A multi-sensor workflow for 3D geomorphological mapping and structural interpretation in karst cave environments

The structural geologic interpretation of reflection seismic data is affected by conceptual uncertainty, particularly in challenging onshore settings. This uncertainty can be significantly reduced by the integration of cross-section restoration and balancing techniques into the seismic interpretation workflow. Moreover, these techniques define a solid and comprehensive basis, grounding the interpretation and allowing a closer investigation of the deformation history that led to the interpreted structures. These benefits are demonstrated on the basis of a case study from the eastern Jura Mountains in northern Switzerland. This mountain range was formed by a thin-skinned foreland fold-and-thrust belt with a multiphase prethrusting tectonic history. Despite significant seismic acquisition and processing efforts, seismic imaging of the strongly deformed parts of the belt widely remains ambiguous. We have developed a detailed systematic interpretation workflow that is exemplified here for a single seismic profile across the Jura Main Thrust. Classical cross-section balancing techniques of equal bed lengths and areas were applied to validate and reinterpret the given seismic interpretation. Our results suggest that most of the observed structures resulted from thin-skinned deformation along a basal décollement in Lower Triassic evaporites, which is generally inferred for the Jura Mountains. Nevertheless, secondary detachment levels in above lying strata have to be considered as well. The stepwise restoration of the analyzed cross section points toward different styles of thin-skinned deformation and possibly several episodes of earlier basement-rooted faulting events, which are indicated by subtle stratigraphic thickness changes. In summary, our workflow allowed us to significantly improve the original seismic interpretation, highlight specific deformation styles, and illuminate possible prethrusting deformation events that would otherwise be easily overlooked.

Interpretation of geologic structures entails ambiguity and uncertainties. It usually requires interpreter judgment and is time consuming. Deep exploitation of resources challenges the accuracy and efficiency of geologic structure interpretation. The application of machine-learning algorithms to seismic interpretation can effectively solve these problems. We analyzed the theory and applicability of five machine-learning algorithms. Seismic forward modeling is a key connection between the model and seismic response, and it can obtain seismic data of known geologic structures. Based on the modeling data, we first optimized the seismic attributes sensitive to the target geologic structure and then we verified the accuracy of the five machine-learning algorithms by the cross-checking method. In this case, the random forest algorithm had the highest accuracy. So we examined the structural interpretation method based on a random forest using the 3D seismic reflection data from coalfield exploration. The prediction effect of this interpretation workflow is verified by comparison with known geologic structures on the plane and profile. The results suggest that the random forest algorithm is feasible to indicate geologic structure interpretations in the case of collapsed column and fault structures and it can effectively improve the efficiency of seismic interpretation and its accuracy. The machine-learning-based workflow provides a new technique for seismic structure interpretation in coal mining.

We present a workflow for seamless real-time navigation and 3D thermal mapping in combined indoor and outdoor environments in a global reference frame. The automated workflow and partly real-time capabilities are of special interest for inspection tasks and also for other time-critical applications. We use a hand-held integrated positioning system (IPS), which is a real-time capable visual-aided inertial navigation technology, and augment it with an additional passive thermal infrared camera and global referencing capabilities. The global reference is realized through surveyed optical markers (AprilTags). Due to the sensor data’s fusion of the stereo camera and the thermal images, the resulting georeferenced 3D point cloud is enriched with thermal intensity values. A challenging calibration approach is used to geometrically calibrate and pixel-co-register the trifocal camera system. By fusing the terrestrial dataset with additional geographic information from an unmanned aerial vehicle, we gain a complete building hull point cloud and automatically reconstruct a semantic 3D model. A single-family house with surroundings in the village of Morschenich near the city of Jülich (German federal state North Rhine-Westphalia) was used as a test site to demonstrate our workflow. The presented work is a step towards automated building information modeling.

This paper presents a workflow for improved detection, extraction and characterization of faulting patterns imaged in seismic. It integrates image processing, seismic interpretation and structural analysis techniques. This workflow is designed to maximize the use of seismic data by preserving uniqueness and integrity of the seismic structural information while improving quality and efficiency of the interpretation. Presentation Date: Wednesday, September 18, 2019 Session Start Time: 1:50 PM Presentation Time: 3:55 PM Location: 221B Presentation Type: Oral

