The deepwater of the northwestern South China Sea is located in the central to southern parts of the Qiongdongnan Basin (QDN Basin), which is a key site for hydrocarbon exploration in recent years. In this study, th...The deepwater of the northwestern South China Sea is located in the central to southern parts of the Qiongdongnan Basin (QDN Basin), which is a key site for hydrocarbon exploration in recent years. In this study, the authors did a comprehensive analysis of gravity-magnetic data, extensive 3D seismic survey, cores and cuttings, paleontology and geochemical indexes, proposed the mechanism of natural gas origin, identified different oil and gas systems, and established the model of hydrocarbon accumulations in the deep-water region. Our basin tectonic simulation indicates that the evolution of QDN Basin was controlled by multiple-phased tectonic movements, such as Indochina-Eurasian Plate collision, Tibetan Uplift, Red River faulting and the expansion of the South China Sea which is characterized by Paleogene rifting, Neogene depression, and Eocene intensive faulting and lacustrine deposits. The drilling results show that this region is dominated by marine- terrestrial transitional and neritic-bathyal facies from the early Oligocene. The Yacheng Formation of the early Oligocene is rich in organic matter and a main gas-source rock. According to the geological-geochemical data from the latest drilling wells, Lingshui, Baodao, Changchang Sags have good hydrocarbon-generating potentials, where two plays from the Paleogene and Neogene reservoirs were developed. Those reservoirs occur in central canyon structural-lithologic trap zone, Changchang marginal trap zone and southern fault terrace of Baodao Sag. Among them, the central canyon trap zone has a great potential for exploration because the various reservoir- forming elements are well developed, i.e., good coal-measure source rocks, sufficient reservoirs from the Neogene turbidity sandstone and submarine fan, faults connecting source rock and reservoirs, effective vertical migration, late stage aggregation and favorable structural-lithological composite trapping. These study results provide an important scientific basis for hydrocarbon exploration in this region, evidenced by the recent discovery of the significant commercial LS-A gas field in the central canyon of the Lingshui Sag.展开更多
To accelerate the petroleum exploration in deep sea of China,since the period of“the 11th Five-Year Plan”,the sedimentary process,source rock formation and hydrocarbon generation and expulsion process in deep-water ...To accelerate the petroleum exploration in deep sea of China,since the period of“the 11th Five-Year Plan”,the sedimentary process,source rock formation and hydrocarbon generation and expulsion process in deep-water area of the Qiongdongnan Basin in the western South China Sea have been studied systematically using the data like large-area 3D seismic survey,logging,drill core(cuttings)and geochemical analysis,providing three innovative understandings,i.e.excellent hydrocarbon source conditions,good accumulation conditions,and grouping and zonal distribution of large exploration targets.From the study,the following conclusions are drawn.First,the deep-water area located in the southern and central parts of the Qiongdongnan Basin was formed under the control of such tectonic events as IndosinianeEurasian Plate collision,Himalayan uplifting and South China Sea expansion,and experienced Paleogene lift and Neogene depression stages.Second,accompanied by lacustrine deposition,faulting activity was violent in Eocene;whereas in Early Oligocene,rift continued to develop under a sedimentary environment of marineeterrestrial transitional facies and littoral-neritic facies.Third,oil generation predominated Eocene lacustrine mudstone and gas generation predominated Lower Oligocene marineeterrestrial transitional facies coal-measure strata compose two sets of major source rocks.Fourth,analysis in respect of thermal evolution level,hydrocarbon generation volume and hydrocarbon generation intensity shows that Ledong,Lingshui,Baodao and Changchang sags belong to potential hydrocarbon-rich kitchens,among which Ledong and Lingshui sags have been proved to have great hydrocarbon generation potential by drilling.Fifth,researches of deep-water sedimentology and hydrocarbon accumulation dynamics reveal that Paleogene and Neogene plays are developed vertically,and favorable hydrocarbon accumulation zones like the Central Canyon lithologic trap zone(group),Changchang circum-sag trap zone(group)and southern Baodao fault terrace zone are developed horizontally in the area.Sixth,with its excellent petroleum accumulation conditions and great exploration potential,the Central Canyon lithologic trap zone should be taken as the preferred drilling target,which has been verified correct by the discovery of the Central Canyon Gas Field d the largest gas field in the northern South China Sea.展开更多
