Walkaway VSP technology is commonly seen in the seismic development stage in the middle and late stages of the oilfield.Its advantage over conventional zero-offset VSP and non-zero well-source distance VSP is mainly d...Walkaway VSP technology is commonly seen in the seismic development stage in the middle and late stages of the oilfield.Its advantage over conventional zero-offset VSP and non-zero well-source distance VSP is mainly due to the higher coverage of the Walkaway VSP acquisition process and the larger acquisition range.The resolution and signal-to-noise ratio are higher.Walkaway VSP technology has a very good application effect on solving complex structural problems and thin interbed reservoir problems.This paper mainly introduces a VSP constrained sparse spike inversion method based on high-precision VSP data.For the data acquired by the eight-azimuth Walkaway VSP in a work area of Bohai Gulf,a new method of 3D seismic-VSP joint seismic inversion is established.In the application of the actual work area,good inversion results based on Walkaway VSP data were obtained,and a new R24 small layer above the top boundary of the NmRIll oil group was depicted.This result meets the needs of development seismic technology and is used to solve thin interbed reservoirs exploration problems that have very important practical significance.展开更多
Topography and space are two important factors determining plant species assemblages in forest communities.Quantification of the contribution of these two factors in determining species distribution helps us to evalua...Topography and space are two important factors determining plant species assemblages in forest communities.Quantification of the contribution of these two factors in determining species distribution helps us to evaluate their relative importance in determining species assemblages.This study aims to disentangle the effect of topography and space on the distributions of 14 dominant species in a subtropical mixed forest.Spearman correlation analysis and the torustranslation test were used to test the species–habitat associations.Variation partitioning was used to quantify the relative contributions of topography and space at three sampling scales and three life stages.Correlation analyses and torus-translation tests showed species abundance was mostly correlated with topographic wetness index,vertical distance from the channel network and convexity.Variation partitioning showed that pure topography,pure space and spatially structured topography explained about 2.1 %,41.2 % and 13.8 %of the variation in species distributions,respectively.For nine species,total topography fractions peaked in 20 m quadrats.For ten species,the pure space fractions peaked in 50 m quadrats.For many species,the total topography fraction andthe pure space fraction were larger for the most abundant life stages,which reflected the importance of sampling effect.However,some cases did not follow this trend suggesting that the effects of ecological processes such as habitat filtering,density dependence or dispersal limitation may exceed the sampling effects.In conclusion,we found that spatially structured topography and pure space primarily shaped the distribution of dominant tree species.Furthermore,their effects were both scale- and life stage-dependent.展开更多
基金supported by the Natural Science Foundation of China(41974124)the China Scholarship Council(201906440068).
文摘Walkaway VSP technology is commonly seen in the seismic development stage in the middle and late stages of the oilfield.Its advantage over conventional zero-offset VSP and non-zero well-source distance VSP is mainly due to the higher coverage of the Walkaway VSP acquisition process and the larger acquisition range.The resolution and signal-to-noise ratio are higher.Walkaway VSP technology has a very good application effect on solving complex structural problems and thin interbed reservoir problems.This paper mainly introduces a VSP constrained sparse spike inversion method based on high-precision VSP data.For the data acquired by the eight-azimuth Walkaway VSP in a work area of Bohai Gulf,a new method of 3D seismic-VSP joint seismic inversion is established.In the application of the actual work area,good inversion results based on Walkaway VSP data were obtained,and a new R24 small layer above the top boundary of the NmRIll oil group was depicted.This result meets the needs of development seismic technology and is used to solve thin interbed reservoirs exploration problems that have very important practical significance.
基金supported by the National Natural Science Foundation of China(31270562 and 31200329)the Chinese Forest Biodiversity Monitoring Network(29200931131101919)
文摘Topography and space are two important factors determining plant species assemblages in forest communities.Quantification of the contribution of these two factors in determining species distribution helps us to evaluate their relative importance in determining species assemblages.This study aims to disentangle the effect of topography and space on the distributions of 14 dominant species in a subtropical mixed forest.Spearman correlation analysis and the torustranslation test were used to test the species–habitat associations.Variation partitioning was used to quantify the relative contributions of topography and space at three sampling scales and three life stages.Correlation analyses and torus-translation tests showed species abundance was mostly correlated with topographic wetness index,vertical distance from the channel network and convexity.Variation partitioning showed that pure topography,pure space and spatially structured topography explained about 2.1 %,41.2 % and 13.8 %of the variation in species distributions,respectively.For nine species,total topography fractions peaked in 20 m quadrats.For ten species,the pure space fractions peaked in 50 m quadrats.For many species,the total topography fraction andthe pure space fraction were larger for the most abundant life stages,which reflected the importance of sampling effect.However,some cases did not follow this trend suggesting that the effects of ecological processes such as habitat filtering,density dependence or dispersal limitation may exceed the sampling effects.In conclusion,we found that spatially structured topography and pure space primarily shaped the distribution of dominant tree species.Furthermore,their effects were both scale- and life stage-dependent.
