The thermal evolution of source rocks in the Paleozoic stratigraphic sequences has been an outstanding problem for petroleum exploration in the Tarim Basin, as the thermal history of the Paleozoic could not be reconst...The thermal evolution of source rocks in the Paleozoic stratigraphic sequences has been an outstanding problem for petroleum exploration in the Tarim Basin, as the thermal history of the Paleozoic could not be reconstructed objectively due to the lack of effective thermal indicators in the early Paleozoic carbonate successions. The (U-Th)/He thermochronometry of apatite and zircon has recently been used as an effective tool to study the structural uplift and thermal history of sedimentary basins. The Paleozoic tectonothermal histories of two typical wells in the Tarim Basin were modeled using the thermal indicators of (U-Th)/He, apatite fission track (AFT), and vitrinite reflectance (Ro) data in this paper. The Paleozoic strata in the two wells were shallow due to persistent uplift and significant erosion during the Hercynian tectonic events (from Devonian to Triassic). Therefore, the paleothermal indicators in the Paleozoic strata may retain the original thermal evolution and can be used to re- construct the Paleozoic thermal history of the Tarim Basin. The apatite and zircon helium ages from core and cuttings samples were analyzed and the Paleozoic thermal histories of wells KQ1 and T1 were modeled by combining helium ages, AFT, and equivalence vitrinite reflectance (VRo) data. The modeling results show that the geothermal gradient evolution is different in the Kongquehe Slop and Bachu Uplift of Tarim Basin during the Paleozoic. The thermal gradient in Well T1 on the Bachu Up- lift was only 28–30°C/km in Cambrian, and it increased to 30–33°C/km in Ordovician and 31–34°C/km during the Silurian and Devonian. The thermal gradient of Ordovician in Well KQ1 on the Kongquehe Slope was 35°C/km and decreased to 32–35°C/km during the Silurian and Devonian. Therefore, the combined use of (U-Th)/He ages and other thermal indicators appears to be useful in reconstructing the basin thermal history and provides new insight into the understanding of the early Paleozoic thermal history of the Tarim Basin.展开更多
The damage evolution and dynamic performance of a cement asphalt(CA)mortar layer of slab track subjected to vehicle dynamic load is investigated in this paper.Initially,a statistical damage constitutive model for the ...The damage evolution and dynamic performance of a cement asphalt(CA)mortar layer of slab track subjected to vehicle dynamic load is investigated in this paper.Initially,a statistical damage constitutive model for the CA mortar layer is developed using continuous damage mechanics and probability theory.In this model,the strength of the CA mortar elements is treated as a random variable,which follows the Weibull distribution.The inclusion of strain rate dependence affords considering its influence on the damage development and the transition between viscosity and elasticity.Comparisons with experimental data support the reliability of the model.A three-dimensional finite element(FE)model of a slab track is then created with the commercial software ABAQUS,where the devised model for the CA mortar is implemented as a user-defined material subroutine.Finally,a vertical vehicle model is coupled with the FE model of the slab track,through the wheel-rail contact forces,based on the nonlinear Hertzian contact theory.The evolution of the damage and of the dynamic performance of the CA mortar layer with various initial damage is investigated under the train and track interaction.The analysis indicates that the proposed model is capable of predicting the damage evolution of the CA mortar layer exposed to vehicle dynamic load.The dynamic compressive strain,the strain rate,and the induced damage increase significantly with an increase in the initial damage,whereas the dynamic compressive stress exhibits a sharp decrease with the increasing initial damage.Also,it is found that the strain rate dependence significantly influences the damage evolution and the dynamic behavior of the CA mortar layer.展开更多
