Exploring pore-scale production characteristics of oil shale after CO_(2) huff‘n’puff in fractured shale with varied permeability

Recent studies have indicated that the injection of carbon dioxide(CO_(2))can lead to increased oil recovery in fractured shale reservoirs following natural depletion.Despite advancements in understanding mass exchange processes in subsurface formations,there remains a knowledge gap concerning the disparities in these processes between the matrix and fractures at the pore scale in formations with varying permeability.This study aims to experimentally investigate the CO_(2) diffusion behaviors and in situ oil recovery through a CO_(2) huff‘n’puff process in the Jimsar shale oil reservoir.To achieve this,we designed three matrix-fracture models with different permeabilities(0.074 mD,0.170 mD,and 0.466 mD)and experimented at 30 MPa and 91℃.The oil concentration in both the matrix and fracture was monitored using a low-field nuclear magnetic resonance(LF-NMR)technique to quantify in situ oil recovery and elucidate mass-exchange behaviors.The results showed that after three cycles of CO_(2) huff‘n’puff,the total recovery degree increased from 30.28%to 34.95%as the matrix permeability of the core samples increased from 0.074 to 0.466 mD,indicating a positive correlation between CO_(2) extraction efficiency and matrix permeability.Under similar fracture conditions,the increase in matrix permeability further promoted CO_(2) extraction efficiency during CO_(2) huff‘n’puff.Specifically,the increase in matrix permeability of the core had the greatest effect on the extraction of the first-cycle injection in large pores,which increased from 16.42%to 36.64%.The findings from our research provide valuable insights into the CO_(2) huff‘n’puff effects in different pore sizes following fracturing under varying permeability conditions,shedding light on the mechanisms of CO_(2)-enhanced oil recovery in fractured shale oil reservoirs.

Production characteristics and displacement mechanisms of infilling polymer-surfactant-preformed particle gel flooding in post-polymer flooding reservoirs:A review of practice in Ng3 block of Gudao Oilfield

The pilot test of infilling polymer-surfactant-preformed particle gel(PPG)flooding has been successfully implemented after polymer flooding in Ng3 block of Gudao Oilfield in China.However,the production characteristics and displacement mechanisms are still unclear,which restricts its further popularization and application.Aiming at this problem,this paper firstly analyzes the production performance of the pilot test and proposed four response types according to the change of water cut curves,including W-type,U-type,V-type response,and no response.Furthermore,the underlying reasons of these four types are analyzed from the aspects of seepage resistance and sweep efficiency.The overall sweep efficiency of gradual-rising W-type,gradual-decreasing W-type,and early V-type response increases from 0.81 to 0.93,0.55 to 0.89,and 0.94 to 1,respectively.And the sum of seepage resistance along the connection line between production well and injection well for U-type and delayed V-type response increases from 0.0994 to 0.2425,and 0.0677 to 0.1654,respectively.Then,the remaining oil distribution after polymer flooding is summarized into four types on the basis of production and geological characteristics,namely disconnected remaining oil,streamline unswept remaining oil,rhythm remaining oil,and interlayer-controlled remaining oil.Furthermore,the main displacement mechanisms for each type are clarified based on the dimensionless seepage resistance and water absorption profile.Generally,improving connectivity by well pattern infilling is the most important for producing disconnected remaining oil.The synergistic effect of well pattern infilling and polymer-surfactant-PPG flooding increases the dimensionless seepage resistance of water channeling regions and forces the subsequent injected water to turn to regions with streamline unswept remaining oil.The improvement of the water absorption profile by polymer-surfactant-PPG flooding and separated layer water injection contributes to displacing rhythm remaining oil and interlayer-controlled remaining oil.Finally,the paper analyzes the relationships between the remaining oil distribution after polymer flooding and production characteristics of infilling polymer-surfactant-PPG flooding.The study helps to deepen the understanding of infilling polymer-surfactant-PPG flooding and has reference significance for more commercial implementations in the future.

