Seismic Interpretation Techniques Research Articles

Seismic geomorphology and reservoir conditions of a Middle Miocene submarine channel system in the Taranaki basin, New Zealand

Deepwater channels function as vital deep-sea hydrocarbon reservoirs and as major routes for moving terrestrial clastic sediment to deepwater environments. A high-resolution sequence stratigraphic framework was built for the deepwater area of the Taranaki Basin using high-resolution three-dimensional (3D) seismic data, and various seismic interpretation techniques, including seismic attribute analysis, were applied. The principal controlling factors and petroleum development potential of the Middle-Miocene channel system were investigated with sequence stratigraphy and seismic geomorphology. Four understandings were primarily attained in this study: (1) depending on the different levels of the channel surfaces, the channel system can be divided into five sedimentary units (SU1-SU5), which correspond to the five stages of channel system evolution. These surfaces include one primary draping surface (PDS), five secondary channel erosion surfaces (SCES), and several tertiary channel erosion surfaces (TCES). (2) with the use of seismic facies analysis, six sedimentary elements were identified in the channel system: pelagic deposits (PDs), mass transport deposits (MTDs), outer levee complex (OLC), inner levee and terrace complex (ILTC), and turbidite channel complexes (TCCs). (3) The sedimentary evolution of the channel system was jointly influenced by multiple factors. The sediment supply and submarine geomorphology can directly affect the internal stacking and migration patterns of the channel. In contrast, tectonic activity and relative sea level fluctuations can indirectly affect the sedimentary characteristics of the channel by regulating the components and scale of clastic sediment. (4) SU1, SU2, and SU3 are primarily filled with coarse-grained sediments, which can serve as high-quality hydrocarbon reservoirs. In contrast, SU4 and SU5 can serve as regional cap rocks because they are filled with fine-grained sediments, and the overall channel system can represent a potential hydrocarbon reservoir-cap combination, which can be viewed as a significant research target for upcoming deepwater exploration. Clarifying the sedimentary properties and primary controlling factors at the various evolutionary stages of deepwater channels is vital for predicting the hydrocarbon development potential of the basin and reducing the drilling risk. This also helps with the development of deepwater basins with similar sedimentary environments in New Zealand and elsewhere in the world.

Seismic geomorphology and evolution of Mid-Late Miocene deepwater channels offshore Taranaki basin, New Zealand

Deepwater channels play a significant role in deep marine environments by transporting sediments to deep marine environments, but they are also hydrocarbon reservoirs. In contrast, traditional seismic interpretation techniques have provided insights into these features; intricate channel-fill heterogeneities present challenges in revealing small features or associated elements. This study integrates high-resolution 3D seismic data, relative time geologic models (RGT), spectral decomposition, and geobody to identify the Middle-late Miocene submarine channels, their evolution, and their associated deposition elements. The geomorphologic and stratigraphic analysis results have revealed four depositional elements in the study area. These include (1) channel complexes, (2) distributary channels, (3) frontal splay channel complexes, and (4) crevasse splays. However, the channels lack constructional levee development outside the channel banks, which is linked to the limited sediment supply to deep areas. The identified channels are characterized by a narrow to wide width (0.37 km–1.92 km), a low to high degree of sinuosity, medium incision depths, and lateral migration. The channel fill geometries are highly variable, displaying horizontal to sub-horizontal, lateral accretion, divergent, and inclined reflection packages. Most channels originate as large and wide channels from the northeast and prograde southwest direction of the Taranaki coastline, and they have evolved differently at different development stages. The channel fills exhibit a variable basal amplitude reflection, ranging from medium to high, indicating the presence of sand-prone and mixed facies, such as sand and mudstone. The spectral decomposition maps show variable color intensity, which implies different facies associations within the channels. The channel evolution is likely to be controlled by the interplay of sediment discharge, faults, sea level changes, variable gravity flow strength, and the type of materials supplied from the shelf edge.

