Two?dimensional transition metal carbides and nitrides (MXenes) have become a high?profile material with a wide range of application prospects due to their efficient adsorption and catalytic properties,wide optical absorption range,and excellent conductivity.Ni?doped Nb₂C material has positive photocatalytic properties.To explore the intrinsic mechanism of photocatalytic property improvement by Ni?doped Nb₂C,the electronic structure properties of Nb₂C and its Ni?functionalized form(i.e.,Ni?Nb₂C) and their adsorption properties for CO₂ gas molecule by using the density functional theory (DFT) were investigated.The results show that the replacement of an Nb atom by a Ni atom makes the charge density around the Ni atom increase and further results in a redistribution of the charge density of the substrate,which leads to an improved electronic environment for catalyzing CO₂ and improves the photocatalytic property for CO₂.

The lattice Boltzmann method is widely used in the simulation of digital core porous media flow because it can handle complex geometric boundaries.The digital core section of the Dongying formation reservoir in the Bohai S oilfield is taken as the research object. Based on the image processing, the lattice Boltzmann method is used to carry out the two⁃dimensional pore flow simulation and velocity field characterization. By changing the simulation conditions, the different production pressure differences are analyzed. The effect of pore throat optimization on the slice seepage channel. The results show that the production pressure difference can only change the seepage strength of each channel. The rock pore size is the main factor affecting the distribution of the seepage channel. The pore throat optimization can effectively adjust the seepage channel and improve the microscopic pore wave degree.

As a clean and effective new energy, fuel cell is regarded as one of the most important energy technologies. Proton conduction in solids has attracted much interest because of its potential application in fuel cells. Metal⁃oxalate compounds constructed by metal ions and oxalate are a sense of inorganic⁃organic hybrid compounds, which have emerged as a new class of proton conductors because of their controllable structures and high chemical variety. We summarized the proton conduction properties of main group⁃oxalate compounds, transition metal⁃oxalate compounds and lanthanide metal⁃oxalate compounds, and their future development was prospected.

When polymer solution is injected into reservoir, if the radius of polymer molecule thread is much larger than the radius of pore throat, it will cause the blockage of polymer in reservoir pore. Selecting a typical block in Sabei oil field, sampling the blocked injection wellbore backflow, and analyzing the composition of backflow by laboratory, it is determined that the main component of backflow blockage is polymer soft micelle. According to the geological structure, sedimentary facies, reservoir property of geological data, the geological model of plugging wells was establish，the concentration of polymer distribution in the reservoir was utilized, the polymer solution flowing trajectory was simulate and the distance of the polymer blockage was confirm. The advancing distance of direction provides a basis for improving the blocking condition of injection wells and taking pertinent measures.

Three⁃dimensional finite element model of buried casing is established using ANSYS software. Through laboratory tests, the relationship between the stress within the center of buried casing and the load on the ground, and the stress distribution in the direction of casing length under different loads is analyzed,respectively. Finally, a three⁃dimensional finite element model is established according to several casing cases in an oilfield. The magnitude of the load on the ground is obtained when the casing reaches the yield strength. The research results can provide a certain reference for the safety protection of pipelines and casing.

This article simulated three mortar systems including mineral filler⁃asphalt,mineral filler⁃emulsified asphalt residue and cement⁃emulsified asphalt residue in cold recycled mixture with emulsified asphalt. The results show that cement⁃emulsified asphalt residue mortar owns higher modulus than the other two mortars because of cement hydration. The change of modulus and phase angle is different from that of ordinary mineral powder⁃asphalt mortar and mineral powder⁃emulsified asphalt mortar, and does not change linearly monotonously with powder⁃to⁃binder ratio. At the same time, the interface adhesive ability of cement⁃ emulsified asphalt residue is similar to that of the mineral filler⁃asphalt mortar, and much higher than that of the mineral filler⁃emulsified asphalt residue mortar in a lower filler dosage. In the process of mixture production, emulsified asphalt provides the initial stability of the mixture, and cement hydration and the formation of composite mortar system are the guarantee of the final cold recycled mixture strength.

Under different temperature and different stress conditions, the creep experiment of polyurethane foam was carried out, and the creep constitutive equation of polyurethane foam under high temperature was obtained by fitting the obtained creeptime curve with Modified Time Harding model. Comparing the steady state creep rate fitted by model with the steady state creep rate measured by experiment, it is found that the creep property of polyurethane polymer has an important relationship with temperature and stress level. As the temperature and the stress level increases, the creep behavior of the material is more pronounced. The creep curve at high temperature is divided into two phases. In the first phase, the creep rate is larger and the creep rate gradually decreases with time. In the second phase, the creep rate is small and remains basically constant. Modified Time Harding model can better predict the creep rate of polyurethane materials under high temperature conditions.

