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

Integrated Analysis of Sequence Stratigraphy, Seismic Interpretation and Petrophysical Data for Cenomanian Reservoirs (Horus Field, Alamein Basin, Egypt): Implications for Siliciclastic/Carbonate Reservoir Distribution and Quality

This study integrates seismic interpretation, sequence‐stratigraphic analysis and petrophysical evaluation to characterise the Cenomanian hydrocarbon potential within the Bahariya Formation and Abu Roash ‘G’ Member at Horus Field, Alamein Basin. Seismic interpretation revealed ENE–WSW and ESE–WNW trending extensional normal faults, forming structural highs (horsts, tilted blocks) that act as primary hydrocarbon traps. The Abu Roash Formation exhibited the highest seismic reflector continuity, aiding robust structural mapping, while the underlying Bahariya, Kharita and Alam El Bueib formations showed increasing discontinuity downwards. Instantaneous Amplitude and Energy attributes were applied to quantitatively show deeper‐layers amplitude decay, reflector continuity and reveal subtle stratigraphic geometries obscured in conventional seismic data. Sequence stratigraphic analysis delineated two depositional sequences. BAHR‐SQ‐1 (Bahariya Fm), a siliciclastic‐dominated sequence (535–640 ft), comprises Lowstand (LST‐1: fluvial‐deltaic to shallow marine sandstones), Transgressive (TST‐1: mixed siliciclastics/carbonates) and Highstand (HST‐1: progradational sandstones) Systems Tracts. ARG‐SQ‐2 (Abu Roash ‘G’ Member; 525–675 ft), a carbonate/siliciclastic sequence, comprises a Transgressive Systems Tract (TST‐2: deep‐shelf dolomites) and a Highstand Systems Tract (HST‐2: progradational mixed facies). Petrophysical assessment identified both sequences as hydrocarbon‐bearing reservoirs but with distinct characteristics. The Upper Bahariya (HST‐1) offers volumetric potential (thickness 220–233 ft., porosity 29%–35%) but exhibits variable, generally poorer quality (lower net‐to‐gross: 2%–12%, higher shale volume: 15%–25%, higher water saturation: 32%–33%, limited pay: 4–29 ft). In contrast, the Abu Roash ‘G’ Dolomite (primarily TST‐2) demonstrates superior and consistent reservoir quality across wells (thickness 60–81 ft., net‐to‐gross: 15%–32%, lower shale volume: 5%–9%, porosity 21%–24%, lower water saturation: 28%–41%, hydrocarbon saturation 59%–73%, pay 12–23 ft). The cleaner lithology and favourable petrophysics make the Abu Roash ‘G’ the key contributor to hydrocarbon potential, despite its lesser thickness compared to the Bahariya. These results underscore the critical control of sequence stratigraphic architecture and depositional facies on reservoir distribution and quality, providing essential insights for future exploration targeting in analogous settings.

INTEGRATED STRATIGRAPHIC AND PETROPHYSICAL ASSESSMENT OF THE MADUKY FIELD, NIGER DELTA, NIGERIA: IMPLICATIONS FOR RESERVOIR ARCHITECTURE AND HYDROCARBON PROSPECTIVITY

The Maduky Field, situated within the Coastal Swamp depobelt of the Niger Delta Basin, represents a structurally complex and geologically heterogeneous marginal field with untapped hydrocarbon potential. This study integrates 3D seismic interpretation, well log correlation, sequence stratigraphy, and petrophysical analysis to characterize its reservoir architecture and evaluate hydrocarbon volumes. Structural mapping reveals prominent listric growth faults and rollover anticlines that define three main field compartments, each with distinct depositional and trapping characteristics. Sequence stratigraphic analysis, guided by five regionally correlated Maximum Flooding Surfaces (MFSs), delineates Genetic Sequences and system tracts (HST, TST, LST), each with unique parasequence stacking patterns and reservoir geometries. The highstand and lowstand system tracts host the most prolific reservoirs, characterized by clean, coarsening-upward sand bodies with high net-to-gross ratios and favorable porosity-permeability relationships. Petrophysical evaluation across five wells indicates effective porosity values of 20–34%, permeability ranging from 2.50 to 18 mD, and low water saturation (8–35%), confirming reservoir quality suitable for commercial exploitation. Crossplots further demonstrate the controls of porosity and depositional environment on fluid distribution and reservoir performance. The study identifies key hydrocarbon-bearing units sealed by marine shales associated with MFSs and quantifies Stock Tank Oil Initially In Place (STOIIP) across fault blocks, highlighting potential development zones. These insights support the redevelopment of Maduky Field and provide a scalable model for optimizing marginal field performance in mature deltaic basins.

