A blockage removal technology for natural gas hydrates in the wellbore of an ultra-high pressure sour gas well

In order to safely, efficiently and economically remove the blockages of natural gas hydrate (NGH) in the wellbores of ultra-high pressure gas wells, this paper utilized the heat released from an independently developed autogenetic heat based solid blockage remover through chemical reaction in the wellbore to dissolve NGH and prevent it from forming again. In addition, adjustable heat generation time and heat generation amount was realized by regulating the dosage of the blockage remover. Finally, the chemically autogenetic heat based blockage removal technology was applied to remove the blockages in ultra-high pressure sour gas wells in the Sichuan Basin. And the following research results were obtained. First, when the independently developed chemically autogenetic heat based solid blockage remover is adopted, the peak temperature (34.2–88.5 °C) and time (24.2–884.0 min) of heat generation can be adjusted by its dosage. What's more, there is NGH inhibitor in the reaction product, which can inhibit the regeneration of NGH. Second, as the concentration of the blockage remover increases, the heat transfer speed increases, leading to an increase of NGH dissociation rate around the blockage remover. Third, blockage removal time increases with the increase of wellbore ID. In addition, the increasing rate of the blockage removal time as the wellbore ID increases from 64 mm to 76 mm is lower than that from 76 mm to 102 mm. Fourth, the coincidence rate between the simulation calculation result of heat diffusion and the on-site actual consumption is more than 85%, which indicates that the proposed model for the heat diffusion of chemically autogenetic heat based blockage remover is reliable and can be used to calculate the dosage of blockage remover. Fifth, solid reagent adding device with resistance to sulfur and pressure of 140 MPa is used to add autogenetic heat based solid blockage remover. This blockage remover has been applied in the ultra-high pressure sour gas wells in the Sichuan Basin three well times. Thanks to its application, NGH blockages in these wells are removed successfully and their production is resumed smoothly. In conclusion, this blockage removal technology has such advantages as effective blockage removal, safe and simple on-site operation and low cost, and a promising application prospect

Construction of eco-security model in the agro-pastoral interconnected zone in northern Shaanxi

Driven by both natural and anthropogenic interference, ecological issues are prevalent in China's environmentally vulnerable areas. The creation of an eco-security model can serve as the empirical basis for environmental rehabilitation. In this study, the agro-pastoral interconnected zone in northern Shaanxi, quintessential ecologically frangible area in the Yellow River basin, is utilized as the research area to analyze the spatio-temporal characteristics of land use and landscape ecological risk from 1990 to 2020, and to construct and optimize the eco-security model based on the identification of ecological corridors, ecological pinchpoints and ecological barriers. The results show (1) Grassland and arable land make up the majority of the landscape matrix, with a rise in the size of woodland and built-up and a considerable decrease in unused land being the preponderating features of land use change. (2) From 1990 to 2020, there is a dynamic shift trend in the landscape ecological risk, initially dropping and then increasing. The territory is primarily in a region of medium–low risk, with a northerly high and a southern low distribution pattern. (3) The eco-security model consists of 9 ecological sources, 13 ecological corridors, 31 ecological pinchpoints, and 35 ecological barriers. The optimized eco-security model shows a distribution pattern of “one center, three belts and four districts”. The outcome of the research can supply a reference for the construction of eco-security model in ecologically fragile areas as well as ecological governance and high-quality development within the region

Leaf Coloration in Acer palmatum Is Associated with a Positive Regulator ApMYB1 with Potential for Breeding Color-Leafed Plants

Anthocyanin biosynthesis and accumulation is closely associated with tissue/organ coloring in plants. To gain insight into the physiological and molecular mechanisms of leaf coloring in Acer palmatum, a deciduous tree during autumnal senescence, we first investigated concentration dynamics of pigments (i.e., chlorophyll, carotenoid and anthocyanin) in leaves with differential coloring. It was found that compared to green leaves (GN), anthocyanins were accumulated actively in semi-red (SR) and total-red (TR) leaves, accompanied with chlorophyll and carotenoid degradation. Then transcriptional profiling on GN and SR leaves identified thousands of transcripts with differential expression in SR compared to GN leaves. An annotation search showed that the entire flavonoid/anthocyanin biosynthesis pathway from the production of naringenin chalcone to modification of flavonoid backbone was extensively activated at the transcriptional level in SR leaves. Phylogenetic analysis of putative MYB proteins identified ApMYB1 as a putative regulator promoting anthocyanin biosynthesis. Expression of ApMYB1 in leaves was induced by exogenous hormones including abscisic acid. Stable overexpression of ApMYB1 in tobacco resulted in leaves with higher accumulation of anthocyanins. Collectively, our results identified ApMYB1 as a positive regulator associated with leaf coloring in Acer palmatum during autumnal senescence, which may be regarded a potential target for breeding color-leafed plants

Preparation of Theophylline-Benzoic Acid Cocrystal and On-Line Monitoring of Cocrystallization Process in Solution by Raman Spectroscopy

Pure theophylline-benzoic acid cocrystal was prepared via slurry and cooling crystallization in solution to overcome the disadvantages of existing preparation methods. The target cocrystal was characterized by powder X-ray diffraction (PXRD), thermalgravimetric analysis (TGA), differential scanning calorimetry (DSC) and Raman spectroscopy. The slurry and cooling cocrystallization process in solution was monitored via on-line Raman spectroscopy. The results obtained from on-line Raman monitoring can exhibit the transformation process from raw materials (theophylline and benzoic acid) to cocrystal and show the cocrystal formation rate. Comparing each transformation process under different conditions in slurry crystallization, we found that suspension density of raw materials and temperature both have an impact on the theophylline-benzoic acid cocrystal formation rate. It could be concluded that the cocrystal formation rate increased with the increase of suspension density of raw materials. Further under the same suspension density, higher temperature will accelerate theophylline-benzoic acid cocrystal formation. Meanwhile, various data from the cocrystallization process in cooling crystallization, including nucleation time, nucleation temperature and suitable cooling ending point can be gained from results of on-line Raman monitoring

Coherence in Polycrystalline Thin Films of Twisted Molecular Crystals

Helicoidal crystallites in rhythmically banded spherulites manifest spectacular optical patterns in small molecules and polymers. It is shown that concentric optical bands indicating crystallographic orientations typically lose coherence (in-phase twisting) with growth from the center of nucleation. Here, coherence is shown to increase as the twist period decreases for seven molecular crystals grown from the melt. This dependence was correlated to crystallite fiber thickness and length, as well as crystallite branching frequency, a parameter that was extracted from scanning electron micrographs, and supported by numerical simulations. Hole mobilities for 2,5-didodecyl-3,6-di(thiophen-2-yl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione (DPP-C12) measured by using organic field-effect transistors demonstrated that more incoherent boundaries between optical bands in spherulites lead to higher charge transport for films with the same twist period. This was rationalized by combining our growth model with electrodynamic simulations. This work illustrates the emergence of complexity in crystallization processes (spherulite formation) that arises in the extra variable of helicoidal radial twisting. The details of the patterns analyzed here link the added complexity in crystal growth to the electronic and optical properties of the thin films.SCOPUS: ar.jinfo:eu-repo/semantics/publishe