15034

13532

كارشناسي ارشد

اكتشاف معدن

اصفهان : دانشگاه صنعتي اصفهان

1398

چهارده، 72ص. : مصور، جدول، نمودار

نادر فتحيان پور

محمد ابطحي فروشاني، سعيد مهدوي

1398/06/24

كتابنامه

مندسي معدن

مهندسي معدن

1398/06/24

2558490

Application of Modified DownHill Simplex Method in Gravity Data Inversion Raziyeh Jafari Raziye jafari22@gmail com July 2019 Department of Mining Engineering Isfahan University of Technology Isfahan 84156 83111 IranLanguage Persian Degree M Sc Supervisor Dr Nader Fathianpour fathian@cc iut ac irAbstractGeophysical methods are considered as the most important and efficient methods for mineralexploration Among them the gravity method is widely used in the early stages of oil andgas as well as salt domes exploration Due to inherent limitations such as inadequate numberof data noise and device limitations the 2D 3D geologically consistent interpretation andmodeling of gravity data is often necessary Inverse modeling is a numerical tool forobtaining 2D 3D images of subsurface structures using measured data In current study amodified downhill simplex method is used to invert gravity data collected from Rudan regionin the Hormozgan province This method is a non derivative geometric method that workswith the objective function values at the vertices of the simplex polygonal In order to modelthe negative anomaly of the probable hidden salt dome at the west of the Rudan region theTalvani s 2D polygonal forward modeling approach was used in current study A number of6 profiles encompassing the low Bouguer anomaly at the west part of the study area wereselected as the inputs for the inverse modeling program written in MATLAB environment For this purpose the response of individual and hybrid 2D polygonal models with different2D polygonal cross sectional shapes was computed and compared with the residual anomalyafter removing the third order regional trend In inverse modeling the results of the modifieddownhill simplex method are compared with other non gradient inversion methods such asgenetic algorithm by applying upper and lower bounds on model parameters It was foundthat although the RMS error for the genetic and simplex algorithms were 0 08 and 0 33respectively but the run time for the recovered final model in the genetic algorithm is muchlonger However the performance of the downhill simplex method is better than the geneticalgorithm in terms of number of iterations in inverse modeling It should also be noted thatalthough the global optimization algorithms such as those employed in current study arecapable of ultimately finding the minimum of the objective function through searching inthe model parameter space in a longer time but through applying different constraints a realand geologically consistent and valid results was obtained using downhill simplex approach Keywords Gravity data Forward and Inverse modeling Downhill simplex Salt domes Talvani s2D polygonal model

نادر فتحيان پور

محمد ابطحي فروشاني، سعيد مهدوي