INNOVATIVE METHODOLOGY AND ALGORITHMS FOR SOLVING GEOPHYSICAL INVERSE PROBLEMS

• Main Author: PRAJAPATI, SRICHAND
• Format: Thesis
• Language: English
• Published: 2017
• Subjects: QE Geology
• Online Access: http://utpedia.utp.edu.my/id/eprint/22058/1/PhD-Srichand_Prajapati_G02126.pdf; http://utpedia.utp.edu.my/id/eprint/22058/

The presence of shallow low velocity zone in the subsurface, which can severely affects the seismic data quality has long been recognized as a significant problem in the seismic data processing. Due to the complex wave propagation and anelastic losses, it becomes more complicated and highly challenging and because of the complex faulting, converted wave (birefringence anisotropy) play a significant role in characterization of reservoir. The reflected events in such region appear with weak amplitude and lower frequency content, which is often refers to as Q-attenuation or intrinsic loss. In offshore peninsular Malaysia major hydrocarbon bearing fields which are affected by shallow low velocity and therefore data quality in Malaysian basins often suffers from serious wipeouts due to shallow gas or gas leaking from a deep reservoir. The existing conventional inversion approach does not provide significant improvement in low velocity imaging, causes serious wipeouts from a deep reservoir. This research thesis objective is to develop innovative methodology and algorithm for inverse problem in exploration geophysics. The proposed methodologies and algorithms are based on full-waveform inversion and contribute to this largely unsolved problem. Analysis of converted waves provide insight of anisotropy characteristics in and around the reservoir. In principle, full waveform inversion (FWI) is a data-driven strategy wave equation based and highly non-linear approach. It is an iterative forward and inverse modeling procedure that takes advantage of full information contained in recorded seismic data. Using minimization of the differences between the observed and calculated simulated data, FWI provide high resolution and accurate subsurface properties.