Interpretation Of 3D Seismic Data Research Articles

Interaction between volcanic and non-volcanic systems and its implication for prospectivity in the Faroe–Shetland Basin, NE Atlantic continental margin

Exploration in the Faroe–Shetland Basin on the Faroese Continental Shelf has revealed thick and complex volcanic successions and discovery of inter-volcanic oil-bearing siliciclastic sandstone fan deposits in the central parts of the basin. The possibility for such play types at the fringe of the North Atlantic Igneous Province requires a better understanding of the interaction between competing sedimentary and volcanic depositional transport systems. We have re-examined volcanic units in cuttings from exploration wells in the greater Judd Sub-basin area for evaluation of facies and geochemical affinity. This allows for chemostratigraphical correlation of wells to the absolute radiometrically age-constrained Faroe Islands Basalt Group. The collective well data were subsequently tied to a regional interpretation of 2D seismic data which facilitated a detailed interpretation of temporal development of the volcanic successions in the Judd Sub-basin area in terms of geometry, volcanic facies, depositional environment, and interdigitation with non-volcanic sedimentary units. The Judd Sub-basin was influenced by major volcanic phases during pre-breakup and syn-breakup. The influence was both direct, in the form of volcanic deposits, and indirect, in the form of obstructing established sedimentary transport systems and creating new provenance areas. The volcanic transport systems reached different areas of the Judd Sub-basin at different times during pre-breakup volcanism. The earliest incursion in the west was during late Mid Paleocene (T-sequence T31/T32). With at least three stratigraphically discrete incursions of volcanic material into the Judd Sub-basin, possibilities arise for sub- and inter-volcanic stratigraphic and structural traps for each incursion.

The tectonic transition from rifting to strike-slip in the Liaodong Bay Depression, offshore China

The Liaodong Bay Depression was shaped by the Bohai Bay rift basin (BBRB) and the Tan-Lu strike-slip fault system (TSFS) in the Cenozoic and has undergone a tectonic transition from rifting to strike-slip. Therefore, it is an ideal region to study the transition from rifting to strike-slip. Based on new 3D serial seismic data interpretation, we investigated the types and formation times of the main faults in the Liaodong Bay Depression and restored them within the palaeogeography of each evolution stage. Our results show that the Liaodong Bay Depression underwent a tectonic transition from rifting to strike-slip: (1) The mantle material upsurge caused by the Izanagi plate trapped in the mantle transition zone led to rifting of the Liaodong Bay Depression from the Palaeocene to the Eocene. (2) In the middle Eocene, the change in the subduction direction of the Pacific plate led to dextral strike-slip movement along the Tan-Lu fault zone. (3) The rifting and strike-slip in the Liaodong Bay depression are related, and the transition from rifting to strike-slip occurred from the middle Eocene to the early Oligocene. The strike-slip faults developed when rifting was weak in the Oligocene. The transition from rifting to strike-slip faulting formed oil-gas accumulation zones along the strike-slip fault zone and thus resulted in the good oil and gas exploration prospects of this area.

Distribution and gas exploration of the strike–slip faults in the central Sichuan Basin

