Structural Control and Evaluation of the Geothermal System in Seulawah Agam, Aceh: A Geological and Geophysical Approach Using Fault Fracture Density, Land Surface Temperature, and Gravity Data

Structural and thermal analysis of geothermal prospectivity in the Midyan Basin, NEOM, Saudi Arabia

The Midyan Basin in the NEOM region of northwestern Saudi Arabia is a promising yet underexplored geothermal province situated within the tectonically active Red Sea Rift and Gulf of Aqaba transform system. Despite evidence of elevated regional heat flow and shallow Curie depths, the structural controls governing geothermal fluid circulation remain poorly constrained. This study identifies structurally controlled geothermal targets by integrating remote sensing, airborne geophysics, and field observations within a unified exploration framework. Multi-temporal Landsat-8 imagery acquired during six months of the year 2024 was used to derive land surface temperature (LST) through radiance-to-brightness temperature conversion and NDVI-based emissivity correction. Surface structural lineaments were interpreted from multidirectional hillshade models derived from a 30-m digital elevation model (DEM), while subsurface fault systems were delineated from airborne magnetic data using tilt-derivative analysis. Fault fracture density (FFD) mapping identified structurally enhanced permeability zones, which were integrated with persistent LST anomalies to delineate geothermal prospectivity. The analysis identified 5,809 surface lineaments and 1,262 basement-rooted magnetic lineaments, both dominated by NW–SE and NE–SW structural trends associated with the Red Sea Rift and Gulf of Aqaba transform system. Geothermal prospectivity is concentrated within discrete basement-rooted fault corridors rather than being uniformly distributed across the basin. The highest-confidence targets occur along the western and northwestern coastal escarpments, where high surface and subsurface fracture densities spatially coincide with persistent multi-season thermal anomalies, indicating enhanced permeability and structurally controlled heat transfer. Three priority geothermal target zones (Surface Zones A, B, and C and corresponding Subsurface Zones A′, B′, and C′) were identified, with Zone B/B′ representing the most prospective area owing to its strong structural continuity across surface and subsurface datasets. Field observations of dense fracture networks, fault-controlled granite–carbonate contacts, and subvertical dike swarms further corroborate the interpreted permeability pathways. Although direct geothermal manifestations and drilling data are not yet available, the integrated structural, thermal, and field evidence demonstrates that the Midyan Basin possesses favorable geological conditions for both hydrothermal resources and Enhanced Geothermal Systems (EGS). The proposed workflow provides a robust, cost-effective screening approach for reducing exploration uncertainty and prioritizing geothermal targets. It also guides future geothermal exploration and development within NEOM.

Integrated satellite gravity analysis and HVSR microtremor measures for geothermal potential assessment in the Suban Curup–Rejang Lebong Hot Spring Area, Indonesia

Abstract A geothermal potential assessment was conducted in the Suban Curup–Rejang Lebong Hot Spring Area, Bengkulu Province, Indonesia. This study aimed to identify subsurface geological structures—faults, volcanic features, and sedimentary layering—that may control the development of geothermal reservoirs and caprock units. Two complementary geophysical approaches were integrated: (1) Three-dimensional (3-D) inversion modeling of Bouguer gravity anomalies derived from Global Gravity Model plus (GGMplus) 2013 and corrected using SRTM2gravity at 1,937 measurement points, and (2) microtremor acquisition at 106 sites with 60-minute recording duration, processed using the Horizontal-to-Vertical Spectral Ratio (HVSR) method. The residual gravity inversion results reveal density contrasts of 2.40–3.40 g/cm3 and sediment thicknesses exceeding 80 m, interpreted as potential geothermal reservoir units. These findings are consistent with the HVSR results, which show moderate to high amplification (A0 = 3–9) and natural frequencies of 1–10 Hz, indicating porous and fractured formations favorable for fluid storage. Overall, the integration of satellite gravity and microtremor data highlights the presence of thick sedimentary deposits and structurally controlled pathways, suggestive of promising geothermal reservoir targets in the Suban Curup area.

