in the pyrolysis temperature resulted in higher weight loss and a corresponding increase in the oil yield. Three-dimensional X-ray micro tomography (XMT) was performed to characterize and to analyze the nature of the pore network structure before and after pyrolysis. XMT scans of the cores at 42μm voxel resolution displayed distinguishable features of reaction products and source rock. Unconstrained pyrolysis of organic rich core produced large pore space during thermal treatment. The three-dimensional pore network structure was established with pores as large as 500μm developed after pyrolysis. Lattice Boltzmann simulation of flow through the developed pore network structure suggested that permeabilities from 173 Darcy to 2919 Darcy can be expected.

Long-term impact of irrigation with olive mill wastewater on aggregate properties in the top soil

Olive mill wastewater (OMW) is the main waste product generated by the olive oil extraction process. The uncontrolled disposal of OMW is becoming a serious environmental problem. The objective of this study was to investigate the long-term effects of OMW irrigation on soil aggregate stability, on solute diffusion into aggregates and on aggregate structure formation. The soil aggregates were sampled from three sites: non-irrigated with OMW (T0) and regularly irrigated with untreated OMW for 5 (T5) and 15 (T15) years. The results showed that the regular application of OMW for 5 and 15 years increased the soil aggregate stability, as a result of a rising organic matter content of OMW sites. OMW application furthermore reduced the effective diffusion coefficient into aggregates, because the organic matter of OMW forms a coating on the aggregates and blocks the pore mouths. OMW is characterized by its adhesive behaviour that affects the aggregation and structure of the topsoil by binding micro-aggregates together to form macro-aggregates and larger pore spaces between micro-aggregates. Consequently, the use of OMW for irrigation over long time periods alters the surface layer of the soil and makes it fragmented, which may increase the risk for preferential solute transport.

Sedimentological Signature of A Deformable Bed Preserved Beneath An Ice Stream In A Late Pleistocene Glacial Sequence, Ross Sea, Antarctica

Abstract Subglacial processes are described using a nested set of samples from AND-1B drill core collected from beneath the Ross Ice Shelf as part of the ANtarctic geologic DRILLing program (ANDRILL). An interval from the late Pleistocene was chosen for study because it is preserved in the sedimentary record, yet the depositional processes are applicable to the widely studied glacial conditions at the Last Glacial Maximum. A complete glacial–interglacial sequence, between two glacial surfaces of erosion (GSEs) at 41.9 and 47.7 meters below sea floor, was studied by centimeter-scale core logging based on X-radiographs of the archive core halves in addition to core description, bulk samples and 45 mm × 65 mm thin sections of diamictites for micromorphology analysis. Above the lower GSE, 4.6 m of subglacial till occurs including a sequence of thin muddy conglomerate with diverse pebble lithologies, massive clast-rich muddy diamictite, and stratified diamictite with clast-rich and clast-free beds. The sand-size fraction of these deposits is dominated by aggregate grains, termed till pellets following terminology used for Ross Sea deposits. We present the first detailed description and two different conceptual models of tillpellet formation beneath an ice stream: one is related to mechanical processes, and the other is related to thermodynamics. Till pellets are rounded, spherical to prolate in form, and are associated with turbate structures and aligned grains in thin sections. The core of the pellet is either a lithic grain or stiff till with additional clay plastered on the outside, forming rounded grains from originally angular ones. Galaxy structures, skelsepic fabric, and pressure shadows around grains are indicative of rotational deformation within the till. Till pellets form in situ within a highly porous deformable bed under an ice stream either by mechanical shearing or by alternating thermal conditions in the till. In the first model, a slow glacial advance under dry subglacial conditions fractures the till, increasing the porosity as shear induces dilation. Basal melting and high pore-water pressure develop as the ice stream thickens, decreasing the intergranular effective stress and inducing rotation of the angular till aggregates. An alternative model calls for basal freezing with preferential ice growth in larger pore spaces causing rotation of fine-grained till aggregates due to concentration of shear stresses in a thin zone beneath the glacier sole. Survival of till pellets is enhanced in subglacial diamictite as the thin zone of deformation moves upward toward the base of the ice stream. A thin granular bed enriched in till pellets is melted out in the grounding zone, and this deposit marks the transition from subglacial till to stratified silty claystone representing sub–ice shelf deposits.