The Sichuan Basin has abundant oil and gas resources and it has been generally acknowledged as a super petroliferous basin. In recent years, immense exploration and development potential of deep natural gas emerges in the Sichuan Basin. The identification of strike–slip faults and their reservoir controlling effects are of great significance to develop a new exploration domain of fault-controlled gas reservoirs. In order to clarify the distribution of strike–slip faults in the Sichuan Basin and their relationships with natural gas exploration, in view that the strike–slip faults in this basin are small and complex with poor seismic data and influenced more by the fold deformation of Triassic gypsum salt beds, this paper identifies strike–slip faults and analyzes their characteristics, distribution and genesis based on the interpretation of continuous 3D seismic data of the central Sichuan Basin. Then, the fault-controlled gas reservoir model of strike-slip fault is established by reviewing old wells and evaluating geological conditions of hydrocarbon accumulation. Finally, the exploration potential and exploration direction of fault-controlled gas reservoirs are discussed. And the following research results are obtained. First, intraplate weak strike–slip faults can be identified by combining the seismic profile marker of strike–slip fault with the plane marker. Second, eight large strike–slip fault zones with a total length of 1280 km are identified and confirmed in the central Sichuan Basin. Third, strike–slip faults are mainly distributed in the Sinian–Permian System, mainly composed of small-displacement oblique faults and echelon faults, and different in stratification, grading, classification and segmentation. Fourth, under the control of the oblique subduction of the Proto-Tethys Ocean and the different structures of the basement, the strike–slip faults in the central Sichuan Basin were formed in the Sinian and there are multiple stages of inherited Caledonian–Hercynian activities. Fifth, the strike–slip faults in the central Sichuan Basin play a role in source–reservoir connection, reservoir stimulation, and gas accumulation and high yield, and constitute the fault-controlled natural gas accumulation system of “three-element controlling reservoir and composite hydrocarbon accumulation” based on source rock, fault and reservoir. In conclusion, a large intraplate strike–slip fault system is developed in the Sichuan Basin, which has the geological conditions of hydrocarbon accumulation to form strike–slip fault-controlled large gas field, and the large source connecting strike-slip fault zones are the main breakthrough directions of natural gas exploration in fault-controlled carbonate rocks.

3D Seismic Data Interpretation in Gumry Field, Melut Basin

This work describes interpretation of 3D seismic data of Gumry area which is located in Blocks 3 & 7 in Melut Basin the South of Sudan. The data used in this study was acquired by Blue Nile Geophysical Company (BGC) in 2004. The 3D data was interpreted by the author at the SUDAPET CO. LTD in Khartoum – Sudan, Vertical Seismic Profiling data (VSP) and Check-Shot data of the Gumry-1 well were used. The data quality is good and adequate for the objectives. Geoframe software has been used which enables to display inline, cross line and time slice and also enables checking of the consistency of the interpretation from line to line. Synthetic seismogram has been generated for Gumry _1 well for seismic data tie. Time and depth maps have been generated for the top of Yabus Formation. The 3D data interpretation clarifies that there are many oil structures found in study area such as normal faults, faulted trap, graben, half graben, and faulted anticline. Faults system in Gumry area consists of normal faults, trending NW-SE, with some of them dipping SW and others dipping NE. Gumry oil field prospects are mainly fault block structure, located at the block up thrown side of the normal Fault block.

Main features of modeling terrigenous deposits in East-Siberia using the example of the Hamakinsky horizon

Background. The article considers the results of updating the geological model of the khamakinskii horizon reservoirs of the Chayandinskoe oid and gas field. The main aim is project the production of the oil rims and form a positive business case of the project. 
 
 Materials and methods. Conceptual sedimentary model bases on the core of the 14 wells. Updating of the petrophysical model is the key to identify post-sedimentary transformations (like anhydritization and halitization) and the opportunity to correct the permeability trend. The tectonic pattern of the horizon based on the interpretation of 3D seismic data. There are two groups of faults were identified: certain and possible. Neural networks algorithm uses for a creating the predictive maps of anhydritization, which are used in the geological model. 
 
 Results. Estuary sands influenced by fluvial and tidal processes dominate the khamakinskii horizon. The reservoir is irregular vertically: at the base of the horizon, there are sandstones of the delta front and there are alluvial valley with fluvial channels in the middle and upper parts. Eustary sands eroded by incised valleys (alluvial channels). According to the core and thin section analysis, the main uncertainty is sedimentary transformations of reservoir. It affects the net thickness and then the volume of oil in productive wells. 3D geological model includes the trends of anhydritization and halitization over the area, which makes it possible to obtain a more accurate production forecast. 
 
 Conclusion. As part of the probability estimate of oil reserves, the main geological parameters that affect the volume of reserves were identified. Pilot project is planning to remove geological and technical uncertainties.