Growth and Production Characteristics of Different Alfalfa Varieties in Jiamusi

[Objective]The growth and production characteristics of different alfalfa varieties in Jiamusi were explored in the paper,in order to better study their cold resistance in northern regions. [Method]The yield traits in different growth periods were measured using randomized block design method. [Results] The plant height of Longmu 803 was the highest of 66. 80 cm on the seeding year; the numbers of plants and branches per unit length of Longmu 808 were the highest of 94 plants and 184 branches,respectively,and its yield was the highest. The overwintering rate of each variety in the region was 100%. The yield of first mowing successively were Longmu 808 】 Longmu 80 】 Xunlu alfalfa 】 Aohan alfalfa 】 Zhaodong alfalfa 】 Longmu 807; the yield and 1 000-grain weight of Longmu803 were the highest,which were 20. 24 and 0. 09 g higher than control Zhaodong alfalfa,respectively. [Conclusion]The test alfalfa varieties have higher cold resistance in Jiamusi. Longmu 803 and Longmu 808 have both high grass production performance and excellent production performance.

Production Characteristics and the Control Factors of Surface Wells for Relieved Methane Drainage in the Huainan Mining Area

Based on the production data of a large number of surface drainage wells in the Huainan mining area,the present study shows that four types of typical production characteristics for relieved methane wells are recognized,of which the stable type for production and gas concentration is the most dominate,as determined by a comprehensive study on the volume and concentration of drained gases, as well as the stress changes of rocks influenced by mining.Some influence factors for the productive differences of the drainage wells were also been discussed.The results indicate that protective coal-seam mining has a significant effect on overlying strata,which promotes the development of pores and fractures of coal reservoirs for methane desorption and migration;however,the production and the stability of drainage wells are affected by deformation and damage of the overlying strata.The second distribution of strata stress is caused by mining engineering,and if the stress load is larger than the carrying capacity of the extraction well,the gas production would be influenced by the drainage well that has been damaged by rock movement.Furthermore,the case damage occurs first in the weak, lithologic interface by its special mechanical properties.The stability of drainage wells and the production status are also influenced by the different drilling techniques,uneven distribution of gas concentration,and combination of gob gas and methane from the protected layer.

Effects of Mechanical Sowing and Transplanting on Characteristics of Dry Matter Production in Middle-season Hybrid Rice

To clarify the effects of mechanical sowing and transplanting on dry mat- ter production of middle-season hybrid rice, a two-factor split plot design was used to study the effects of different sowing and transplanting methods and their interac- tion with the seedling number per hill or seeding time on dry matter accumulation, distribution and transformation of F You 498, a middle-season hybrid rice variety, under field conditions in 2012 and 2013. The results showed that there was a marked effect of the sowing and transplanting methods and their interaction with the seedling number per hill or seeding time on dry matter accumulation, distribution and transformation. The total population dry matter accumulation of the treatments with mechanical direct seeding （MDS） and machine-based transplanting （MT） was lower than that of the treatment with traditional manual transplanting （TMT）. How- ever, MDS had higher dry matter accumulation and accumulating rate in the joint- ing-earing stage,and maintained higher stem-sheath exportation, export rate and transformation than MT and TMT; MT had higher dry matter accumulation and ac- cumulating rate in the heading-maturity period than MDS and TMT. Moreover, the treatments with low seedling number per hill or early seeding enhanced the assimi- lation of dry matter after heading,the ratio of dry matter accumulation after earing to biomass yield and the contribution rate of dry matter accumulation after earing, and a reasonable early sowing was favorable to increase the harvest index of middle- season hybrid rice under mechanical sowing and transplanting conditions.

