Lithium⁃sulfur (Li⁃S) battery was a new battery for high⁃performance energy storage. It was widely used in portable electronic equipment and electric vehicles and was considered to be one of the most promising batteries. The improvement of the electrochemical performance of lithium⁃sulfur batteries could be achieved by developing different electrolyte additives without increasing the cost of the battery.This paper introduced the research progress of additives in lithium⁃sulfur battery electrolytes. Based on the different functional groups of additives,the working principle, advantages and disadvantages of different additives are expounded. Finally,the development direction of lithium⁃sulfur battery electrolyte was prospected.
The supported SnCl4 catalyst was prepared using activated carbon as the carrier. Different contents of BiCl3 and CuCl2 were added into SnCl4 catalyst as assistant in order to study the effect of assistant on the catalytic performance of acetylene hydrochlorination. The results showed that when the ratio of BiCl3⁃CuCl2⁃SnCl4 was 5%,10%,10%.The catalyst showed the highest activity for acetylene hydrochlorination. The conversion of acetylene can reach 94% under the conditions of hydrogen chloride/acetylene ratio 1∶1.1, reaction temperature 170 ℃ and GHSV(C2H2) of 60 h-1. The characterization results showed that the introduction of additives inhibited the loss of Sn during the reaction and thus improved the stability of the catalyst. Finally, the activity of Sn based catalyst was effectively improved.
p⁃Methylsulfonyl toluene is a common chemical raw material,and its peroxides,p⁃methylsulfonyl toluene,p⁃methylsulfonyl benzaldehyde and p⁃methylsulfonyl benzoic acid,are important intermediates of medicines,veterinary drugs and pesticides.Oxygen was used as oxidant,THICA was used as catalyst, and Co(OAc)2•4H2O was used as co⁃catalyst to investigate the selective oxidation of p⁃methylsulfonyl toluene.It was found that the recovery of p⁃methylsulfonylbenzoic acid was 96% when acetic acid was used as solvent,6 mol/L nitric acid was used as solvent, the recovery of p⁃methylsulfonylbenzaldehyde was 46%.
Ni⁃MOF⁃74 and Li⁃Ni⁃MOF⁃74 were synthesized by solvothermal method.The microstructure and decarburization properties of Ni⁃MOF⁃74 and modified Li⁃Ni⁃MOF⁃74 were studied. XRD, N2 adsorption and desorption experiments，and CO2/N2 dynamic penetration experiments were carried out. The results showed that the XRD patterns of the two adsorbents were consistent, and the introduction of metal Li in the modified material increases the interplanar spacing. The BET specific surface areas were 391.14，1 024.89 m2/g, respectively, the pore volumes were 0.346，0.645 cm3/g, respectively, and the pore size distributions were all in the range of 0.7 to 1.2 nm. At 298 K and 0.1 MPa, when the inlet flow rate is 50 mL/min,the breakthrough times of Ni⁃MOF⁃74 and Li⁃Ni⁃MOF⁃74 were 114 s and 142 s, respectively, indicating that the modified MOFs had better adsorption and separation performance.
There are some problems in the process of drilling and shut⁃in of major oil fields at present. For example, the rising speed of water cut in the process of water injection recovery is fast, and the impact of drilling and shut⁃in on oil production is great. It is necessary to make clear the influence of different water content stages and different shut⁃in time on development indexes dynamic change. Taking the drilling pass area of block B3 as an example, the theoretical model is established by selecting appropriate formation parameters. Based on the actual static and dynamic data, different drilling schemes are worked out and numerical simulation is carried out. The change law of pressure drop, liquid production, water cut and oil production during drilling and shut⁃in process is studied and the production dynamics of different reservoirs during shut⁃in are compared and analyzed. The field experiment results show that the numerical model is in good agreement with the actual conditions, which can be used to guide the design of the drilling and shut⁃in schemes and the later development adjustment. The research method of this paper provides a valuable reference for the dynamic prediction of other drilling and shut⁃in areas.
Different from conventional reservoirs, fluid percolation in tight reservoirs does not conform to the classic Darcy's law, but has both dynamic starting pressure gradient and stress sensitive effect. The JBN method don't take these two factors into account when calculating relative permeability, which is bound to cause calculation errors. The seepage mechanism of tight gas reservoir was analyze, then a two phase seepage calculation method was built and verified considering the dynamic threshold pressure gradient and stress effect. The results show that when consider the dynamic threshold pressure gradient and stress effect, the seepage ability of gas and water phase both decrease obviously, and the decrease degree of water is bigger than the gas phase. The isotonic point of relative permeability decreases and the residue water saturation increases in rock sample. With the decline of pore pressure, the effect of dynamic threshold pressure gradient and stress becomes more and more significant. The new relative permeability curves calculated by the new method is more different with the curves calculated by the JBN method. The new method can describe the seepage of fluid in tight formation more accuracy.
