Preparation of a functional fracturing fluid with temperature-and salt-resistance,and low damage using a double crosslinking network

Fracturing fluids(FFs)have been widely used to stimulate the tight reservoir.However,current FFs will not only lose their rheological property at high temperatures and high salt but also show an incomplete gel-breaking property.Herein,a double crosslinking network FF with pretty superiorities in rheology and low damage to the core was constructed by introducing both physical crosslinking and chemical crosslinking into the system.The construction of double crosslinking networks enhanced the rheology of this functional FF.The particle sizes of gel-breaking fluids are mainly distributed in 1.0e10,000 nm;furthermore,for every 10,000 mg/L increase in salinity,the particle size of the gel-breaking fluid is decreased by almost half.The adsorption capacity(<1.0 mg/g)gradually decreased with the increase of salinity at 20℃.Moreover,the adsorption of gel-breaking fluids on the rock decreased first and then kept stable with temperature increasing at a salinity of ≤30,000 mg/L,however,showed the opposite trend at 40,000 mg/L.The results of rheology,particle size,static adsorption,and core damage showed that this functional FF could be an alternative for the stimulation of a tight reservoir with high temperature and recycling of produced water with high salinity.

Research and Application of an Environmental-Friendly Low-Damage and High Salt-Resistance Slick Water Fracturing Fluid System

The Sulige gas field is a typical low-pressure low-permeability tight sandstone gas reservoir. The reservoir has poor seepage capacity, strong heterogeneity, high mineralization of formation water and extremely scarce water resources on the site. These unfavorable factors have brought great difficulties to the on-site mining process. Now, a nano-composite green environmental protection slick water fracturing fluid system CQFR can be quickly dissolved because of the larger specific surface area, and the small molecular size makes the damage to the reservoir less than 5%, and the average drag reduction effect can reach more than 73%. It can quickly and well dissolve and maintain performance under high salinity conditions and fracturing flowback fluids. It responds well to the complex reservoir conditions on the construction site and makes the flowback fluid recyable, which greatly reduces the consumption of water resources on the construction site and effectively improves the construction efficiency and economic benefits.

Floristic composition of the halophilic and salt-resistant plant population in Hammam-Boughrara (Oran-Algeria)

This phyto-ecological study is on halophilic and salt-resistant vegetation of Oran region. The semiarid and sometimes arid climate has been defined and confirmed from a bioclimatic point of view. The pedological approach used shows a soil with sandy to silty-sandy texture, favoring regression of the vegetation and a halophilic vegetation set up. In this study, we analyze the floristic composition of the northern region of Hammam Boughrara using multiple floristic surveys conducted at three stations along the Tafna wadi. Dominated by Mediterranean and Saharo-Sindian elements, the relatively poor flora (88 species in total) is biologically characterized by a clear dominance of therophytes (>33%) and chamaephytes (>19%) to the detriment of phanerophytes.

Effect of Plant Density on the Yield of Hydroponically Grown Heat-Tolerant Tomato under Summer Temperature Conditions

Producing enough tomato to meet market demand sustainably has not been feasible in the tropics like Ghana. Attempts to improve production using greenhouse facilities have not addressed the challenge because of high-temperature conditions in the greenhouse, which are difficult to manage. Heat stress, arising from high temperatures, hinder the performance of tomato in terms of fruit set and yield. Moreover, the impending climate change is expected to impose more unfavorable environmental conditions on crop production. An experiment was conducted in (greenhouse at Chiba University, Japan) summer period, which has similar high-temperature conditions like Ghana. This work sought to increase the yield of a heat-tolerant tomato using a state-of-the-art hydroponic system through high-density planting. The outcome of this work was intended for adoption and practice in Ghana. A Heat-tolerant tomato “Nkansah HT” along with Lebombo and Jaguar cultivars, were grown at high and low plant densities (4.1 and 2.7 plants m-2 respectively). Each plant was grown in a low substrate volume culture (0.5 L plant-1) in a recirculating nutrient film technique (NFT) hydroponic system. Parameters measured were plant growth and dry matter assimilation at 12 weeks after transplanting, and the generative components. Results showed that a high plant density increased plant height but reduced chlorophyll content by 9.6%. Under temperature stress conditions, the three cultivars recorded more than 95% fruit set, but plant density did not affect the fruit set and the incidence of blossom end rot (BER). The incidence of BER reduced the marketable yield of the Jaguar cultivar by 51% but, this physiological disorder was not recorded in the HT and the Lebombo cultivars. A high-density planting increased the yield per unit area increased by 38.9%. However, it is uneconomical to cultivate the Jaguar cultivar under a heat stress condition due to its high susceptibility to blossom end rot. To improve the yield of tomatoes under tropical heat stress with a threatening climate change condition, the HT is a better cultivar suited for high-density planting. This study shows that high-density cultivation of the HT cultivar in NFT hydroponic system has the potential to increase Ghana’s current tomato yield by 4.8 times.