Entropy Production Analysis for Hump Characteristics of a Pump Turbine Model

The hump characteristic is one of the main problems for the stable operation of pump turbines in pump mode.However,traditional methods cannot reflect directly the energy dissipation in the hump region.In this paper,3D simulations are carried out using the SST k-ω turbulence model in pump mode under different guide vane openings.The numerical results agree with the experimental data.The entropy production theory is introduced to determine the flow losses in the whole passage,based on the numerical simulation.The variation of entropy production under different guide vane openings is presented.The results show that entropy production appears to be a wave,with peaks under different guide vane openings,which correspond to wave troughs in the external characteristic curves.Entropy production mainly happens in the runner,guide vanes and stay vanes for a pump turbine in pump mode.Finally,entropy production rate distribution in the runner,guide vanes and stay vanes is analyzed for four points under the 18 mm guide vane opening in the hump region.The analysis indicates that the losses of the runner and guide vanes lead to hump characteristics.In addition,the losses mainly occur in the runner inlet near the band and on the suction surface of the blades.In the guide vanes and stay vanes,the losses come from pressure surface of the guide vanes and the wake effects of the vanes.A new insight-entropy production analysis is carried out in this paper in order to find the causes of hump characteristics in a pump turbine,and it could provide some basic theoretical guidance for the loss analysis of hydraulic machinery.

Comparative analysis of hydrogen-producing bacteria and its immobilized cells for characteristics of hydrogen production

A strain of hydrogen producing bacteria was immobilized by polyvinyl alcohol-boric acid method, with the addition of a small amount of calcium alginate. The immobilized cells were insensitive to the presence of traces of O2. Moreover, the immobilized cells increased both the evolution rate and the yield of hydrogen production. Batch experiments with a medium containing 10 g/L glucose demonstrated the yields of hydrogen production by the immobilized and free cells were 2.14 mol/mol glucose and 1.69 mol/mol glucose, respectively. In continuous cultures at medium retention time of 2.0 h, the yield and the evolution rate of hydrogen production by the immobilized cells were 2.31 mol/mol glucose and 1 435.4 ml/（L·h） respectively. However, at medium retention time of 6.0 h, the yield and the evolution rate of hydrogen production by free cells were only 1.75 mol/mol glucose and 362.9 ml/（L·h）, respectively.

Research of Blockchain Technology in the Traceability of Characteristic Agricultural Products

With the increasingly prominent problem of food safety,the quality traceability of characteristic agricultural products has become a pressing issue.This study focuses on the application of blockchain technology in the traceability of characteristic agricultural products,aiming to explore its potential and practical value in improving the efficiency and transparency of the traceability system of agricultural products.Through the combination of case analysis and model construction,a blockchain-based traceability system for characteristic agricultural products was established.The results showed that the traceability system could effectively record the whole process information of agricultural products from production and processing to sales,and greatly improve the immutability and traceability of data.Lastly,this paper also points out that the use of blockchain technology can improve the market trust in characteristic agricultural products,provide consumers with authentic and reliable product information,and provide new technical means for the quality management of agricultural products.

Erosion and Sediment Production in Small Watershed in Purple Hilly Areas and Prevention Techniques

Purple Soil distributes extensively and mainly in China. Because of abundant easily weatherable parent rocks/ materials and unstable soil structure, and also influenced by parent materials, usage systems, and slope gradients, erosion and sediment production of purple soils are very severe with main fashions of water erosion and gravitational erosion. Basing on observed data in small watersheds, rainfall erosivity, vegetation coverage, previous soil water content, flow and relating factors such as climate, topograph of small watershed, land usage, and soil kinds are all the influence factors of erosion and erodibility of purple soil as well as sediment production and transport in small watershed of purple hilly areas. The effective technological countermeasures of ecosystem restoration, agricultural tillage for water conservation and erosion prevention, agriculture project, and soil changing for fertility and anti-erosion were provided.

