Susanti Alawiyah
Department of Physics Engineering, Faculty of Mining and Petroleum Engineering Institut Teknologi Bandung, Bandung

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Journal : Journal of Engineering and Technological Sciences

Designing a Genetic Algorithm for Efficient Calculation in Time-Lapse Gravity Inversion Wahyudi, Eko Januari; Santoso, Djoko; Kadir, Wawan Gunawan Abdul; Alawiyah, Susanti
Journal of Engineering and Technological Sciences Vol 46, No 1 (2014)
Publisher : ITB Journal Publisher, LPPM ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (595.019 KB) | DOI: 10.5614/j.eng.technol.sci.2014.46.1.4

Abstract

As an advanced application of soft computation in the oil and gas industry, genetic algorithms (GA) can contribute to geophysical inversion problems in order to achieve better results and efficiency in the computational process. Time-lapse gravity responses to pore-fluid density changes can be modeled to provide the density distribution in the subsurface. This paper discusses the progress of work in inverse modeling of time-lapse gravity data using value encoding with alphabet formulation. The alphabet formulation was designed to provide the solution for positive and negative density change with respect to a reference value (0 gr/cc). The inversion was computed using a genetic algorithm as the optimization method. Working with genetic algorithms, time-intensive computational processes are a challenge, so the algorithm was designed in steps through the evaluation of a GA operator performance test. The performances of several combinations of GA operators (selection, crossover, mutation, and replacement) were tested with a synthetic model of a single-layer reservoir. Sharp boundaries of density changes in the reservoir layer were derived from interpretation of the averaged calculation of several model samples. Analysis showed that the combination of stochastic universal sample–multipoint crossover–quenched simulated annealing per generation–no duplicity achieved the most promising results.
ANNOTATION OF USING BOREHOLE TIME-LAPSE GRAVITY BY GENETIC ALGORITHM INVERSION FOR SUBSURFACE MODELING Gunawan, Indra; Wahyudi, Eko Januari; Alawiyah, Susanti; Kadir, Wawan Gunawan Abdul; Fauzi, Umar
Journal of Engineering and Technological Sciences Vol 52, No 2 (2020)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2020.52.2.2

Abstract

We present the annotation to a genetic algorithm (GA) method for an inverse synthetic subsurface density model using surface and borehole time-lapse gravity data. The objective of the inversion is to find the boundaries of the object area and background, where one bit of the chromosome represents the densities. The model that was used in this paper was a simple homogeneous body anomaly and a simplified real water mass injection model in order to argue that the code is suitable for field modeling. We show the influences of the existence of borehole gravity data and location towards the inversion, where the result indicates that an additional good borehole location could increase the success rate up to 13.33% compared to without gravity borehole data for the simple model and up to 4.39% for the field model. The inversion produced the best results when the borehole positions were placed in a state of symmetry towards the body object?s mass.