Prediction of Thin Shoal Reservoirs Under Reef Controlled by Isochronous Stratigraphic Framework

Despite the great success in the global exploration and development of reef reservoirs, research on bioclastic shoals under reefs is still in its infancy. Bioclastic shoal reservoirs are very thin, with multiple vertical levels and fast lateral changes, which makes accurate prediction of the reservoir’s location much tougher. To further implement the reservoir distribution, under the guidance of sequence stratigraphy, the prediction of thin shoals under the control of an isochronous stratigraphic framework was established. Using the combination of spectrum shaping and F-X domain noise suppression techniques and utilizing the signal-to-noise ratio spectrum set as the reference, logging curve as supervision, and well seismic calibration and isochronal amplitude slicing as quality control, the seismic frequency band was extended, and the seismic data resolution and signal-to-noise ratio were improved. After frequency extension, the global optimal seismic automatic interpretation technique was used to construct an isochronal stratigraphic framework model. Through waveform facies-controlled inversion and waveform facies-controlled simulation techniques, the elastic properties of the shoal reservoir were obtained, from which the planar distribution of the reservoir was accurately predicted. The above methods were applied to the prediction of the bioclastic shoal reservoir in the lower submember of the Changxing formation in the Yuanba gas field (China). The plane distribution of bioclastic shoal in the first and second levels was identified, which provides a guideline for the prediction of thin shoal reservoirs.

Icehouse mixed carbonate and siliciclastic sequence evolution based on 3D seismic analysis: Insights from the Eastern Shelf of the Permian Basin, Texas

Reciprocal model was introduced for mixed carbonate and siliciclastic sequences within the Virgilian (Upper Pennsylvanian – Gzhelian) and Wolfcampian (Lower Cisuralian) on the Eastern Shelf of the Permian Basin in Texas. This model emphasizes carbonate dominance during transgressive and highstand on the slope, and siliciclastic dominance in the basin during lowstand. Contradictory observations from other mixed basins, such as compositionally mixed lithology in slope cores, accumulation of siliciclastics behind carbonate highs on the outer shelf, off-shelf transport of siliciclastics during highstands, and carbonate deposition on the slope during falling stage, require a re-evaluation of the reciprocal model. This research examines mixed sequences in the Cisco Group and maps lithology distribution by integrating geological and geophysical data, using advanced seismic interpretation techniques, wireline-log crossplot analyses, model-based post-stack inversion, probabilistic neural networks, and supervised Bayesian classification. Observations from the investigation are presented at two scales. In ∼400kyr sequences, relative sea level fall starts with carbonate deposition on the slope while siliciclastics persist near the inner shelf. As the falling stage progresses, siliciclastics reach the shelf edge, forming offlapping fans at the toe of the slope, likely truncating part of the siliciclastic topsets. Subsequently, mixed facies were deposited during the early stages of rising relative sea level, followed by carbonate deposition on the slope and shelf throughout transgression. The mixed facies found inland of transgressive carbonates indicate that prodelta siliciclastics mixed with carbonate mud. Occasionally, transgressive carbonates create shelf-edge build ups, hindering the transport of highstand siliciclastics to the slope. In the composite sequence spanning ∼1200kyr, siliciclastic input decreases significantly with the onset of sea-level fall. The fall truncates topsets with limited siliciclastics, preserving carbonate and mixed facies-dominated foresets with offlapping fans at the toe of the slope. This study advances our understanding of mixed sequences, challenges existing models and lays the groundwork for future investigations in similar geological settings.

The linear canonical W-transform

The time-frequency spectrum of seismic data is commonly used as an attribute in the analysis and interpretation of nonstationary seismic signals. To improve the capability of the W-transform to analyze nonstationary data, we introduce the linear canonical W-transform (LCWT) by implementing an affine matrix along with scaling parameters to generate high resolution and energy-concentrated time-frequency spectra. More features of nonstationary signals can be explored in the time-linear canonical frequency domain by transforming the time-frequency plane, which makes the algorithm more applicable to seismic signals. For the completeness of the LCWT, we also develop the inverse LCWT to extend its applications. Examples of synthetic and field seismic data show that a highly resolved and energy-concentrated time-frequency spectrum can be estimated with the LCWT with negligible additional computational burden. In addition, our algorithm is promising for several seismic data processing and interpretation techniques, such as reservoir characterization and thin layer identification.