Effects of Different Sterilization Methods on the Product Characteristics of Sichuan Industrialized Huiguorou

Pasteurization,116 and 121℃sterilization were used in the development of Sichuan Industrial Huiguorou.The sensory,color,texture,lipid oxidation,preservation and flavor substance types and contents of the products were determined,and the effects of different sterilization methods on product characteristics were compared.The results showed that pasteurization was the best way to maintain the edible quality of products,but the storage period of products was very short,so the products could only be quickly distributed and consumed.Sterilization at 116℃and sterilization at 121℃could ensure the shelf life of Huiguorou under non-refrigeration conditions,and effectively solve the problem of long-term storage and transportation of Sichuan meat dishes.However,higher temperature had more or less adverse effect on the flavor of the product,and the product texture was too soft.It suggested that the better way was to sterilize at 116℃,which had less adverse effect on the flavor of the product,and could greatly prolong the non-refrigerated storability of the product,and increase the content of aldehydes and esters,so as to improve the flavor.

Production of Lettuce Seedlings with Association of Diazotrophic Bacteria and Humic Acids

The objective of this work was to verify the responses in agronomic and physiological characters of lettuce seedlings when submitted to different doses of humic acids and the presence or absence of inoculation of the bacterium Azospirillum brasilense. The experiment was carried out at the Protected Cultivation Station and Biological Control Teacher Mário César Lopes, belonging to the Experimental Stations Nucleus of the State University of the West of Paraná. The experimental design was a randomized block design, in a 5 × 2 factorial scheme, with four repetitions, totaling 40 plots. The first factor consisted of five solutions containing humic acid (100%, 75%, 50%, 25% and 0%) and the second factor was the presence or absence of the diazotrophic bacterium Azospirillum brasilense obtained by commercial product. Germination tests were carried out in addition to the determination of agronomic characters such as the number of fully expanded leaves, plant height, stem diameter, main root length, shoot dry mass, root dry mass, total dry mass, and Dickson quality index. The association of diazotrophic bacteria and humic acids did not influence the emergency rate, mean emergence time, mean speed of emergency, emergence speed index, plant height, and root length of lettuce seedlings. The dilutions of humic acids, regardless of inoculation with bacteria diazotrophic favored the development of the number of leaves, stem diameter and Dickson quality index. Inoculation of lettuce seeds with diazotrophic bacteria associated with the addition of humic acids, favored the development of the dry mass of root and total dry matter.

Analysis of Wellbore Flow in Shale Gas Horizontal Wells

Theflow behavior of shale gas horizontal wells is relatively complex,and this should be regarded as the main reason for which conventional pipeflow models are not suitable to describe the related dynamics.In this study,numerical simulations have been conducted to determine the gas-liquid distribution in these wells.In particular,using the measuredflow pressure data related to 97 groups of shale gas wells as a basis,9 distinct pipeflow models have been assessed,and the models displaying a high calculation accuracy for different water-gas ratio(WGR)ranges have been identified.The results show that:(1)The variation law of WGR in gas well satisfies a power function relation.(2)The well structure is the main factor affecting the gas-liquid distribution in the wellbore.(3)The Beggs&Brill,Hagedorn&Brown and Gray models exhibit a high calculation accuracy.

Pore scale performance evaluation and impact factors in nitrogen huff-n-puff EOR for tight oil

Nitrogen huff-n-puff(N_(2)HnP) appears to be an economical and high-efficiency enhanced oil recovery(EOR) technique for tight oil reservoirs.There is however a lack of understanding of the pore-level EOR performance of N2HnP under tight reservoir conditions.In this work,a non-magnetic reactor was created and combined with a nuclear magnetic resonance(NMR) device for real-time monitoring of oil distribution in the HnP experiment.N_(2)HnP experiments were then performed in a tight sandstone core sample at a temperature of 353 K and an injection pressure≥ 24 MPa.The pore-level oil distribution under reservoir conditions was monitored and the EOR performance of N2HnP in specific pores was analyzed.The pore throat structures of the core sample and the phase behavior of the N_(2)-Oil system were analyzed to elucidate the EOR mechanism of N_(2)HnP.An oil recovery factor of 37.52% can be achieved after four cycles,which proves the EOR potential of N_(2)HnP for tight reservoirs.The highest recoveries after N_(2)HnP are obtained in the large pores,followed by the medium pores,the small pores,and finally the micro pores.Increases in soaking time and injection pressure resulted in slight and pronounced increases in oil recovery,respectively,both of which are mainly reflected in the first cycle.Specifically,increasing the soaking time only slightly improves the cumulative oil recovery in the small pores while increasing the injection pressure significantly improves the cumulative oil recovery in the small,medium,and large pores simultaneously.However,variations in both injection pressure and soaking time have a negligible effect on the cumulative oil recovery of the micro pores.

