Bulletin of the Geological Society of Malaysia, Volume 72, November 2021, pp. 101 – 111
Nur Shafiqah Shahman1,2,*, Norazif Anuar1,2, Mohamed Elsaadany1,2, Deva Prasad Ghosh1,2
1 Department of Geoscience, Universiti Teknologi PETRONAS (UTP), 32610 Seri Iskandar, Perak, Malaysia
2 Centre of Excellence in Subsurface Seismic Imaging & Hydrocarbon Prediction (CSI), Universiti Teknologi PETRONAS (UTP), 32610 Seri Iskandar, Perak, Malaysia
* Corresponding author email address: nurshafiqah_hafish94@yahoo.com
Abstract: Over two decades, analysis of seismic attributes had been an integral part of seismic reflection interpretation. Seismic attributes are an influential assistance to seismic interpretation, delivering geoscientists with alternative images of structural (faults) and stratigraphic features (channels), which can be utilised as mechanisms to identify prospects, ascertain depositional environment and structural deformation history more rapidly even provide direct hydrocarbon indicators. The additional steps are obligatory to compute and interpret the attributes of faults and channels from seismic images, which are often sensitive to noise due to the characteristically computed as discontinuities of seismic reflections. Furthermore, on a conventional seismic profile or poor quality data, faults and channels are hard to visible. The current research review these geological structures through a case study of 3D seismic data from N-field in the viewpoint of Malay Basin. This study aimed to characterise the structure and stratigraphic features by using seismic attributes on the N-field below seismic resolution. Also, two different methods are proposed to improve seismic reflections, i.e., faults and channels that are hard to see on the conventional 3D data set. The first method, to detect faults in seismic data, which this paper employs the ant tracking attribute as a unique algorithm to be an advanced forwarding that introduces a new tool in the interpretation of fault. The effective implementation of ant tracking can be achieved when the output of other faults sensitive attributes are used as input data. In this work, the seismic data used are carefully conditioned using a signal. Chaos and variance that are sensitive to faults are applied to the seismic data set, and the output from these processes are used as input data that run the ant tracking attribute, which the faults were seen difficult to display on the raw seismic data. Meanwhile, for the second method, spectral decomposition was adopted to deliberate the way its method could be utilised to augment stratigraphic features (channels) of the N-field, where the channel is ultimately considered being one of the largest formations of the petroleum entrapment. The spectral decomposition analysis method is an alternative practice concentrated on processing S-transform that can offer better results. Spectral decomposition has been completed over the Pleistocene channels, and results propose that application of its methods directs to dependable implications. Respective channel in this area stands out more obviously within the specific frequency range. The thinner layer demonstrates higher amplitude reading at a higher frequency, and the thicker channel displays higher amplitude reading at a lower frequency. Implementation of spectral decomposition assists in deciding the channels that were placed within incised valleys and helps in recognising the orientation and the relative thickness of each channel. By doing this, the ant tracking attribute and spectral decomposition approach have generated the details of subsurface geologic features through attributes by obtaining enhanced reflections and channels and sharpened faults, respectively.
Keywords: Seismic attributes, faults, ant tracking, channels, spectral decomposition
DOI: https://doi.org/10.7186/bgsm72202108