Integrated gravity and landsat analyses for hydrothermal alteration and fault zone mapping in the lokop geothermal prospect, Indonesia

Geomorphic and Remote Sensing‐Based Evaluation of Active Faults and Geological Hazards in the Muzaffarabad Region, NW Himalaya

Geomorphic features, drainage patterns and topography are key indicators of active tectonics. This study examines geomorphological characteristics and geological hazards, specifically earthquakes and landslides, in the Muzaffarabad region. The findings contribute to disaster risk reduction and achievement of sustainable development goals (SDGs). Field‐based geomorphological studies and satellite imagery were used to analyse the geomorphological characteristics of the region. Five geomorphic indices, namely asymmetry factor (AF), drainage basin shape index (Db), slope analysis, valley floor width‐to‐height ( V f ) ratios and hypsometric curves, were calculated using shuttle radar topography mission digital elevation model (SRTM DEM). Features such as drainage offsets, stream deflections, faceted spurs, seismicity, deformed recent sediments and point bars dissection near the Jhelum and Muzaffarabad faults suggest left‐lateral oblique‐slip motion, indicating the tectonically active nature of these faults. The geomorphic and neotectonics analysis concludes that the Muzaffarabad region is highly susceptible to earthquakes and landslides, particularly, in fault‐affected areas. A flood susceptibility analysis using multi‐criteria decision analysis (MCDA) in ArcGIS was conducted to enhance climate resilience and disaster preparedness (SDG 13) and support (SDG 6) by identifying flood‐prone areas. Three high‐risk flood zones were identified: Neelum River–Shawai Nala confluence, Jhelum–Neelum rivers convergence at Domel and a low‐lying area near the Lohargali landslide. This study highlights the importance of integrating morphometric, geomorphological and geospatial techniques for effective disaster risk reduction (SDGs 11 and 13), climate‐resilient infrastructure (SDG 9), addressing SDG 6 and sustainable urban development, ensuring long‐term safety in tectonically active regions. Additionally, the methodology in this study, integrating multiple existing techniques, can be expanded for hazard assessment in other regions.

Casing Program and Well Trajectory Design for a Geothermal Well Based on Stratigraphic Analysis of the Malili Sheet: A Conceptual Study in the Parara Geothermal Prospect, South Sulawesi, Indonesia

Recent geopolitical instability in the Middle East, accompanied by significant increases in global oil and gas prices, has further exposed the vulnerability of fossil fuel-dependent energy systems. Concurrently, global commitments toward decarbonization and sustainable development have accelerated the transition toward renewable energy sources. Among the available alternatives, geothermal energy offers a reliable and low-carbon solution, especially in Indonesia, where substantial geothermal potential remains underdeveloped despite favorable geological conditions. Nevertheless, the advancement of geothermal energy development requires technically reliable exploration and drilling approaches to address subsurface complexity and reduce risks. In this context, this study presents a conceptual design of casing, drilling mud system, and well trajectory for a frontier geothermal exploration well in the Parara Geothermal Prospect, Indonesia. The design was developed based on regional stratigraphic interpretation derived from the Malili Geological Sheet, surface manifestation data, and regional structural information. The prospective target zone is conceptually estimated to occur at depths of approximately 1000-1500 m, primarily within the ultramafic units of the Wasuponda Complex, which may function as secondary geothermal reservoirs via tectonic fracturing and hydrothermal alteration. Formation temperature was estimated using a regional geothermal gradient of 40-45 °C/km, while initial formation pressure was approximated using a hydrostatic pressure approach. The Lahendong geothermal field was employed as a conceptual analogue to infer the subsurface geological framework (e.g., fracture-controlled permeability zones), while the LOKA-1 and TONDON-1 wells were used to infer regional drilling operational risks. A four-stage casing design, interval-based drilling mud program, and deviated well trajectory were proposed to improve the probability of intersecting permeable fracture zones. 3D visualization was utilized to illustrate the integrated relationship between well trajectory, casing placement, and interpreted stratigraphy. The results provide an initial technical framework for geothermal exploration drilling evaluation in the Parara prospect. Although the proposed parameters require further validation, the results are expected to reduce exploration uncertainty and facilitate future geothermal development in the Parara prospect.

Geothermal genesis mechanisms in the Huichang-Xunwu area: Constraints from joint inversion of ambient seismic noise and gravity data