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The quest for conditional independence in prospectivity modeling： weights-of-evidence, boost weights-of-evidence, and logistic regression

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Frontiers of Earth Science 2016年第3期10卷 389-408页

作者： Helmut SCHAEBEN Georg SEMMLER department of geophysics and geoinformatics TU Bergakademie Freiberg Freiberg 09596 Germany

The objective of prospectivity modeling is prediction of the conditional probability of the presence T = 1 or absence T = 0 of a target T given favorable or prohibitive predictors B, or construction of a two classes {0,1} classification of T. A special case of logistic regression called weights-of-evidence （WofE） is geolo- gists＇ favorite method of prospectivity modeling due to its apparent simplicity. However, the numerical simplicity is deceiving as it is implied by the severe mathematical modeling assumption of joint conditional independence of all predictors given the target. General weights of evidence are explicitly introduced which are as simple to estimate as conventional weights, i.e., by counting, but do not require conditional independence. Complementary to the regres- sion view is the classification view on prospectivity modeling. Boosting is the construction of a strong classifier from a set of weak classifiers. From the regression point of view it is closely related to logistic regression. Boost weights-of-evidence （BoostWofE） was introduced into prospectivity modeling to counterbalance violations of the assumption of conditional independence even though relaxation of modeling assumptions with respect to weak classifiers was not the （initial） purpose of boosting. In the original publication of BoostWofE a fabricated dataset was used to ＂validate＂ this approach. Using the same fabricated dataset it is shown that BoostWofE cannot generally compensate lacking condi- tional independence whatever the consecutively proces- sing order of predictors. Thus the alleged features of BoostWofE are disproved by way of counterexamples, while theoretical findings are confirmed that logistic regression including interaction terms can exactly com- pensate violations of joint conditional independence if the predictors are indicators.

关键词： general weights of evidence joint conditionalindependence naive Bayes model Hammersley-Cliffordtheorem interaction terms statistical significance

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Spatiotemporal variability/stability analysis of NO_(2),CO,and land surface temperature(LST)during COVID-19 lockdown in Amman city,Jordan

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Geo-Spatial Information Science 2023年第3期26卷 540-557页

作者： Ali Almagbile Khaled Hazaymeh department of Geography Applied Geoinformatics LaboratoryYarmouk UniversityIrbidJordan

The massive lockdown of human socioeconomic activities and vehicle movements due to the COVID-19 pandemic in 2020 has resulted in an unprecedented reduction in pollutant gases such as Nitrogen Dioxide(NO_(2))and Carbon Monoxide(CO)as well as Land Surface Temperature(LST)in Amman as well as all countries around the *** this study,the spatial and temporal variability/stability of NO_(2),CO,and LST throughout the lockdown period over Amman city have been *** NO_(2) and CO column density values were acquired from Sentinel-5p while the LST data were obtained from MODIS satellite during the lockdown period from 20 March to 24 April in 2019,2020,and *** statistical analysis showed an overall reduction in NO_(2) in 2020 by around 27% and 48% compared to 2019 and 2021,***,an increase of 7% in 2021 compared to 2019 was observed because almost all anthropogenic activities were allowed during the *** temporal persistence showed almost constant NO2 values in 2020 over the study area throughout the lockdown *** addition,a slight decrease in CO(around 1%)was recorded in 2020 and 2021 compared to the same period in *** on human activities resulted in an evident drop in LST in 2020 by around 13%and 18% less than the 5-year average and 2021 *** study concludes that due to the restrictions imposed on industrial activities and automobile movements in Amman city,an unprecedented reduction in NO_(2),CO,and LST was recorded.

