Reflection Seismic Interpretation Research Articles

3D ground-penetrating radar data analysis and interpretation using attributes based on the gradient structure tensor

In near-surface geophysics, ground-penetrating radar (GPR) surveys are routinely used in a variety of applications including those from archaeology, civil engineering, hydrology, and soil science. Thanks to recent technical developments in GPR instrumentation and antenna design, 3D surveys comprising several hundred thousand traces can be performed daily. Especially in complex environments such as sedimentary systems, analyzing and interpreting the resulting GPR volumes is a time-consuming and laborious task that is still largely performed manually. In the past few decades, several data attributes have been developed to guide and improve such tasks and assure a higher degree of reproducibility in the resulting interpretations. Many of these attributes have been developed in image processing or computer vision and are routinely used, for example, in reflection seismic data interpretation. Especially in sedimentary systems, variations in the subsurface are accompanied by variations of GPR reflections in terms of the amplitudes, continuity, and geometry in view of the dip angle and direction. A promising tool to analyze such structural features is known as the gradient structure tensor (GST). To date, the application of the GST approach has been limited to a few 2D GPR examples. Thus, we take the basic idea of GST analysis and introduce and evaluate the corresponding attributes to analyze 3D GPR data. We apply our GST approach to one synthetic and two field data sets imaging diverse sedimentary structures. Our results demonstrate that our set of GST-based attributes can be efficiently computed in three dimensions and that these attributes represent versatile measures to address different typical interpretation tasks and, thus, help for an efficient, reproducible, and more objective interpretation of 3D GPR data.

AUTOMATED HIGH-PRECISION ALIGNMENT OF GEOLOGICAL MAPS WITH WELL ORIENTATION

The 3D reflection seismic interpretation entails the creation of structure maps of subsurface horizons across extensive areas, often spanning tens of thousands of square kilometers within sedimentary basins. In order to be correlated with well measurements, maps made from 3D reflection seismic are routinely assigned the correct depth at well control points. However, integrating orientation information measured from wells remains a challenge due to the absence of upscaling guidelines. We address the scale-dependent nature of geological structure and well orientation information in subsurface mapping, particularly focusing on integrating kilometer-scale seismic interpretation with centimeter-scale well-measured dip and azimuth data. Our pioneering methodology streamlines this integration process through three essential steps: first, transforming well dip and azimuth into a gradient representation; second, smoothly extending gradient differences between the map and well within a user-defined radius of influence; and third, constructing an updated horizon map by Bicubic spline interpolation to ensure automated and high-precision alignment. Additionally, a structure-oriented interpolation technique is introduced to preserve faults and local structures during orientation correction. Application of the methodology to a 3D reflection seismic horizon demonstrates its effectiveness in automating the complex task of tying subsurface maps to well orientation information. This not only reduces the need for manual interventions but also introduces a new perspective in subsurface mapping. It provides a robust framework that enhances the accuracy and reliability of geological interpretation, offering significant advancements beyond previous efforts in the literature.

Structural and Stratigraphic Interpretations for Mishrif Formation in Kumait Oil Field, Using Seismic Reflection Data, Southern-Eastern Iraq

The Kumait oil field is located in the Maysan Governorate southeastern Iraq, which was studied and interpreted by using 2D and 3D seismic data provided by the Oil Exploration Company using Petrel software. The study concerned the Mishrif Formation belongs to the Cretaceous Age. The reflector was detected based on synthetic seismograms and well logs for Kt-1 well. Structural maps (two-way time, velocity, and depth) were derived from seismic reflection interpretations to show several structural features, such as four isolated irregular enclosures representing the Kumait structure plunging NW-SE and demonstrating that the Kumait oil field is influenced by the Najd fault system trending NW-SE. The stratigraphic interpretation used the variance attribute to delineate the edge of the fault, which extended from the Mishrif Formation with a depth of 3090m and used the Direct Hydrocarbon Indicators (DHI) to identify the stratigraphic features in the research region and the extraction of seismic attributes. The applied seismic attributes, such as the instantaneous phase, show dim spots, flat spots, and mounds and is followed by down-lap; the instantaneous frequency, which offers low-frequency areas indicating a high probability of hydrocarbon accumulation; and the RMS amplitude, which shows high amplitude in the seismic data that conforms to the structure and confirms the presence of hydrocarbon.