In this article, low temperature pyrolysis upgrading experiment was conducted with the low rank coal from Shanyin, Shanxi. The influence of temperature and holding time on the product yield and properties was investigated by tube furnace. The results showed that the optimized pyrolysis temperature of the experiment was 500~550 ℃，and holding time was 60 minutes. The semi-coke yield of the low rank coal was high, the sulfur content decreased significantly, and the desulfurization rate was up to 55%. The volatile matter, high ash content and higher heating value can meet the requirements of clean coal quality index in Beijing-Tianjin-Hebei region, and it can be used as clean fuel for heating, heating and so on. The tar yield was high, the density of tar was low, and the light oil component content was high. So, high quality fuel oil can be obtained through hydrogenation. The gas yield was high, and H ₂ can be gotten using the produced gas as raw material by pressure swing adsorption technology.

In view of the characteristics of coalbed methane "multi-point intervening, flexible gathering" and the complex flow pattern of the gas-water two-phase flow in the pipe, under the complicated terrain, the pipeline network pressure fluctuates frequently, seriously affecting the gas gathering and transportation system efficiency and operational safety. In order to more accurately calculate the pressure of the pipe network, based on the multiphase hydraulic and thermodynamic calculation method, the steady-state calculation model of coal-bed gas pipeline network is established by using the pipe network node method. A method of steady-state simulation of segmented pipe network considering terrain fluctuation is put forward. Through the calculation and analysis of the pipe network, it can be seen that the pressure calculation results of the pipe network calculation model under the terrain fluctuation are more accurate and reliable, which provide a reference for rational design and operation of coalbed gas pipeline network in complex terrain.

In order to measure the concentration of mixed oil transported in pipeline more precisely, the conductivity probe is modified and applied to determin concentration of mix oil in the pipeline based on the principle of the conductance measurement of gas-liquid two-phase flow's liquid holdup. The experimental apparatus can be used to calibrate the probe by measuring the different concentration of brine to obtain the corresponding output signal. The calibrated experimental apparatus can easily measure the concentration of mixed oil at different times and different positions of the pipeline cross section.

        As one of the important fracture parameters, stress intensity factor plays an important role in the fracture analysis of engineering structures.Based on the concept of  J ₂-Integralintegral and the elementary theory of strength of materials,the stress intensity factors of the transverse crack of the six prismatic shell and the six prismatic shell with reinforcing rib are analyzed and solved. A method for solving the stress intensity factor of complex structure by using  J ₂-Integral method is presented.

        In recent years, a series of pipeline leakage accidents frequently occur due to aging, corrosion and manmade damage. At present, most of related software focuses on the qualitative accidental assessment and localization of the leaking point while the study correlated with practical calculation of leakage volume is rare. An efficient quantitative calculation of the volume of leakage is essential to provide guidance for subsequent accidental management, environmental evaluation and division of the hazardous area. Connected with the alarm system and the online calculation module, a software with the function of online and offline calculation is developed on the basis of transient flow model coupled with hydraulic and thermal factors. A real case study is presented to demonstrate the relative error which is less than 5% and the results prove that it is of practical value and able to offer reference and guidance for engineers.

Locating the combustion front timely is helpful to production control. The prediction methods of combustion front used in field were researched, then a set of application method specific to reservoirs with different feature was obtained. Infrared photography was suitable for shallow layer reservoirs, and direct testing method using thermometric component was suitable for reservoirs with intensive observation well and production well. Method combining production performance and material balance was suitable for homogeneous reservoirs with regular well pattern, and method combining tracer monitoring and production performance was suitable for heterogeneous reservoirs or reservoirs with irregular well pattern. The pressure drop test method was so complicated that it needed further study. At last the suggestions were proposed that on the basis of geological screening in advance, the aim of "less air injection and more oil production" should be achieved, besides, the management of production well should be strengthened by combining analysis of production performance, so that the combustion front could be moving forward evenly and steadily.

Active fractions were extracted from series petroleum sulfonates by extraction and back－extraction method，the equivalent weight distribution of them were analyzed by ESI－MS spectrum and the average equivalent weight could be calculated，as well as gas－phase osmotic method was conducted to determine the average relative molecule mass of their oleophylic groups which were obtained by desulfonation．The interfacial tension of oil／water system respectively consisted of series petroleum sulfonates or their active fractions were measured by rotated dropping method．The results show that the difference of the equivalent weight distribution mainly existed in the low and high equivalent weight section，and the one which has properly hydrophile－lipophile balance for the complementation of molecule structure benefiting from broad equivalent molecule weight distribution，its oil／water system can obtain the ultralow interfacial tension．