Study on the Mechanism of Natural Gas Hydrate Decomposition and Seabed Seepage Triggered by Mass Transport Deposits

Previous studies indicate that mass transport deposits are related to the dynamic accumulation of natural gas hydrates and gas leakage. This research aims to elucidate the causal mechanism of seabed seepage in the western region of the southeastern Qiongdongnan Basin through the application of seismic interpretation and attribute fusion techniques. The mass transport deposits, bottom simulating reflector, submarine mounds, and other phenomena were identified through seismic interpretation techniques. Faults and fractures were identified by utilizing variance attribute analysis. Gas chimneys were identified using instantaneous frequency attribute analysis. Free gas and paleo-seepage points were identified using sweetness attributes, enabling the analysis of fluid seepage pathways and the establishment of a seepage evolution model. Research has shown that in areas where the mass transport deposits develop thicker layers, there is a greater uplift of the bottom boundary of the gas hydrate stability zone, which can significantly alter the seafloor topography. Conversely, the opposite is true. The research indicates that the upward migration of the gas hydrate stability zone, induced by the mass transport deposits in the study area, can result in the rapid decomposition of gas hydrates. The gas generated from the decomposition of gas hydrates is identified as the principal factor responsible for inducing seabed seepage. Moderate- and low-speed natural gas seepage can create spiny seamounts and domed seamounts, respectively.

Carbon capture integration in seismic interpretation: Advancing subsurface models for sustainable exploration

Sustainable exploration in the energy industry necessitates innovative approaches that address environmental concerns without compromising the efficiency (or robustness) of subsurface modeling. This paper explores the integration of carbon capture technologies into seismic interpretation as a means to advance subsurface models for sustainable exploration. The study leverages existing seismic interpretation techniques and incorporates carbon capture data to enhance the accuracy and environmental sustainability of exploration practices. The key concepts discussed include an overview of seismic interpretation methods, an introduction to carbon capture technologies, and the rationale for integrating carbon capture into seismic models. The practical application section provides insights into the proposed integration method, supported by real-world examples showcasing successful applications and potential benefits for sustainable exploration. Challenges and considerations in the integration process are identified, accompanied by strategies to overcome obstacles and considerations for industry-wide adoption. A detailed case example illustrates the step-by-step application of the integration, emphasizing its impact on subsurface models. The paper concludes with a forward-looking perspective, outlining potential technological advancements for further integration, suggesting areas for future research and development, and anticipating improvements in sustainability and exploration practices. This paper aims to contribute to the ongoing discourse on sustainable exploration by providing a practical framework for integrating carbon capture in seismic interpretation, paving the way for environmentally conscious and efficient subsurface modeling in the energy sector.

Stratigraphic evolution and sediment dispersal in a marine rift-basin: The case of the Lewis trough, Eastern Dampier sub-basin (Australia)

The understanding of the stratigraphic evolution of marine rift basins is important for both “pure” scientific and economic reasons. From a hydrocarbon exploration point of view the main goal is to develop tools to predict reservoir location, quality, and extent. Stratigraphic models try to do that, and only historical cases can be used to test those models. On the other hand, depositional model cannot precisely predict reservoir location as factors unique to the specific basin under analysis affect sediment distribution (basin physiography, type of flows, among others). This aspect can be assessed only on a case-by-case basis and can be used for initial hypothesis generation based on analogues. This paper shows a case history study based on the integration of well logs, and 3D seismic data across the Eastern Dampier sub-basin, Northwester Shelf of Australia. Advanced seismic interpretation techniques, calibrated to well data, enable the definition of a chrono-stratigraphic framework of the late syn-rift sequence (Late Jurassic) of the Lewis Trough, and the description of the sediment distribution through the interpretation of geomorphological features. During the Late Jurassic three different channel systems deliver sandstones to the deep-water part of the basin through multiple entry points. The timing of the sediment input seems to be linked to variation of sediment input as during that time relative sea-level was slowly rising. The location of the entry points is related to local physiography and defies any attempt of prediction based on general “rules.” From a stratigraphic point view, the findings of the study support the idea that, in rift basin, mechanical subsidence is the primary control for accommodation space, with episodic pulses of extension followed by longer periods of tectonic quiescence. It is during these episodic movements along the basin's bounding faults that space for sedimentation is created. This interpretation is in striking contrast with the basic assumptions of the conventional sequence stratigraphy model.