Interplay of positive structural inversion and salt tectonics: The case study of the central Algerian margin, Western Mediterranean

Convergence between African and European plates generates compressional strain, primarily concentrated along the northern African margin. This is testified on the Algerian margin by numerous earthquakes (e.g. Bougrine et al., 2019) and by the presence of active folds and thrusts. Multi-channel seismic reflection profiles from the MARADJA I survey reveal north-verging thrusts rooted below the Messinian units, and the geometries of the Messinian salt structures. This study examines the characteristics of salt tectonics offshore Algiers and Dellys, focusing on the effect of the positive structural inversion of the former passive margin on geometries, timing, and mechanisms of salt deformation. The interpretation of seismic reflection and multi-beam bathymetric data of the MARADJA I survey, along with its comparison with analogue models, allowed us to reconstruct the salt tectonics processes on the margin and to identify the predominant role of a plateau uplift on salt deformation. Early and ubiquitous salt deformation by downbuilding was followed by a major phase of plateau uplift (end of Messinian Crisis), leading to westward gravity gliding and a slowdown of the salt deformation above the plateau. Km-tall salt structures were developed and thick minibasins deposited. Salt tectonics is nowadays active only where the relationship between salt and overburden thickness is favorable.

Extensional fault geometry and evolution within rifted margin hyper-extended continental crust leading to mantle exhumation and allochthon formation

Abstract. Seismic reflection interpretation at magma-poor rifted margins shows that crustal thinning within the hyper-extended domain occurs by in-sequence oceanward extensional faulting which terminates in a sub-horizontal reflector in the topmost mantle immediately beneath tilted crustal fault blocks. This sub-horizontal reflector is interpreted to be a detachment surface that develops sequentially with oceanward in-sequence crustal faulting. We investigate the geometry and evolution of active and inactive extensional faulting due to flexural isostatic rotation during magma-poor margin hyper-extension using a recursive adaptation of the rolling-hinge model of Buck (1988) and compare modelling results with published seismic interpretation. In the case of progressive in-sequence faulting, we show that sub-horizontal reflectors imaged on published seismic reflection profiles can be generated by the flexural isostatic rotation of faults with initially high-angle geometry. Our modelling supports the hypothesis of Lymer et al. (2019) that the S reflector on the Galician margin is a sub-horizontal detachment generated by the in-sequence incremental addition of the isostatically rotated soles of block-bounding extensional faults. Flexural isostatic rotation produces shallowing of emergent fault angles, fault locking, and the development of new high-angle shortcut fault segments within the hanging wall. This results in the transfer and isostatic rotation of triangular pieces of hanging wall onto exhumed fault footwall, forming extensional allochthons which our modelling predicts are typically limited to a few kilometres in lateral extent and thickness. The initial geometry of basement extensional faults is a long-standing question. Our modelling results show that a sequence of extensional listric or planar faults with otherwise identical tectonic parameters produce very similar seabed bathymetric relief but distinct Moho and allochthon shapes. Our preferred interpretation of our modelling results and seismic observations is that faults are initially planar in geometry but are isostatically rotated and coalesce at depth to form the seismically observed sub-horizontal detachment in the topmost mantle. In-sequence extensional faulting of hyper-extended continental crust results in a smooth bathymetric transition from thinned continental crust to exhumed mantle. In contrast, out-of-sequence faulting results in a transition to exhumed mantle with bathymetric relief.

Structural Interpretations for Zubair Formation in Kumait oil field, Using 3D Seismic Reflection Data, Southern-East Iraq

This study deals with the interpretation of structural 3D seismic reflection of the Kumait oil field in southern Iraq within the administrative boundaries of the Maysan Governorate. Synthetic seismograms are prepared by using available data of the Kt-1 oil field by using Petrel software to define and pick the reflector on the seismic section of the Zubair Formation, Which represents the Cretaceous Age. The study shows that the Kumait structure is an anticline fold. It is thought to be a structure trap caused by the collision of the Arabian and Iranian plates and trending in the same direction as driving factors in the area, which are from the northwest to the southeast, and the overall trend of strata is north and northeast. Seismic structure interpretation results show the top of the Zubair Formation and several structure closures. The stratification Phenomenon of the study area was clear evidence of the existence of closures which are probable to be hydrocarbon traps.

