Abstract:The Sichuan Basin is a superimposition basin composed of terrestrial and marine sediments that is well known for its abundant petroleum resources. Thermal history reconstruction using paleogeothermal indicators, including vitrinite reflectance and thermochronological data, shows that different structural subsections of the Sichuan Basin have experienced various paleogeothermal episodes since the Paleozoic. The lower structural subsection comprising the Lower Paleozoic to Middle Permian (Pz-P 2 ) successions ex… Show more
“…(2015) studied the heat flow of the Sichuan basin using apatite fission track data and (U-Th)/He thermochronology 47 . The results suggest that the following heat flux history for the Sichuan Basin: (1) the heat flux was 55 ± 5 mW/m 2 before and during the Late Carboniferous; (2) an abrupt rise in the heat flux to 80 ± 5 mW/m 2 occurred in the Permian; (3) the heat flux gradually decreased after the Triassic, and the present day heat flux was calculated to be as low as 50 mW/m 2 47 . To ensure the reliability of the modeling results, an interactive optimization process was carried out until the vitrinite-like reflectance values were matched (Fig.…”
Section: Resultsmentioning
confidence: 99%
“…A good fit to the maturity data suggests that our calculated burial depths are relatively reliable. Figure 9 ( a ) Reconstructed stratigraphic burial, thermal histories and paleo-heat flux history plots for well GS6 47 ( b ) (%Ro) modeled-maturity profiles. …”
Section: Resultsmentioning
confidence: 99%
“… ( a ) Reconstructed stratigraphic burial, thermal histories and paleo-heat flux history plots for well GS6 47 ( b ) (%Ro) modeled-maturity profiles. …”
Natural gas of organic origin is primarily biogenic or thermogenic; however, the formation of natural gas is occasionally attributed to hydrothermal activity. The Precambrian dolomite reservoir of the Anyue gas field is divided into three stages. Dolomite-quartz veins were precipitated after two earlier stages of dolomite deposition. Fluid inclusions in the dolomite and quartz are divided into pure methane (P-type), methane-bearing (M-type), aqueous (W-type), and solid bitumen-bearing (S-type) inclusions. The W-type inclusions within the quartz and buried dolomite homogenized between 107 °C and 223 °C. Furthermore, the trapping temperatures and pressures of the fluid (249 °C to 319 °C and 1619 bar to 2300 bar, respectively) are obtained from the intersections of the isochores of the P-type and the coeval W-type inclusions in the quartz. However, the burial history of the reservoir indicates that the maximum burial temperature did not exceed 230 °C. Thus, the generation of the natural gas was not caused solely by the burial of the dolomite reservoir. The results are also supported by the presence of paragenetic pyrobitumen and MVT lead-zinc ore. A coupled system of occasional invasion by hydrothermal fluids and burial of the reservoir may represent a new genetic model for natural gas accumulation in this gas field.
“…(2015) studied the heat flow of the Sichuan basin using apatite fission track data and (U-Th)/He thermochronology 47 . The results suggest that the following heat flux history for the Sichuan Basin: (1) the heat flux was 55 ± 5 mW/m 2 before and during the Late Carboniferous; (2) an abrupt rise in the heat flux to 80 ± 5 mW/m 2 occurred in the Permian; (3) the heat flux gradually decreased after the Triassic, and the present day heat flux was calculated to be as low as 50 mW/m 2 47 . To ensure the reliability of the modeling results, an interactive optimization process was carried out until the vitrinite-like reflectance values were matched (Fig.…”
Section: Resultsmentioning
confidence: 99%
“…A good fit to the maturity data suggests that our calculated burial depths are relatively reliable. Figure 9 ( a ) Reconstructed stratigraphic burial, thermal histories and paleo-heat flux history plots for well GS6 47 ( b ) (%Ro) modeled-maturity profiles. …”
Section: Resultsmentioning
confidence: 99%
“… ( a ) Reconstructed stratigraphic burial, thermal histories and paleo-heat flux history plots for well GS6 47 ( b ) (%Ro) modeled-maturity profiles. …”
Natural gas of organic origin is primarily biogenic or thermogenic; however, the formation of natural gas is occasionally attributed to hydrothermal activity. The Precambrian dolomite reservoir of the Anyue gas field is divided into three stages. Dolomite-quartz veins were precipitated after two earlier stages of dolomite deposition. Fluid inclusions in the dolomite and quartz are divided into pure methane (P-type), methane-bearing (M-type), aqueous (W-type), and solid bitumen-bearing (S-type) inclusions. The W-type inclusions within the quartz and buried dolomite homogenized between 107 °C and 223 °C. Furthermore, the trapping temperatures and pressures of the fluid (249 °C to 319 °C and 1619 bar to 2300 bar, respectively) are obtained from the intersections of the isochores of the P-type and the coeval W-type inclusions in the quartz. However, the burial history of the reservoir indicates that the maximum burial temperature did not exceed 230 °C. Thus, the generation of the natural gas was not caused solely by the burial of the dolomite reservoir. The results are also supported by the presence of paragenetic pyrobitumen and MVT lead-zinc ore. A coupled system of occasional invasion by hydrothermal fluids and burial of the reservoir may represent a new genetic model for natural gas accumulation in this gas field.
