By measuring carbon and hydrogen isotope compositions for C1, C2 and C3 of 74 gas samples, natural gases from the Tarim Basin can be divided into six groups on the basis of their origins: (1) coal-type gas derived from coal measures; (2) coal-type gas generated from the T-J lacustrine mudstones; (3) oil-type gas derived from the Cambrian and low Ordovician marine source rocks; (4) oil-type gas from the source rocks deposited in the marine-transitional facies; (5) mixing gas between gas derived from the Carboniferous transitional source rocks and the Mesozoic humic gas, and (6) mixing gases of thermal genetic gas and little deep gas in the Southwest depression of the Tarim Basin. The δ D values of methane in natural gases originating from different type kerogens are affected by both palaeo-environments of the source rock formation (kerogen types) and thermal maturity, with sedimentary environment (kerogen type) as the main controlling factor. Under the similar thermal maturity, the hydrogen isotope composition of methane is more enriched in deuterium in marine environments than lacustrine one. With the increase of thermal maturity and the increase of carbon atomic numbers of gaseous alkanes, the hydrogen isotopes become enriched in deuterium. The δ D values of ethane and propane (δ D2, δ D3) are controlled mainly by thermal maturity and to a lesser degree by sedimentary environment of the source rock formation. The partial reversal of hydrogen isotopes for gaseous alkanes would be related to the microbial oxidation, mixing of sapropelic and humic gases and / or mixing of gases from similar kerogen sources with various thermal maturities. In the oil-type gas, the sulfate reduction reaction would result in the reversed order of δ D1 and δ D2 (e.g. δ D1>δ D2). 相似文献
The components and carbon isotope of gases in inclusions are one of the most important geochemical indexes for gas pools. The analysis results of the components and carbon isotope of gases from inclusions in reservoir layers of Upper Palaeozoic gas pools in the Ordos Basin show that most inclusions grown in reservoir sandstone are primary inclusions. There is only a little difference about the components and carbon isotope between the well gases and the secondary inclusions gases. This indicated that the epigenetic change of gas pools is little. This difference between the well gases and the secondary inclusions gases is caused by two reasons: (i) The well gases come from several disconnected sand bodies buried in a segment of depth, while the inclusion gases come from a point of depth. (ii) The secondary inclusions trapped the gases generated in the former stage of source rock gas generation, and the well gases are the mixed gases generated in all the stages. It is irresponsible to reconstruct the palaeo-temperature and palaeo-pressure under which the gas pool formed using carbon dioxide inclusions. 相似文献
四川盆地海相层系发现的大气藏部含或高舍硫化氢,都发育一定厚度的优质储层,而且优质储层与硫化氢分布具有密切的关系,即气藏硫化氢含量越高,储层性质越好,气藏产能也越大。研究发现,在 TSR(硫酸盐热化学还原反应)过程中,随着膏质岩类的溶解(为 TSR 反应提供 SO_4~(2-)),使储集孔隙初步得到改善;而 TSR 产生的硫化氢溶于水形成的氢硫酸,具有强烈腐蚀性,加速了储层中白云岩的溶蚀,形成孔隙极其发育的海绵状孔洞体系,并呈层状分布。电镜下可以清晰看到白云石晶面的溶蚀坑及溶孔中 TSR 产生的硫磺晶体。溶孔中自生碳酸盐的碳同位素在-10.3‰～18.2‰,而地层碳酸盐的碳同位素在 3.7‰～ 0.9‰,证实了 TSR 过程中有机-无机的相互作用,即有机成因烃类中的碳转移到次生碳酸盐岩中。包裹体分析表明,次生方解石中的包体富含硫化氢,且均一温度多数在160℃以上,具备 TSR 发生的温度条件;硫化氢和硫磺的硫同位素比地层硫酸盐的硫同位素偏轻8‰左右,是 TSR 作用的证据。因此高含硫化氢气藏的优质储层是在早期埋藏溶蚀作用的基础上,后期发生 TSR 及其形成的酸性流体对深埋碳酸盐岩储层再次进行深刻改造和强烈溶蚀作用的结果;同时可以运用硫化氢来预测碳酸盐岩优质储层的分布。 相似文献
Satellite images are used extensively in studying the urban heat island (UHI) phenomenon. We evaluated the suitability of thermal infrared (TIR) data from the HJ-1B satellite for detecting UHI using a case study in Beijing. Two modified algorithms for retrieving the land surface temperature (LST) from HJ-1B data were tested. The results were compared with LST images derived from a Landsat TM thermal band and the MODIS LST output. The spatial pattern of UHI generated using HJ-1B data matched well with that produced using TM and MODIS data. Of the two algorithms, the mono-window algorithm performed better but further tests are necessary. With more frequent coverage than TM and higher spatial resolution than MODIS, the HJ-1B TIR data present a unique opportunity to study thermal environments in cities in China and neighboring countries.
Satellite images are used extensively in studying the urban heat island (UHI) phenomenon. We evaluated the suitability of thermal infrared (TIR) data from the HJ-1B satellite for detecting UHI using a case study in Beijing. Two modified algorithms for retrieving the land surface temperature (LST) from HJ-1B data were tested. The results were compared with LST images derived from a Landsat TM thermal band and the MODIS LST output. The spatial pattern of UHI generated using HJ-1B data matched well with that produced using TM and MODIS data. Of the two algorithms, the mono-window algorithm performed better but further tests are necessary. With more frequent coverage than TM and higher spatial resolution than MODIS, the HJ-1B TIR data present a unique opportunity to study thermal environments in cities in China and neighboring countries. 相似文献
By the end of the year 2010,a total of 15 large tight gas fields have been found in China,located in the Ordos,Sichuan,and Tarim basins.The annual production and total reserves of these fields in 2010 were 222.5×108and 28657×108m3,respectively,accounting for 23.5%and 37.3%,respectively,of the total annual production and reserves of natural gases in China.They took a major part of all natural gas production and reserves in China.According to the analyses of 81 gas samples,the stable carbon and hydrogen isotopic compositions of tight gases in China have following characteristics:(1)Plots of 13C1-13C2-13C3,13C1-C1/C2+3and 13C1-13C2demonstrate the coal-derived origin of tight gases in China;(2)For the primary alkane gases,both carbon and hydrogen isotopic values increase with increasing molecular mass,i.e.,13C113C213C313C4and2H12H22H3;(3)The isotopic differences of 13C2-13C1,13C3-13C1,2H2-2H1and 2H3-2H1decrease with increasing Ro(%)and C1/C1–4;(4)There are seven causes for the carbon and hydrogen isotopic reversal,however,the carbon and hydrogen isotopic reversal of tight gases in China is caused mainly by multiple stages of gas charge and accumulation. 相似文献
The components and carbon isotope of gases in inclusions are one of the most important geochemical indexes for gas pools. The analysis results of the components and carbon isotope of gases from inclusions in reservoir layers of Upper Palaeozoic gas pools in the Ordos Basin show that most inclusions grown in reservoir sandstone are primary inclusions. There is only a little difference about the components and carbon isotope between the well gases and the secondary inclusions gases. This indicated that the epigenetic change of gas pools is little. This difference between the well gases and the secondary inclusions gases is caused by two reasons: (i) The well gases come from several disconnected sand bodies buried in a segment of depth, while the inclusion gases come from a point of depth. (ii) The secondary inclusions trapped the gases generated in the former stage of source rock gas generation, and the well gases are the mixed gases generated in all the stages. It is irresponsible to reconstruct the palaeo-temperature and palaeo-pressure under which the gas pool formed using carbon dioxide inclusions.
