The Experts below are selected from a list of 150 Experts worldwide ranked by ideXlab platform
Gregory P Asner - One of the best experts on this subject based on the ideXlab platform.
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remote sensing of selective Logging in amazonia assessing limitations based on detailed field observations landsat etm and textural analysis
Remote Sensing of Environment, 2002Co-Authors: Gregory P Asner, Michael Keller, Rodrigo Pereira, Johan C ZweedeAbstract:We combined a detailed field study of forest canopy damage with calibrated Landsat 7 Enhanced Thematic Mapper Plus (ETM+) reflectance data and texture analysis to assess the sensitivity of basic broadband optical remote sensing to selective Logging in Amazonia. Our field study encompassed measurements of ground damage and canopy gap fractions along a chronosequence of postharvest regrowth of 0.5–3.5 years. We found that canopy damage and regrowth rates varied according to the Logging Method used, either conventional Logging or reduced impact Logging. Areas used to stage felled trees prior to transport, log decks, had the largest gap fractions immediately following cutting. Log decks were quickly colonized by early successional plant species, resulting in significant gap fraction decreases within 1.5 years after site abandonment. Although log decks were the most obvious damage areas on the ground and in satellite imagery, they accounted for only 1–2% of the total harvested area of the blocks studied. Other forest damage features such as tree-fall gaps, skid trails, and roads were difficult to recognize in Landsat reflectance data or through textural analysis. These landscape features could be only crudely resolved in the most intensively logged forests and within about 0.5 years following harvest. We found that forest damage within any of the landscape strata (decks, roads, skids, tree falls) could not be resolved with Landsat reflectance or texture data when the canopy gap fraction was <50%. The basic Landsat ETM+ imagery lacks the resolution of forest structural features required for quantitative studies of Logging damage. Landsat textural analyses may be useful for broad delineation of logged forests, but detailed ecological and biogeochemical studies will probably need to rely on other remote sensing approaches. Until spatial gradients of canopy damage and regrowth resulting from selective Logging operations in tropical forests in the Amazon region are resolved, the impacts of this land use on a continental scale will remain poorly understood. D 2002 Elsevier Science Inc. All rights reserved.
Yidong Cai - One of the best experts on this subject based on the ideXlab platform.
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evaluation of coal texture distributions in the southern qinshui basin north china investigation by a multiple geophysical Logging Method
International Journal of Coal Geology, 2015Co-Authors: Juan Teng, Yanbin Yao, Dameng Liu, Yidong CaiAbstract:Abstract Coal texture is indicative of coal mechanical strength, which is important not only for evaluating coalbed methane (CBM) reservoir permeability but also for evaluating the possibility of coal and gas outbursts in underground coal mining. This paper begins with a foundation of a geophysical Logging-based coal texture evaluation Method that compares the digital Logging data with the results from 108 coring samples. Then, the Method was applied to the analyses of coal textures in 39 CBM wells, the results of which are discussed in terms of the vertical distribution of coal textures in the study area. Finally, a ternary diagram based on thickness proportions of coal textures was used to identify reservoir compartments in the Zhengzhuang field of the southern Qinshui basin. The results show that undeformed coals are easily distinguished from cataclastic and granulated coals because of the high DEN and GR of undeformed coals. Meanwhile, cataclastic coal has lower response values of AC and LLD than granulated coal, which can be used in identifying cataclastic from granulated coal. A multiple geophysical Logging Method combining the log data of DEN, GR, AC, and LLD was provided for predication of the coal textures in the Zhengzhuang field. The predicated results show that the coal seam can be vertically divided into three to eight sub-layers, with a typical interbedded pattern of undeformed and cataclastic coals on the upper and lower parts and granulated coal in the middle at a relatively large thickness. The study area is divided into four major regions and 11 sub-regions based on the classification of coal texture types. The undeformed coal-dominated region is located in the southwestern part of the study area, indicating a low permeability in the coal reservoir. The granulated coal-dominated region is mainly in the northern and eastern parts of the study area and has resulted from deep burial and multi-period structural activities. The cataclastic coal-dominated region is in the middle of the study area; the coal reservoir in this region is possibly the most favorable for CBM production.
Jianshen Gao - One of the best experts on this subject based on the ideXlab platform.
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a new electrical imaging Logging Method in oil based mud for low resistivity formation based on concave electrode couples
Journal of Petroleum Science and Engineering, 2020Co-Authors: Jianshen Gao, Xin Liu, Jianpeng Zhao, Xicao XieAbstract:Abstract Electrical imaging Logging can provide high-resolution information and occupies a pivotal position in reservoir exploration and evaluation. To realize clear electrical imaging in high-resistivity oil-based mud (OBM), researchers have tried various Methods. In the existing Methods, there are some worrisome issues such as the challenge in clear imaging in low-resistivity formation, the complication and robustness in the inversion of quantitative interpretation and few obtained parameters etc. In this paper, a gratifying way with the help of concave electrode couple is presented and analyzed particularly to focus on the quantitative evaluation in low-resistivity formation. The imaging pad structure and its work principle are first introduced. Then, a systematical and mathematical statement is carried out to obtain desired formation resistivity and standoff between imaging pad and borehole wall. Furthermore, sensitivity analysis is implemented to make clear the performances of measured values including equivalent formation resistance, tool factor and calculated standoff under the influence of multiple parameters. Finally, several imaging tests are shown to demonstrate the effectiveness of this new Method presented in this paper. The results shown that profiting from the change of traditional electrode array to concave electrode couples, the formation resistivity and standoff between the pad and borehole wall in low-resistivity formation can be measured simultaneously. Another major advantage of this new Method is that the unknown OBM parameters are unnecessarily mastered, and the entire process is free from complicated iterative computation. This study provides another new choice for the electrical imaging Logging in OBM.
