Mechanical Analysis for Two-layered Ultrahigh Pressure Apparatus with Interlayer Pressure

To improve the bearing pressure capacity of ultrahigh pressure apparatus,the internal autofrettaged cylinder with interlayer pressure(ACCIP)is introduced,and the analytical model for the ACCIP structure and its derivation are presented as well.Calculation showed that the ACCIP method enhance bearing pressure of the apparatus obviously;optimization results revealed that under the working pressure pw=1.07σs and different radius ratios,the ACCIP method can keep the apparatus in deformed-elastically state;And when the pw=1.07σs,the minimum radius ratio was approximate 3.29,in this case,no yielding happened.The above results demonstrate that the ACCIP method is a promising technique to improve the bearing pressure of ultrahigh pressure apparatus,and the analytical model for the ACCIP method is also reasonable.In addition,the minimum radius ratio ro/ri under randomly specified workload can be Fig.d out by the analytical model proposed in this work.

Deciphering the structural evolution and real active ingredients of iron oxides in photocatalytic CO_(2)hydrogenation

Photocatalytic CO_(2)hydrogenation reactions can produce high-value-added chemicals for industry,solving the environmental problems caused by excessive CO_(2)emissions.Iron oxides are commonly used in photocatalytic reactions due to their various structures and suitable band gaps.Nevertheless,the structural evolution and real active components during photocatalytic CO_(2)hydrogenation reaction are rarely studied.Herein,a variety of iron oxides including a-Fe_(2)O_(3),y-Fe_(2)O_(3),Fe_(3)O_(4)and FeO were derived from Prussian blue precursors to investigate the CO_(2)hydrogenation performance,structural evolution and active components.Especially,the typical a-andγ-Fe_(2)O_(3)are converted to Fe_(3)O_(4)during the reaction,while Fe/Fe_(x)O_(y)remains structurally stable.Meanwhile,it is confirmed that Fe_(3)O_(4)is the main active component for CO production and the formation of hydrocarbons(CH_(4)and C_(2)-C_(4))are highly dependent on the Fe/Fe_(x)O_(y)heterojunctions.The optimal yields of CO,CH_(4)and C_(2)-C_(4)hydrocarbons over the best catalyst(FeFe-550)can achieve 4 mmol g^(-1)h^(-1),350μmol g^(-1)h^(-1)and 150μmol g^(-1)h^(-1),respectively due to their suitable metal/oxide component distribution.This work examines the structural evolution of different iron oxide catalysts in the photocatalytic CO_(2)hydrogenation reaction,identifies the active components as well as reveals the relationship between components and the products,and offers valuable insights into the efficient utilization of CO_(2).

Study on process and model of CBM dissipating

Coal Bed Methane(CBM) occurs in coal seams in the states of adsorption gas, free gas and water-dissolved gas. Its dissipating starts with desorption, and then it dissipates outwards in the states of free gas and water-dissolved gas. The dissipating approach is classified to three patterns: Free gas in pores dissipates through the cover rocks; hydrocarbon molecules in the cap-rocks and reservoir diffuse because of concentration gradient; gas dissolving in water is directly taken away by water. According to the controlling factors of CBM conservation and considering the cover rocks, soleplate, hydrological region identification and dissipating theory, three geological models of CBM dissipating are built: closed system model, lateral hydrological closed model and open system model.

Formation condition of deep gas reservoirs in tight sandstones in Kuqa Foreland Basin

Due to the high expense of deep oil and gas exploration,prediction of gas-bearing properties before drilling is crucial for deep gas reservoir of tight sandstone.Deep tight sandstone gas fields in Kuqa Foreland Basin are characterized by high abundance,high gas saturation,high pressure,high and stable yield,which belong to high-efficiency tight gas reservoir.Based on theoretical analysis of controlling factors and mechanisms of gas-bearing properties for tight sandstone gas reservoir,and taking tight sandstone gas fields with high effectiveness such as Dibei,Keshen and Dibei gas fields in Kuqa Foreland Basin as examples,formation condition and mechanism of high-efficiency tight sandstone gas reservoir in Kuqa area are studied through a comparative analysis of typical tight sandstone gas reservoir in Sichuan Basin and Ordos Basin.The results show that the formation condition of deep gas reservoir of tight sandstone in Kuqa foreland basin includes four factors:i.e.,overpressure gas charging,fracture development,“early-oil and late-gas”accumulation process and favorable preservation condition.The overpressure gas charging and fracture development are the most important factors for formation of high-efficiency tight gas reservoirs in Kuqa Foreland Basin.High-quality source rocks,high sourcereservoir pressure difference,and overpressure filling induced thereby are preconditions for formation of tight sandstone with high gas saturation.The fracture development controls gas migration,accumulation,and high yield of tight sandstone gas reservoir.The reservoir wettability changed by the early oil charging is beneficial to late natural gas charging,and the preservation condition of high-quality gypsum cap rocks is the key factor for gas reservoirs to maintain overpressure and high gas saturation.Matching of above four favorable factors leads to the tight sandstone gas reservoir with high abundance,high gas saturation and high gas production in Kuqa Foreland Basin,which is very different from other basins.Under the condition of little difference in physical property of tight sandstone reservoir,excessive source-reservoir pressure difference,facture development,preservation condition and current formation overpressure are the most significant factors to be considered in exploration and evaluation of deep tight sandstone gas.