Laboratory Simulation System Research Articles

Long‐term fracture conductivity in tight reservoirs

AbstractReservoir stimulation using hydraulic fracturing technology is one of the most common stimulation measures to develop tight oil and gas reservoirs, and the conductivity of fractures after fracturing is the key to the stimulation effect of oil fields. In this paper, the laboratory simulation system of fracture conductivity is used to study the long‐term fracture conductivity under the displacement of formation water and fracturing fluid. The experimental results show that the fracture conductivity decreases with the increase of displacement time under the displacement of formation water and fracturing fluid, and the decrease of fracture conductivity under the displacement of fracturing fluid with time is greater than that of formation water displacement because of the plugging effect of fracturing fluid residue on pore channels. The use of formation water and fracturing fluid circulation displacement can delay the decline rate of conductivity with time. The conductivity increases with the increase of sand concentration, proppant particle size, and elastic modulus, and decreases with the increase of closure pressure. In addition, by studying the influence of elastic modulus on fracture width, it is found that the smaller the elastic modulus is, the more serious the embedding phenomenon of proppant is, and the smaller the fracture width is.

Evaluation of laboratory and environmental exposure systems for protein modification upon gas pollutants and environmental factors

Chemical modifications of proteins induced by ambient ozone (O3) and nitrogen oxides (NOx) are of public health concerns due to their potential to trigger respiratory diseases. The laboratory and environmental exposure systems have been widely used to investigate their relevant mechanism in the atmosphere. Using bovine serum albumin (BSA) as a model protein, we evaluated the two systems and aimed to reduce the uncertainties of both the reactants and products in the corresponding kinetic study. In the laboratory simulation system, the generated gaseous pollutants showed negligible losses. Ten layers of BSA were coated on the flow tube with protein extraction recovery of 87.4%. For environmental exposure experiment, quartz fiber filter was selected as the upper filter with low gaseous O3 (8.0%) and NO2 (1.7%) losses, and cellulose acetate filter was appropriate for the lower filter with protein extraction efficiency of 95.2%. The protein degradation process was observed without the exposure to atmospheric oxidants and contributed to the loss of protein monomer mass fractions, while environmental factors (e.g., molecular oxygen and ultraviolet) may cause greater protein monomer losses. Based on the evaluation, the study exemplarily applied the two systems to protein modification and both showed that O3 promotes the protein oligomerization and nitration, while increased temperature can accelerate the oligomerization and increased relative humidity can inhibit the nitration in the environmental exposure samples. The developed laboratory and environmental systems are suitable for studying protein modifications formed under different atmospheric conditions. A combination of the two will further reveal the actual mechanism of protein modifications.

Assessment of using solid residues of fish for treating soil by the biosolarization technique as an alternative to soil fumigation

Organic food-waste is an ever growing environmental, economic, and social problem. One way to address this problem is to find new ways to valorise food waste in a circular economical manner. In this study, the concept of separating food from waste at its source in eateries was applied to obtain separated fish waste residues from the general waste of our university's canteen. This study is the first known attempt to use separated fish residues as soil amendments for soil biosolarization (SBS), a soil treatment method which is an environment-friendly alternative to chemical fumigation of soil. In this study a unique laboratory simulation system was used which mimics the conditions of field temperature, monitors the soil respiration and the follows the temporal profile of emitted volatile organic compounds. The fish waste residues were used as soil amendment in 2% wt. and the results showed elevated levels of aerobic soil respiration without unwanted CH4 emission. A different profile of volatile organic compounds (VOCs) was also identified in the soils treated with fish residues. The profile of volatiles found in the soil with fish residues included changes in the amounts of compounds such as: Dimethylsulfide, Methanethiol and C9-aldehydes that have been found to supress soilborne plant pathogens. This is the first indication that VOCs can be used as indicators for the SBS process. Greenhouse studies and analyses of soils treated by fish residues showed no soil residual phytotoxicity affecting later growth of lettuce seedlings while not hindering the herbicidal effect of SBS on unwanted Bidens (Bidens pilosa) weeds. These results indicate that fish waste residues can be used as a soil amendment in the SBS process.

A preliminary study on the eco-environmental geological issue of in-situ oil shale mining by a physical model

As traditional methods of oil shale production emitting high levels of pollutants, in-situ exploitation has aroused great concerns. In order to study the effect of in-situ pyrolysis products on the underground environment, an in-situ oil shale exploitation of underground environment impact laboratory simulation system was designed. Based on the hydrogeological condition of oil shale area in Nong'an City, a physical simulation test was conducted. It was found the temperature of surrounding layers continued to be perturbed after heating of the formation had stopped. The time during which the temperature was perturbed was about 4–5 times the heating period. During the simulation test, stray gas migration through fractures and faults was considered a mechanism for groundwater contamination. In the test, the maximum TOC content in aquifer was the value of 97.0 mg/L. The maximum total petroleum hydrocarbon (TPH) content of the simulated formation was 129 mg/kg after oil pyrolysis.