Due to the strong stress sensitivity and threshold pressure gradient of the tight oil reservoir in Jimsar, Xinjiang, the current nonlinear seepage model cannot reflect the seepage characteristics of the tight reservoirs. Therefore, based on the physical simulation experiment of indoor core flooding, a new nonlinear seepage model of compact reservoir considering threshold pressure gradient and stress sensitivity is established, and the pressure gradient utilization map is drawn according to the model. The results show that the threshold pressure gradient of the tight reservoir has logarithmic relationship with permeability. The error between the seepage characteristic curve of the new model and the actual seepage characteristic curve of the reservoir is less than 5.00%, which can truly reflect the actual seepage characteristics of the reservoir. The higher the permeability, the higher the pressure gradient utilization rate (N), the less the pressure loss. With the pressure gradient increases, N increases logarithmically. Therefore, in order to improve the effective utilization of the tight reservoir pressure gradient, it is necessary to increase the production pressure difference, and take acidizing and fracturing measures to improve the reservoir permeability.
The construction process of "carrying liquid + supporting agent" has been adopted in field fracturing. The preparation and transportation of carrying liquid not only cost a lot of manpower and material resources, but also have poor ability to deal with emergencies in the mine. The self⁃suspension proppant has been prepared and injected at the scene, and its product filtration and its influence on reservoir permeability have been highly concerned by petroleum technicians. The experimental study and mechanism analysis of the effect of fluid loss of self⁃suspension proppant on core permeability are carried out. The results show that when the injection speed was constant, with the core permeability increased, the filtration loss got increased, the damage rate decreased. With the gel breaking time increased, the amount of filtration loss got larger and the damage rate decreased. The degree of influence of gel breaking fluid on core permeability had little relation with its viscosity, which mainly depended on the amount of residue retention and erosion resistance in porous media after glue breaking. Under the condition of "constant pressure experiment", the larger the pressure difference of filter loss, the larger the amount of filter loss, and the damage rate presented the trend of "first increase and then tend to be stable". Compared with the constant speed test, although the amount of filtration loss is relatively small, the damage rate is high. Relationship between the damage rate of three kinds of coating materials to reservoir: hydrophobic associative polymer > medium molecular weight polymer > guanidine adhesive.
The morphology,swelling performance,temperature resistance and plugging performance of a novel double⁃crosslinked structure temperature⁃resistant polymer microsphere were studied by scanning electron microscopy,laser particle size analyzer and microporous membrane filtration experiments.The results show that the original shape of the microspheres is spherical with smooth surface,and the particle size is mainly distributed between 200 nm and 300 nm.The microspheres swell 5 times after swelling for 30 days at 140 ℃ in an aqueous solution with a salinity of 10 000 mg/L.With the swelling time,swelling temperature and microsphere concentration increasing,the plugging characteristics of the microspheres to the microporous membrane is gradually enhanced.The microspheres with the swelling for 30 d at 140 ℃ have the best plugging effect;with the increase of the pore size of the membrane, the microsphere plugging effect is weakened.The microspheres still have good plugging performance after swelling at 140 ℃ for 30 d,indicating that the microspheres have good temperature resistance.
The re⁃injection block containing the sewage in the Xing 13 area is affected by the residual polymer,which leads to a decrease in the water absorption effect of the block and affects the development effect of the oil field. Therefore,the formulation and supporting process parameters of the depressurization and infusion injection of the sewage⁃containing block were studied.Firstly,the total water quality of injected water was analyzed; Then the petroleum sulfonate was used as the basic agent to screen the compounding agent and additives by measuring the interfacial tension;After the performance evaluation of the system, the indoor core flooding experiment was carried out to optimize the injection parameter.The results show that the optimal formulation of the anti⁃hypertensive surfactant is(mass fraction):0.7% petroleum sulfonate+2.0% HABS+0.5% absolute ethanol+1.0% NaCl,and the interfacial tension between the crude oil and the interfacial tension is 6×10-3 mN/m.In the core flooding experiment,the optimal injection rate is 0.15 mL/min,the optimal injection volume is 1 PV,and the optimal slug combination is 0.5 PV+0.3 PV+0.2 PV. Under different permeability conditions,the pressure rate is more than 24%.