基金China National Major Special Project under contract No.2011ZX05025-002
摘要The deepwater of the northwestern South China Sea is located in the central to southern parts of the Qiongdongnan Basin (QDN Basin), which is a key site for hydrocarbon exploration in recent years. In this study, the authors did a comprehensive analysis of gravity-magnetic data, extensive 3D seismic survey, cores and cuttings, paleontology and geochemical indexes, proposed the mechanism of natural gas origin, identified different oil and gas systems, and established the model of hydrocarbon accumulations in the deep-water region. Our basin tectonic simulation indicates that the evolution of QDN Basin was controlled by multiple-phased tectonic movements, such as Indochina-Eurasian Plate collision, Tibetan Uplift, Red River faulting and the expansion of the South China Sea which is characterized by Paleogene rifting, Neogene depression, and Eocene intensive faulting and lacustrine deposits. The drilling results show that this region is dominated by marine- terrestrial transitional and neritic-bathyal facies from the early Oligocene. The Yacheng Formation of the early Oligocene is rich in organic matter and a main gas-source rock. According to the geological-geochemical data from the latest drilling wells, Lingshui, Baodao, Changchang Sags have good hydrocarbon-generating potentials, where two plays from the Paleogene and Neogene reservoirs were developed. Those reservoirs occur in central canyon structural-lithologic trap zone, Changchang marginal trap zone and southern fault terrace of Baodao Sag. Among them, the central canyon trap zone has a great potential for exploration because the various reservoir- forming elements are well developed, i.e., good coal-measure source rocks, sufficient reservoirs from the Neogene turbidity sandstone and submarine fan, faults connecting source rock and reservoirs, effective vertical migration, late stage aggregation and favorable structural-lithological composite trapping. These study results provide an important scientific basis for hydrocarbon exploration in this region, evidenced by the recent discovery of the significant commercial LS-A gas field in the central canyon of the Lingshui Sag.
基金Special and Significant Project of National Science and Technology“Evaluation on hydrocarbon-rich sags in deep water regions of northern South China Sea”(No.:2011ZX05025-002).
摘要To accelerate the petroleum exploration in deep sea of China,since the period of“the 11th Five-Year Plan”,the sedimentary process,source rock formation and hydrocarbon generation and expulsion process in deep-water area of the Qiongdongnan Basin in the western South China Sea have been studied systematically using the data like large-area 3D seismic survey,logging,drill core(cuttings)and geochemical analysis,providing three innovative understandings,i.e.excellent hydrocarbon source conditions,good accumulation conditions,and grouping and zonal distribution of large exploration targets.From the study,the following conclusions are drawn.First,the deep-water area located in the southern and central parts of the Qiongdongnan Basin was formed under the control of such tectonic events as IndosinianeEurasian Plate collision,Himalayan uplifting and South China Sea expansion,and experienced Paleogene lift and Neogene depression stages.Second,accompanied by lacustrine deposition,faulting activity was violent in Eocene;whereas in Early Oligocene,rift continued to develop under a sedimentary environment of marineeterrestrial transitional facies and littoral-neritic facies.Third,oil generation predominated Eocene lacustrine mudstone and gas generation predominated Lower Oligocene marineeterrestrial transitional facies coal-measure strata compose two sets of major source rocks.Fourth,analysis in respect of thermal evolution level,hydrocarbon generation volume and hydrocarbon generation intensity shows that Ledong,Lingshui,Baodao and Changchang sags belong to potential hydrocarbon-rich kitchens,among which Ledong and Lingshui sags have been proved to have great hydrocarbon generation potential by drilling.Fifth,researches of deep-water sedimentology and hydrocarbon accumulation dynamics reveal that Paleogene and Neogene plays are developed vertically,and favorable hydrocarbon accumulation zones like the Central Canyon lithologic trap zone(group),Changchang circum-sag trap zone(group)and southern Baodao fault terrace zone are developed horizontally in the area.Sixth,with its excellent petroleum accumulation conditions and great exploration potential,the Central Canyon lithologic trap zone should be taken as the preferred drilling target,which has been verified correct by the discovery of the Central Canyon Gas Field d the largest gas field in the northern South China Sea.