关键词： Air quality COVID-19 lockdown spatiotemporal analysis NO_(2) CO Land Surface Temperature(LST) Sentinel-5p and MODIS satellites

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Estimation of petrophysical parameters using seismic inversion and neural network modeling in Upper Assam basin, India

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Geoscience Frontiers 2019年第3期10卷 1113-1124页

作者： Triveni Gogoi Rima Chatterjee department of applied geophysics Indian Institute of Technology (Indian School of Mines)

Estimation of petrophysical parameters is an important issue of any reservoirs. Porosity, volume of shale and water saturation has been evaluated for reservoirs of Upper Assam basin, located in northeastern India from well log and seismic data. Absolute acoustic impedance(AAI) and relative acoustic impedance(RAI) are generated from model based inversion of 2-D post-stack seismic data. The top of geological formation, sand reservoirs, shale layers and discontinuities at faults are detected in RAI section under the study area. Tipam Sandstone(TS) and Barail Arenaceous Sandstone(BAS) are the main reservoirs,delineated from the logs of available wells and RAI section. Porosity section is obtained using porosity wavelet and porosity reflectivity from post-stack seismic data. Two multilayered feed forward neural network(MLFN) models are created with inputs: AAI, porosity, density and shear impedance and outputs: volume of shale and water saturation with single hidden layer. The estimated average porosity in TS and BAS reservoir varies from 30% to 36% and 18% to 30% respectively. The volume of shale and water saturation ranges from 10% to 30% and 20% to 60% in TS reservoir and 28% to 30% and 23% to 55% in BAS reservoir respectively.

关键词： Upper Assam basin Relative acoustic impedance Porosity Volume of shale Water saturation Neural network model

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环境地球物理学:新概念(英文)

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地学前缘 2001年第1期8卷 47-57页

作者： GueliS.Vakhromeev department of applied geophysics and geoinformatics

环境地球物理学是勘探地球物理学新科学和新应用分支。环境地球物理定义为用仪器对以各种物理场形式出现的物质和能量进行测量进而对环境进行多重目的监控。环境地球物理再细分为灾害、防护及医学环境地球物理。对环境物理异常及其天然... 详细信息

环境地球物理学是勘探地球物理学新科学和新应用分支。环境地球物理定义为用仪器对以各种物理场形式出现的物质和能量进行测量进而对环境进行多重目的监控。环境地球物理再细分为灾害、防护及医学环境地球物理。对环境物理异常及其天然和人工源进行了整理、分类。文中说明了地质生态目标和过程的静态和动态物理地质模型系统 ,以及多元建模原则。环境地球物理场的变化可作为地质环境演变部分或全部丧失其稳定性乃至被破坏的明显标志 ,且意义重大。灾害事件 (地震、滑坡、海震等 )的预报被证明是可能的。这些灾祸是各种技术因素或触发地质过程的结果 ,它们发展潜隐而发生突然 ,正如缓发生态地质炸弹一样。

关键词：环境地球物理学灾害地球物理防护地球物理医学地球物理地质生态目标

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An improved reverse time migration for subsurface imaging over complex geological structures:A numerical study

Energy Geoscience

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Energy Geoscience 2024年第2期5卷 290-297页

作者： Alok Kumar Routa Priya Ranjan Monahty department of applied geophysics IIT(ISM)DhanbadJharkhandIndia

In seismic exploration,it is a critical task to image and interpret different seismic signatures over complex geology due to strong lateral velocity contrast,steep reflectors,overburden strata and dipping *** understand the behavior of these seismic signatures,nowadays Reverse Time Migration(RTM)technique is used extensively by the oil&gas *** the extrapolation phase of RTM,the source wavefield needs to be saved,which needs high storage memory and large computing *** two are the main obstacles of RTM for production *** order to overcome these disadvantages,in this study,a second-generation improved RTM technique is *** this improved form,a shift operator is introduced at the time of imaging condition of RTM algorithm which is performed automatically both in space and time *** effort is made to produce a better-quality image by minimizing the computational time as well as numerical *** proposed method is applied over various benchmark models and validated by implementing over one field data set from the Jaisalmer Basin,*** the analysis,it is observed that the method consumes a minimum of 45%less storage space and reduce the execution time by 20%,as compared to conventional *** proposed RTM is found to work efficiently in comparison to the conventional RTM both in terms of imaging quality and minimization of numerical artefacts for all the benchmark models as well as field data.