The causes and impacts for heat stress in spring maize during grain filling in the North China Plain--A review

High-temperature stress （HTS） at the grain-filling stage in spring maize （Zea mays L.） is the main obstacle to increasing productivity in the North China Plain （NCP）. To solve this problem, the physiological mechanisms of HTS, and its causes and impacts, must be understood. The HTS threshold of the duration and rate in grain filling, photosynthetic characteristics （e.g., the thermal stability of thylakoid membrane, chlorophyll and electron transfer, photosynthetic carbon assimilation）, water status （e.g., leaf water potential, turgor and leaf relative water content） and signal transduction in maize are reviewed. The HTS threshold for spring maize is highly desirable to be appraised to prevent damages by unfavorable temperatures during grain filling in this region. HTS has negative impacts on maize photosynthesis by damaging the stability of the thylakoid membrane structure and degrading chlorophyll, which reduces light energy absorption, transfer and photosynthetic carbon assimilation. In addition, photosynthesis can be deleteriously affected due to inhibited root growth under HTS in which plants decrease their water-absorbing capacity, leaf water potential, turgor, leaf relative water content, and stomatal conductance. Inhibited photosynthesis decrease the supply of photosynthates to the grain, leading to falling of kernel weight and even grain yield. However, maize does not respond passively to HTS. The plant transduces the abscisic acid （ABA） signal to express heat shock proteins （HSPs）, which are molecular chaperones that participate in protein refolding and degradation caused by HTS. HSPs stabilize target protein configurations and indirectly improve thylakoid membrane structure stability, light energy absorption and passing, electron transport, and fixed carbon assimilation, leading to improved photosynthesis. ABA also induces stomatal closure to maintain a good water status for photosynthesis. Based on understanding of such mechanisms, strategies for alleviating HTS at the grain-filling stage in spring maize are summarized. Eight strategies have the potential to improve the ability of spring maize to avoid or tolerate HTS in this study, e.g., adjusting sowing date to avoid HTS, breeding heat-tolerance varieties, and tillage methods, optimizing irrigation, heat acclimation, regulating chemicals, nutritional management, and planting geometric design to tolerate HTS. Based on the single technology breakthrough, a com- prehensive integrated technical system is needed to improve heat tolerance and increase the spring maize yield in the NCP.

Improvement of heat－tolerance by training I．Evaluation of effects of long－distance running and march training on heat－toleran

in order to verify the heat-tolerance effect, two trainings, 90 min marching with load (WBGT 24. 6～35.6℃) and 10 km running (WBGT 25.0～31.1℃) were performed in laboratory and field under hot climate.Ten to twelve times (days) of training were carried out

In Vitro Propagation, Isolation and Expression Studies of Suaeda edulis Genes Involved in the Osmoprotectants Biosynthesis

