trend surface analysis
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2021 ◽  
Vol 22 (4) ◽  
pp. 231
Author(s):  
Hidayat Hidayat ◽  
Marjiyono Marjiyono ◽  
Zulilmatul S Praromadani ◽  
Januar H.Setiawan ◽  
G.M. Lucki Junursyah ◽  
...  

A study using gravity methods in the Banyumas Basin, located in the southern part of Central Java, Indonesia had been conducted to generate a map for regional geological features in sub-volcanic basin related to petroleum system. This study used the first and second-order of Trend Surface Analysis (TSA) to separate gravity anomaly into regional and residual components. Matrix inversion is applied to obtain constants values for both the first and second-order of TSA. To interpret geological features related to oil and gas study, residual components are used for gravity anomaly. Residual anomaly is also compared for both first and second order of TSA with a regional geological map to validate the result. Residual anomaly from the second order of TSA showed a very comparable result to geological features, as shown in the regional geological map, compared to those of the first order of TSA. These results also showed a strong contrast of some important geological features such as the Gabon-Nusakambangan Formation outcrop, Karangbolong outcrop, and the eastern part of the south Serayu mountain arc. This study also displayed two potential subbasins i.e Citanduy and Majenang sub-Basin that might be a possible setting in which source rocks of the Banyumas Basin were deposited. From this study, it can be concluded that TSA showed a reliable result of separating gravity anomaly data set into regional and residual components.Keywords: Gravity anomaly, Banyumas Basin, petroleum system, trend surface analysis (TSA).


2021 ◽  
pp. 102-115
Author(s):  
Purwaditya Nugraha ◽  
Nono Agus Santoso

The separation of regional anomalies and residual anomalies in gravity data is an important part in interpreting gravity data. This process aims to obtain gravity anomalies that have been associated with exploration targets. The Trend Surface Analysis method is a mathematical approach to the earth field that can be used to separate maps into regional components and local components. The application of this method into gravity data can be used to separate regional anomalies and residual anomalies. The process of processing the trend surface analysis method can be done using Microsoft Excel. This method is tested first on synthetic gravity data, the purpose of this test is to determine the performance of the trend surface analysis method in performing anomaly separation. Based on the test results of the trend surface analysis method on synthetic gravity data, it was found that this method was quite good at separating regional anomalies and residual anomalies. This is evidenced by the anomalous pattern that is already the same between the regional gravity anomaly resulting from the separation of the anomaly using the trend surface analysis method and the regional anomaly resulting from synthetic data. The same anomaly pattern can also be seen in the residual anomaly resulting from the separation of the anomaly using the trend surface analysis method with the residual anomaly resulting from synthetic data. The application of the trend surface analysis method to field data has been carried out by producing regional anomalies and residual anomalies. This method is very good at separating regional anomalies and residual anomalies, especially in regional anomalies located at deep depths.Pemisahan anomali regional dan anomali residual pada data gayaberat merupakan bagian penting dalam melakukan interpretasi data gayaberat. Proses ini bertujuan untuk mendapatkan anomali gayaberat yang sudah berasosiasi dengan target eksplorasi. Metode Trend Surface Analysis merupakan teknik pendekatan matematika pada bidang kebumian yang dapat digunakan untuk memisahkan peta kedalam komponen regional dan komponen lokal. Penerapan metode ini ke dalam data gayaberat dapat digunakan untuk memisahkan anomali regional dan anomali residual. Proses pengolahan metode trend surface analysis dapat dilakukan dengan menggunakan microsoft excel. Metode ini diuji terlebih dahulu pada data gayaberat sintetis, tujuan pengujian ini adalah untuk mengetahui performa metode trend surface analysis dalam melakukan pemisahan anomali. Berdasarkan hasil pengujian metode trend surface analysis pada data gayaberat sintetis didapatkan bahwa metode ini cukup baik dalam memisahkan anomali regional dan anomali residual. Hal ini dibuktikan pada pola anomali yang sudah sama antara anomali gayaberat regional hasil pemisahan anomali metode trend surface analysis dengan anomali regional hasil data sintetis. Pola anomali yang sama juga dapat dilihat pada anomali residual hasil pemisahan anomali metode trend surface analysis dengan anomali residual hasil data sintetis. Penerapan metode trend surface analysis pada data lapangan telah dilakukan dengan menghasilkan anomali regional dan anomali residual. Metode ini sangat baik dalam memisahkan anomali regional dan anomali residual terutama pada anomali regional yang berada pada kedalaman dalam


2021 ◽  
Author(s):  
Wei He ◽  
Wen-jie Yu ◽  
Guang-jia Zhang ◽  
Sha Liao ◽  
Qi Wang ◽  
...  