A Quantification of the Effects of Erosion on the Productivity of Purple Soils

Research on the effects of soil erosion on soil productivity has attracted increasing attention.Purple soil is one of the main soil types in China and plays an important role in the national economy.However,the relationship between erosion and the productivity of purple soils has not been well studied.The purpose of this research was to determine if soil depth,which is dependent on the rate of erosion,has an influence on crop yield and growth.Plot and pot experiments at different soil depths were performed.Results indicate that soils from different parental materials had different growth features and crop yields due to the differential fertility of the derived soils.The yield reduction rate increases exponentially with the depth of eroded soil(level of erosion).The yield reduction rate per unit eroded soil horizon(10 cm) is approximately 10.5% for maize and wheat.

The role and potential of attapulgite in catalytic pyrolysis of refinery waste activated sludge

Pyrolysis is a promising technology for the treatment of refinery waste activated sludge(rWAS).In this study,attapulgite as a natural clay was used to enhance the pyrolysis of rWAS.The yields,characteristics of pyrolytic products,pyrolytic kinetics and mechanisms were investigated.The attapulgite improved the conversion of rWAS into non-condensable gases and pyrolytic liquids.The bio-oil quality improved and the biochar yield reduced.The average activation energy of Stage Ⅰ(230-400℃)and Stage Ⅱ(400-500℃)decreased by 36.5%and 49.7%,respectively,compared to rWAS alone.Al_(2)O_(3)and Fe_(2)O_(3)in attapulgite enhanced the dealkylation reaction and cracking of C-C bonds.The content of the gasoline(<C_(13))fraction of bio-oil doubled relative to rWAS alone.Attapulgite promoted the deoxygenation,dehydroxylation and dehydrogenation reactions of O-containing compounds,and the content of CO and CO_(2) in non-condensable gases increased.Addition of attapulgite(rWAS:attapulgite ratio of 1:1)decreased the O mobility from 14.6%to 12.8%relative to rWAS alone.Also,the content of saturates in bio-oil increased from 38.5 wt%to 47.2 wt%and the lower heating value(LHV)increased from 6.8 kcal/kg to 8.4 kcal/kg.The heavy metals originally in rWAS were fixed into the pyrolytic residue and the environmental risks are low.This study demonstrates the role and potential of attapulgite in catalytic pyrolysis of rWAS with an added advantage of increased cost-effectiveness.

Numerical Simulation Considering Non-Equilibrium Phase Change Volatile Oil Reservoir: A Case Study of Wenchang 8-3 Oil Reservoir

As a typical volatile oil reservoir, the actual production characteristics of Wenchang 8-3 reservoir are inconsistent with the results of traditional phase equilibrium experiments. The conventional isothermal instantaneous phase equilibrium theory cannot meet the production performance or numerical simulation analysis requirements of this type of reservoir. The thermodynamic properties of volatile oil reservoirs are like those of condensate gas reservoirs. As the formation pressure drops below the dew point pressure during the mining process, the balance between the liquid phase and the gas phase is not completed instantaneously. Based on the non-equilibrium phase recovery treatment method of the condensate gas reservoir, the phase behavior change curve of the A4h well of Wenchang 8-3 oil reservoir recovered from the saturation pressure to three different pressures is analyzed. The accuracy of the numerical simulation results with or without non-equilibrium phase transition is compared. The results show that the non-equilibrium phase change has a great impact on the production performance of volatile oil reservoirs;the numerical simulation results considering the non-equilibrium phase transition are in good agreement with the actual production performance of a single well and can better reflect the actual situation of this type of reservoir. Therefore, considering the effects of non-equilibrium phase transitions has important guiding significance for the dynamic analysis of volatile oil reservoirs, numerical simulation, and the formulation of development management strategies.