Unravelling Cenozoic carbonate platform fluid expulsion: Deciphering pockmark morphologies and genesis in the Tanintharyi shelf of the Andaman Sea as promising hydrocarbon reservoirs

Pockmarks, intriguing seafloor geological and geomorphological features, are commonly observed in marginal basins with hydrocarbon potential. As a Cenozoic marginal sea, the Andaman Sea is known for its significant petroleum reserves, and exploring its back-arc continental margin has revealed favourable conditions for petroleum occurrences. This study focuses on the Tanintharyi passive continental margin in the Andaman Sea, employing extensive stratigraphic and morphological analyses based on 2D and 3D seismic data interpretation techniques. Specifically, sub-seafloor characteristics of the Tanintharyi shelf region were investigated, focusing on comprehensively understanding pockmark morphologies, including their generation, evolution, migration, preservation, and the complete process leading to seabed leakage. This study revealed the potential of the Oligocene/Early Miocene carbonate platform in the Tanintharyi shelf region as a significant hydrocarbon reservoir for the upwelling buoyant fluids from the deep East Andaman Basin. Besides reservoir function, this carbonate platform serves as a passageway for the migration of fluids from the deep-sea area to the shallow-sea area, thereby playing a pivotal role in supporting fluid expulsion mechanisms in shaping a pockmark train adjacent to truncated sedimentary formations surrounding a geomorphological high on the contemporary seafloor. Additionally, the study examines the influence of changes in sedimentary facies and the tectonic setting of the Andaman Sea on pockmark evolutions, with a specific emphasis on the role of the uppermost shallow marine shale beds in developing sub-seafloor overpressure systems due to their impermeable seal rock properties. The article presents substantial evidence for the initiation of pockmark fields during the Middle Miocene period, followed by their transformation into pockmark trains on the present-day seafloor, attributed to the triggering effect of sub-seafloor overpressure systems due to changes in sedimentary dynamics in the Andaman Sea.

Collaborative Approach Solves Upstream R&D Challenges

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 211115, “IBTIKAR Digital Laboratory: A Collaborative Approach Toward Research and Development Challenges in Oil and Gas Upstream,” by Rauf Iqbal, Pranav Kumar, and Muhammad Aamir, ADNOC, et al. The paper has not been peer reviewed. _ The complete paper describes creation of an approach involving a research and development (R&D) environment that supports the business community. The operator’s Ibtikar laboratory is the result of an initiative to develop and provide in-house infrastructure (hardware and software) support within a national oil company’s operations. This synopsis is mostly devoted to a description of R&D challenges faced by the developers and the steps taken to overcome them. Efficient Seismic Attribute Extraction for Azimuthal or Angle Stacks An asset team acquired a few high-density broadband single-source, single-sensor seismic surveys characterized by an enormous amount of data. From acquisition to processing, multiple subcubes (90 GB/cube) were produced for the purpose of capturing subtle geological features. On a conventional machine, loading of the seismic cubes took 40 hours and realizing them took more than 7 days—and this was for only one seismic attribute. To fully use the data in the static and dynamic models of the respective reservoirs, the asset team collaborated with the team behind the described “digital laboratory” to provide a solution best suited for such a large processing requirement. The latter team analyzed the existing system, estimated requirements, and provided a high-performance computing (HPC) system that could handle the massive workload. Table 1 of the complete paper shows the results of a comparison of the conventional workstation with the HPC system. Computationally Intensive Fault-Likelihood Attribute Generation and Fault-Extraction Process In complex geological settings, fault identification and extraction of fault planes has always been a challenging task using traditional seismic-interpretation techniques. Conventional discontinuity-based seismic attributes often face limitations in delineating complex fault patterns, especially in areas of strike/slip and compressional-tectonics regimes. To address these limitations, geoscientists often use sophisticated seismic attributes such as fault likelihood, which follows a sequential multiattribute work flow to generate a fault-imaging volume used later to extract fault planes directly. The key challenge associated with running a computationally intensive attribute with a traditional workstation is that the process is time-consuming and performance is highly compromised because of hardware limitations. The fault-likelihood process itself generates six different seismic volumes during the automatic computation process. The task becomes even more challenging when multiple scenarios are required with varying parameters to assess and finalize the outcomes of fault-imaging volumes and extraction of fault planes. The digital laboratory was used to run this computing-intensive fault-likelihood process on a high-end machine with 800 GB random access memory and 96 cores with improved efficiency. It took only 10 days to run this multiattribute work flow on a seismic volume after running multiple scenarios using different attribute parameters to reduce fault uncertainty and automatically extract fault planes.