Abstract BackgroundEchinococcosis is a global zoonotic parasitic disease caused by the larvae of Echinococcus, which affects both humans and animals. In China, this disease is highly endemic in Sichuan Province. In this study, we investigated the prevalence and spatial distribution characteristics of human echinococcosis at the township level in Sichuan province, so as to provide a reference for the development of precise prevention and control strategies in the future.MethodsWe explored the prevalence of echinococcosis using the B-ultrasonography diagnostic method in Sichuan province between 2016 and 2019, where patients and transmission conditions had been identified in the past. All data were inputted using Epi-Info software, while SPSS software was used for statistical analysis. We then employed ArcGIS software to draw the spatial distribution map and perform trend surface analysis. Finally, Geoda software was used to analyze spatial autocorrelation and draw Lisa clustering map.ResultsA total of 2 542 135 people from 649 towns in 35 counties of Sichuan province were screened for echinococcosis, of which 11 743 echinococcosis patients were detected. The prevalence of echinococcosis in humans was 0.462%, among which the occurrence of cystic echinococcosis [CE] was 0.221%, while that of alveolar echinococcosis [AE] was 0.244%. We also observed that the predominance of echinococcosis in humans decreased gradually from west to east and from north to south based on the results of the spatial distribution map and trend surface analysis. The Global Moran's I index was 0.77 (Z = 32.07, P < 0.05), which indicated that the prevalence of echinococcosis in humans was spatially clustered, exhibiting a significant spatial positive correlation. Further, the findings of local spatial autocorrelation analysis revealed that the “high-high” concentration areas were primarily located in some townships in the northwest of Sichuan province. On the other hand, the “low-low” concentration areas were predominantly located in some townships in the southeast of Sichuan province. ConclusionOur findings demonstrated that the prevalence of echinococcosis in humans of Sichuan province is following a downward trend, implying that the current prevention and control work has achieved some substantial outcomes. However, the prevalence in humans at the township level is widely distributed and differs greatly, with a clear clustering in space. Therefore in the future, precise prevention and control strategies should be formulated for clusters, particularly strengthening the “high-high” clusters at the township level.


2021 ◽  
Author(s):  
P Wozniakowska ◽  
D W Eaton ◽  
C Deblonde ◽  
A Mort ◽  
O H Ardakani

The Western Canada Sedimentary Basin (WCSB) is a mature oil and gas basin with an extraordinary endowment of publicly accessible data. It contains structural elements of varying age, expressed as folding, faulting, and fracturing, which provide a record of tectonic activity during basin evolution. Knowledge of the structural architecture of the basin is crucial to understand its tectonic evolution; it also provides essential input for a range of geoscientific studies, including hydrogeology, geomechanics, and seismic risk analysis. This study focuses on an area defined by the subsurface extent of the Triassic Montney Formation, a region of the WCSB straddling the border between Alberta and British Columbia, and covering an area of approximately 130,000 km2. In terms of regional structural elements, this area is roughly bisected by the east-west trending Dawson Creek Graben Complex (DCGC), which initially formed in the Late Carboniferous, and is bordered to the southwest by the Late Cretaceous - Paleocene Rocky Mountain thrust and fold belt (TFB). The structural geology of this region has been extensively studied, but structural elements compiled from previous studies exhibit inconsistencies arising from distinct subregions of investigation in previous studies, differences in the interpreted locations of faults, and inconsistent terminology. Moreover, in cases where faults are mapped based on unpublished proprietary data, many existing interpretations suffer from a lack of reproducibility. In this study, publicly accessible data - formation tops derived from well logs, LITHOPROBE seismic profiles and regional potential-field grids, are used to delineate regional structural elements. Where seismic profiles cross key structural features, these features are generally expressed as multi-stranded or en echelon faults and structurally-linked folds, rather than discrete faults. Furthermore, even in areas of relatively tight well control, individual fault structures cannot be discerned in a robust manner, because the spatial sampling is insufficient to resolve fault strands. We have therefore adopted a structural-corridor approach, where structural corridors are defined as laterally continuous trends, identified using geological trend surface analysis supported by geophysical data, that contain co-genetic faults and folds. Such structural trends have been documented in laboratory models of basement-involved faults and some types of structural corridors have been described as flower structures. The distinction between discrete faults and structural corridors is particularly important for induced seismicity risk analysis, as the hazard posed by a single large structure differs from the hazard presented by a corridor of smaller pre-existing faults. We have implemented a workflow that uses trend surface analysis based on formation tops, with extensive quality control, combined with validation using available geophysical data. Seven formations are considered, from the Late Cretaceous Basal Fish Scale Zone (BFSZ) to the Wabamun Group. This approach helped to resolve the problem of limited spatial extent of available seismic data and provided a broader spatial coverage, enabling the investigation of structural trends throughout the entirety of the Montney play. In total, we identified 34 major structural corridors and number of smaller-scale structures, for which a GIS shapefile is included as a digital supplement to facilitate use of these features in other studies. Our study also outlines two buried regional foreland lobes of the Rocky Mountain TFB, both north and south of the DCGC.


2020 ◽  
Vol 9 (11) ◽  
pp. e4369119858
Author(s):  
Antonio Samuel Alves da Silva ◽  
Rômulo Simões Cezar Menezes ◽  
Borko Stosic

A precipitação no Nordeste do Brasil (NE) é caracterizada por apresentar alta variabilidade temporal e espacial. No entanto, a disponibilidade de dados de precipitação ainda é limitada nesta região, por vários motivos. O Acesso a dados de precipitação fornece informações úteis para melhor entender a distribuição da chuva e apoiar gerenciamento do ecossistema. Neste artigo, apresentamos o programa Guarda Chuvas, o qual viabiliza o acesso e visualização de dados passados de precipitação pluviométrica do estado de Pernambuco, NE, Brasil, por meio de uma interface de fácil uso. O método de interpolação, trend surface analysis, foi utilizado para estimar a precipitação mensal () para o estado de Pernambuco em uma grade com resolução de 0,01 grau, totalizando 81.544 séries mensais de precipitação distribuídas espacialmente para estado de Pernambuco. O programa foi implementado em linguagem C, com uma interface gráfica construída utilizando interface de programação de aplicativos para o Windows. As séries históricas fornecidas pelo programa podem ser usadas como insumo para modelos de simulação e apoiar estudos direcionados ao desenvolvimento de políticas agrícolas, hídricas, ambientais e socioeconômica para o estado de Pernambuco. Além do interesse regional nas informações fornecidas pelo programa, a abordagem atual deve ser considerada útil para aplicações em outras partes do Brasil e do mundo.


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