论天然气形成机制与相关地球科学问题

论述了细菌成因气、热成因气、深层气和非生物成因气的物质来源和成气机制,指出,不同物质来源、不同成气机制和成气环境,构成了天然气的多种成因类型和不连续成气特征。评述了深层气、非生物成因气研究进展和它们的资源前景。讨论了形成非生物成因气的聚合反应和同位素动力学分馏效应以及鉴别非生物成因气的地球化学指标的有效性。认为松辽盆地诸多气井天然气的非生物成因特征,为研究和寻找非生物成因天然气资源提供了一个典型实例;松辽盆地昌德-肇州西和徐家围子深层气勘探的重大突破,使该盆地非生物成因气的储量超过500×108m3,展现了松辽盆地非生物成因气的良好资源前景。

天然气来源的多种途径及其意义

天然气和石油的形成相比具有多种地质来源性,表现在成因类型的多样性、成气机制的多样性和成气母质赋存状态的多样性。天然气成因类型的多样性主要体现在有机来源和无机来源、单一来源和复合来源以及单一来源有机质成气演化过程的多阶段性和连续性。而成气机制的多样性主要表现为在天然气形成的不同阶段,由于气源岩母质和物理化学条件的差异,不同的成气机制(如生物化学、脱羧、缩聚、热解、裂解、力化学,以及催化和加氢等多种化学反应)发挥着不同的作用。在成气母质赋存状态的多样性中,除生物可利用物质的水溶有机质,CO2及早期形成的有机质外,分散和聚集型不溶和可溶有机质均是成气母质的主要赋存状态。在叠合盆地中,分散型可溶有机质沥青伴随盆地的再次沉降,由于其具有更好的催化条件,使石油裂解的活化能降低,更利于干酪根裂解形成气态烃。

Cold stamping for AZ31B magnesium alloy sheet of cell phone house

Electric product house of magnesium alloy sheet is usually obtained by warm stamping owing to its poor plasticity and formability at room temperature.The formability of AZ31B magnesium alloy sheet can be improved by repeated unidirectional bending(RUB)process through control of(0002)basal texture.Compared with as-received sheet,the Erichsen value(IE)of the sheet underwent RUB process increases to 5.90 from 3.53 at room temperature.It is also confirmed that cell phone houses could be stamped successfully in crank press with AZ31B magnesium alloy sheets underwent RUB process.It provides an alternative to the electronics industry in the application of magnesium alloys.

Geological factors associated with unsuccessful exploration wells in the northern margin of the Qaidam basin

We investigated the geological factors associated with unsuccessful exploration wells in the northern margin of the Qaidam basin to better understand their cause.The structural situation,the hydrocarbon accumulation mechanism and unsuccessful well data collected from 1996 to 2005 were studied.The results show that the main geological factors associated with unsuccessful exploration wells are a lack of effective source rocks and a lack of effective traps,as well as the migration-accumulation conditions that exist in this area.The basin was reformed by Meso-Cenozoic tectonic evolution.Multi-stage tectonic activities have both positive and negative effects on hydrocarbon accumulation.Source rocks distribution,effective migration channels,effective traps and the tectonic evolution effects on hydrocarbons should be the key objects for further studies.

Role and Mechanism of Functional Components in Promoters for Enhancing FCC Propylene Yield

Phosphorus （P） and metal （M） components were incorporated into promoters for enhancing FCC propylene yield, and the reactive behavior of promoters, before and after modification, were investigated. The results showed that both LPG and propylene yields were increased, and propylene selectivity was improved after the incorporation of P or M into the matrix, resulting in an increased C3 to C4 ratio in LPG during FCC process. But the sole incorporation of M into the matrix also led to an increase in coke and H2 yields on the other hand. Simultaneous modification of the matrix by P and M components resulted in more enhancement in propylene yield and selectivity along with little influence on FCC product distribution. Physico-chemical characterizations and model compound reactions were used to assist in analyzing the mechanism for improving propylene selectivity. Two types of active centers could strengthen the oligomerization of C4 olefins in LPG and these oligomers could be further cracked into C3 olefins on ZSM-5 zeolite, therefore maximizing the ratio of C3 to C4 in liquefied petroleum gas obtained during FCC process.

The origin mechanism of coalbed methane in the eastern edge of Ordos Basin

In the eastern edge of the Ordos Basin,the coalbed methane(CBM)development has not made substantial progress in the past20 years,and the origin of gas can be used to guide the CBM block-selecting and development.Based on the 37 sets of carbon isotope data,the origin of the gas was determined and the origin mechanism was studied in this work.The 13CPDB of methane ranges from 70.5‰to 36.19‰in the eastern edge in the Ordos Basin and the value becomes heavier from the north to the south.The secondary biogenic gas and the thermogenic gas are mixed in the shallow area and the thermogenic gas occurs in the medium and deep levels.The phenomenon is controlled mainly by the distribution of coal rank and hydrodynamics.Firstly,based on the relationship between China coal rank and methane 13CPDB,the medium rank coal is dominant in the eastern edge of the Ordos Basin,and the mixture of the secondary biogenic gas and the thermogenic gas is formed in the coal of vitrinite reflectant ratio(Rmax)between 0.5%and 2.0%if there is appropriate hydrodynamics;at the same time,because of the shallow burial depth,and the well-developed coal outcrop,meteoric water and other surface water carrying bacteria recharge the coal reservoir,metabolize the organic compounds at a relatively low temperature,and generate methane and carbon dioxide.Wherever the trapping mechanisms occur in the coal,such as Liulin and Hancheng,modern gas content should be high.

Numerical Investigation on Effectiveness of Flow Separation Control in Two-dimensional High-load Compressor Cascade by Synthetic Jet

The effectiveness of flow separation control in two-dimensional high load cascade by synthetic jet is investigated through numerical simulation of the effect of excitation frequency and amplitude together with the adaptability of synthetic jet to off-design conditions. Test results indicate that synthetic jet can be used to effectively control the large-scale two-dimensional flow separation in compressor cascade. Preferable results can be obtained when excitation frequency is close to or times of the characteristic frequency of original flow field. Excitation amplitude has a more important effect on the effectiveness of flow separation control, and the increase in excitation amplitude can bring about a dramatic decrease in the loss of total pressure. Synthetic jet has also a very good adaptability to off-design conditions. It can therefore be concluded that the incidence sensitivity of compressor cascade can be effectively reduced by synthetic jet.

Investigation of Phase Excitation Effect on Mixing Control in Coaxial Jets

Detailed unsteady numerical simulation has been carried out to investigate the mechanism of adjacent syntheticjets and the influence of different phases on the mixing of coaxial jets. The results show the combined jet, formedby coupling the vortex pairs at the orifice of two adjacent actuators, can exhibit better controlling effect. Spanwisepressure difference appears because of the existence of phase difference between the left jet and right jet, whichresults in the variation of the combined jet. When the phase difference is greater than zero, mixing enhancementof coaxial jets can be achieved, but there are maximum phase difference and optimal phase difference. On thecontrary, application of adjacent synthetic jets always leads to the mixing reduction when phase difference is lessthan zero.