Origin of seafloor pockmarks overlying submarine landslides: Insights from semi-automated mapping of 3D seismic horizons (North West Shelf, Australia)

Pockmarks are geohazards that can impact offshore developments, and an understanding of their formation assists in determination of their physical characteristics and in the prediction of their future behaviour. This study documents how the presence of submarine landslides - either on the seafloor or buried - can favour pockmark formation through the characterisation of two pockmark fields from the Australian North West Shelf. Analysis was carried out through an innovative workflow combining full-volume interpretation of exploration 3D seismic data and semi-automated mapping of seismic horizons. The Gorgon Pockmark Field (GPF) extends over ∼125 km2 in water depths ranging from 210 to 480 m. It contains ∼500 pockmarks with diameters of ∼150–200 m. The pockmark field overlies a submarine landslide and was likely created by the expulsion of fluids and/or liquefied sediment during or after the formation of the landslide. The Carnarvon Pockmark Field (CPF), located 100 km southwest of the GPF, covers around ∼150 km2 in water depth ranging from 680 to 930 m. It contains ∼250 pockmarks, each having a diameter of ∼250–300 m. The CPF developed on a buried paleo-landslide. While the seafloor pockmarks and the paleo-landslide are physically disconnected by a sedimentary drape, seafloor pockmarks are abundant above the paleo-landslide and present a characteristic morphology, then suggesting that fluids circulating through the paleo-landslide induced the formation of the seafloor pockmarks. Study of the Gorgon and Carnarvon pockmark fields presents new evidence that submarine landslides - either on the seafloor or buried - can control the development of pockmarks over huge areas of the seafloor.

Structural description and tectonic development history of the mesozoic deposits in the Vilyui hemisyneclise

We present the interpretation of 2D seismic data in the Vilyui hemisyneclise located in the Republic of Sakha (Yakutia). The model identifies structural and tectonic features and tectonic development history of the Mesozoic deposits in the Vilyui hemisyneclise. Structure contour maps for the reflecting horizons of the Mesozoic are qualitatively the same. Traced faults attenuate at various stratigraphic levels. The structures of the hemisyneclise are known to be formed during the Cretaceous stage of development.

Interpretation of 3D Seismic Reflection Data to Reveal Stratigraphic Setting of the Reservoir of Mishrif Formation in Dujaila Oil Field, Southeast of Iraq

This research is an attempt to solve the ambiguity associated with the stratigraphic setting of the main reservoir (late Cretaceous) of Mishrif Formation in Dujaila oil field. This was achieved by studying a 3D seismic reflection post-stack data for an area of ​​602.62 Km2 in Maysan Governorate, southeast of Iraq. Seismic analysis of the true amplitude reflections, time maps, and 3D depositional models showed a sufficient seismic evidence that the Mishrif Formation produces oil from a stratigraphic trap of isolated reef carbonate buildups that were grown on the shelf edge of the carbonate platform, located in the area around the productive well Dujaila-1. The low-frequency attribute illustrated that it is restricted in the area around the productive well Dujaila-1, which confirmed the existence of reef porous carbonate buildups and hydrocarbon accumulation in this region. The pay zone of the reef mound trap extends for about 7 km from the well Dujaila-1 toward the southwest side and 4 km toward the well Dujaila-2, without reaching it, which is explaining why it was dry. Therefore, this area to the south of the productive well Dujaila-1 represents a good area for low-risk drilling. Consequently, the hydrocarbon system observed in the Dujaila oil field provides a new opportunity to explore and produce oil in Mishrif Formation in other areas on the flank of the productive structures and in flat areas situated on the belt of the carbonate platform edge.

