A series of significant discoveries in marine carbonate rocks show great petroleum exploration potential in the Tarim Basin. However, the oil and gas fields discovered in the carbonate rocks are mainly distributed aro...A series of significant discoveries in marine carbonate rocks show great petroleum exploration potential in the Tarim Basin. However, the oil and gas fields discovered in the carbonate rocks are mainly distributed around the Manjiaer Sag in the eastern Tarim Basin. Some explorations occurred and no oil or gas field was discovered around the Awati Sag in the western Tarim Basin. Information from wells and outcrops reveals that there are excellent oil and gas source rock conditions around the Awati Sag. Transformed reef-shoal reservoirs could be formed in the Ordovician carbonate rocks with paleo-geographic background and hydrothermal conditions. Therefore, it is necessary to make a systematical study and overall evaluation of the potential of the periphery of the Awati Sag in terms of source rock evolution, resource potential, high-grade reservoir formation and distribution, and main factors controlling hydrocarbon migration and accumulation.展开更多
The origin of natural gases in central Tarim Basin is very complicated and there has been no definite conclusion in this aspect. Based on the results of systematic research on their composition and carbon isotopic cha...The origin of natural gases in central Tarim Basin is very complicated and there has been no definite conclusion in this aspect. Based on the results of systematic research on their composition and carbon isotopic characteristics, natural gases in central Tarim Basin are composed mainly of hydrocarbon gas, Ordovician natural gas with the characteristics of crude oil-cracking gas, and Carboniferous natural gas not only originating from kerogen cracking, but also from oil cracking. There are significant differences in composition and carbon isotope of natural gases between the eastern and western areas. The causes for the differences in geochemical characteristics of natural gases are presented as follows: different thermal evolution degrees of organic matter. Natural gases in the western region may have generated from the Middle- Upper Ordovician source rocks, and natural gases in the eatern region may be derived from the Cambrian source rocks, which entered into high to over mature stages; the gases migrated from west to east and caused the different compositional and carbon isotopic characteristics of natural gases; difference in the strength of thermal sulfate reduction between the eastern and western parts, with the reduction in the eastern part being stronger than that in the western part.展开更多
Lunnan heave had experienced denudation during late Caledonian and Hercynian movements and reconstruction during Indosinian movement. Lunnan heave and its circumference areas are located on the direction of petroleum ...Lunnan heave had experienced denudation during late Caledonian and Hercynian movements and reconstruction during Indosinian movement. Lunnan heave and its circumference areas are located on the direction of petroleum migration, and experienced three reservoir formation cycles that are divided by wave cycle: The first reservoir formation cycle is characterized by breakage, the second by alteration, and the third by enrichment. Three layers of dissolving-cave developed on the vertical in Lunnan area. Development degree of slit-cave system and their connectivity are important factors to control petroleum enrichment in the weathering crust reservoir. The area where dissolving-caves are communicated by silts and faults was a fine petroleum enrichment area, and water was often encountered in the area with isolation cave while drilling because of no oil and gas origin. The top part of the faulted-horst as a leaking area is bearing water area, and the higher part of slope nearing the top part of the展开更多
文摘A series of significant discoveries in marine carbonate rocks show great petroleum exploration potential in the Tarim Basin. However, the oil and gas fields discovered in the carbonate rocks are mainly distributed around the Manjiaer Sag in the eastern Tarim Basin. Some explorations occurred and no oil or gas field was discovered around the Awati Sag in the western Tarim Basin. Information from wells and outcrops reveals that there are excellent oil and gas source rock conditions around the Awati Sag. Transformed reef-shoal reservoirs could be formed in the Ordovician carbonate rocks with paleo-geographic background and hydrothermal conditions. Therefore, it is necessary to make a systematical study and overall evaluation of the potential of the periphery of the Awati Sag in terms of source rock evolution, resource potential, high-grade reservoir formation and distribution, and main factors controlling hydrocarbon migration and accumulation.
基金supported by the National Natural Science Foundation of China (Grant No. 40973041)
文摘The origin of natural gases in central Tarim Basin is very complicated and there has been no definite conclusion in this aspect. Based on the results of systematic research on their composition and carbon isotopic characteristics, natural gases in central Tarim Basin are composed mainly of hydrocarbon gas, Ordovician natural gas with the characteristics of crude oil-cracking gas, and Carboniferous natural gas not only originating from kerogen cracking, but also from oil cracking. There are significant differences in composition and carbon isotope of natural gases between the eastern and western areas. The causes for the differences in geochemical characteristics of natural gases are presented as follows: different thermal evolution degrees of organic matter. Natural gases in the western region may have generated from the Middle- Upper Ordovician source rocks, and natural gases in the eatern region may be derived from the Cambrian source rocks, which entered into high to over mature stages; the gases migrated from west to east and caused the different compositional and carbon isotopic characteristics of natural gases; difference in the strength of thermal sulfate reduction between the eastern and western parts, with the reduction in the eastern part being stronger than that in the western part.
文摘Lunnan heave had experienced denudation during late Caledonian and Hercynian movements and reconstruction during Indosinian movement. Lunnan heave and its circumference areas are located on the direction of petroleum migration, and experienced three reservoir formation cycles that are divided by wave cycle: The first reservoir formation cycle is characterized by breakage, the second by alteration, and the third by enrichment. Three layers of dissolving-cave developed on the vertical in Lunnan area. Development degree of slit-cave system and their connectivity are important factors to control petroleum enrichment in the weathering crust reservoir. The area where dissolving-caves are communicated by silts and faults was a fine petroleum enrichment area, and water was often encountered in the area with isolation cave while drilling because of no oil and gas origin. The top part of the faulted-horst as a leaking area is bearing water area, and the higher part of slope nearing the top part of the