Petroleum system analysis and thermal evolution of the deepwater NW Borneo fold-thrust belt

The generation of hydrocarbons in source rocks can lead to overpressure, which can support development of detachments and the deformation of sedimentary rocks. In turn, the deformation of rock units by e.g., large-scale overthrusting can lead to tectonic-driven burial. Tectonic-driven burial can generate overpressure, which in turn can influence the petroleum system. In fold-thrust belts, an integrated understanding of both, the tectonic and the petroleum systems is important for understanding the potentially complex interaction of faulting, folding and fluid geochemistry. This study combines structural restoration and basin-modeling techniques to provide a comprehensive view of the fold-thrust system offshore northwest Borneo.In the deepwater region offshore northwest Borneo a major fold-thrust belt is present. The thrust belt is characterized by a mix of gravity-driven folding and faulting in a southwestern domain, and deep-seated crustal deformation in a northeastern domain. Oil and gas preferentially accumulated in thrust-top anticlines. The NW Borneo fold-thrust belt has a low taper angle; likely related to fluid overpressure along the basal detachment. The basin models presented in this study are based on an integration of regional 3D seismic-reflection interpretation, borehole analysis and 2D kinematic restoration. 2D petroleum systems modeling shows oil and gas generation and expulsion from Middle Miocene coaly source rocks since the Late Miocene, migration of the hydrocarbons through carrier beds and faults, and the accumulation of oil and gas in thrust-hangingwall anticlines. Vertical gas leaks modeled are comparable with gas clouds observed on 3D seismic-reflection data. The risk of biodegradation was estimated for reservoirs shallower than 1000–1500 m, and their burial is influenced by uplift due to thrusting. Combined tectonic and thermal modeling of the fold-thrust belt indicates the initiation of shortening at the time when the maturation of the source rock at the basal detachment was within the oil window. The timing of the maximum shortening rate, however, exhibits regional variations across the fold-thrust belt. In the gravity-driven fold thrust system in the southwest, the primary control on the peak of shortening is the maturation of the source rock at basal detachment level (gas window). In contrast, the peak of shortening in the northeast with the deep-seated crustal-driven system is interpreted as being primarily controled by the intensity and timing of the external stress.

Visualizing subtle structural and stratigraphic features on 3D seismic-reflection data: A case study from offshore Libya

Seismic-reflection data contain residual noise after processing, which can cause geologic misinterpretation of noise-sensitive seismic attributes. For detailed subsurface imaging, seismic data conditioning can enhance the visualization of subsurface reflection features down to the limit of seismic resolution. This study on the Gabes-Tripoli Basin of western offshore Libya demonstrates the potential of postprocessing seismic data conditioning using a standard industry 3D-seismic data set. The seismic data exhibit distinct reflection discontinuities and configurations interpreted as folds, reverse faults, and crustal- and gravity-driven normal faults. Other reflection discontinuities are interpreted as imaging the external form and internal architecture of buried carbonate platforms. The seismic-reflection interpretation finds that seismic data conditioning by filtering strongly supports the interpretation of the 3D geometry, type, and trend of distinct subsurface reflection features, particularly if used as input for a structural-attribute generation. Postprocessing seismic conditioning initially improved the signal-to-noise ratio by structure-oriented filtering with edge preservation. Application of this filter configuration emphasized subtle geologic features supporting, e.g., the detection of faults close to the limit of the seismic resolution. At the same time, the filtering resulted in a higher lateral continuity of the individual seismic reflectors, supporting the autotracking of the horizons. Structural attributes generated from the conditioned data such as the variance and curvature imaged more subsurface reflection detail when compared with the structural attributes generated from nonconditioned data. The filter-based workflow proposed can be applied in most seismic interpretation software packages and is recommended to be used as a standard procedure preceding a structure-attribute calculation and structural interpretation of the seismic-reflection data of limited quality.

An Improved Unscale S-Transform in Frequency Domain

The time–frequency analysis methods are powerful tools in seismic interpretation and bright spot identification. The S-transform (ST), as a hybrid of the short-time Fourier transform (STFT) and continuous wavelet transform (CWT), can achieve progressive time–frequency resolution. However, limited by its linear-frequency-dependent term, the ST obtains a deviated frequency distribution. By removing this term, the frequency form of unscaled ST (FUST), as a variation of the ST, is proposed to preserve the reliable frequency distribution. The fly in the ointment is that the FUST decreases the temporal resolution of the low-frequency components, which may not be suitable for seismic reflection interpretation and reservoir location. In addition, the ST cannot tailor the time–frequency resolution for particular applications. To solve these problems, a simple and effective method is proposed by substituting the basis of the FUST. The proposed method can obtain the desired time resolution by adjusting two adjustable parameters. The corresponding inverse transform is also derived to guarantee its energy conservation and inevitable property. Numerical experiments and real data examples show better performance of the proposed method in improving temporal resolution and reservoir location over the ST and FUST.