Imaging Lowstand prograding stratigraphic pinch-out traps of a Lower Cretaceous clastic system using inverted seismic-based porosity simulation of SE-Asian Basin: Implications for petroleum exploration

Prograding sandstone-filled incised valleys of the Lowstand System tract (LST) form stratigraphic plays. The band-limited seismic data interpretation techniques constrain the prediction of porous and gas-bearing reservoir facies. Therefore, the development of a cost-economic petroleum-bearing reservoir system is a challenge for reservoir geophysicists. This research is intended to predict the porosity and thickness of incised valleys by executing the continuous wavelet transforms (CWT)-based spectrum decomposition (SD), seismic static inverted simulation (SWM), and inverted seismic-based porosity simulation (IVPS) on a Lower Cretaceous LST system of Pakistan. The seismic, root-mean-square (RMS), and absolute average seismic attributes have provided a limited capability to image the gas-bearing sandstones. The 24-Hz tuning frequency has imaged the progradational sandstone-filled incised valley and retrogradational fluvial point bars. The 37-Hz has imaged the aggradational barrier bars. The amalgamation of multiple attributes has accurately demarcated the reservoir sandstone and sealing shale. The SWS has resolved a 32-m-thick prograding incised valley, 30-m-thick aggrading barrier bars, and 23-m-thick retrograding point bars within the complete fluvial hierarchy. The well correlation has provided evidence for the distribution of point bars, barrier bars, and shallow-marine incised valley reservoir facies. The 24-Hz CWT waveform-based conventional IVPS has predicted 94 and 42 m-thick valleys and "point bars" between 25 and 13% pseudo-porosity wells. The 24-Hz waveforms-based treatment of conventional IVPS has predicted enhanced thicknesses of 75 and 29 m for valley and point bar deposits with porosities between 25 and 13%. The 24-Hz IVPS has resolved two valleys compared to the conventional IVPS during the rapid fall of sea level and negligible rise, which have accumulated the coarse-grained point bar deposits of a fluvial meandering stream. The integration of IVPS and GR (API) has provided strong implications for the exploration of a pure stratigraphic trap within a shallow marine sedimentary system of Pakistan. A NE to SW oriented regional change was observed in the lithology, thickness, and depositional environments of the petroleum system. The dominant lithology in the eastern zones was point bar sandstones. The dominant lithology in the central zones was barrier bar sandstones. The dominant lithology in the western zone was incised valley sandstone. The thickness of the reservoir was 18 m thick in the west, which was reduced to 8 m in the eastern flanks of this gas field. The depositional environment in the northeast was fluvial, which changed to shallow-marine in the southwestern zones of the Indus basin. These lateral fluctuations have proved that a pure stratigraphic fairway was present within the LST of the Indus Basin of the sedimentary system of Pakistan. The porous incised valley stratigraphic reservoirs are embedded inside the non-porous shales, which validates the presence of a pure stratigraphic petroleum play inside the Indus Basin, Pakistan.

