Karst geomorphology analysis for geohazard assessment via seismic relief and dip attributes in Jx carbonate field, Central Luconia Province, Malaysia

Carbonate reservoirs in the Central Luconia Province of Malaysia underwent significant karstification during the Miocene. Such features have a detrimental impact on drilling operations, as has been reported for over 40 years in this province. This implies that the karst architecture and geometry may exhibit potentially high-risk behaviours during drilling activities, necessitating a thorough investigation of the features. This study aims to achieve several objectives using Jx field subsurface data, i.e., 3D seismic data and well data, including (1) analysing the interrelationship between karsts and faults, (2) examining the appropriate and effective attributes for analysing the geomorphology of the karst surfaces, and (3) conducting comparative and analog studies to gain a comprehensive understanding of karst formation and characteristics. This research attempted to determine the dimensions and extent of the faults and karsts, which were discovered to be highly connected, and this endeavor is critical for assessing the potential hazardous risk features within the platform. The major fault lineaments that bound the study field were interpreted using the Automatic Fault Extraction (AFE) module application combined with the manual fault-picking technique in the PaleoScan 2022 software. Four main horizon surfaces within the carbonate interval were selected for evaluating karst geomorphology using appropriate seismic attributes, as geomorphology is an important subject that requires serious attention, particularly when determining low-risk regions for drilling programs. Two attributes were extracted from the horizon surfaces: seismic relief and dip attributes, which efficiently distinguish the karst features and define the structural morphology of karsts. Dendritic karst networks, as well as karst collapses or sinkholes, are the most common karst features observed. These features exhibit discontinuity form and synclinal expression (high dip magnitude) when viewed in seismic and using the applied attributes. The comparative and analog study was conducted in Niah Caves, Miri, Sarawak, Malaysia, using karst interpretation employing digital elevation model (DEM) maps and fieldwork. Most of the delineated karst features observed on the DEM map of the Niah Caves are similar to those discovered in the Jx field; however, their dimensions vary between the two carbonate buildups.