Seismic data in the Yubei region has a relatively low signal-to-noise ratio, with multiple interbed multiples developed in the Ordovician strata, significantly affecting the accurate imaging of complex structures and reservoirs, leading to considerable uncertainty in structural interpretation and reservoir prediction. This paper first determines the styles of complex structural belts influenced by interbed multiples through wave equation forward modeling. The parallel-layered reflection at the top of complex structures is due to the alteration of effective strata reflection caused by strong interbed multiples at the top. Second, integrating data from drilling, logging, and geological aspects in the region, seismic wavefield characteristic forward modeling analyses for different types of reservoir are conducted. The results show that factors such as the scale and spatial development position of fractured-vuggy reservoirs have significant impacts on seismic reflection characteristics, strong reflective interfaces may mask the reflection characteristics of the top reservoir, the development of fractured-vuggy reservoirs at different positions can weaken or enhance the reflection of strata interfaces; locally intensive development of fractures in the Ordovician manifests as weak bead anomalies, while large-scale fracture reservoirs exhibit chaotic reflections, and karst caves are characterized by distinct moderately strong bead or tabular amplitude anomalies. By comparing with actual seismic data, the correctness of the complex structural interpretation model is effectively verified, and seismic wavefield characteristics of various types of Ordovician reservoir are summarized, providing a certain basis for understanding the interpretation of complex structures and the reflection characteristics of fractured-vuggy reservoirs in the region.

Structural interpretation is considered as a conventional method for oil exploration and commonlyused. The use of unconventional methods could lead to achieve significant results and reduce the drilling risk. Thesubsurface image is completely objective, while merging the unconventional tool, like seismic attributes and theconventional seismic interpretation workflow, to highlight the structural elements, which matched together. Also toidentify the general prospective area of interest, the multi-dimensional seismic attributes computation, along with theuse of time slices, are both independent of interpretation.This means that no prior interpretation is necessarily requiredand no interpretational bias to the seismic attributes results. Seismic attributes were used to enhance fault image andenhance the continuity of picked horizons. The main objective of this paper is to determine the structural tectonics ofthe study area using, the conventional method combined with the unconventional methods with respecting thegeological backgroundof the study area. Upon the horizon flattening, the encountered pre-Cretaceous faults within thevertically animated three dimensional seismic cube were better imaged and picked carefully. Drilled Jurassic playswithin Southwest Abu Sennan (SWS) area were dry, due to low structural plays during the Jurassic before the LateCretaceous tectonic event which brought the Jurassic rocks high as per the current day situation. AR/”G” Member andKhoman Formation depth structure contour maps were generated to show the main fault sets, a dominant northwestsoutheastset and a set trending northeast-southwest due to Syrian arc structure system.

This study investigates the geological diversity of the Tanjung Api region in Tojo Una-Una Regency, Central Sulawesi, with the aim of identifying potential sites for geotourism and geological heritage designation. Through field observations, lithological and geomorphological mapping, petrographic analysis, and structural interpretation, ten geological sites were inventoried. Among them, Gua Kehidupan and Tanjung Api were identified as fulfilling national criteria for geological heritage due to their exceptional features, including fossil-bearing caves, sinkholes, and active gas seeps related to tectonic brecciation. The remaining sites exhibit significant geotourism value, particularly in coastal, volcanic, and sedimentary contexts. Findings from this study highlight the relevance of geodiversity in supporting sustainable tourism and geoconservation. By integrating geological features with educational and community-based values, Tanjung Api demonstrates strong potential to be developed into a geotourism destination that balances scientific significance, cultural relevance, and ecological preservation. The inventory and qualitative assessment serve as a reference for future geoheritage planning and site management. The study recommends involving local stakeholders in the promotion and conservation of these sites to ensure long-term sustainability and community benefits.

Detecting hypogenic karst features in the northeastern Delaware Basin, west Texas: Applications of Full Tensor Gradient (FTG) gravity data

Summary The utilization of seismic methods for mineral exploration, particularly in Western Australia has become widespread in the last few years. In the initial stage the use of seismic data was limited to the structural interpretation only. Subsequent lithological interpretation however required introduction and testing of new techniques and methodologies, such as inversion and attributes analysis. While these techniques are considered mature by hydrocarbon standards, their application in hard-rock environments still requires extensive study to determine the veracity of the results. Challenges to hard-rock seismic methods begin at the acquisition phase where factors such as remoteness and inaccessibility of the site and environmental restrictions, result in seismic lines being misaligned with the dip of the dominant structures. Further, massive shear zones, faulting, folding, and dyke intrusions, common for these areas, result in extremely complex subsurface structures which also compound seismic images. The regolith, a near surface zone up to 150 meters thick comprised of altered, transported, and weathered material causes energy dissipation and time delays in seismic mapping of hard rock environments. The lack of borehole data with sonic logs also contributes to the difficulty of seismic data calibration and hence full utilization and analysis of seismic information. Preservation of amplitude, frequency content and phase of original signal is a prerequisite for inversion and attribute analysis. However, the complex structure, seen in mineral exploration in Western Australia, makes this task cumbersome. Inherently low signal to noise ratio and variable receiver and source ground coupling, presents a problem for true amplitude processing of hard rock seismic data. We show that each of the challenges facing hard-rock seismic has a systematic solution. This leads towards the final aim which is to accomplish the lithological interpretation by directly relating seismic impedance and attributes to the various rock formations in contact.