South Chukchi–Hope Composite Tectono-Sedimentary Element, Chukchi Sea

Abstract The South Chukchi–Hope Composite Tectono-Sedimentary Element (CTSE) rests on the Neocomian folded basement formed as a result of the South Anyui palaeo-ocean closure. The interpretation of 2D seismic data, as well as results of onshore structural field studies and dating of post-kinematic granite plutons, suggest post-collisional extensional/transtensional regimes potentially driving development of the South Chukchi–Hope Basin. The orogenic collapse occurred during the Aptian–Albian, and was followed by continued polyphase extensional/transtensional regime during the Late Cretaceous and Cenozoic. Depositional environments in the basin were most likely to have been non-marine in the Cretaceous and Early Tertiary, and marine from the Late Oligocene (?)–Miocene onwards. Three onshore wells in the adjacent depocentres penetrated Tertiary sediments and have had gas shows from two sites. Geochemical surveys registered anomalies of thermogenic and biogenic methane, and in some instances higher molecular ethane–penthane gases in sea-bottom sediments above gas chimneys observed on seismic lines. The CTSE is characterized by a very high present-day thermal gradient of up to 48°C km −1 recorded in the Alaskan wells and was previously considered to be gas prone.

Synthetic transfer zone characterization using seismic attributes: An example from the Parihaka fault system in the Taranaki Basin, New Zealand

Synthetic transfer zones develop between fault segments that dip in the same direction, with relay ramps connecting the fault blocks separated by the different fault segments. The characteristics of the transfer zones are controlled by the lithology, deformation conditions, and strain magnitude. The Parihaka fault is a northeast–southwest-trending set of three major en echelon faults connected by relay ramps in the Taranaki Basin, New Zealand. The structure in the basin is defined by extension during two episodes of deformation between the late Cretaceous and Paleocene and between the late Miocene and recent. To better understand the evolution of a synthetic transfer zone, we studied the geometry and secondary faulting between the individual fault segments in the Parihaka fault system using structural interpretation of 3D seismic data and seismic attributes. This interpretation allows for a unique application of seismic attributes to better study transfer zones. Seismic attributes, such as coherence, dip, and curvature, are effective tools used to understand the detailed geometry and variation in displacement on the individual faults, the nature of secondary faulting along the transfer zones, and the relationship between the faults and drape folds. The seismic characterization of the fault system of Miocene to Pliocene age horizons highlights variations in the degree of faulting, deformation, and growth mechanism associated with different stages of transfer zone development. The coherence, dip, and curvature attributes indicate a direct correlation with structural parameters such as deformation, folding, and breaching of relay ramps. All three attributes enhance the visualization of the major and associated secondary faults and better constrain their tectonic history. The observed correlation between the seismic attributes and structural characteristics of transfer zones can significantly improve the structural interpretation and exploration workflow.

Seismic and sequence stratigraphy of the Oligocene-Miocene Asmari reservoir in the Marun oilfield, SW Iran

The Oligocene-Lower Miocene Asmari Formation shows considerable reservoir heterogeneity because of variations in the lithology, depositional facies and diagenesis. This paper aim to investigate reservoir heterogeneities using seismic, core and well logs data. Twelve carbonate microfacies and three siliciclastic petrofacies are identified in the Asmari Formation based on well log and core data from 7 wells in the Marun field, which generally indicate a shallowing-up profile. Microfacies changes suggest that the Asmari Formation was deposited in a restricted lagoonal and carbonate ramp setting with periodic clastic sediment supply due to relative sea level fall. Six third-order sequences are recognized in the Asmari Formation from studies of core and well log data, while interpretation of 3D seismic data shows that the formation consists of two second-order seismic sequences. The lowest sequence boundary between the Pabdeh and Asmari Formations (SBI) is a type-2 boundary, and the six others are type-1 sequence boundaries. Six distinct packages of reflectors are interpreted on seismic data through the Cenozoic. The Pabdeh and Asmari Formations can be divided into three packages. Package 1 corresponds to transgressive and highstand systems tract deposits, which mainly consist of shales, marls, and carbonates with interbedded sandstones. This package is overlain by mounded and lenticular seismic facies (package 2) and high-amplitude and continuous seismic reflectors (package 3). Package 2 is predominantly sandstone with interbedded shale, and package3 mainly consists of carbonates. Inversion of seismic data shows that high-porosity zones are present in the western and southern Marun field. A lower high-porosity zone corresponds to lowstand fluvial-deltaic sediments and the upper zone to the beach and shallow marine sandstones.