Study of Subsurface Structural Image and Model Using 2D Seismic Reflection Method of Injana Field Area, Northeastern Iraq

The Injana field area is located to the north of Baquba city within Diyala. which was studied and interpreted by using 2D seismic data from the Oil Exploration Company. The study was concerned with the Jeribe Formation which is located within the Injana field area and belongs to the Tertiary Age. Two reflectors were detected based on synthetic seismograms and well logs of the Khashim Al-Ahmer-2 well. The structural maps were derived from seismic reflection interpretations to determine the location and direction of the basin. The depth maps were conducted depending upon the structural interpretation of the picked reflectors to show several structural features. Structurally, seismic sections show that the Injana area is affected by two types of reverse fault systems trending in a NW-SE direction, the first represents thrust faults affected on the lower Fars (Red Beds & Seepage) and the layers above it, the salt bed within Lower Fars Formation being as a detachment surface of this fault, the second represents two reverse faults affected on the bottom part of the Lower Fars (Transition beds) and the layers beneath. In addition, the reverse faults become dense in the north part. The structural maps reveal an elongated asymmetrical narrow anticline affected by one major thrust fault at Lower Fars Formation, and an elongated asymmetrical narrow anticline surrounded by two major reverse faults and consisting of three domes separated, Injana, Khashim Al-Ahmer and Khashab domes at the Jeribe Formation.

Oceanward rift migration during formation of Santos–Benguela ultra-wide rifted margins

Abstract This paper presents the time and space evolution of crustal deformation and their respective sedimentary infill of the 600 km wide, asymmetric conjugate rifted margin of the Santos–Benguela basins. Based on a geoseismic transect obtained with interpretation of long-offset seismic reflection and tied by wells, we interpret six main synrift unconformities, corresponding to different deformation phases processed from the Valanganian to Early Albian. Confined by these unconformities, sedimentary growths with progressively young relative ages towards the boundary with the oceanic crust are interpreted as evidence of oceanward rift migration. The combination of this information with crustal structure derived from long-offset seismic reflection illuminating the deep crust of the Santos–Benguela conjugate margins, resulted in a complete view of sedimentary infill, internal compartments, and crustal structure. These data were used to guide a dynamic model of rifting resulting in a simulated lithospheric section. We show that the margin architecture can be explained by the combination of an early, protracted phase of distributed deformation, followed by basinward rift migration. Distributed deformation lasted from the Valanginian to Early Aptian (135–117 Ma), initiating with isolated lakes that later coalesced into a wide basin-scale lake (>450 km). From the Mid Aptian to Early Albian (117–110 Ma), rift migration formed the main structural compartments and unconformities, as well as the distal hinge zones we observe today in the seismic lines. During this time, the inner proximal margins were left behind to thermally subside, whereas outer proximal and distal margins were tectonically active. Coexistence of these two processes explains the enigmatic simultaneous formation of proximal sag-like geometries, with late synrift accumulation of a salt layer up to 3 km thick, with tectonically active faults in the distal margin, promoting crestal block uplift that could explain the deposition of Late Aptian, shallow water, pre-salt carbonate rocks.

Processes controlling volcanic and epiclastic reservoir formation in a buried polygenetic stratocone

Abstract Understanding the formation of volcanic and epiclastic reservoirs is pivotal for exploring geoenergy resources such as geothermal energy, hydrocarbons, and new CO 2 sequestration and hydrogen storage opportunities. This paper examines the processes controlling the quality of pyroclastic and epiclastic reservoirs of the Kora volcano, an extinct stratocone presently buried in the offshore Taranaki Basin, New Zealand. We conduct detailed seismic reflection interpretation, drillcore lithofacies and wireline-log description, petrographic analysis, and analytical tests to generate a unified framework that explains the formation of volcaniclastic reservoirs from basin to pore-scale. Each stage of construction and degradation of the Kora volcano is associated with particular processes that increase or reduce reservoir quality. Primary processes include quench fragmentation, deuteric mineral dissolution, and epiclastic sedimentation. Secondary processes comprise mineral alteration (mainly meteoric; minor hydrothermal and diagenetic), mechanical stress fracturing (mainly tectonic; minor magmatic and burial deformation), and pervasive biogenic cementation. Epiclastic conglomerates present the highest reservoir quality (average 23% porosity and up to 997 mD permeability), followed by lapilli-tuffs and tuff-breccias. In contrast, bioclastic epiclastic sandstones are typically cemented by carbonates and pyrite. Our models and interpretations will increase understanding of the formation of volcaniclastic reservoirs and aid exploration of geoenergy resources in volcanic terrains.