Structural and petroleum system analysis using seismic data interpretation techniques to Upper Cretaceous rock units: A case study, West Abu-Sennan oil field, Northern Western Desert, Egypt

South West Abu-Sennan (SWS) area is located in the Abu-Gharadig basin, Northern Western Desert in Egypt. This area is characterized by being a multi-reservoir with a complex structure and reservoir architecture. Therefore, we analyzed several datasets and practices to assess the Upper Cretaceous rock unit's hydrocarbon potentiality by combining the unconventional (using seismic attributes) and conventional interpretation approaches, moreover, analyzing the petroleum system elements to uplift the hydrocarbon potentiality figure. The structural features of the SWS are characterized by northeast-southwest (NE-SW) axis-directed anticlinal forms that are dissected by northwest-southeast (NW-SE) trending faults. the axis of these anticlines is most probably curved due to the effect of the cross-cutting normal faults. Reference analysis of the well HF35/1 geochemical data, burial history, and source rock pyrolysis evaluation proved the maturity of Masajid and Khatatba (Jurassic time) source rock units and the ability to expel hydrocarbons of types 2 and 3 to the probable reservoirs. The structural analysis illustrates that the anticlines are dissected by NW-SE faults, and act as structural traps for the migrated hydrocarbon from the deep source rocks at the Jurassic levels. An event chart has been created to clarify the petroleum system story. The conducted workflow in this study can be utilized to better understand similar reservoirs in neighboring areas.

Unsupervised seismic facies classification using deep convolutional autoencoder

With the increased size and complexity of seismic surveys, manual labeling of seismic facies has become a significant challenge. Application of automatic methods for seismic facies interpretation could significantly reduce the manual labor and subjectivity of a particular interpreter present in conventional methods. A recently emerged group of seismic interpretation techniques is based on deep neural networks. These approaches are data-driven and require large labeled data sets for network training. We have developed a deep convolutional autoencoder for unsupervised seismic facies classification, which does not require manually labeled examples. The facies maps are generated by clustering the deep-feature vectors obtained from the input data. Our method yields accurate results on real data and provides them instantaneously, which allows an interpreter to identify the dominant seismic features. The proposed approach opens possibilities to analyze geologic patterns in real time without human intervention.

From the Andes and the Drake Passage to the Rio Grande Submarine Fan: Paleoclimatic and paleogeographic evidence in the Cenozoic Era from the South Atlantic – Austral Segment, Pelotas Basin

The Cenozoic depositional history of the Pelotas Basin was driven by the interaction between the spreading processes of the Atlantic Ocean and the formation of the Andean Cordillera. We integrated seismic interpretation and backstripping techniques with evaluation of spreading rates in the South Atlantic and subduction beneath the Andes to unveil the main climatic, eustatic and active tectonic events in the Cenozoic. The achieved results integrated with regional geology and Cenozoic history data show the tectonic control that the Andean Cordillera exerted over the Pelotas Basin's passive margin. On the other hand, climatic and glacioeustatic changes that influenced the Pelotas Basin's sedimentation were mostly controlled by the tectonic opening of Drake Passage and the consequent onset of the Antarctic Circumpolar Current. These processes were directly connected to motions of the Antarctic, South American, and Nazca plates since the beginning of the Cenozoic. Our results allow us to detail the geological events of the Pelotas Basin and more accurately define its eustatic, tectonic, and climatic controls by closely observing the interaction between compressive tectonics and passive margins. • Drake Passage and Antarctic Circumpolar Current are recorded in the Pelotas Basin (PB). • Cenozoic glacioeustatic and tectonic events in the PB are connected to compressive and extensional margins. • Interaction between South American, Nazca, and Antarctic plates are crucial for South Atlantic Ocean sedimentation. • South Atlantic sea-floor spreading and Andean compressive tectonics control the sedimentation of the PB. • Rio Grande Submarine Fan shows Rio de la Plata contribution and contourites associated with ACC.

Mapping the geological structures in the Ras El Ush field (Gulf of Suez, Egypt), based on seismic interpretation and 3D modeling techniques