Halophytes are an excellent choice for the study of genes conferring salt tolerance to salt-sensitive plants and,they are suitable for reclamation and remediation of saline soil.We develop an in vitro plant propagation protocol and studies of genes involved with GB and Pro biosynthesis in Suaeda edulis.Axillary buds were used as explants and cultured in different treatments on Murashige and Skoog(MS)medium supplemented with different concentrations and combinations of plant growth regulators.The highest number of multiple shoots was on MS medium containing 1 mg/L Benzyladenine(BA)and/or 2 g/L activated carbon with 5.5±06 shoots per explant.The identification and expression analysis of genes involved in glycine betaine(GB)biosynthesis were S-adenosyl-methionine synthetase(SAMS),choline monooxygenase(CMO)and betaine alde-hyde dehydrogenase(BADH),and for proline(Pro)was pyrroline 5-carboxylate synthetase(P5CS).These sequences shared 90–95%of identity with others plant homologous in public databases.The amino acids sequence analysis showed that all these peptides contain some of the conserved motifs of those kinds of enzymes.The qRT-PCR analysis revealed a higher expression of SeBADH,SeCMO,and,SeP5CS genes in the roots and leaves from plants collected in the field in contrast with from in vitro plants.However,the expression level of SeSAMS was higher only in the leaves of plants collected in the field when com-pared to those cultivated in vitro.

Improvement of heat－tolerance by training Ⅱ．Evaluation of effects of cross－country race and heat－bath training on heat－tolera

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Implication of Ions and Organic Solutes Accumulation in Amaranth (<i>Amaranthus cruentus</i>L.) Salinity Resistance

Salinity is one of the major environmental constraints limiting agricultural productivity in the world. The effects of salt stress on growth, ions and organic solutes accumulation were investigated in two amaranth (Amaranthus cruentus) cultivars: Rouge (salt-resistant) and Locale (salt-sensitive). Young plants of these cultivars were exposed, in hydroponic system, to three concentrations of NaCl: 0, 30 and 90 mM. Growth parameters, ions, free proline and soluble sugars concentrations were determined after 2 weeks of stress. NaCl effect resulted in plant growth reduction in both cultivars but plants of cultivar Rouge were less affected compared to that of cv. Locale. Na+, proline and soluble sugars concentrations increased significantly in leaves and roots under salinity while K+, Ca2+ and Mg2+ concentrations decreased in both cultivars. Proline and soluble sugars increased significantly in leaves and roots of cultivar Locale whereas in cultivar Rouge, proline increase was significant only in roots and soluble sugars increase was significant only in leaves. The highest increase of Na+ concentration occurred in leaves of cv. Rouge coupled with the lowest reduction in K+ concentration. The highest increase of proline occurred in leaves of cultivar Locale whereas the highest increase of soluble sugars was observed in leaves of cultivar Rouge. The reduction of the Ca2+ concentration under salt stress was more accentuated in both leaves and roots of cultivar Rouge than cultivar Locale while cv. Rouge maintained higher content in Mg2+ either in leaves or in roots in the presence of NaCl than cultivar Locale. These results suggest an implication of Na+, K+ and Mg2+ in salt resistance in these cultivars and that soluble sugars may play an important role in salt-resistance in Amaranthus cruentus. However, proline appears as a symptom of injury in stressed plants rather than an indicator of resistance.

β-cyclodextrin assists salt-resistance polymer flooding:Injectivity improvement

Polymer flooding method has attracted wide attentions in petroleum industry because of its relatively simple process equipment,low cost of agents and good performance on enhancing oil recovery.However,common polymer can hardly meet the technical requirements of the oilfields with high salinity.Existing salt-resistance polymer solutions get a large viscosity in high salinity condition by changing polymer molecules aggregation which,however,may result in the poor adaptability between polymer molecules and the pore sizes of reservoir.β-cyclodextrin(β-CD),a kind of chemical agent,is found to enhance the injectivity of salt-resistance polymer solutions by wrapping the hydrophobic groupings of salt-resistance polymer molecules.For a certain reservoir,the addition ofβ-cyclodextrin into salt-resistance polymer solution can balance the effect of plugging the layers with high permeability and the purpose of diverting to the layers with low and medium permeability.In this paper,viscosity of polymer solution is tested in condition of different concentrations ofβ-CD.On that basis,experiments on seepage characteristics are carried out to evaluate the injectivity of salt-resistance polymer solution.Finally,an appropriate concentration ofβ-CD,which is added into salt-resistance polymer solution,is chosen to adapt a certain reservoir with heterogeneity.