The prediction method of the sand body outside the delta is put forward, that is, through logging curve pretreatment, seismic synthetic record making, virtual mudstone time window technology, curve reconstruction inversion and other technical means, the purpose of thin differential reservoir prediction is realized. It has been proved that the field application of the results in the oilfield is mainly reflected in two aspects: One is to guide the division of sedimentary microfacies, the other is the application of risk well location deployment. That is to say, the idea of well point phasing and inversion section configuration is adopted to guide the drawing of sedimentary microfacies in key units of putaohua reservoir. In other words, based on the comprehensive understanding of the structure and thin differential reservoir geology, a cross⁃fault horizontal well is successfully deployed by adopting the method of exploration and evaluation well injection optimization and implementing the "four injection and one production" well pattern principle. Therefore, the proposed reconstruction inversion method can be used as an effective technical means for characterization of thin differential reservoirs, which is of great significance for further exploration of oil⁃bearing potential of thin differential reservoirs.
According to the characteristics of lithofacies, seismic section facies and logging facies, combined with the data of thin sections of rocks, the types and characteristics of sedimentary systems developed in the lower Cretaceous Nantun Formation in Beixi area, Beier depression, Hailaer basin are systematically studied. It is considered that the Nantun Formation in the study area mainly develops fan deltaic sedimentary systems, and three types of subfacies: fan delta plain, fan delta front and front delta are identified. There are eleven microfacies, i.e. subfacies, plain distributary channel, plain distributary channel and front underwater main channel. On this basis, the fan delta sedimentary model of Nantun Formation in Beixi area of Beier depression is established, which has certain reference value for the prediction of dominant reservoirs.
In view of the gradual change zone between the sub phases of shallow water delta，it is difficult to demarcate accurately the boundary position and meet the demand for oilfield development. In order to achieve the purpose of demarcate accurately sedimentary facies，according to sedimentary dynamics theory of shallow water delta， the identification sign of sedimentary facies is established by making use of the data of core analysis and well⁃logging of dense well pattern， and analyzing the plane evolution of facies indicator. Distributary plain is characterized by onshore stream sedimentation，inner front surfaces is characterized by combination of underwater distributary channel and sheet sand，outer front surfaces is characterized by contiguous thin sheet sand.The method of dividing facies belt boundary of "core locating and microfacies locating" has been established， and the reasonable definition of sedimentary facies zones is realized，which has laid a solid foundation for reservoir classification, reserves calculation and development planning .
Due to the effects of service environment, corrosion defects inevitably appear on pipeline surface, which will cause stress concentration and promote crack nucleation. In this study, a coupled stress and electrochemical multi⁃physical field model for predicting the morphological development of corrosion defects was established based on the finite element method. The time dependence of stress corrosion behavior and corrosion morphology of X70 pipeline steel in sea mud simulated solution were studied by using the established model via deformation geometry and dynamic mesh technology. The results showed that the mechanical⁃electrochemical effect played an important role in the nucleation of stress corrosion cracks. The smaller the width of corrosion defects, the greater the stress concentration, the negative shift of the electrode potential and the higher the corrosion rate. With the increase of the operating pressure, there was a large area of high stress concentration area in the bottom of the corrosion defect, and the area of metal loss caused by corrosion increased.
The denoising effect of the negative pressure wave signal and the extraction of the feature vector are the key factors affecting the accuracy of the oil pipeline leakage detection. Aiming at the false negatives and false positives in pipeline leak detection, this paper proposed an improved fully integrated empirical mode decomposition algorithm (improved CEEMDAN) with adaptive white noise to preprocess the negative pressure wave signal. The CEEMDAN decomposition is performed on the negative pressure wave signal measured by the upstream and downstream pressure sensors of the pipeline to obtain a plurality of intrinsic mode functions (IMF). And the effective IMF component is selected according to the correlation coefficient principle of the dual channel sensor. An entropy⁃based eigenvector is proposed, and the energy entropy, kurtosis entropy and permutation entropy of the effective IMF component are input to support vector machine (SVM) to distinguish different working conditions. Through field data verification, the improved CEEMDAN combined with the entropy⁃based feature vector can effectively improve the accuracy of oil pipeline leakage condition identification, and has certain field application value.