The Ras El Ush field (Gulf of Suez, Egypt) is characterized by various complex structural features, such as evaporite deposits and faulting. Such complex geologic setting results in difficulties in terms of high-resolution seismic interpretation. The seismic energy was masked by the Pre-Miocene salt formation and attenuated by evaporite deposits in the upper Miocene, complicating the seismic interpretation process. Proper geophysical seismic imaging and interpretation of Ras El Ush field's associated structures and sedimentation can provide insights into the geological controls on hydrocarbon systems in the Gulf of Suez rift zone. This study interpreted post-stacked reflection seismic and well data comprising the check shot velocity data to obtain and investigate detailed information about the structural fault orientation and dip of Ras El Ush field. Seismic attributes were employed for improving the fault attributes by eliminating noise and residue of non-faulting events. Additionally, depth maps and 3D structural models were constructed for Rudeis, Nukhul and Matulla formations, the main geological formations within the area of interest. This study presents results from seismic attributes analyses to enhance the detection of the Clysmic fault-offsetting aggregate as well as the minor and major cross faults that passed through the Ras El Ush field. The structural model of the Rudeis, Nukhul, and Matulla formations in the Ras El Ush field exhibits distinct NW-SE to NE-SW fault systems. The models helped in defining geological discontinuities and structural traps, which would help in the development of the field and nearby similar hydrocarbon fields in the Gulf of Suez (Egypt).

Random noise attenuation via convolutional neural network in seismic datasets

With the explosive growth in seismic data acquisition and the successful application of convolutional neural networks to various image processing tasks within multidisciplinary fields, many researchers have begun to research convolutional neural networks based seismic interpretation techniques. Seismic random noise attenuation is a key step in seismic data processing. In seismic data interpretation, faults are an important geological structure that has great significance for accumulation and migration of oil and gas reservoirs. Random noise within seismic data will seriously affect the accuracy of subsequent data processing and interpretation. Therefore, it is crucial to eliminate random noise in seismic data. This paper aimed to improve the Signal-to-Noise Ratio of seismic data, and proposed an intelligent convolutional neural network noise reduction framework. In this paper, the median filtering, the mean filtering, and the proposed algorithm is used to denoise seismic fault data. Experimental results show that the method not only yields a higher Signal-to-Noise Ratio, but also preserves more useful fault information.

An Assessment of Geophysical Survey Techniques for Characterising the Subsurface Around Glacier Margins, and Recommendations for Future Applications

Geophysical surveys provide an efficient and non-invasive means of studying subsurface conditions in numerous sedimentary settings. In this study, we explore the application of three geophysical methods to a proglacial environment, namely ground penetrating radar (GPR), seismic refraction and multi-channel analysis of surface waves (MASW). We apply these geophysical methods to three glacial landforms with contrasting morphologies and sedimentary characteristics, and we use the various responses to assess the applicability and limitations of each method for these proglacial targets. Our analysis shows that GPR and seismic (refraction and MASW) techniques can provide spatially extensive information on the internal architecture and composition of moraines, but careful survey designs are required to optimise data quality in these geologically complex environments. Based on our findings, we define a number of recommendations and a potential workflow to guide future geophysical investigations in analogous settings. We recommend the initial use of GPR in future studies of proglacial environments to inform (a) seismic survey design and (b) the selection of seismic interpretation techniques. We show the benefits of using multiple GPR antenna frequencies (e.g., 25 and 100 MHz) to provide decimetre scale imaging in the near surface (e.g., < 15 m) while also enabling signal penetration to targets at up to ∼40 m depth (e.g., bedrock). This strategy helps to circumvent changes in radar signal penetration resulting from variations in substrate conductivity or abundant scatterers. Our study also demonstrates the importance of combining multiple geophysical methods together with ground-truthing through sedimentological observations to reduce ambiguity in interpretations. Implementing our recommendations will improve geophysical survey practice in the field of glacial geology and allow geophysical methods to play an increasing role in the interpretation of glacial landforms and sediments.

The Influence of Interference Layer on the Prediction of Seismic Information of Channel Sedimentary Reservoir

