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The perishable nature of strawberry fruit is one of the key factors that limit its consumption, specified by its decreased freshness and shelf life after harvest. The suitable packaging conditions, low temperature storage, and desired atmosphere composition inside packaged are important to preserve the quality attributes and extend the shelf life of perishable fruits. In this study, the packaging films based on PLA (such as neat PLA, PLA/TA10, and PLA/C20A1/TA10) with two different gas mixtures (such as 10 KPa O2+15 KPa CO2+75 KPa N2 (MAP-A) and 15 KPa O2+10 KPa CO2+75 KPa N2 (MAP-B)) and a control sample without gas injection on fresh strawberry fruit were evaluated. The effects of the mentioned treatments on some physicochemical properties such as weight loss, total soluble solid, tritratable acidity, pH, and firmness kept at 4 °C for 23 days of storage period were evaluated based on a completely randomized design. The results showed that the weight loss and firmness of strawberry fruit decreased during storage time, while pH value increased. The total soluble solid and tritratable acidity of all the treatments increased throughout the storage time and decreased at the end of the storage time. It has been also reported that fruits packaged in PLA/C20A1/TA10 caused better quality attributes due to lower water vapor permeability and oxygen transmission rate than two films of neat PLA and PLA/TA10. In addition, the gas mixture of MAP-A was more suitable in comparison to MAP-B due to higher carbon dioxide inside packages and lower respiration rate of strawberry fruit. Therefore, the use of nanocomposite film with modified atmosphere has been proposed to maintain strawberry fruit at a low temperature. [ABSTRACT FROM AUTHOR]

Natural gas is accumulated in the reservoirs as either separate gas reservoir or the gas cap in an oil reservoir. Besides, gas is also injected into a hydrocarbon reservoir for IOR/EOR or gas storage purposes. Due to the reservoir heterogeneity or fault pattern in reservoir, gas could move to unplanned parts of the reservoir or could even be leaked, which in turn, deviates from the purpose of the gas injection. To overcome this problem and to monitor the fate of injected gas, 4D seismic data has recently been employed by oil and gas companies. 4D seismic, that is indeed, the repeated 3D seismic through the time has been recently revealed to be a successful tool for this purpose. However, there has been reported some challenges about the quantitative estimation of injected gas using 4D seismic data. The source of this challenge is mainly due to the non-linear response of elastic properties of saturated rock versus gas saturation. Once the gas is injected into core plug in the laboratory, the compressional velocity is significantly decreased for a few percents of gas saturation. Nonetheless, for higher gas saturation variation, not a considerable change is observed in compressional velocity. Because of this extremely non-linear behaviour, some researchers have concluded that the quantification of gas response is not possible using seismic data. In this research, it is tried to understand the reservoir scale gas distribution that is found to be different from the laboratory scale. Gas is migrated towards the upper part of the reservoir due to the gravity effect. It is quickly reached at a fixed gas saturation that is around maximum gas saturation (1-Swir). Continuation of gas injection increases gas thickness from top to base of reservoir, while gas saturation is practically fixed. Therefore, unlike the laboratory scale, the only variable on the reservoir scale would be the gas thickness, and not gas saturation. This is the key observation that would assist to understand proper 3D and 4D seismic response to injected gas. Two main 4D seismic attributes are chosen in this paper to understand those responses. The response of time shift and amplitude change were derived analytically and investigated numerically. The variety of reservoir models with different thickness and heterogeneities were made to analyze the seismic response. It can be concluded that for the medium to high-quality reservoirs, seismic response to the injected gas is simply linear; therefore, 4D seismic is still a powerful tool to quantitatively estimate the volume, distribution and migration path of the injected gas. It is proposed to continue this research to understand the seismic response on low quality (permeability and porosity) reservoirs. [ABSTRACT FROM AUTHOR]

Large natural gas reserves are a great potential economic advantage for Iran's economy. As long as the consumption and production of the natural gas increase in the country, gas industry will play a vital role in meeting oil industry's needs. This paper aims to investigate optimal usage of the Iranian natural gas reserves among different applications and also opportunity cost of allocations by developing the gas industry over a long time horizon. Using welfare function, nonlinear dynamic model is applied to solve the problem of gas allocation among alternatives such as domestic consumption, gas injection, gas exports or gas salvaging using the data over the period 2006-2031. The constraints include gas production, requirements of gas injection, domestic growth, gas consumption and other effective variables and parameters related to the natural gas reserves allocation. Findings confirm that priorities and the values of optimal allocation gas depend on the constraints of natural gas production, energy policy, target of injection for preservation or increasing the pressure of oil reservoirs and gas imports. Furthermore, low discount rate gas injection has an absolute priority to gas exports. In the baseline scenario, if domestic gas consumption continuously growth at its average rate of last 11 years performance, it won't be possible to allocate gas injection according to the preservation pressure of oil reservoirs scenario and gas exports. The results of optimal gas salvage and its shadow price shows that the lack of gas production ability has a very high opportunity cost at the beginning years.