The southern Ordos Basin has excellent petroleum exploration prospects.However,the tectono-thermal history and the controls on petroleum generation,accumulation and preservation conditions in southern basin are unclea...The southern Ordos Basin has excellent petroleum exploration prospects.However,the tectono-thermal history and the controls on petroleum generation,accumulation and preservation conditions in southern basin are unclear.In this study,we analyzed the present geothermal field,paleo-geothermal gradient,maturity of the hydrocarbon source rocks,uplift and cooling process and tectono-thermal evolution history.In the study area,for the Ordovician,Permain and the Triassic strata,the present temperature is low(3070℃)in the southeastern area but high(80140℃)in the northwestern area.The paleogeothermal gradient varied from 24℃/km to 30℃/km with a heat flow of 58—69 m W/m^(2)(i.e.,a medium-temperature basin).The paleo-temperatures are higher than the present temperatures and the maximum paleo-temperatures controlled the thermal maturity of the source rocks.The vitrinite reflectance(Ro)values of the Triassic strata are>0.7%and the thermal maturity reached the middlemature oil generation stage.The Rovalues of the Permian-Ordovician strata are>1.8%and the thermal maturity reached the over-mature gas generation stage.The southern Ordos Basin has experienced the multiple tectonic events at the Late Ordovician Caledonian(452 Ma),Late Triassic(215 Ma),Late Jurassic(165160 Ma),End-Early Cretaceous(110100 Ma)and Cenozoic(since 40 Ma).A large-scale tectonothermal event occurred at the End-Early Cretaceous(110100 Ma),which was controlled by lithospheric extension,destruction and thinning.This event led to the highest paleo-temperatures and thermal maturities and coeval with the peak period of petroleum generation and accumulation.The southern Ordos Basin has undergone rapid and large-scale uplift since the Late Cretaceous due to expansion of the northeastern margin of the Tibetan Plateau,uplift of the Qinling orogenic belt and thrust faulting in the Liupanshan tectonic belt.The southern Ordos Basin experienced tectonic overprinting that was strong in the south and weak in the north.The strongest overprinting occurred in the so展开更多
基金supported by Key Project of Ministry of Education of China (Grant No. 308005)National Basic Research Program of China (Grant No. 2005CB422102)State Key Laboratory of Petroleum Resource and Prospecting (Grant No. PRPJC2008-01)
文摘The thermal evolution of source rocks in the Paleozoic stratigraphic sequences has been an outstanding problem for petroleum exploration in the Tarim Basin, as the thermal history of the Paleozoic could not be reconstructed objectively due to the lack of effective thermal indicators in the early Paleozoic carbonate successions. The (U-Th)/He thermochronometry of apatite and zircon has recently been used as an effective tool to study the structural uplift and thermal history of sedimentary basins. The Paleozoic tectonothermal histories of two typical wells in the Tarim Basin were modeled using the thermal indicators of (U-Th)/He, apatite fission track (AFT), and vitrinite reflectance (Ro) data in this paper. The Paleozoic strata in the two wells were shallow due to persistent uplift and significant erosion during the Hercynian tectonic events (from Devonian to Triassic). Therefore, the paleothermal indicators in the Paleozoic strata may retain the original thermal evolution and can be used to re- construct the Paleozoic thermal history of the Tarim Basin. The apatite and zircon helium ages from core and cuttings samples were analyzed and the Paleozoic thermal histories of wells KQ1 and T1 were modeled by combining helium ages, AFT, and equivalence vitrinite reflectance (VRo) data. The modeling results show that the geothermal gradient evolution is different in the Kongquehe Slop and Bachu Uplift of Tarim Basin during the Paleozoic. The thermal gradient in Well T1 on the Bachu Up- lift was only 28–30°C/km in Cambrian, and it increased to 30–33°C/km in Ordovician and 31–34°C/km during the Silurian and Devonian. The thermal gradient of Ordovician in Well KQ1 on the Kongquehe Slope was 35°C/km and decreased to 32–35°C/km during the Silurian and Devonian. Therefore, the combined use of (U-Th)/He ages and other thermal indicators appears to be useful in reconstructing the basin thermal history and provides new insight into the understanding of the early Paleozoic thermal history of the Tarim Basin.