Characterization and biostability of HA/Ti6Al4V ACL anchor prepared by simple heat-treatment

Here, we report a simple heat-treatment process to prepare hydroxyapatite (HA)-coated Ti6Al4V anterior cruciate ligament (ACL) anchor that has good hard tissue compatibility and biostability. Heat treatment was carried out for 1.5h at temperature range of 700–900°C. Morphological characterization showed rougher surface and larger pore spaces as the heat treatment temperature was increased. The Ti6Al4V heat-treated at 800°C had the highest diffused titanium phosphide formation, thus making it high in biocompatibility. For in vivo test, the most bone integration ability was obtained for heat-treatment at 800 and 900°C. Furthermore, the HA/Ti6Al4V ACL anchor heat-treated at 800°C had the highest amount of new bone formation. The present results suggest that an implant with complex shape like an ACL anchor could be prepared and used with an easy and low-cost technique by simple heat treatment surface modification method after dip-coating with HA.

Silica nanoparticles with enlarged nanopore size for the loading and release of biological proteins

Silica nanoparticles (SNs) with a nanoporous structure are attractive for the delivery of biomolecules. This study developed a SNs-based protein delivery system with nanopore sizes large enough to uptake protein molecules. The use of trioctylmethylammonium bromide (TOMAB) as an auxiliary chemical facilitated a dramatic increase in pore size from 2.6 nm to 17.4 nm. The surface was highly negatively-charged with a zeta potential of approximately − 35 at pH 7. Positively-charged protein cytochrome C was encapsulated effectively within the large pore spaces of the SNs, with a protein loading capacity of almost 2-fold increase due to the pore size increase. The loaded protein exhibited sustained release for approximately one week with an initial burst in a day, suggesting the SNs tailored with enlarged nanopores should be useful for the delivery of large protein molecules for tissue regeneration.

A multiple-continuum model for simulating single-phase and multiphase flow in naturally fractured vuggy reservoirs

The existence of vugs or cavities in naturally fractured reservoirs has long been observed. Even though these vugs are known for their large attribution to reserves of oil, natural gas, or groundwater, few quantitative investigations of fractured vuggy reservoirs have been conducted. In this paper, a multiple-continuum conceptual model is presented, based on geological data and observations of core samples from carbonate formations in China, to investigate single-phase and multiphase flow behavior in such vuggy fractured reservoirs. The conceptual model has been implemented into a three-dimensional, three-phase reservoir simulator with a generalized multiple-continuum modeling approach. The conceptual model considers fractured vuggy rock as a triple- or multiple-continuum medium, consisting of (1) highly permeable and well-connected fractures, (2) low-permeability rock matrix, and (3) various-sized vugs. The matrix system may contain a large number of small or isolated cavities, whereas vugs are larger cavities, indirectly connected to fractures through small fractures, microfractures or matrix. Similar to the conventional double-porosity model, the fracture continuum is primarily responsible for the occurrence of global flow, while vuggy and matrix continua, providing storage space, are locally connected to each other and interacting with globally connecting fractures. In addition, flow in fractured vuggy reservoirs may be further complicated by occurrence of non-Darcy's and other nonlinear flow behavior, because of large pore space and high-permeability flow channels. To account for such complicated flow regime, our model formulation includes non-Darcy flow using the multiphase extension of the Forchheimer equation as well as flow according to parallel-wall fracture and tube models, based on solutions of flow through a parallel-wall, uniform fracture and Hagen–Poiseuille tube flow.

Integration of Deep Biosphere Research into the International Continental Scientific Drilling Program

<strong class="journal-contentHeaderColor">Abstract.</strong> No abstract available. <br><br> doi:<a href="http://dx.doi.org/10.2204/iodp.sd.10.0.2010" target="_blank">10.2204/iodp.sd.10.0.2010</a>