Based on organic petrology,organic geochemistry and SEM method,type,formation period and source of bitumens in the Cambrian Longwangmiao Formation in the central Sichuan Basin were well investigated,and combined with ...Based on organic petrology,organic geochemistry and SEM method,type,formation period and source of bitumens in the Cambrian Longwangmiao Formation in the central Sichuan Basin were well investigated,and combined with fluid inclusions and tectonic evolution characteristics,the hydrocarbon accumulation history of the gas reservoir of the Longwangmiao Formation in the Anyue gasfield was also studied.The result shows that all bitumens in the Longwangmiao Formation was from the Lower Cambrian source rocks,it had multiple genetic types which was dominated by the pyrolysis genetic type;the bitumens were formed into three stages,i.e.,the bitumen of the oxidized water-washing type in the first stage,the bitumen of the precipitated type in the second stage,and the bitumen of the pyrolyzed type in the third stage;the gas reservoir in the Anyue gasfield experienced five stages of hydrocarbon charging,including two stages of liquid hydrocarbon charging,charging of the kerogen pyrolysis gas in the Late Triassic-Early Jurassic,charging of the crude oil pyrolysis gas in the Late Jurassic-Early Cretaceous and charging of the dry gas charging in the Himalayan trap reformation and adjustment process.展开更多
Methane dominated gas is one of the cleanest energy resources;however, there is no direct method to determine its source rock. Natural gases produced from the eastern Sichuan Basin together with seismic data were stud...Methane dominated gas is one of the cleanest energy resources;however, there is no direct method to determine its source rock. Natural gases produced from the eastern Sichuan Basin together with seismic data were studied for their sources and secondary alteration by thermochemical sulfate reduction(TSR). Our results demonstrate that Upper Permian to Lower Triassic(P_(3)ch-T_(1)f) gases in the surrounding of the Kaijiang-Liangping area show volatile organic sulfur compounds(VOSCs) δ^(34)S values close to those of the associated H_(2)S, and may have been altered by methane-dominated TSR, resulting in positive shift in methane δ^(13)C_(1)values with increasing TSR extents. Other(or group 2) gases produced from the P_(3)ch-T_(1)f reservoirs from the southern area and the Upper Carboniferous to Middle Permian(C_(2)h-P_(2)q) from the eastern Sichuan Basin are not significantly changed by TSR, show similar δ^(34)S values between the kerogens and some VOSCs, and may have been derived from the Lower Silurian and Middle Permian source rocks. This study demonstrates a case for the first time showing the δ^(34)S values of VOSCs can be used as a tool for direct correlation between non-TSR altered gas and source rocks. Methane-dominated gas pools can be found using gas and source rock geochemistry combined with seismic data.展开更多
基金The work was supported by the National Research Council of Science and Technology Major Project(No.2011ZX05004-001).
文摘Based on organic petrology,organic geochemistry and SEM method,type,formation period and source of bitumens in the Cambrian Longwangmiao Formation in the central Sichuan Basin were well investigated,and combined with fluid inclusions and tectonic evolution characteristics,the hydrocarbon accumulation history of the gas reservoir of the Longwangmiao Formation in the Anyue gasfield was also studied.The result shows that all bitumens in the Longwangmiao Formation was from the Lower Cambrian source rocks,it had multiple genetic types which was dominated by the pyrolysis genetic type;the bitumens were formed into three stages,i.e.,the bitumen of the oxidized water-washing type in the first stage,the bitumen of the precipitated type in the second stage,and the bitumen of the pyrolyzed type in the third stage;the gas reservoir in the Anyue gasfield experienced five stages of hydrocarbon charging,including two stages of liquid hydrocarbon charging,charging of the kerogen pyrolysis gas in the Late Triassic-Early Jurassic,charging of the crude oil pyrolysis gas in the Late Jurassic-Early Cretaceous and charging of the dry gas charging in the Himalayan trap reformation and adjustment process.
基金financially supported by the National Natural Science Foundation of China (Grant No.41961144023)the Israeli Science Foundation (Grant No.3195/19)。
文摘Methane dominated gas is one of the cleanest energy resources;however, there is no direct method to determine its source rock. Natural gases produced from the eastern Sichuan Basin together with seismic data were studied for their sources and secondary alteration by thermochemical sulfate reduction(TSR). Our results demonstrate that Upper Permian to Lower Triassic(P_(3)ch-T_(1)f) gases in the surrounding of the Kaijiang-Liangping area show volatile organic sulfur compounds(VOSCs) δ^(34)S values close to those of the associated H_(2)S, and may have been altered by methane-dominated TSR, resulting in positive shift in methane δ^(13)C_(1)values with increasing TSR extents. Other(or group 2) gases produced from the P_(3)ch-T_(1)f reservoirs from the southern area and the Upper Carboniferous to Middle Permian(C_(2)h-P_(2)q) from the eastern Sichuan Basin are not significantly changed by TSR, show similar δ^(34)S values between the kerogens and some VOSCs, and may have been derived from the Lower Silurian and Middle Permian source rocks. This study demonstrates a case for the first time showing the δ^(34)S values of VOSCs can be used as a tool for direct correlation between non-TSR altered gas and source rocks. Methane-dominated gas pools can be found using gas and source rock geochemistry combined with seismic data.