Experimental Study on Product Characteristics of Typical Pulverized Coal Preheated by a Self-Preheating Burner

As the major primary energy source in China,coal has been proved to be capable to improve its physical and chemical characteristics by the pretreatment of the self-preheating burner.In this study,the effects of altering operating conditions including preheating temperature(T_(p))and primary air equivalence ratio(λ_(p))on preheating characteristics of three typical pulverized coal were investigated on a bench-scale test rig.The high-temperature coal gas compositions along the axis of the riser and at the outlet of the self-preheating burner were measured,and the coal char and coal tar produced in the preheating process were collected and analyzed separately.The results indicated that with the significant release of volatile and the occurrence of chemical reactions,cracks and micropores emerged on the surface of the particles,making the pore structure on the surface more developed,and T_(p)had the most significant effect on the structure of coal particles.Additionally,there were evident differences in the corresponding operating conditions when the preheating characteristics of the three typical coal reached optimally.And preheating had the strongest influence on the degree of anthracite modification.With respect to coal tar,the increase of T_(p)andλ_(p)further promoted its secondary cracking and oxidation,resulting in a decrease in production yield.In this study,for bituminous coal and lignite,a large amount of coal tar were produced during preheating and the highest production yields could reach 5.74%and 6.15%,respectively.While for anthracite,the production yield was intensely low due to its own coal properties,all below 1.02%.

Experimental Study on Coal Partial Gasification Coproducing Char,Tar,and Gas

The coal partial gasification process produces a large number of chars.They have similar combustion characteristics to anthracite and can be utilized as a material manufacturing clean briquette to replace residential coal to achieve clean combustion.Moreover,the coal partial gasification produced more tar at relatively low temperature,which can be applied as naphtha or diesel after purification and hydrogenation.Herein,experiments of coal partial gasification coproducing char,tar,and gas are carried out on a bench-scale fluidized bed reactor during the temperature range of 625–762℃.The effect of equivalence ratio on the characteristics of coal partial gasification products is studied.The results show that the equivalence ratio increasing from 0.06 to 0.13 leads to a higher partial gasification temperature and lower char yield,and tar yield reaches a maximum value and the lower calorific value of gas reaches as high as 6.14 MJ/m^(3).When the gasification temperature is lower than 643℃,the increase in temperature promotes the generation of oxygen-containing functional groups and aromatic compounds in coal particles,and the microstructures of char become more disordered.The combustion stability of char is getting worse,whereas the pore structures in char become abundant at high temperatures.From the analysis of the tar chromatography column,it is observed that asphaltene and non-hydrocarbon account for 77%–88%of the total amount of tar.

Research on assistant decision-makings of Ecommerce platform with refinement tools

Most existing studies of consumer search behaviour focus on page-level analysis,and some scholars start to examine the effect of refinement tools and characteristics in terms of products.However,it still remains undeveloped on the product-level.To fill this gap,we reproduced the consumer shopping process in accordance with the topology of the Taobao platform from where we collected the clickstream data.We modelled consumers’sequential decision-making behaviour based on the taxonomy with Bayesian approach and found that not all the refinement tools are utilised for optimising decisions by users and it’s surprising that there exists no significant impact of all sorting tools.Besides,consumers are highly concerned with the characteristics of products.On the basis of the findings,platform function announcement and platform design suggestions were provided for improving platform functionality and optimising consumer decision-making,which also points out the direction of future research.