Characterization of stratigraphic interfaces and embedded limestone cavities using integrated geophysical and geological data

3D Seismic Interpretation and Geological Modelling for Petroleum Reserves Estimation of I Sequence, Lower Miocene, X Field, Block Y, Malay – Tho Chu Basin, Viet Nam

Seismic attributes are widely used to enhance geological interpretation by extracting quantitative information from seismic data. They provide insights into both structural and stratigraphic features, enabling interpreters to detect subtle changes in lithology, continuity, and geometry of subsurface formations. Attributes are especially useful in improving the resolution of seismic images, helping to delineate horizons, identify fault patterns, and visualize depositional features. This study focuses on using seismic attribute analysis to clarify the distribution of sand bodies within a reservoir interval. The objective is to identify zones with favourable sand development, define their geometry and connectivity, and outline areas with high hydrocarbon reservoir potential. The interpreted I Sequence was divided into three sub-sequences, each modelled with a geological grid size of 50m×50 m and subdivided into 150 layers. The porosity model showed mean values ranging from 0.228 to 0.2484 across the main reservoir zones, while water saturation varied from 0.90659 to 0.92747. After calculating seismic attributes, the authors delineated sand bodies in the I38_upper layer located in the North–Northwest, Northeast, and smaller bodies in the South. In the I90 layer, sand bodies were identified in the North–Northeast, East, and Southeast, along with narrow, laterally restricted sands in the western part of the study area. The P2 reserve with 50% confidence for the most potential interval (I23–I38) was estimated at 86 million cubic meters after running 200 cases.

3D models from geological maps: strengths and weaknesses from the Pasubio Massif (Southern Alps)

3D geological models provide digital representations of subsurface architecture and are increasingly applied in both academic research and industry. Their construction can follow implicit or explicit approaches, depending on data availability and final modelling applications. While 3D models based on subsurface data are traditionally employed in several fields of study, models derived from outcrop data are increasingly being developed. In this study, newly acquired geological mapping data from the Pasubio Massif (Southern Alps, northern Italy), covering an area of ~36 km² within the geographic extent of the CARG sheet 081 “Rovereto”, were used to develop and test an iterative explicit workflow for 3D geological modelling using Move software. The workflow is based on the construction of a structured grid of geological cross-sections, followed by the interpolation of stratigraphic horizons and fault surfaces through Ordinary Kriging. Field observations indicate that the lithostratigraphic units cropping out in the study area form a gently NW-dipping monoclinal structure, exhibit overall constant thicknesses and are affected by the Schio-Vicenza fault system. Model validation first involved a qualitative comparison between mapped geological boundaries and faults with those obtained from the intersection of the modelled surfaces with the topography (DEM), followed by thickness maps evaluation as an internal consistency check. Where inconsistencies emerged, cross-sections were refined and the model was iteratively updated until geological geometries and thickness trends became consistent with field-mapped evidence. A final quantitative assessment was then performed by analysing thickness deviations from mean unit thicknesses and by measuring the spatial overlap between mapped and model-interpolated geological boundaries and fault traces. Comparison between the preliminary and validated models, supported by thickness deviation statistics, indicates that most residual discrepancies are constrained within ±10–20% of expected thickness values. The results highlight the critical role of iterative validation in ensuring geologically robust 3D models, emphasising common sources of uncertainty in explicit geomodelling workflows. This study provides a methodological framework for producing reliable 3D geological models in data-poor regions, complementing the recently published ISPRA guidelines for the organisation and standardisation of model datasets and supporting future applications in academic research and regional or national geological surveys.

A machine learning-assisted geophysical–geotechnical approach for improved engineering site assessment

INTEGRATED GEOSCIENCE, AND GEOSPATIAL ANALYSIS FOR HYDROCARBON EXPLORATION IN THE KHEWARI BLOCK, SINDH, PAKISTAN

The Khewari Block, located in the structurally complex Lower Indus Basin of Sindh, Pakistan, occupies a tectonically favorable yet insufficiently explored sector of a Mesozoic–Cenozoic rifted basin known for its hydrocarbon prospectivity. This study employs an integrated geophysical geospatial workflow to confine subsurface architecture and assess reservoir potential. Extensive interpretation of 2D seismic profiles identifies a system of NE-SW oriented normal faults, horsts, grabens, and local compressional structures, producing a wide range of trap geometries, including fault-bounded closures, rollover anticlines, and tilted fault blocks. Time and depth structure mapping refines horizon geometries and identifies structurally isolated blocks with enhanced trapping potential. Bouguer and residual gravity anomaly maps further resolve density differences associated with uplifted carbonate platforms and sediment filled troughs, confirming segmentation of the structure based on seismic data. Surface dataset complements, such as DEM-based elevation, slope models, and land-use classification, offer further limitations on terrain accessibility, drainage systems, and operational capabilities. The integration of surface and subsurface datasets reduces the uncertainty in the interpretation process, improves the delineation of traps, and contributes to the most effective well-placement planning. The multidisciplinary approach illustrates the effectiveness of integrating seismic reflection, gravity modelling, and surface-based GIS analysis to create a coherent structural framework of frontier basins. The workflow is transferable to other data-limited regions and provides a robust foundation for evidence-based hydrocarbon exploration and decision making.

Well-log interpolation with relative geological time constraints for poststack seismic inversion

Correlating geophysical anomalies with subsurface lithology: Insights into gold mineralisation

Accurate delineation of gold mineralization in deeply weathered tropical terrains requires the integration of indirect geophysical data with direct subsurface observations. Electrical resistivity imaging (ERI) and induced polarization (IP) are widely used in mineral exploration; however, interpretation is often limited by non-uniqueness without borehole validation. This study evaluates the reliability of combined resistivity and induced polarization (Res-IP) methods for identifying sulphide-associated gold mineralization in the Central Belt of Peninsular Malaysia (CBPM) through correlation with borehole lithological data. The investigation was conducted in Jeli, Kelantan, a known gold-bearing region, using two intersecting 400 meters survey lines (SL-1 and SL-2) acquired with 61 electrodes at 5 to 10 meters Schlumberger spacing to generate two-dimensional (2D) Res-IP models. Boreholes Y (BH-Y) and Z (BH-Z) were drilled along SL-1 to validate geophysical anomalies, with detailed geological logging performed at 1.5 meters intervals to document lithology, alteration, quartz veining, and sulphide occurrence. The results reveal a consistent geophysical signature characterized by low resistivity (<100 Ωm) and high chargeability (>100 msec), indicative of disseminated to vein-hosted sulphides. These signatures correlate directly with quartz–sulphide vein intersections at depths of 70 to 72 meters in BH-Z and 102 to 102.6 meters in BH-Y, confirming subsurface structural and mineralogical continuity. This study establishes calibrated resistivity–chargeability thresholds for sulphide-bearing formations in tropical Malaysian geology, improving ERI interpretive confidence in highly weathered environments. The findings highlight the value of integrated geophysical and geological approaches for enhancing drill targeting and reducing exploration uncertainty in gold-prospective regions of Malaysia.