Synthetic Aperture Radar (SAR) images are being used more extensively than ever before for geoscience applications in the moist tropics. In this investigation, a RADARSAT1-1 C-HH SAR image acquired in 1998 was used for coastal mapping and land-cover assessment in the Bragança area, in the northern Brazil. The airborne GEMS 1000 X-HH radar image acquired in 1972 during the RADAM Project was also used for evaluating coastal changes occurring over the last three decades. The research has confirmed the usefulness of RADARSAT-1 image for geomorphological mapping and land-cover assessment, particularly in macrotidal mangrove coasts. It was possible to map mangroves, salt marshes, chenier sand ridges, dunes, barrier-beach ridges, shallow water morphologies and different forms of land-use. Furthermore, a new method to estimate shoreline changes based on the superimposition of vectors extracted from both sources of SAR data has indicated that the shoreline has been subjected to severe coastal erosion responsible for retreat of 32 km² and accretion of 20 km², resulting in a mangrove land loss of almost 12 km². In an application perspective, orbital and airborne SAR data proved to be a fundamental source of information for both geomorphological mapping and monitoring coastal changes in moist tropical environments.

Karst caves are a unique environment significantly different from the external environment; adaptation of cave-dwelling animals to the cave environment is often accompanied by shifts in the sensory systems. Aquatic and terrestrial leeches have been found in the karst caves. In this study, we conducted a transcriptome analysis on the cave-dwelling leech Sinospelaeobdella wulingensis. A total of 29,286 unigenes were obtained by assembling the clean reads, and only 395 genes are differentially expressed in winter and summer samples. Two piezo-type mechanosensitive ion channels (Piezos), eight transient receptor potential channels (TRPs), and six ionotropic glutamate receptors (iGluRs) were identified in the transcriptome. These channels/receptors are transmembrane proteins sharing conserved structural features in the respective protein families. SwPiezo1 shares high identity with Piezos in non-caving leeches. SwiGluRs are conserved in protein sequence and share high identities with homologous proteins in other leeches. In contrast, SwTRPs belong to different subfamilies and share diverse identities with TRPs in other species. Gene expression analysis showed that two SwPiezos, five SwTRPs, and one SwiGluR are abundantly expressed in both winter and summer samples. These results suggest that SwPiezos, SwTRPs, and SwiGluRs are candidate sensory channels/receptors that may have roles in mechanosensory and chemosensory systems. High expression levels of Piezo and TRP genes imply a mechanosensory adaptation of S. wulingensis to the hanging living style in caves. Furthermore, enrichment of sensory genes in the oral sucker indicates the important role of this tissue in response to environmental stimuli. Similar gene expression profiles in winter and summer samples imply a stable physiological status of S. wulingensis in the cave environment.

Mites are among the most abundant invertebrates in subsurface ecosystems, and their community assemblages and distributions are often significantly influenced by the diversity of habitat resources. The cave ecosystem encompasses drastic changes in nonbiological factors, such as changes in lighting conditions from bright to extraordinarily dark and habitat gradients of surface plant resources from abundant to scarce or even disappearing, providing an ideal unique environment for evaluating the assembly mechanism of soil animal communities. Nevertheless, there still needs to be a sufficient understanding of the biodiversity patterns and drivers of mite communities across environmental gradients in karst caves. We conducted a comprehensive survey on the composition and diversity of soil mites in three photometric zones (dark, twilight, and light) of a typical karst cave and its adjoining extractive environments (forest scrub and farmland). Our research aimed to investigate the ecological relationships of mite communities between above- and below-ground habitats and the effects of abiotic factors on mite communities. We collected 49 families, 86 genera, and 1284 mites. In the external cave environment, we captured 1052 mites from 72 genera and 45 families; in the internal cave environment, we captured 232 mites from 46 genera and 29 families. The abundance, richness of genera, and diversity parameters of the mite community decreased from the cave entrance to the cave interior with decreasing light intensity. Oribatid mites dominated the mite community. Protoribates and Scheloribates were the dominant genera, along with Tectocepheus and 11 other genera, which primarily distinguished the mite communities among different habitats. Forty endemic taxa were found in the external cave environment, compared to 14 endemic taxa in the internal cave environment. The mite community showed a strong preference for the cave ecosystem habitat. Temperature, humidity, and soil nitrogen content significantly influenced the distribution pattern of mite communities (VIP > 0.8, p < 0.05).