关键词： Imaging condition Reverse time migration(RTM) Seismic imaging Velocity-depth model Wave propagation

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Prediction of abnormal pressure from AVO velocities over“Safety”field,onshore Niger delta,Nigeria

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Petroleum Research 2021年第1期6卷 26-41页

作者： O.Abiola T.G.Ayenuro department of applied geophysics Federal University of TechnologyAkureNigeria

Abnormal pressure prediction was undertaken in“Safety”field,onshore Niger Delta,Nigeria using amplitude variation with offset(AVO)velocities *** of the methods used form an integral part of a process that produces AVO Analysis,AVO velocity inversion,extraction of seismic velocity from AVO velocities inversion results and pore pressure *** pressure predicted from the seismic velocity has a better resolution than the pressure predicted from the interval transit *** pore pressure within the field ranges from 14.7psi to *** and underpressured zones were delineated on the field from the pressure predicted from the seismic *** the field,the overpressured zones were delineated at depth 6855 fte7802 *** pressure top was delineated at a depth of 6855 ft with a pore pressure of 3053psi and a corresponding hydrostatic pressure of *** under-pressured zones were also delineated at depth 7883 fte9288 *** under pressure top was delineated at a depth of 7883 ft with a pressure of 1093psi and a corresponding hydrostatic pressure of *** values within the over pressure zone ranges from 23%to 53%which could be considered as relatively *** could be as a result of the fact that the pore fluid cannot be expelled rapidly thereby causing the pore fluid to increase rapidly since they are no longer compacted;thus leading to *** a result of overpressure top which is directly above the reservoir top within the shale zone,drilling this reservoir vertically could not be suggested so as to avoid possible blow *** was also observed that the primary cause or mechanism of overpressure within this field could be disequilibrium compaction.

关键词： Abnormal pressure Amplitude variation with offset Velocities information Pore pressure Disequilibrium compaction

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Determination of gas reservoir(s) using AVO inversion within “XY” field offshore Niger Delta

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Petroleum Research 2019年第1期4卷 52-58页

作者： B.S.Ajanaku O.J.Akintorinwa department of applied geophysics Federal University of TechnologyAkureNigeria

The AVO inversion analysis of pre-stack seismic data of“XY”field located within the offshore,Niger Delta Basin has been considered in this research work with the aim of using AVO inversion to delineate gas reservoirs within the *** different inversion techniques are carried out in order to obtain accurate reservoir *** conventional AVO inversion analysis of the field do not identify the gas reservoirs clearly as there are other zones without gas with similar signatures,however,the cross-plots analysis of elastic parameters and the inverted volumes are used to delineate two gas reservoirs at 2000 and 2100 ***,the inversion techniques help to map the reservoir zone in a better way by increasing the vertical *** inversion analysis as used in this research help for better understanding of the physical properties of the delineated reservoirs.

关键词： Pre-stack seismic Reservoir AVO inversion Cross-plots Compressional Shear wave

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Sequence stratigraphy and depositional sequence interpretation:A case study of“George”Field,offshore Niger Delta,Nigeria

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Petroleum Research 2018年第1期3卷 25-32页

作者： O.Abiola M.T.Olowokere J.S.Ojo department of applied geophysics Federal University of TechnologyAkureNigeria

The seismic sequence stratigraphic analysis revealed four depositional sequences(DS-1,DS-2,DS-3 and DS-4).The accompanying systems tracts were interpreted and mapped in the study area based on the log motifs of the reference well and the spatial distribution of the recognized constrained surfaces:maximum flooding surfaces(MFSs),sequence boundaries(SBs)and transgressive surfaces(TSs)on the seismic *** systems in the study area comprise lowstand systems tracts(LSTs),transgressive systems tracts(TSTs)and highstand systems tracts(HSTs).The LSTs are represented by coeval facies dominated by deposition basinward of the shelf-edge during maximum regression and are characterized by shallow-water deposition from gravity flows and/or traction processes within the shelf-edge or canyon-head *** sediments associated with lowstand systems tracts recognized in the study area are the fluvial channel sands and slope fans(SF).The transgressive sand units were interpreted as shoreface sands deposited in the shelf region during rising sea *** systems tracts are characterized by intervals of coarsening and shallowing upwards,with both fluvial and deltaic sands prograding laterally into neritic *** the study area,the units are very *** highstand and lowstand system tracts exhibit blocky log patterns and are associated with the reservoirs while the transgressive system tracts serve as seals to the *** environment of sediments deposition in this area is delta plain,shelf,slope to toe of slope.