Laboratory simulation of uranium metal corrosion in different soil moisture regimes

A novel laboratory simulation system has been developed for the study of the corrosion of uranium metal in soils. Corrosion and transportation of depleted uranium (DU) as the metal undergoes weathering as a buried material within the soil environment. The corrosion of uranium metal in soil was not well understood due to the gas-liquid-solid phase of the soil. This study presents a novel method to investigate the change of uranium species during the process of process of oxidation of metallic uranium in these environments. Compared with other techniques used for the study of environmental corrosion of metals in soils, this method has the advantage of low secondary uranium pollution, no energy consumption, and ease of operation. The simulation system has been used for the following studies:•Simultaneously simulate the corrosion of uranium metal in different soil moisture regimes•Study the influence of biogeochemical factors on the corrosion of uranium metal•Investigate the change of uranium species during oxidation

A novel laboratory simulation system to uncover the mechanisms of uranium upward transport in a desert landscape

After depleted uranium (DU) is deposited in the environment, it corrodes producing mobile uranium species. The upward transport mechanism in a desert landscape is associated with the dissolution/precipitation of uranium minerals that vary in composition and solubility in soil pore water. The objective of this study is to develop the laboratory column simulation to investigate the upward transport mechanism with cyclic capillary wetting and drying moisture regimes. Results showed that evaporation driven upward transport occurred even during the first 2 months of wetting-drying regimes. Evaporation driven upward transport may control the U movement in the soil profile in an arid climate. The new system did not generate any uranium-containing wastewater.•Simulates the upward transport process of pollutants with different pollution levels and species.•Simultaneously simulate the transport process of multiple pollutants simultaneously.•Evaluate the influence of biogeochemical factors on pollutant transport such as various cations and anions (Ca, Mg and carbonates) in water.

A New Degradation Model for Imaging in Natural Water and Validation Through Image Recovery

Scattering and turbulence are the main factors affecting imaging in natural water environment. A new model for underwater turbulent degradation is obtained by calculating the scattering transfer factors including the intensity distribution of beam propagation, turbulent fluid medium and suspended particle. In order to verify the proposed model, a controlled laboratory simulation system of turbulent water is established, from which the degradation transfer factor is measured and compared by image restoration and reconstruction. The new model is also applied for field tests in natural ocean water. Experimental results show that based on the proposed model, effect of image restoration and reconstruction can be substantially improved, which proves the correctness and validity of the model.

Study on Pantograph Arcing in a Laboratory Simulation System by High-Speed Photography

Phenomena of the pantograph arcing have become a challenge for the further development of high-speed electrified railway system. Despite of the large attention that has been paid to the radiated electromagnetic interference, materials ablation as well as the power-quality decline resulted from pantograph arcing, the specific dynamics of pantograph arcing with a high time resolution are still in absence. In this paper, the pantograph arcing phenomena in a laboratory simulation system were experimentally studied by high-speed photography. Synchronized electrical voltage and current waveforms were obtained to acquire a more comprehensive understanding on the underlying physics. The overall dynamics of the pantograph arcing from ignition to extinguishment were recorded. Three stages of the electric-contact process, from approaching arc, mechanical contact to the drawn arc, were well distinguished. A much intensified drawn arc was observed than the approaching arc. Typical lasting time of the drawn arcing is found $\sim 4$ times larger than the approaching arcing for our test setup. Maximum diameter of 3.3 mm was reached at around the current-peak moment. An interesting stable arc voltage of $\sim 23$ V was found during the drawn arcing. Intense material splash above the carbon strip was observed during the arcing process. The transient resistance during a typical arcing period was also analyzed, and a minimum value of $\sim 100~\text{m}\Omega $ was determined.

Laboratory simulation system, using Carcinus maenas as the model organism, for assessing the impact of CO2 leakage from sub-seabed injection and storage

The capture and storage of CO2 in sub-seabed geological formations has been proposed as one of the potential options to decrease atmospheric CO2 concentrations in order to mitigate the abrupt and irreversible consequences of climate change. However, it is possible that CO2 leakages could occur during the injection and sequestration procedure, with significant repercussions for the marine environment. We investigate the effects of acidification derived from possible CO2 leakage events on the European green crab, Carcinus maenas. To this end, a lab-scale experiment involving direct release of CO2 was conducted at pH values between 7.7 and 6.15. Female crabs were exposed for 10 days to sediment collected from two different coastal areas, one with relatively uncontaminated sediment (RSP) and the other with known contaminated sediment (MZ and ML), under the pre-established seawater pH conditions. Survival rate, histopathological damage and metal (Fe, Mn, Cu, Zn, Cr, Cd and Pb) and As accumulation in gills and hepatopancreas tissue were employed as endpoints. In addition, the obtained results were compared with the results of the physico-chemical characterization of the sediments, which included the determination of the metals Fe, Mn, Cu, Zn, Cr, Pb and Cd, the metalloid As, certain polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs), as well as nonchemical sediment properties (grain size, organic carbon and total organic matter). Significant associations were observed between pH and the histological damage. Concentrations of Fe, Mn, Cr, Pb, Cd and PAHs in sediment, presented significant negative correlations with the damage to gills and hepatopancreas, and positive correlations with metal accumulation in both tissues. The results obtained in this study reveal the importance of sediment properties in the biological effects caused by possible CO2 leakage. However, a clear pattern was not observed between metal accumulation in tissues and pH reduction. Animals' avoidance behavior and degree of tolerance to acidification are confounding factors for assessing metal bioaccumulation. Further research is required to find a suitable assay that would allow us to predict the risk to environmental health of possible negative side effects of metal mobility derived from CO2 leakage during its injection and storage in sub-seabed formations.