Well logs and seismic data integration for 3D structural, facies, and petrophysical static modeling approach of the Albian–Cenomanian reservoirs in the Silah field, El Fayoum concession, Egypt

Seismic Attribute-Based Characterization of Heterogeneous Sand Reservoirs in the Niger Delta Basin, Nigeria

Accurate characterization of heterogeneous reservoirs in the Niger Delta remains challenging because conventional seismic interpretation alone often fails to resolve complex structural features and lateral variations in reservoir properties. These limitations increase uncertainty in identifying hydrocarbon-bearing intervals and predicting reservoir continuity. This study integrates structural interpretation with seismic attribute analysis to improve reservoir characterization and hydrocarbon prospect identification in the onshore Omicron Field, Niger Delta, Nigeria. High-quality 3D seismic data, check-shot data, and well logs from four wells were integrated to delineate reservoir units, correlate lithologies, interpret faults and horizons, generate time and depth structure maps, and analyse coherency and root-mean-square (RMS) amplitude attributes. Two laterally continuous reservoir sands (Sand A and Sand B) were identified across the field, together with five major faults and two key seismic horizons. Structural interpretation revealed a fault-supported NW–SE-trending anticlinal closure, with structural highs concentrated in the central part of the field and structural lows toward the northwest. RMS amplitude maps show pronounced high-amplitude anomalies in the western part of both reservoirs, indicating potential hydrocarbon accumulation, while Sand B exhibits stronger amplitude responses than the shallower Sand A. The mapped fault-controlled closures and bright-spot anomalies collectively indicate favourable hydrocarbon potential within the study area. The results demonstrate that integrating seismic attributes with structural interpretation reduces uncertainty in reservoir characterization and provides a robust workflow for evaluating heterogeneous reservoirs and identifying exploration targets in the Niger Delta.

Integrating Surface Geological Mapping and Multi-Year Subsurface Data to Identify Lateral Lithological Variations Along the Jatinegara Diversion Tunnel, Central Java, Indonesia

Tunnel design in tropical regions requires careful attention to subsurface variability due to intense weathering and complex lithology. The ongoing design of the Jatinegara Diversion Tunnel, with a diameter of 6 meters and a length of 439 meters, relies solely on the 2024 borehole data without considering the recent 2017 data, revealing a contrast subsurface geological characteristic. This study investigates lateral lithological variations along the tunnel alignment by integrating surface geological mapping with multi-year borehole data from 2017 and 2024. The methodology includes geological mapping of a 2.0 × 2.0 km area, corebox analysis, surface-subsurface stratigraphic correlation, and rock mass quality evaluation using the Rock Mass Rating (RMR) system. Results show the tunnel traverses five zones with distinct rock mass characteristics. Zone 1, Zone 3, and Zone 5 consist of andesitic breccia with RMR values ranging from 20.21 – 39.57, indicating poor quality of rock mass. Zone 2 comprises interbedded carbonate sandstone and siltstone overlain by andesitic breccia, with RMR values ranging from 42.82 – 52.40 (fair). Zone 4 consists of interbedded carbonate sandstone and siltstone overlain by massive sandstone with siltstone intercalation with an RMR of 52.43 (fair). Given these rock mass conditions, the recommended excavation method is a top heading and bench approach with 1.0–1.5 meters advance in the top heading with support system consist of rock bolt, shotcrete, and steel set. These findings highlight the importance of integrating multi-year geotechnical data to support an adaptive and safe tunnel design in complex geological environments.

Hydrogeological Response to Low-Magnitude Seismicity: Fracture Sealing, Ground Deformation, and Lake Depletion in the Sikkim Himalaya

Earthquake-induced fracturing and microcrack development in subsurface strata are widely recognized as important processes influencing seepage and the hydrological behaviour of surface water bodies, particularly in tectonically active mountainous terrains. However, the hydrogeological response to repeated low-magnitude (<4) seismic events remains poorly understood. This study presents an integrated geoelectrical and remote sensing investigation of the Nagi Lake region in the Sikkim Himalaya, India, based on Vertical Electrical Sounding (VES) surveys conducted in May 2022 and March 2026, following a seismic sequence of 74 low-magnitude earthquakes recorded during February 2026. Comparative analysis of four VES profiles (VES1–VES4), supported by validatory factor analysis, reveals spatially heterogeneous changes in subsurface electrical characteristics between the two survey periods. VES1, VES2, and VES3 indicate reduced signatures of pre-existing microcracks that are consistent with sediment densification and partial sealing, whereas VES4 suggests localized development or persistence of microfractures. Because the surveys span approximately four years, these changes likely reflect the combined influence of long-term hydrogeological, environmental, and geomorphic processes, with the February 2026 seismic sequence representing one potential contributing factor rather than the sole driver. To further evaluate ground deformation, Sentinel-1A Synthetic Aperture Radar (SAR) data acquired between January 2019 and March 2026 were analysed using Persistent Scatterer Interferometric SAR (PS-InSAR). The results indicate cumulative Line-of-Sight (LOS) displacements ranging from −17.9 cm (movement away from the satellite) to +3.5 cm (movement toward the satellite) in the vicinity of Nagi Lake, reflecting localized surface deformation with millimetre-scale precision. These observations provide complementary evidence of ongoing subsurface adjustment that may promote sediment compaction and microcrack modification. Overall, the study demonstrates measurable temporal changes in the subsurface structure of the Nagi Lake area and suggests that repeated low-magnitude seismicity may contribute to subsurface restructuring alongside other environmental processes. The findings highlight the value of integrating geophysical monitoring and satellite-based deformation analysis for understanding groundwater–surface water interactions and supporting the sustainable management of vulnerable Himalayan water bodies.