关键词： Sequence stratigraphic analysis Depositional systems Log motifs Systems tracts Environment of sediments deposition

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Myanmar-Andaman-Sumatra Subduction Margin Revisited:Insights of Arc-Specific Deformations

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Journal of Earth Science 2017年第4期28卷 683-694页

作者： Prosanta Kumar Khan Sk Shamim Manoranjan Mohanty Prabhat Kumar Jayashree Banerjee department of applied geophysics Indian Institute of Technology(ISM)Dhanbad 826 004India

We address the role of the concave and convex arcs （as observed from the subducting plate） on the deformation occurring along the Myanmar-Andaman-Sumatra margin. We categorize the pre- and post-seismic deformations of the lithosphere using earthquake database occurring either prior to 26th December 2004 Mw 9.3 off-Sumatra mega-event or after the incidence. Analysis under pre-seismic domain shows that area near Sumatra records highest seismicity, which largely drops in the area past the North Andaman, and further increases towards north. Shallowest depth and mini- mum dip of the subducting lithosphere is recorded at the central segment where the arc transformed into concave shape. The annual moment energy release during earthquake decreases to more than two orders of magnitude past the North Andaman towards north under post-seismic deformation phase. Higher depths of continuity of events are presumably associated with more dipping Benioff zones in both the Indo-Myanmar and Andaman-Nicobar convex arcs. These observations obviously account for tectonic subdivision of the margin near concave shape arc around the central part. Absence of vol- canism, presence of splay faults in the back-arc, sharp reduction in seismicity near central segment are interpreted to be caused by major tectonic impact of the NNE-ward converging buoyant Ninety-east Ridge against the Asian Plate. Shallowest dip, small elastic thickness, weak converging Indian litho- sphere, and evidences of series of en-echelon blocks off the eastern side of the broken northern Ninety- east Ridge might be incapable of generating great earthquake in this area.

关键词： Myanmar-Andaman-Sumatra margin double arc Ninety-east Ridge buoyancy.

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Geometries, stabilities, and electronic properties analysis in In_nNi^((0,±1)) clusters: Molecular modeling and DFT calculations

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Chinese Physics B 2017年第8期26卷 130-139页

作者：史顺平张传瑜赵晓凤李侠闫珉蒋刚 department of applied Physics College of Geophysics Chengdu University of Technology Institute of Atomic and Molecular Physics Sichuan University

Density functional theory（DFT） with the B3 LYP method and the SDD basis set is selected to investigate In_nNi,In_nNi^-, and In_nNi~＋（n = 1–14） clusters. For neutral and charged systems, several isomers and different multiplicities are studied with the aim to confirm the most stable structures. The structural evolution of neutral, cationic, and anionic In_nNi clusters, which favors the three-dimensional structures for n = 3–14. The main configurations of the In_nNi isomers are not affected by adding or removing an electron, the order of their stabilities is also nearly not affected. The obtained binding energy exhibits that the Ni-doped In_（13） cluster is the most stable species of all different sized clusters. The calculated fragmentation energy and the second-order energy difference as a function of the cluster size exhibit a pronounced even–odd alternation phenomenon. The electronic properties including energy gap（E_g）, adiabatic electron affinity（AEA）, vertical electron detachment energy（VDE）, adiabatic ionization potential energy（AIP）, and vertical ionization potential energy（VIP） are studied. The total magnetic moments show that the different magnetic moments depend on the number of the In atoms for charged In_nNi. Additionally, the natural population analysis of In_nNi^（（0,±1）clusters is also discussed.

关键词： InnNi(0,±1) clusters stability electronic property density functional theory

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