2D Seismic Structural and Stratigraphic Study of Kirkuk Group Formation in Amara Oil Field- Southeastern Iraq

The Amarah Oil field structure was studied and interpreted by using 2-D seismic data obtained from the Oil Exploration company. The study is concerned with Maysan Group Formation (Kirkuk Group) which is located in southeastern Iraq and belongs to the Tertiary Age. Two reflectors were detected based on synthetic seismograms and well logs (top and bottom Missan Group). Structural maps were derived from seismic reflection interpretations to obtain the location and direction of the sedimentary basin. Two-way time and depth maps were conducted depending on the structural interpretation of the picked reflectors to show several structural features. These included three types of closures, namely two anticlines extended in the directions of S-SW and NE, one nose structure (anticline) in the middle of the study area, and structural faults in the northeastern part of the area, which is consistent with the general fault pattern. The seismic interpretation showed the presence of some stratigraphic features. Stratigraphic trap at the eastern part of the field, along with other phenomena, such as flatspot (mound), lenses, onlap, and toplap, were detected as indications of potential hydrocarbon accumulation in the region.

Gravity modeling reveals a Messinian foredeep depocenter beneath the intermontane Fucino Basin (Central Apennines)

Residual gravity anomalies over Central Italy clearly indicate a prominent regional minimum over the Fucino Basin. Here, we forward model this anomaly along seven cross-sections. The modeling results validate the geometries and petrophysical properties of the Plio-Quaternary units previously proposed by reflection seismic data interpretation. Moreover, we suggest that a thick wedge-shaped sequence is present beneath the Plio-Quaternary post-orogenic units. Based on the inferred density and velocity properties, as well as outcrop evidence from around the Fucino Basin, this sequence would likely represent thick (~1700 m) siliciclastic syn-orogenic Messinian foredeep deposits. The proposed model implies a long-lasting tectonic inheritance history for the Fucino area, which originally hosted primary paleogeographic Mesozoic-Miocene boundaries. In the Messinian-Recent time, the Fucino has continuously represented a first-order tectonic depocenter for siliciclastic sediments, despite differences in tectonic regime (syn-orogenic Messinian, post-orogenic Plio-Quaternary) and palaeoenvironments (Messinian marine flysch, Plio-Quaternary alluvial-lacustrine facies). The compaction-corrected sedimentation rate (~0.89 mm yr−1), suggests a foredeep activity possibly spanning the entire pre-evaporitic, evaporitic and post-evaporitic Messinian time and is comparable to the sedimentation rate observed in the larger Pliocene Apennine foredeep, ~100 km northeast of the study area, suggesting a self-similarity of the belt-foreland system across time and space.

Seismic Attributes For Enhancing Structural And Stratigraphic Features: Application To N-Field, Malay Basin, Malaysia

