Based on the cores from 47 wells and logging data of 130 wells,the main types of sand bodies in the shallow water delta of the Chang 8_(2) sub-member in the Triassic Yanchang Formation,Longdong Area,Ordos Basin were c...Based on the cores from 47 wells and logging data of 130 wells,the main types of sand bodies in the shallow water delta of the Chang 8_(2) sub-member in the Triassic Yanchang Formation,Longdong Area,Ordos Basin were comprehensively analyzed,the distribution characteristics of sand bodies more than 20 m thick were identified,and the genetic types of the thick sand bodies were sorted out.In this region,thick-bed sand bodies can be divided into two types according to the shape and position:type 1 is the sand body in wide strip and is distributed between the average high water mark and the average low water mark;type 2 is distributed on both sides of the average low water mark and is in irregular lump shape.Based on the principle of the volume distribution of sediments and the change rule of accommodation space,the genetic models of two types of thick-bed sand bodies in the Chang 8_(2) sub-member are superimposed distributary channel sand bodies in high accommodation space and superimposed composite sand bodies in low accommodation space.展开更多
Currently, the historical archive images of Landsat family sensors are probably the most effective data products for tracking global longitudinal changes since the 1970 s. However, the issue of the degree and extent o...Currently, the historical archive images of Landsat family sensors are probably the most effective data products for tracking global longitudinal changes since the 1970 s. However, the issue of the degree and extent of cloud coverage is always a challenge and varies distinctively worldwide. So far, acquisition probability（AP） analyses of cloud cover（CC） of Landsat observations have been conducted with different sensors at regional scale. To our knowledge, CC probability analysis for the newly-launched Landsat-8 Operational Land Imager（OLI） across China is not reported. In this paper, monthly, seasonal, and annual APs for Landsat OLI（44,228 in total） images over China acquired from April 2013 to October 2016 with various CC thresholds were analyzed. The results showed that： first, the cumulative average APs of all OLI data over China at the CC thresholds ≤30% was about 49.6% which illustrated the availability of OLI imagery across China. Second, the spatial patterns of 10%, 20%, and 30% CC thresholds of OLI observations, coincided well with the precipitation distributions separated by the respective 200 mm, 400 mm, and 800 mm isohyetal lines. Third, the APs of images with the 30% CC threshold are the highest in autumn and winter especially in October of 58.7%, while the corresponding lowest probability occurred in June of 41.0%. Finally, the spatial differences in APs of targeted images with ≤30% CC thresholds were quite significant. At regional scales, the arid and semi-arid areas, Inland River and Songliao River basins, and northwestern side of the Hu Huanyong population line had the larger probabilities of obtaining high-quality images. Our study suggested that OLI imagery satisfy the data requirements needed for land surface monitoring, although there existed obvious spatio-temporal differences in APs over China at the 30% CC threshold.展开更多
基金Supported by the National Basic Research Program of China (973 Program)(2014CB239000)China Petroleum Scientific Research and Technology Development Project (YJXK2019-16)。
文摘Based on the cores from 47 wells and logging data of 130 wells,the main types of sand bodies in the shallow water delta of the Chang 8_(2) sub-member in the Triassic Yanchang Formation,Longdong Area,Ordos Basin were comprehensively analyzed,the distribution characteristics of sand bodies more than 20 m thick were identified,and the genetic types of the thick sand bodies were sorted out.In this region,thick-bed sand bodies can be divided into two types according to the shape and position:type 1 is the sand body in wide strip and is distributed between the average high water mark and the average low water mark;type 2 is distributed on both sides of the average low water mark and is in irregular lump shape.Based on the principle of the volume distribution of sediments and the change rule of accommodation space,the genetic models of two types of thick-bed sand bodies in the Chang 8_(2) sub-member are superimposed distributary channel sand bodies in high accommodation space and superimposed composite sand bodies in low accommodation space.
基金National Natural Science Foundation of China,No.41430861National Key Research and Development Program of China,No.2016YFC0503500Opening Fund of Key Laboratory of Poyang Lake Wetland and Watershed Research,Ministry of Education,Jiangxi Normal University,No.PK2016004
文摘Currently, the historical archive images of Landsat family sensors are probably the most effective data products for tracking global longitudinal changes since the 1970 s. However, the issue of the degree and extent of cloud coverage is always a challenge and varies distinctively worldwide. So far, acquisition probability（AP） analyses of cloud cover（CC） of Landsat observations have been conducted with different sensors at regional scale. To our knowledge, CC probability analysis for the newly-launched Landsat-8 Operational Land Imager（OLI） across China is not reported. In this paper, monthly, seasonal, and annual APs for Landsat OLI（44,228 in total） images over China acquired from April 2013 to October 2016 with various CC thresholds were analyzed. The results showed that： first, the cumulative average APs of all OLI data over China at the CC thresholds ≤30% was about 49.6% which illustrated the availability of OLI imagery across China. Second, the spatial patterns of 10%, 20%, and 30% CC thresholds of OLI observations, coincided well with the precipitation distributions separated by the respective 200 mm, 400 mm, and 800 mm isohyetal lines. Third, the APs of images with the 30% CC threshold are the highest in autumn and winter especially in October of 58.7%, while the corresponding lowest probability occurred in June of 41.0%. Finally, the spatial differences in APs of targeted images with ≤30% CC thresholds were quite significant. At regional scales, the arid and semi-arid areas, Inland River and Songliao River basins, and northwestern side of the Hu Huanyong population line had the larger probabilities of obtaining high-quality images. Our study suggested that OLI imagery satisfy the data requirements needed for land surface monitoring, although there existed obvious spatio-temporal differences in APs over China at the 30% CC threshold.
