The processes of solution in, and exsolution from, formation water influence the component content of natural gas by contrasting the relative contents of components before the natural gas dissolves in water and those ...The processes of solution in, and exsolution from, formation water influence the component content of natural gas by contrasting the relative contents of components before the natural gas dissolves in water and those after exsolving from water under different conditions of high temperatures and pressures. Compared with the composition of original natural gas, the relative content of methane and nitrogen increased after the natural gas dissolved in water. The increase of nitrogen content exceeds that of methane, but the content of ethane, propane, pentane etc reduced. At the same temperature and with pressure increasing the content of methane increased and that of heavier hydrocarbons reduced. At the same pressure the content of methane increased quickly from 90~C to 120~C, and the content of heavier hydrocarbons reduced. But at even higher temperatures, the increase of methane slowed down and the content of heavier hydrocarbons increased slightly. At the same temperature and different pressures, heavier hydrocarbons reduced much more with increasing carbon atom number, while with temperature increasing the content difference of heavier hydrocarbons reduced. Therefore, the influence of the solution and exsolution should be considered in the study of the migration and accumulation mechanism of natural gas.展开更多
The dolomitic rocks of the Fengcheng Formation are considered to be formed under special geologic conditions, and are significant hydrocarbon reservoir rocks in the Wu-Xia area in the Junggar Basin. Analyses of petrol...The dolomitic rocks of the Fengcheng Formation are considered to be formed under special geologic conditions, and are significant hydrocarbon reservoir rocks in the Wu-Xia area in the Junggar Basin. Analyses of petrologic characteristics and stable isotope composition indicate that the dolomitizing host rock is volcanic and the dolomitizing fluids probably consists of brine from shore- shallow lakes with great evaporation and salinity in the Fengcheng Formation, which have formed under arid climatic conditions, as well as residual Mg-rich seawater from the underlying Jiamuhe Formation and Carboniferous. Dust tuff in the area has significant plagioclase content. Anorthite and labradorite hydrolysis by CO2 can be coupled with calcite precipitation. Late Mg-rich brine percolated and replaced calcite formed in the early time, which lead to precipitate dolostones with different occurrences, such as graniphyric, random bedded or lumpy. The diagenetic dolostones with different occurrences resulting from particular formation conditions occurred in different tectonic settings. The dolomitizing fluid has been driven by the thermal convection flow generated by volcanic eruptions. At the same time, the overthrusts of the Wu-Xia growth fault have speeded up the flow of deep Mg-rich water upwards, and induced the water to quickly penetrate and horizontally migrate in the strata. Fracture is the major and the most important reservoir space in dolomitic reservoir of the Fengcheng Formation. Fracture and fault plays a decisive role in controlling the formation of dolostone and the distribution of favorable reservoirs. The deliverability of oil and gas is determined by the development and match relations of dissolved pores and fractures to a certain degree.展开更多
Crude oils in the BZ35/BZ36 fields found within the Paleogene Dongying and Shahejie formations in the Huanghekou Sag of the Bohai Bay Basin,China have generally high density,viscosity,and sulfur content.Their physical...Crude oils in the BZ35/BZ36 fields found within the Paleogene Dongying and Shahejie formations in the Huanghekou Sag of the Bohai Bay Basin,China have generally high density,viscosity,and sulfur content.Their physical properties and geochemical features have obvious differences when compared with crude oils from other structures within the Huanghekou Sag.The comparison and analysis of biomarkers(e.g.,pristine/phytane,gammacerane,C24Te/C26TT,C2920S/(20Sþ20R),C29bb/(bbþaa),etc.)show that sour crude oil from the BZ35/BZ36 fields is similar to the sour oil in the Miaoxi Sag adjacent to the eastern of Huanghekou Sag.Sour,low maturity oils in the Miaoxi Sag have likely migrated southwest,while the sweet,higher maturity oils in the Huanghekou Sag have migrated northeast.Crude oils generated from these two sags have focused in the BZ35/BZ36 structures.The source rock of the sour crude oil was most likely formed in a dry climate and strong reducing saline lake.展开更多
文摘The processes of solution in, and exsolution from, formation water influence the component content of natural gas by contrasting the relative contents of components before the natural gas dissolves in water and those after exsolving from water under different conditions of high temperatures and pressures. Compared with the composition of original natural gas, the relative content of methane and nitrogen increased after the natural gas dissolved in water. The increase of nitrogen content exceeds that of methane, but the content of ethane, propane, pentane etc reduced. At the same temperature and with pressure increasing the content of methane increased and that of heavier hydrocarbons reduced. At the same pressure the content of methane increased quickly from 90~C to 120~C, and the content of heavier hydrocarbons reduced. But at even higher temperatures, the increase of methane slowed down and the content of heavier hydrocarbons increased slightly. At the same temperature and different pressures, heavier hydrocarbons reduced much more with increasing carbon atom number, while with temperature increasing the content difference of heavier hydrocarbons reduced. Therefore, the influence of the solution and exsolution should be considered in the study of the migration and accumulation mechanism of natural gas.
基金supported by the National Program for Fundamental Research and Development(973 Program 2011CB201104)
文摘The dolomitic rocks of the Fengcheng Formation are considered to be formed under special geologic conditions, and are significant hydrocarbon reservoir rocks in the Wu-Xia area in the Junggar Basin. Analyses of petrologic characteristics and stable isotope composition indicate that the dolomitizing host rock is volcanic and the dolomitizing fluids probably consists of brine from shore- shallow lakes with great evaporation and salinity in the Fengcheng Formation, which have formed under arid climatic conditions, as well as residual Mg-rich seawater from the underlying Jiamuhe Formation and Carboniferous. Dust tuff in the area has significant plagioclase content. Anorthite and labradorite hydrolysis by CO2 can be coupled with calcite precipitation. Late Mg-rich brine percolated and replaced calcite formed in the early time, which lead to precipitate dolostones with different occurrences, such as graniphyric, random bedded or lumpy. The diagenetic dolostones with different occurrences resulting from particular formation conditions occurred in different tectonic settings. The dolomitizing fluid has been driven by the thermal convection flow generated by volcanic eruptions. At the same time, the overthrusts of the Wu-Xia growth fault have speeded up the flow of deep Mg-rich water upwards, and induced the water to quickly penetrate and horizontally migrate in the strata. Fracture is the major and the most important reservoir space in dolomitic reservoir of the Fengcheng Formation. Fracture and fault plays a decisive role in controlling the formation of dolostone and the distribution of favorable reservoirs. The deliverability of oil and gas is determined by the development and match relations of dissolved pores and fractures to a certain degree.
文摘Crude oils in the BZ35/BZ36 fields found within the Paleogene Dongying and Shahejie formations in the Huanghekou Sag of the Bohai Bay Basin,China have generally high density,viscosity,and sulfur content.Their physical properties and geochemical features have obvious differences when compared with crude oils from other structures within the Huanghekou Sag.The comparison and analysis of biomarkers(e.g.,pristine/phytane,gammacerane,C24Te/C26TT,C2920S/(20Sþ20R),C29bb/(bbþaa),etc.)show that sour crude oil from the BZ35/BZ36 fields is similar to the sour oil in the Miaoxi Sag adjacent to the eastern of Huanghekou Sag.Sour,low maturity oils in the Miaoxi Sag have likely migrated southwest,while the sweet,higher maturity oils in the Huanghekou Sag have migrated northeast.Crude oils generated from these two sags have focused in the BZ35/BZ36 structures.The source rock of the sour crude oil was most likely formed in a dry climate and strong reducing saline lake.