Over two decades, analysis of seismic attributes had been an integral part of seismic reflection interpretation. Seismic attributes are an influential assistance to seismic interpretation, delivering geoscientists with alternative images of structural (faults) and stratigraphic features (channels), which can be utilised as mechanisms to identify prospects, ascertain depositional environment and structural deformation history more rapidly even provide direct hydrocarbon indicators. The additional steps are obligatory to compute and interpret the attributes of faults and channels from seismic images, which are often sensitive to noise due to the characteristically computed as discontinuities of seismic reflections. Furthermore, on a conventional seismic profile or poor quality data, faults and channels are hard to visible. The current research review these geological structures through a case study of 3D seismic data from N-field in the viewpoint of Malay Basin. This study aimed to characterise the structure and stratigraphic features by using seismic attributes on the N-field below seismic resolution. Also, two different methods are proposed to improve seismic reflections, i.e., faults and channels that are hard to see on the conventional 3D data set. The first method, to detect faults in seismic data, which this paper employs the ant tracking attribute as a unique algorithm to be an advanced forwarding that introduces a new tool in the interpretation of fault. The effective implementation of ant tracking can be achieved when the output of other faults sensitive attributes are used as input data. In this work, the seismic data used are carefully conditioned using a signal. Chaos and variance that are sensitive to faults are applied to the seismic data set, and the output from these processes are used as input data that run the ant tracking attribute, which the faults were seen difficult to display on the raw seismic data. Meanwhile, for the second method, spectral decomposition was adopted to deliberate the way its method could be utilised to augment stratigraphic features (channels) of the N-field, where the channel is ultimately considered being one of the largest formations of the petroleum entrapment. The spectral decomposition analysis method is an alternative practice concentrated on processing S-transform that can offer better results. Spectral decomposition has been completed over the Pleistocene channels, and results propose that application of its methods directs to dependable implications. Respective channel in this area stands out more obviously within the specific frequency range. The thinner layer demonstrates higher amplitude reading at a higher frequency, and the thicker channel displays higher amplitude reading at a lower frequency. Implementation of spectral decomposition assists in deciding the channels that were placed within incised valleys and helps in recognising the orientation and the relative thickness of each channel. By doing this, the ant tracking attribute and spectral decomposition approach have generated the details of subsurface geologic features through attributes by obtaining enhanced reflections and channels and sharpened faults, respectively.

Zircon U-Pb ages of the Benom Complex: Implications for a Late Triassic uplift event in Central Peninsular Malaysia

Over two decades, analysis of seismic attributes had been an integral part of seismic reflection interpretation. Seismic attributes are an influential assistance to seismic interpretation, delivering geoscientists with alternative images of structural (faults) and stratigraphic features (channels), which can be utilised as mechanisms to identify prospects, ascertain depositional environment and structural deformation history more rapidly even provide direct hydrocarbon indicators. The additional steps are obligatory to compute and interpret the attributes of faults and channels from seismic images, which are often sensitive to noise due to the characteristically computed as discontinuities of seismic reflections. Furthermore, on a conventional seismic profile or poor quality data, faults and channels are hard to visible. The current research review these geological structures through a case study of 3D seismic data from N-field in the viewpoint of Malay Basin. This study aimed to characterise the structure and stratigraphic features by using seismic attributes on the N-field below seismic resolution. Also, two different methods are proposed to improve seismic reflections, i.e., faults and channels that are hard to see on the conventional 3D data set. The first method, to detect faults in seismic data, which this paper employs the ant tracking attribute as a unique algorithm to be an advanced forwarding that introduces a new tool in the interpretation of fault. The effective implementation of ant tracking can be achieved when the output of other faults sensitive attributes are used as input data. In this work, the seismic data used are carefully conditioned using a signal. Chaos and variance that are sensitive to faults are applied to the seismic data set, and the output from these processes are used as input data that run the ant tracking attribute, which the faults were seen difficult to display on the raw seismic data. Meanwhile, for the second method, spectral decomposition was adopted to deliberate the way its method could be utilised to augment stratigraphic features (channels) of the N-field, where the channel is ultimately considered being one of the largest formations of the petroleum entrapment. The spectral decomposition analysis method is an alternative practice concentrated on processing S-transform that can offer better results. Spectral decomposition has been completed over the Pleistocene channels, and results propose that application of its methods directs to dependable implications. Respective channel in this area stands out more obviously within the specific frequency range. The thinner layer demonstrates higher amplitude reading at a higher frequency, and the thicker channel displays higher amplitude reading at a lower frequency. Implementation of spectral decomposition assists in deciding the channels that were placed within incised valleys and helps in recognising the orientation and the relative thickness of each channel. By doing this, the ant tracking attribute and spectral decomposition approach have generated the details of subsurface geologic features through attributes by obtaining enhanced reflections and channels and sharpened faults, respectively.

Analysis of submarine landslide potential that can trigger tsunami based on seismic reflection interpretation

The megathrust at the west part of Sumatera can produce a lot of earthquakes. Several earthquakes in Sumatera that occurred from 2004 to 2007 raised tsunami with various heights. The high tectonic activity in this area can trigger landslides in the ocean which may lead to tsunami. Therefore, research about seabed landslides needs to be done in this zone. The study identified the seabed geological structure from 2D seismic section in the east part of Siberut Island. The seismic section was generated from seismic processing of Seismic Line-05 (AA’). The seismic data were acquired using LIPI Baruna Jaya VIII research vessel on the Pre-Tsunami Investigation of Seismic Gap (PreTI-Gap) marine expedition in 2008. Seismic section interpretation shows the presence of backthrust on this seismic line. The bathymetry data from the Geospatial Information Agency and marine survey are used to make bathymetry map, bathymetry charts, and slope map. Analysis using 2D seismic section, bathymetry data, and slope map shows the steep zones at 3–5 km and at 15–16 km from the south west edge of Seismic Line-05 (AA’) with 180 m and 300 m bathymetry drop, respectively. These steep zones must be watched because they can trigger submarine landslides and tsunami.