“…On the one hand, the conduction of thermal fluids through rocks and faults brings thermal energy to source rocks and promotes source rock maturation and hydrocarbon generation (Rullkötter et al, 1988). On the other hand, the H 2 brought by the deep fluids can considerably improve the hydrocarbon generation rate through the kerogen hydrogenation process (Zhu et al, 2017). Consequently, compared with unaffected source rocks, source rocks influenced by deep thermal fluids may CNACG, 2016).…”
Section: Tectonic Movement Stratigraphic Age and Other Factorsmentioning
Abstract. Fossil fuel resources are invaluable to economic growth
and social development. Understanding the formation and distribution of
fossil fuel resources is critical for the search and exploration of them.
Until now, the vertical distribution depth of fossil fuel resources has not
been confirmed due to different understandings of their origins and the
substantial variation in reservoir depths from basin to basin. Geological
and geochemical data of 13 634 source rock samples from 1286 exploration
wells in six representative petroliferous basins were examined to identify
the maximum burial depth of active source rocks in each basin, which is
referred to in this study as the active source rock depth limit (ASDL). Beyond
the ASDL, source rocks no longer generate or expel hydrocarbons and become
inactive. Therefore, the ASDL also sets the maximum depth for fossil fuel
resources. The ASDLs of basins around the world are found to range from 3000 to 16 000 m, while
the thermal maturities (Ro) of source rocks at the
ASDLs are almost the same, with Ro ≈3.5±0.5 %. The Ro of
3.5 % can be regarded as a general criterion to identify ASDLs. High heat
flow and more oil-prone kerogen are associated with shallow ASDLs. In
addition, tectonic uplift of source rocks can significantly affect ASDLs;
21.6 billion tons of reserves in six representative basins in China and
52 926 documented oil and gas reservoirs in 1186 basins around the world are
all located above ASDLs, demonstrating the universal presence of ASDLs in
petroliferous basins and their control on the vertical distribution of
fossil fuel resources. The data used in this study are deposited in the
repository of the PANGAEA database at: https://doi.org/10.1594/PANGAEA.900865 (Pang et al., 2019).
“…The Sichuan basin that experienced several stages of 30 tectonic uplift in the geological history epitomizes the influence of these factors on ASDL. For example, the Ro of the upper Triassic source rock is about 1.0% at the depth of ~2000 m in the southern Sichuan basin (Zhu et al, 2016). At the same burial depth of southern Sichuan basin, however, the Ro of the lower Triassic source rock can reach about 2.0% (Zhu et al, https://doi.org/10.5194/essd-2019-72…”
Section: Heat Flow and Geothermal Gradientmentioning
Abstract. Fossil resources are valuable wealth given to human beings by nature. Many mysteries related to them have been revealed such as the origin time and distribution area, but their vertical distribution depth has not been confirmed for people’s different understanding of their origin and the big depth variations from basin to basin. Geological and geochemical data of 13,634 source rock samples from 1,286 exploration wells in six representative petroliferous basins are examined to study their Active Source Rock Depth Limits (ASDL), defined in this study as the maximum burial depth of active source rocks beyond which the source rocks no longer generate or expel hydrocarbons and become inactive, to identify the maximum depth for fossil fuel resources distribution. Theoretically, the maximum depth for the ASDLs of fossil fuel resources ranges from 3,000 m to 16,000 m, while their thermal maturities (Ro) are almost the same with Ro≈3.5±0.5 %. A higher heat flow and more oil-prone kerogen are associated with a shallower ASDL. Active source rocks and the discovered 21.6 billion tons of reserves in six representative basins in China and 52,926 oil and gas reservoirs in the 1,186 basins over the world are found to be distributed above the ASDL, illustrating the universality of such kind of depth limit. The data are deposited in the repository of the PANGAEA database: https://doi.org/10.1594/PANGAEA.900865 (Pang et al., 2019).
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