There are abundant bitumens and oil seepages stored in vugs in a Lower-Triassic Daye formation(T_1d)marlite in Ni'erguan village in the Southern Guizhou Depression. However, the source of those oil seepages has no...There are abundant bitumens and oil seepages stored in vugs in a Lower-Triassic Daye formation(T_1d)marlite in Ni'erguan village in the Southern Guizhou Depression. However, the source of those oil seepages has not been determined to date. Multiple suites of source rocks of different ages exist in the depression. Both the oil seepages and potential source rocks have undergone complicated secondary alterations, which have added to the difficulty of an oil-source correlation. For example, the main source rock, a Lower-Cambrian Niutitang Formation"(∈_1n) mudstone, is over mature, and other potential source rocks, both from the Permian and the Triassic, are still in the oil window. In addition, the T_1d oil seepages underwent a large amount of biodegradation. To minimize the influence of biodegradation and thermal maturation, special methods were employed in this oil-source correlation study. These methods included catalytic hydropyrolysis, to release covalently bound biomarkers from the over mature"kerogen of ∈_1n mudstone, sequential extraction, to obtain chloroform bitumen A and chloroform bitumen C from the T_1d marlite, and anhydrous pyrolysis, to release pyrolysates from the kerogen of T_1d marlite. Using the methods above, the biomarkers and n-alkanes releasedfrom the oil samples and source rocks were analysed by GC–MS and GC-C-IRMS. The oil-source correlation indicated that the T_1d oil seepage primarily originated from"the ∈_1n mudstone and was partially mixed with oil generated from the T_1d marlite. Furthermore, the seepage also demonstrated that the above methods were effective for the complicated oil-source correlation in the Southern Guizhou Depression.展开更多
The interest of this research: there is oil seepage at the contact between coal seam-A and sandstone facies of Warukin Formation, so it is necessary to study where is the source rock. The correlation between HI and Tm...The interest of this research: there is oil seepage at the contact between coal seam-A and sandstone facies of Warukin Formation, so it is necessary to study where is the source rock. The correlation between HI and Tmax as result from rock eval pyrolysis shows that the shale of the Warukin Formation is immature while the correlation between HI and OI shows oil prone. The vitrinite (Ro) reflectance of Central Wara coal is between 0.48% up to 0.5% (immature), the content of the vitrinite group is 68.0 - 84.8 (% Vol.), Liptinite 3.0 - 14.0 (% Vol.) and inertinite 0.48 - 25.0 (% Vol.). The high content of liptinite mineral groups (14% Vol.) and the presence of exsudatinite maceral are as an initial indication of bitumenization of oil formation when there is a change in reflectance and fluorescence. Therefore, Central Wara coal plays an important role as the source rock of the Warukin Formation, although the maturity level is immature, the presence of exsudatinite maceral is believed to be the source of origin for producing oil, where the organic material comes from terrestrial.展开更多
基金supported jointly by the National Science and Technology Major Project of China (Grant Nos: 2011ZX05008002 and 2011ZX05005-001)
文摘There are abundant bitumens and oil seepages stored in vugs in a Lower-Triassic Daye formation(T_1d)marlite in Ni'erguan village in the Southern Guizhou Depression. However, the source of those oil seepages has not been determined to date. Multiple suites of source rocks of different ages exist in the depression. Both the oil seepages and potential source rocks have undergone complicated secondary alterations, which have added to the difficulty of an oil-source correlation. For example, the main source rock, a Lower-Cambrian Niutitang Formation"(∈_1n) mudstone, is over mature, and other potential source rocks, both from the Permian and the Triassic, are still in the oil window. In addition, the T_1d oil seepages underwent a large amount of biodegradation. To minimize the influence of biodegradation and thermal maturation, special methods were employed in this oil-source correlation study. These methods included catalytic hydropyrolysis, to release covalently bound biomarkers from the over mature"kerogen of ∈_1n mudstone, sequential extraction, to obtain chloroform bitumen A and chloroform bitumen C from the T_1d marlite, and anhydrous pyrolysis, to release pyrolysates from the kerogen of T_1d marlite. Using the methods above, the biomarkers and n-alkanes releasedfrom the oil samples and source rocks were analysed by GC–MS and GC-C-IRMS. The oil-source correlation indicated that the T_1d oil seepage primarily originated from"the ∈_1n mudstone and was partially mixed with oil generated from the T_1d marlite. Furthermore, the seepage also demonstrated that the above methods were effective for the complicated oil-source correlation in the Southern Guizhou Depression.
文摘The interest of this research: there is oil seepage at the contact between coal seam-A and sandstone facies of Warukin Formation, so it is necessary to study where is the source rock. The correlation between HI and Tmax as result from rock eval pyrolysis shows that the shale of the Warukin Formation is immature while the correlation between HI and OI shows oil prone. The vitrinite (Ro) reflectance of Central Wara coal is between 0.48% up to 0.5% (immature), the content of the vitrinite group is 68.0 - 84.8 (% Vol.), Liptinite 3.0 - 14.0 (% Vol.) and inertinite 0.48 - 25.0 (% Vol.). The high content of liptinite mineral groups (14% Vol.) and the presence of exsudatinite maceral are as an initial indication of bitumenization of oil formation when there is a change in reflectance and fluorescence. Therefore, Central Wara coal plays an important role as the source rock of the Warukin Formation, although the maturity level is immature, the presence of exsudatinite maceral is believed to be the source of origin for producing oil, where the organic material comes from terrestrial.