Active tectonics and kinematics of Fethiye-Göcek Bay, SW Turkey: Insight about the eastern edge of Pliny-Strabo Trenches

Pliny-Strabo Trench (PST)is a Subduction Transform Edge Propagator (STEP) fault developed at the northern edge of the African oceanic lithosphere connecting the Aegean and Cyprian trenches in the eastern Mediterranean. Recent studies have demonstrated that the PST terminates close to Turkish Border and links to the Cyprian trench east of Rhodes and south of Fethiye-Göcek Bay. However, it is also claimed that the PST extends into SW Anatolia along a sinistral transtensional shear zone, so-called Fethiye-Burdur Fault Zone (FBFZ) implying that a lithospheric tear in the downgoing plate extends into the over-riding plate, although, this is kinematically almost impossible since full mechanical coupling between down going and the over-riding plate is necessary. To test this hypothesis and understand the kinematics of the transition zone between PST and Cyprian trench we have conducted a rigorous paleostress inversion study combined with interpretation of 2D seismic data of which 228 km total length obtained from Fethiye-Göcek Bay.The seismic reflection data are used for the interpretation and delineation of off-shore faults and to determine their recent activity. The geometry and kinematics of the exposed on-land faults are determined by analyzing 13969 fault slip data obtained from 211 sites distributed evenly throughout in an area encompassing the bay in an area extending 70 km in E-W and 50 km in N–S that cover the whole area where the Pliny-Strabo STEP fault would emerge on-land.Results of analyses indicated that most of the faults in the study area are developed under multi-directional extension, except for some NE-SW-striking faults, which have dextral strike-slip components contrary to proposed sinistral nature of Fethiye-Burdur Fault Zone. Although there are numerous normal faults some which have been active until recently, however, there is almost no NE-SW striking sinistral strike-slip fault in the region to justify the presence of Fethiye-Burdur Shear Zone. Additionally, there are a number of earthquakes with dominantly strike-slip moment tensor solutions in the deeper part of the bay while they are in normal character in the on-shore areas suggesting that the Pliny-Strabo Trench stops very close to the shoreline and it does not propagate into SW Anatolia. Therefore, existence and alleged characteristics of the Fethiye-Burdur Fault Zone could not be verified.

Cenozoic evolution of Zhangjiakou‐Penglai Fault Zone in the western offshore Bohai Bay Basin: Evidence from 3D seismic data

The Zhangjiakou‐Penglai Fault Zone (ZPFZ) is an NW‐trending strike‐slip fault zone in Eastern China that contains abundant petroleum resources and has induced massive seismic hazards. It is left‐lateral and behaves as a conjugate relationship with the Tan‐Lu Fault Zone (TLFZ). Present studies on the ZPFZ are mainly conducted on its seismology and field exposure features, with subsurface characteristics and evolution history poorly understood. In this study, we investigated the ZPFZ in the western offshore Bohai Bay Basin based on the detailed interpretation of 3D seismic data, specializing in subsurface geometric characters and evolution history. The profile flower structure and plan broom‐like pattern featured the ZPFZ in the study area and indicate its sinistral strike‐slipping. We further investigated and discusssd the Cenozoic evolution history based on evidence in (a) distinguished tectonics in fault releasing and restraining bends, (b) strata thickness map before and after the strike‐slipping, and (c) geometry of composite flower structures. The result suggests the evolution of the ZPFZ mainly comprises three stages: (a) the initial extension from 65 to 38 Ma, (b) the sinistral strike‐slipping in transtension from 38 to 25 Ma, and (3) the sinistral strike‐slipping in transpression from 25 Ma to present. The proposed evolution of the ZPFZ had good consistency with that of the conjugate TLFZ and was closely related to the Cenozoic surrounding plate tectonism, especially the Pacific Plate subduction.