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review and analysis on the development and applications of electrical imaging Logging in oil based mud
Journal of Applied Geophysics, 2019Co-Authors: Jianshen Gao, Liming Jiang, Yanping Liu, Yunxia ChenAbstract:Abstract This review focuses on the overall development and applications of the electrical imaging Logging in oil-based mud (OBM) with the aims to help researchers learn more from past and extend more relevant study. Because of the normally larger resistivity of OBM than that of water-based mud (WBM), the imaging quality of conventional electrical imaging Logging Method is poor in OBM, resulting in the imperative requirement of the electrical imaging Logging Method and technology in OBM. The electrical imaging Logging in WBM is initially summarized. Then, the emphasis is on the attempt to acquire clear imaging in OBM. The main Methods include the development of conductive OBM, the mudcake-scrapped Method, the four-terminal measurement Method, the capacitive coupling Method and inversion processing etc. On the perspective of imaging results, the clear and quantitative resistivity imaging is more popular than the only qualitative results, and furthermore, more information can be obtained to uncover additional formation features, such as the formation dielectric permittivity image and the standoff image between the imaging pad and formation, which extends the interpretation and applications of electrical imaging Logging in OBM. This study will contribute to the development of electromagnetic Logging technique in OBM. The sufficient verification and interpretation of the imaging results in OBM and artificial intelligence-based data processing may be the improvement direction in the future.
Johan C Zweede - One of the best experts on this subject based on the ideXlab platform.
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remote sensing of selective Logging in amazonia assessing limitations based on detailed field observations landsat etm and textural analysis
Remote Sensing of Environment, 2002Co-Authors: Gregory P Asner, Michael Keller, Rodrigo Pereira, Johan C ZweedeAbstract:We combined a detailed field study of forest canopy damage with calibrated Landsat 7 Enhanced Thematic Mapper Plus (ETM+) reflectance data and texture analysis to assess the sensitivity of basic broadband optical remote sensing to selective Logging in Amazonia. Our field study encompassed measurements of ground damage and canopy gap fractions along a chronosequence of postharvest regrowth of 0.5–3.5 years. We found that canopy damage and regrowth rates varied according to the Logging Method used, either conventional Logging or reduced impact Logging. Areas used to stage felled trees prior to transport, log decks, had the largest gap fractions immediately following cutting. Log decks were quickly colonized by early successional plant species, resulting in significant gap fraction decreases within 1.5 years after site abandonment. Although log decks were the most obvious damage areas on the ground and in satellite imagery, they accounted for only 1–2% of the total harvested area of the blocks studied. Other forest damage features such as tree-fall gaps, skid trails, and roads were difficult to recognize in Landsat reflectance data or through textural analysis. These landscape features could be only crudely resolved in the most intensively logged forests and within about 0.5 years following harvest. We found that forest damage within any of the landscape strata (decks, roads, skids, tree falls) could not be resolved with Landsat reflectance or texture data when the canopy gap fraction was <50%. The basic Landsat ETM+ imagery lacks the resolution of forest structural features required for quantitative studies of Logging damage. Landsat textural analyses may be useful for broad delineation of logged forests, but detailed ecological and biogeochemical studies will probably need to rely on other remote sensing approaches. Until spatial gradients of canopy damage and regrowth resulting from selective Logging operations in tropical forests in the Amazon region are resolved, the impacts of this land use on a continental scale will remain poorly understood. D 2002 Elsevier Science Inc. All rights reserved.
K. O. Ruchko - One of the best experts on this subject based on the ideXlab platform.
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SELECTION OF LOW-RESISTIVITY RESERVOIRS AND DETERMINATION THE NATURE OF SATURATION ACCORDING TO THE DATA OF PULSED NEUTRON-NEUTRON Logging Method
Ukrainian State Geological Research Institute (UkrSGRI), 2018Co-Authors: V. O. Ruchko, K. O. RuchkoAbstract:An actual problem is improved material interpretation of geophysical studies of wells in geological sections with a complex structure. In support of this line of evidence obtained by the inflow of oil and gas reservoirs with complicated structure, among which the most important are reservoirs with low electrical resistance. A large amount of hydrocarbons from low-resistivity layers are the reason for their in-depth study. In the interpretation of geological and geophysical studies in low-reservoir have difficulty with solving such important geological problems as the selection of collectors, their determination the nature of saturation and definition of saturation parameters. In this paper we consider the possibility of solving these problems above according netron pulsed-neutron Logging (INNK) using the system of “Geopoisk”