This study aimed to evaluate the landslide risk map in the Algerian Western coasts. This evaluation was based on three steps. The first step requires evaluating the landslide hazard. To reach this, a field surveys data, combined with Geographical Information System (GIS) analysis and Remote Sensing (RS) image processing were carried out. Seven controlling factors were considered: lithology, geomorphology, slope, land use, distance to stream, rainfall and distance to fault. A topographic map of 1/ 25 000 was used to generate a Digital Elevation Model (DEM) with 15 × 15 m of resolution. From this DEM, the slope was extracted. Based on knowledge approach, the different factors were weighted according a scale value ranging from 1 to 9. The lowest values were assigned to the factors which have a minor influence on landslide triggering, and the highest values were given to the important parameters for landslide occurrence. These factors were combined using weighted linear combination (WLC). The landslide hazard map was classified into five levels: very low, low, moderate, high and very high. The landslide vulnerability was evaluated through the identification of the elements at risk. Three vulnerabilities aspects were considered: physical, environmental and socio-economic. The weights of each factor were given depending on the magnitude and the rate of landslide. Landslide Vulnerability Map (LVM) for Algerian western coasts was generated by the combination of the physical, environment and socio-economic vulnerability maps. Landslide risk was evaluated by combining the hazard map and the vulnerability map, and it was divided into four classes: very low, low, moderate and high.

Karstification (carbonate rock dissolution during sub aerial exposure), although frequent in modern analogues is often underestimated and not properly modeled in carbonate petroleum reservoirs. Poorly understood in cores and borehole image logs, too often the presence of rock property enhancing Karst networks is rather attributed to elusive high permeability faults or fractures. The F6 field, located in the Central Luconia carbonate province (offshore Sarawak, Malaysia) is the largest gas field within the Sarawak Shell portfolio. The reservoir is an elongated carbonate build-up of Miocene age characterised by steep flanks, a generally flat top and a central pinnacle. So far, the field was modelled as a layered carbonate reservoir with laterally homogeneous properties. Gas is contained in three major zones, namely the highly porous Zone1, which forms the central pinnacle, the tighter Zone2, which extends over the central half of the build-up, and the good quality Zone3, which extends over the whole build-up. Commissioned in 1987, the field is now maturing, with over half the reserves produced. A 3D seismic survey was acquired in mid 2002 to support an infill drilling campaign and a potential field re-development. Initial coherency seismic attributes used for the structural interpretation suggested an extensive dendritic Karst network within Zone3. Also initial 3D dynamic simulation suggested the need for enhanced properties in Zone3 and possibly higher volumes to match the combination of contact rise and pressure data in the field. Karst networks are often poorly expressed features on 3D seismic due to their inherent complex shapes and lateral variability. In order to image the Karst, special post-processing attributes based on coherency, phase or frequency algorithms have been tested. None of these attributes would give a full image of the Karst (mostly due to the rapid lateral variation in thickness). Therefore, these attributes were then combined using a multi-attributes volume interpretation workflow in order to build a realistic Karst model. The model was then tested against drilling operational data (mud losses). The multi-attributes interpretation allowed for the merger of different Karst "signatures" while the 3D volume based approach allowed for the spatial definition of complex geometries. Karst network geometries were subsequently incorporated into a deterministic reservoir model and risked properties could be tested and further refined against 15 years of production history in an iterative dynamic simulation workflow. This detailed reservoir architecture mapping based on 3D seismic had considerable impacts on the F6 field projects: Large (open) Karst features, combined with a depleted reservoir pressure, could create major drilling problems. Therefore, strategies had to be defined by the subsurface and drilling team to mitigate the risk of Karst-induced major losses while drilling the planned development wells.Although not fully sampled by wells, the Karst network effective properties could be roughly derived from seismic then refined during dynamic modelling by history matching of multiple scenarios. This work is still on going and will be used to screen re-development opportunities to safeguard and increase reserves.

Delineating salt is an inherently difficult problem. Currently, there are several methods to detecting salt bodies in seismic. However, the result and volumes are often noisy, and are therefore hard to use for voxel based segmentation interpretation. We present a new method of using a 3D Sobel edge detector in combination with dip guiding to generate clearer images. We also introduce elements of weighting and normalization to achieve our results.