Structural Interpretation of Yamama and Naokelekan Formations in Tuba Oil Field Using 2D Seismic Data

This research includes structure interpretation of the Yamama Formation (Lower Cretaceous) and the Naokelekan Formation (Jurassic) using 2D seismic reflection data of the Tuba oil field region, Basrah, southern Iraq. The two reflectors (Yamama and Naokelekan) were defined and picked as peak and tough depending on the 2D seismic reflection interpretation process, based on the synthetic seismogram and well log data. In order to obtain structural settings, these horizons were followed over all the regions. Two-way travel-time maps, depth maps, and velocity maps have been produced for top Yamama and top Naokelekan formations. The study concluded that certain longitudinal enclosures reflect anticlines in the east and west of the study area representing Zubair and Rumaila fold confined between them a fold consist of two domes represents Tuba fold with the same trending of Zubair and Rumaila structures. The study confirmed the importance of this field as a reservoir of the accumulation of hydrocarbons.

The Late Quaternary geological history of the lower Sydney estuary (Australia)

Sydney estuary is a dendritic, drowned river valley on the mid-east coast of Australia and comprises an upper and central section of narrow, sinusoidal channels and embayments and a wide, more marine lower estuary. The current work considered only the lower estuary.Minimal research has been undertaken into the structure of the lower Sydney estuary and previous attempts to integrate geologic and geophysical information are limited. The current study combines previously uninterpreted seismic records and poorly-accessible borehole data into a Late Quaternary history of the lower estuary.High-resolution, continuous reflection seismic (212-line km) interpretation matched borehole-based stratigraphy reasonably well. A bedrock paleo-valley deepened from approximately 40 m below present sea level (bpsl) at the Sydney Harbour Bridge (SHB) to > 90 m bpsl at the estuary mouth. Stratigraphy was dominated by two estuarine sequences, which, in the lower part of the estuary comprised mainly fine-grained, organic-rich sediments with peat, that manifest as multiple, strong dark and light-reflectors on seismic. At the SHB, the upper estuarine sequence developed into a transgressive marine to tidal delta deposit. A thin veneer (up to 10 m) of Modern estuarine sands mantled most of the lower estuary. The elevation of the estuarine sediments at approximately present-day levels and at 20 to 30 m bpsl respectively, strongly indicated deposition during periods of high-level marine transgression, i.e. the Last Interglacial (Marine Isotope Stage, MIS 5.5) event at 130 kyPB to 115 kyBP and the Penultimate Interstadial event (MIS 5.1 at 110–80 kyBP), respectively.Late Pleistocene aeolian sands contributed sediment in the south of the estuary, and remobilisation may have dispersed these sediments more widely. Present-day bathymetric features frequently reflected subsurface erosional structures due to starvation of bedload sediment.

Geometry and kinematics of tugerming structural belt in the east of Kuqa Depression, Tarim Basin

Accurate interpretation of clutter seismic reflection is of great significance to make clear the structural geometry and kinematics characteristics. Based on field investigations, boreholes and seismic data, forward modeling is carried out under the trishear model of fault-propagated fold principle, and the activity characteristics of the main faults in the study area are quantitatively analyzed using the balanced restoration technique, which may provide important indication for the potential petroleum exploration and development. The results show that separated by Tuziluoke and Tugerming fault, the structural style of the study area can be divided into the deeply buried forelimb, the kink band and the tiny anticline backlimb section. The Tuziluoke fault has been active with strong intensity since the sedimentary period of the Kuqa Formation and, which controls the formation of the growth strata in the deep buried forelimb of the Tuziluoke anticline. The Tugerming fault has been active intermittently since the end of the Jurassic, causing the strata denudation of the Late Jurassic to Paleogene in varying degrees and the development of series of regulating faults. The multi-stage tectonic activities caused the structural high of the anticline migrated from east to west.