Geochemistry of Heavy Oil in the T Block,Oriente Basin and its Origin Mechanism

Exploration and development experience show that there is obvious oil gravity difference between the southern part and northern part of the ＂M1＂reservoir in the Fanny oil field in the slope of the Oriente Basin, Ecuador. The American Petroleum Institute Gravity （API） values of oils in the northern part are higher than the one in the southern part of the Fanny oil field, with the values of 20° and 10.0°-13.0°, respectively. So the primary purpose of this study was to analyze the heavy oil characteristics of biodegradation and the oil-oil correlation according to the biomarker data and the δ^13C signature of oil samples from T block. The results of the hydrocarbon gas chromatography fingermark and the inversion attribute characteristics indicated that there are fluid compartments between the ＂M1＂ reservoir of Fanny south. Finally, the models of oil-gas accumulation under the control of multiple-activities of complicated fault systems, as well as the origin of heavy oil, are contended. The early stage oils from the western part of the basin were biodegraded heavily in varying degrees in the whole basin, and the later stage oils were derived from the southern part in a large scale and were mature and lighter. Generally, oil mixing is the primary control of net oil properties, such as API gravity in Oriente Basin. We therefore predicted that the API gravity variation of oil pools radically depends on the injection amount of the later stage oil. Because of the shale barrier in the ＂M1＂reservoir of Fanny south, the later stage hydrocarbon could not pass through and contribute to increase the oil API value.

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.

The origin mechanisms of nitrate (NO_3^-) ions in Antarctic surface snow

There was a complete set of cross-polar distributive data of nitrate （NO3-） content inthe surface snow of the Antarctic ice sheet along the route of the 1990 International Trans-Antarctica Expedition. We have shown the profiles of nitrate concentration and flux alongthe route as the plots associated with geomagnetic latitude for further analysis on the

Origin and Distribution of Hydrogen Sulfide in Oil-Bearing Basins,China

The concentration of hydrogen sulfide gas （H2S） varies greatly in the oil-bearing basins of China, from zero to 90%. At present, oil and gas reservoirs with high H2S concentration have been discovered in three basins, viz. the Bohai Bay Basin, Sichuan Basin and the Tarim Basin, whereas natural gas with low H2S concentration has been found in the Ordos Basin, the Songliao Basin and the Junggar Basin. Studies suggest that in China H2S origin types are very complex. In the carbonate reservoir of the Sichuan Basin, the Ordos Basin and the Tarim Basin, as well as the carbonatedominated reservoir in the Luojia area of the Jiyang depression in the Bohai Bay Basin, Wumaying areas of the Huanghua depression, and Zhaolanzhuang areas of the Jizhong depression, the H2S is of Thermochemical Sulfate Reduction （TSR） origin. The H2S is of Bacterial Sulphate Reduction （BSR） origin deduced from the waterflooding operation in the Changheng Oilfield （placanticline oil fields） in the Songliao Basin. H2S originates from thermal decomposition of sulfur-bearing crude oil in the heavy oil area in the Junggar Basin and in the Liaohe heavy oil steam pilot area in the western depression of the Bohai Bay Basin. The origin types are most complex, including TSR and thermal decomposition of sulfcompounds among other combinations of causes. Various methods have been tried to identify the origin mechanism and to predict the distribution of H2S. The origin identification methods for H2S mainly comprise sulfur and carbon isotopes, reservoir petrology, particular biomarkers, and petroleum geology integrated technologies; using a combination of these applications can allow the accurate identification of the origins of H2S. The prediction technologies for primary and secondary origin of H2S have been set up separately.

The original mechanism of vari-toned song production in mingming cicada(Oncotympana maculaticollis Motsch)

In this paper, the original process of vari-toned song in the Mmgming cicada is revealed, and the brand-new recognition for studies of the song mechanism in cicadas is opened up. Each vari-toned syllable 'Weiying' is composed of 'Wei' with the basic sound (BS) as the dominant tone and 'ying' with the upper partials (UP2) as the dominant tone, and the upper partials (UP1) is a sound accompaniment of low intensity.The BS, UP1 and UP2 are produced by vibrations of the long ribs LR2,3 and LR1 in sounding membrane driven, separately, by two kinds of the twich in sounding muscle, 'Wei' and 'ying' are separately produced by the prin-subordinate vibrations of LR2,3 -LR1 and LR1-LR2,3. The LR1 and LR2,3 are analogous to a string tensioned two ends and a beam hinged two ends with a load in the middle respectively. Obtained the acoustic properties of sounding vibration are not only suited to the structural characteristics of LR1, 2, 3 but also consist basically with the acoustic properties of song.