本文研究了深海钻探(DSDP)31航次296站晚新生代介形类动物群的性质及其古海洋学意义。此站钻孔上部上新统至全新统以超微浮游生物软泥和粘土为主的16块岩芯中,共分析获得介形类化石8属11种,计有:Po-seidonamicus major Benson,P.anterop...本文研究了深海钻探(DSDP)31航次296站晚新生代介形类动物群的性质及其古海洋学意义。此站钻孔上部上新统至全新统以超微浮游生物软泥和粘土为主的16块岩芯中,共分析获得介形类化石8属11种,计有:Po-seidonamicus major Benson,P.anteropunctatus Whatley et al.,P.punctatus Whatley et al.,Pennyella dorsoser-rata(Brady),Henry howella sp.,Pterygocythere mucronalatum(Brady),Abyssocythere sp.,Abyssocythereis sul-catoperforata(Brady),Pelecocythere sp.,Krithe sp.1和Krithe sp.2。这些介形类属种均为冷海域深海区介形类分子。由此表明,西北太平洋边缘地区在晚新生代曾为一深海区。在第四纪,其深度可能和现今296站的深度大致相当;在上新世,其深度可能更深一些。研究结果证实,深海底栖介形类属种的分布具全球性;在相当长的地质时期内,介形类属种的形态和壳饰都非常稳定,无明显变化。同时,进一步证实,介形类个体大小变化与深度相关,同一种介形类壳体随水域深度加深而增大。展开更多
Since deep-sea gas hydrate-bearing sediments were drilled for the first time in the Blake Ridge in 1970,gas hydrates have been discovered at 53 drill sites in the continental margins of global oceans with internationa...Since deep-sea gas hydrate-bearing sediments were drilled for the first time in the Blake Ridge in 1970,gas hydrates have been discovered at 53 drill sites in the continental margins of global oceans with international scientific ocean drilling(DSDP/ODP/IODP Programs).As a result,massive amounts of geophysical well-logging data have been accumulated,which provide critical information for understanding the in-situ properties of gas hydrates and their host sediments.Gas hydrates have such physical and chemical properties as non-conductivity,low density,high acoustic velocity,and high hydrogen content,which form the basis of identifying gas hydrate reservoirs and predicting their distribution by well-logging data.A series of well-logging evaluation methods have been proposed to estimate gas hydrate saturation of sediments,including Archie equation,combined methods of density and nuclear magnetic resonance well logging,various forms of three-phase acoustic wave equations,and elastic wave velocity simulations based on different rock physical models.The distribution of gas hydrates is highly heterogeneous,which is mainly manifested in the selectivity of hydrate occurrence to the lithology of host sediments and to the nucleation sites within a host sediment of the same lithology.The scientific-ocean-drilling well logging data have also been preliminarily used for evaluating the heterogeneity of gas hydrate distribution and inferring the growth habit of gas hydrates in host sediments.Nevertheless,there still exist some problems.The formation models used in logging evaluation are in general oversimplified,in which only two or three stratal components are involved.The application of high-resolution logging while-drilling(LWD)data remains limited.Log interpretation is not closely integrated with core geology.Therefore,joint inversion of lithologic components,porosity and gas hydrate saturation based on more complex formation models,together with the applications of high-resolution LWD logging data and core calibration,may represent an important direction in future welllogging evaluation of gas hydrate reservoirs.展开更多
基金Projects funded by the National Natural Science Foundation of China“Turbidites in the Abyssal Plain of the South China Sea and Their Tectonic Implications”(No.41676029)“Gravity Flow Deposits in the Ocean-Continent Transition Zone of the Northern South China Sea”(No.41876049).
文摘Since deep-sea gas hydrate-bearing sediments were drilled for the first time in the Blake Ridge in 1970,gas hydrates have been discovered at 53 drill sites in the continental margins of global oceans with international scientific ocean drilling(DSDP/ODP/IODP Programs).As a result,massive amounts of geophysical well-logging data have been accumulated,which provide critical information for understanding the in-situ properties of gas hydrates and their host sediments.Gas hydrates have such physical and chemical properties as non-conductivity,low density,high acoustic velocity,and high hydrogen content,which form the basis of identifying gas hydrate reservoirs and predicting their distribution by well-logging data.A series of well-logging evaluation methods have been proposed to estimate gas hydrate saturation of sediments,including Archie equation,combined methods of density and nuclear magnetic resonance well logging,various forms of three-phase acoustic wave equations,and elastic wave velocity simulations based on different rock physical models.The distribution of gas hydrates is highly heterogeneous,which is mainly manifested in the selectivity of hydrate occurrence to the lithology of host sediments and to the nucleation sites within a host sediment of the same lithology.The scientific-ocean-drilling well logging data have also been preliminarily used for evaluating the heterogeneity of gas hydrate distribution and inferring the growth habit of gas hydrates in host sediments.Nevertheless,there still exist some problems.The formation models used in logging evaluation are in general oversimplified,in which only two or three stratal components are involved.The application of high-resolution logging while-drilling(LWD)data remains limited.Log interpretation is not closely integrated with core geology.Therefore,joint inversion of lithologic components,porosity and gas hydrate saturation based on more complex formation models,together with the applications of high-resolution LWD logging data and core calibration,may represent an important direction in future welllogging evaluation of gas hydrate reservoirs.