基金supported by the National Basic Research Program of China("973"Project)(Grant Nos.2013CB036202,2013CB036200)the National Natural Science Foundation of China(Grant No.51008254)+3 种基金the Funds from the Key Laboratory for Precision&Non-traditional Machining of the Ministry of Education,Dalian University of Technology(Grant No.JMTZ201002)the Fundamental Research Funds for the Central Universities(Grant No.2682013CX029)the Funds from the China Scholarship Councilthe 2013 Cultivation Program for the Excellent Doctoral Dissertation of Southwest Jiaotong University
文摘The damage evolution and dynamic performance of a cement asphalt(CA)mortar layer of slab track subjected to vehicle dynamic load is investigated in this paper.Initially,a statistical damage constitutive model for the CA mortar layer is developed using continuous damage mechanics and probability theory.In this model,the strength of the CA mortar elements is treated as a random variable,which follows the Weibull distribution.The inclusion of strain rate dependence affords considering its influence on the damage development and the transition between viscosity and elasticity.Comparisons with experimental data support the reliability of the model.A three-dimensional finite element(FE)model of a slab track is then created with the commercial software ABAQUS,where the devised model for the CA mortar is implemented as a user-defined material subroutine.Finally,a vertical vehicle model is coupled with the FE model of the slab track,through the wheel-rail contact forces,based on the nonlinear Hertzian contact theory.The evolution of the damage and of the dynamic performance of the CA mortar layer with various initial damage is investigated under the train and track interaction.The analysis indicates that the proposed model is capable of predicting the damage evolution of the CA mortar layer exposed to vehicle dynamic load.The dynamic compressive strain,the strain rate,and the induced damage increase significantly with an increase in the initial damage,whereas the dynamic compressive stress exhibits a sharp decrease with the increasing initial damage.Also,it is found that the strain rate dependence significantly influences the damage evolution and the dynamic behavior of the CA mortar layer.
基金supported by the National Natural Science Foundation of China(Grant Nos.42102164,42241204,41630312and 42272174)the Petro China Changqing Oilfield Company Science and Technology Major Project(ZDZX 2021-01)。
文摘The southern Ordos Basin has excellent petroleum exploration prospects.However,the tectono-thermal history and the controls on petroleum generation,accumulation and preservation conditions in southern basin are unclear.In this study,we analyzed the present geothermal field,paleo-geothermal gradient,maturity of the hydrocarbon source rocks,uplift and cooling process and tectono-thermal evolution history.In the study area,for the Ordovician,Permain and the Triassic strata,the present temperature is low(3070℃)in the southeastern area but high(80140℃)in the northwestern area.The paleogeothermal gradient varied from 24℃/km to 30℃/km with a heat flow of 58—69 m W/m^(2)(i.e.,a medium-temperature basin).The paleo-temperatures are higher than the present temperatures and the maximum paleo-temperatures controlled the thermal maturity of the source rocks.The vitrinite reflectance(Ro)values of the Triassic strata are>0.7%and the thermal maturity reached the middlemature oil generation stage.The Rovalues of the Permian-Ordovician strata are>1.8%and the thermal maturity reached the over-mature gas generation stage.The southern Ordos Basin has experienced the multiple tectonic events at the Late Ordovician Caledonian(452 Ma),Late Triassic(215 Ma),Late Jurassic(165160 Ma),End-Early Cretaceous(110100 Ma)and Cenozoic(since 40 Ma).A large-scale tectonothermal event occurred at the End-Early Cretaceous(110100 Ma),which was controlled by lithospheric extension,destruction and thinning.This event led to the highest paleo-temperatures and thermal maturities and coeval with the peak period of petroleum generation and accumulation.The southern Ordos Basin has undergone rapid and large-scale uplift since the Late Cretaceous due to expansion of the northeastern margin of the Tibetan Plateau,uplift of the Qinling orogenic belt and thrust faulting in the Liupanshan tectonic belt.The southern Ordos Basin experienced tectonic overprinting that was strong in the south and weak in the north.The strongest overprinting occurred in the so