Channel sedimentary reservoirs are the main oil and gas accumulation sites at home and abroad. With the deepening of oil and gas exploration, channel-related oil and gas reservoirs with obvious seismic characteristics have been mostly discovered, and the rest are basically oil and gas reservoirs with unobvious seismic characteristics and difficult to be discovered. The difficulty and risk of discovering these oil and gas reservoirs are on the increase. In order to reduce the exploration risk, it is necessary to form a more reliable time window control theory with a better seismic interpretation technique for channel reservoir reliability. In this paper, 2D forward modeling was used to study the influence of the upper and lower interference layers on the imaging of channel reservoir. When the lithological composition is relatively stable, the degree of interference of the interference layer is closely related to the seismic wavelet, and it is especially susceptible to the main frequency of the seismic wavelet. The lower the main frequency of seismic wavelet, the greater the degree of interference of interference layers on the imaging of channel reservoir, and vice versa. Further analysis on the characteristics of the Ricker wavelet was made and showed that the influence of the upper and lower interference layers on the imaging information of the channel reservoir is concentrated in half apparent major period. Then, considering the dynamic change of distance between the interference layers and the top and bottom interfaces of channel reservoir, the influence of interference layers on the imaging of channel reservoir was studied through 1D forward modeling. The interference area was divided into maximum interference area and main interference area depending on the degree of influence. On this basis, the time window control theory of channel reservoir prediction was clarified. The seismic information which reflects the channel reservoir reliably can be obtained by avoiding the maximum interference area, especially the main interference area.

ARCHITECTURAL COMPLEXITIES AND MORPHOLOGICAL VARIATIONS OF THE SEDIMENT WAVES OF PLIO-PLEISTOCENE CHANNEL LEVEE BACKSLOPE OF THE INDUS FAN

The architecture of the turbidity current sediment waves exhibits intricate morphologies and patterns on the Indus Fan channel levee backslope. The sediment waves are present on the channel levee of Plio-Pleistocene age and are absent in the deeper sections of the study area. The architecture of channel levee backslope on the Indus Fan is poorly understood. We used seismic interpretation techniques and modelling by utilizing high-resolution seismic data to approach this problem. The morphological variations in wavelength, crest dimensions and potential wave formation patterns suggest the autogenic and allogenic processes associated with wave development. Wavelengths reach up to 1473 m with an average of 486.84 m and the height of the levee ranges between 10 m and 60 m (average 30 m). The angle of the channel levee and dimension of the sediment wave here are independent of each other. Low angle levees have accommodated high dimension sediment waves and vice versa at multiple points downslope. Characteristically, the waves have formed on the outer levee (usually left) of the channels marked by steep margins suggesting that flow overspill caused the development of the waves. Generally, the younger sediment waves followed the patterns of older sediment waves, but the varying trends are often observed in the study area. The patterns of the sediment waves towards the younger sections of the levee indicate the modified and varying architectural style of growth. Sediment waves are generated by downslope turbidity currents. However, the deformation features have also possibly triggered the development of sediment waves.

New method for the reconstruction of sedimentary systems including lithofacies, environments, and flow paths: A case study of the Xisha Trough Basin, South China Sea

Existing seismic facies analysis schemes, including traditional seismic facies analysis, seismic slice analysis, and automatic classification of seismic facies, can reconstruct the sedimentary systems of basins; however, they are not ideal for basins with few boreholes and many rock types. Herein, we propose a new method for reconstructing sedimentary systems using seismic data, considering the Xisha Trough Basin in the Northern South China Sea as the research object to demonstrate the principles, methods, and technologies of this novel scheme. Based on the six commonly used seismic parameters, three additional seismic parameters (smoothness, neatness, and special waveform) and one geological marker (provenance) were added to improve the recognition of lithofacies. The scanned seismic interpretation technique was used to describe the distribution of sandstone and other skeleton lithofacies; sedimentary environments were determined according to the coastline, shelf break line, and slope toe line; flow path systems were determined according to the paleotopography, incised valleys, and sandstone distribution; and the sedimentary systems of the trough basin were reconstructed through the superposition of skeleton lithofacies, depositional environments, and flow paths. Results show that the sedimentary system reconstructed using the new method contains three elements, namely, lithofacies, the environment, and flow path, which fully reflect the concept of the sedimentary system defined by Fisher and McGowen (1967) ; this overcomes the inherent defects of previous schemes, such as poor lithofacies recognition and the uncertainty of types and boundaries of sedimentary bodies. This method enabled identifying subdivided seismic lithofacies directly from seismic profiles and enhanced the ability to obtain sedimentary information from seismic data. The proposed reconstruction method can be used in areas without boreholes or with many rock types and is significant for marine geology research and oil and gas exploration conducted in the deep sea.