Divergent modulation of swine ileal microbiota by formic acid and methionine hydroxy analogue-free acid

Management of intestinal microbiota of monogastric animals has increased in importance since the ban of growth promoting antibiotics in many countries. Organic acids have been used as alternatives to antibiotics by many feed manufacturers. Regardless of the wide usage, the effect, dose response and mode of action of acids on intestinal microbes is poorly understood. In this study, we investigated the effects of dietary supplementation of three commonly used products, namely formic acid (FA) (90%), dl-methionine (DLM) (99%) and liquid methionine hydroxy analogue-free acid (88%), on ileal microbiota of pigs. Laboratory simulation system, mimicking swine ileum, was used to study the products at various concentrations and combinations. Furthermore, selected combinations were tested in a piglet trial to confirm the findings made in in vitro studies. FA turned out to have a dual effect on ileal microbiota. At concentrations below 0.5%, it significantly stimulated bacteria, but at higher inclusion rates it was highly inhibitory. This finding, which was consistent in in vitro and in vivo studies, implies that reducing the dose of FA does not lead to a diluted inhibitory effect, but in fact, an opposite, stimulatory effect on intestinal microbiota. It is highly important that feed compounders acknowledge this finding. Unlike FA, the inhibitory effect of methionine hydroxy analogue on ileal bacteria was linearly dose dependent and significant at inclusion levels above 0.2%, in vitro. Partial replacement of methionine hydroxy analogue by FA, or FA by methionine hydroxy analogue, led to an unpredictable outcome due to the dual effects of FA; e.g., a minor inclusion of added FA changed the inhibitory effect of methionine hydroxy analogue into microbial stimulation by FA. Inhibition of ileal microbiota by methionine hydroxy analogue was detected only in in vitro studies, suggesting that intact methionine hydroxy analogue may not have reached the ileum, in live animals. Therefore, if the target is to ensure the inhibitory effect of FA, the FA level in feed should be kept above 0.6%, and not reduced, if methionine hydroxy analogue is used as a methionine source instead of DLM. DLM was totally inert with regard to bacterial growth and metabolism, both in vitro and in vivo. The results of these studies reveal the importance of knowing how each acid product works. Inconsistent results in animal trials may have been partly due to quadratic dose–response effects of products, and unpredictable product combination effects.

The simulation of coke handling systems and developments in pilot scale oven tests

For the efficient operation of the blast furnace, it is essential to take into account the changes in coke properties brought about by handling systems. This has been made possible by the use of a laboratory simulation system of coke degradation under representative conditions of coke handling in the plant. It is also important to be able to obtain meaningful comparison criteria for pilot scale oven cokes and plant cokes. Procedures allowing to do this are described.

Carbonaceous particles on carbonate building stones in a simulated system

A laboratory simulation system for studying the interaction between carbonaceous particles and carbonate building stones is presented and described. Three types of building stones with the common characteristic of a carbonate matrix were used: 1) Carrara marble, 2) Travertine, 3) Trani stone. The carbonaceous particles used in our experiments were sampled at the emission points of two oil-combustion sources, chosen as representative of a centralized domestic heating system and an electric generating plant, and were characterized by means of chemical and physical analyses.

Variations of temperature, concentration, and supersaturation in a laboratory-scale saturated solar pond

A laboratory simulation system of a saturated solar pond using alum potash was operated in a series of experiments of 30 to 120 days' duration. The system consisted of an insulated column 100 cm deep, heated at the bottom by heat exchangers with varying energy output. The supersaturation, temperature and concentration in the upper layer as a function of time are presented. Both insufficient and excessive heat flow cause failure of the layered configuration. Suitably adjusted heat flow allows preservation of the layered structure. The concentration of the upper layer and the supersaturation display cyclic character: after attaining high supersaturation massive crystallization occurs with crystals sinking to the bottom where they are dissolved. The upward diffusion from the highly concentrated bottom solution completes the solute cycle and maintains the stability of the pond.

Insulators with Contaminated Surfaces, Part I: Field Conditions and Their Laboratory Simulation

Physical and chemical analyses done on suspension insulator surface contaminants and fog water collected in the field showed significant water-soluble material in both. At one location the soluble material in both the fog water and surface deposit was gypsum, whereas the insoluble component of the surface deposit was mostly alpha quartz. A laboratory simulation system was used to produce flashover on a single-suspension insulator with contamination conditions and voltage typical of field experience. To achieve this it was required that the laboratory simulation of the fog include a horizontal wind and that of the surface deposit include a substance (bentonite was used here) that would allow water to permeate (spread out) on the surface. The simulation produced the major phenomena believed to occur when suspension insulators suffer contamination flashover.