Seismic attributes aided fault detection and enhancement in the Sirte Basin, Libya

Abstract

Cambrian-Ordovician and Upper Cretaceous reservoir formations, the primary producing formations in the Sirte Basin, Libya have complex structures which affect the performance of the reservoirs. It is critical to understand the complicated relationships between fault networks, fractures, and stratigraphy of the area for future field development. However, detecting faults especially subtle faults and fractures is a challenging task using conventional seismic data due to the low signal-to-noise ratio. Seismic attributes provide effective tools in identifying and enhancing fault and fracture interpretation beyond the seismic resolution of the conventional seismic data. In this study, we focus on coherence and curvature attributes extracted from the poststack 3D seismic data acquired in the central Sirte Basin to delineate subtle fault and fracture zones. We applied a median filter and spectral whitening to enhance the data quality and remove noise resulted from acquisition and processing effects. We utilized these methods to produce high-resolution data and preserve structural features. A total of 17 faults have been identified in the study area. The most common fractures in the Cambrian-Ordovician reservoir formations are in the northwest and southeast of the field. Seismic data conditioning and seismic attribute analyses applied on the 3-D seismic data effectively increased our understanding of the reservoir complex and help detect and identify subtle faults and fracture zones in the study area.

Integrated geologic, geophysical, and petrophysical data to construct full field geologic model of Cambrian-Ordovician and Upper Cretaceous reservoir formations, Central Western Sirte Basin, Libya

“…Shallow horizons were easy to track over the study area because they represent strong reflection contrasts with better seismic resolution. Data quality deteriorates with increasing depth and increases the uncertainty of the interpretation of the deep horizons (Abdelnabi et al, 2017). Nevertheless, there is enough well control to constrain the interpretation and produce accurate structural maps of the deep horizons.…”

“…Nevertheless, there is enough well control to constrain the interpretation and produce accurate structural maps of the deep horizons. We also interpreted faults using 2D and 3D seismic data in which the minor faults were identified from frequency-enhanced seismic data (Abdelnabi et al, 2017). We picked the faults in every inline and crossline.…”

“…Because the availability and variability of well data that were acquired by different companies in different years and quality of seismic data, it was required to use certain analysis techniques and data enhancement to overcome data limitations. Applications of frequency enhancement and filtering of seismic data on some oil fields in Libya, for example, demonstrated the importance of data conditioning to illuminate some of the unrevealed geologic features (Hamarbatan et al, 2006;Serpa, 2016, 2018;Abdelnabi et al, 2017). In a previous study (Abdelnabi et al, 2017), the authors used frequency enhancement and curvature attributes to identify minor faults in the study area and the distribution of the fractures in the Cambrian-Ordovician reservoirs.…”