Physical modeling of the Bazhenov formation in combination with CSEM and seismic methods

To predict the properties of the Bazhenov formation and to identify the areas in which oil deposits are localized the use of electrical prospecting methods is promising. The main goal of the current research is to evaluate the effectiveness of using Controlled Source Electro Magnetics (CSEM) exploration for the area forecast of the properties of the Bazhenov formation. The main objectives of physical modeling in this research are: Creation of an isotropic physical model corresponding to the electrical and elastic parameters of the section of the studied area, and performing 3D modeling on it with survey parameters that reproduce real seismic and CSEM surveys To convince that the contrast of the elastic properties and the ratio of the resistivity of the target interval of the Bazhenov formation and overlying rocks in the created physical model corresponds to the real petrophysical characteristics of the section of the studied area; Obtaining initial data for testing algorithms for synchronous inversion of seismic + electric and testing various approaches to processing and interpretation of CSEM and 3D seismic data.

A Discussion on the Characteristics of Tectonic Transformation and Its Mechanism of 2nd Episode of Zhu-Qiong Movement in Zhu 1 Depression, South China

Based on the detailed interpretation of high-accuracy 3D seismic data, the characteristics of regional unconformities, fracture systems, sedimentary filling and paleo-stress field in Zhu 1 depression were comprehensively analyzed. The results showed that 2nd episode of Zhu-Qiong movement was an important tectonic transformation that occurred during rifting, basin structure patterns above and below the regional angular unconformity caused by 2nd episode had distinct differences. The orientations of those basin-controlling faults changed from NE, NEE to EW, NWW, which indicated that the paleo-stress field veered from NNW extension clockwise to sub-NS extension and basin structures patterns transformed from NE, NEE strong rifting to sub-EW, NWW weak rifting. The depocenter showed seesaw-like migration from S to N. And the sedimentary systems transformed from semi-deep-deep lacustrine facies to braided river delta facies developed in shore-shallow lacustrine. Combined with its tectonic recombination of periphery plates that period, the mechanism of above tectonic transformation had direct correspondence to the readjustment of the Indian plate and the Pacific plate. The southward subduction of the pro-to-south China Sea is the direct cause of this tectonic transformation.

3D seismic survey data processing and interpretation by use of latest tools applied for discovery of new traps in Pleistocene deposits of Hovsan field

<abstract> The paper is devoted to outlining of hydrocarbon traps in Absheron suite by use of seismostratigraphy, standardless classification, taxonomy and attribute analysis. The paper gives a brief description of area under the study, its geographical position and research history. Correlation of seismic horizons traced within interval of seismic record embracing Absheron suite has been analyzed in detail. It has been noted that Absheron suite is rich with oil and gas deposits, which has been evidenced by discovery of fields located near to the study area. Six seismic horizons were picked off within the limits of target deposits. The described methodology of study reveals the essence of applied standardless classification and taxonomy. Analysis of dynamic parameters of seismic record led to outlining of amplitude anomalies related to zones of development of stratigraphic traps attributed to unconformity surfaces. Three such zones have been outlined. Classification and taxonomy cubes have been designed for the interval of Absheron suite. The internal structure of studied series is well traced in sections of "Classification" and "Taxonomy". Classification results allowed to outline traps characterized by abnormal grouping of some classes. Three "bright spot" anomalies are outlined in the Absheron deposits. Seismic anomalies are well correlated with sedimentation environment favorable for evolution of stratigraphic traps. The area of anomalies is 10.1 sq.km in summary. Burial depth of these anomalies is 450–950 m. Earlier drilled wells did not recover studied anomalies. </abstract>

THE NEPSKY-1 IMPACT CRATER AND ITS FILL DEPOSITS ON THE BASEMENT ROOF OF THE SIBERIAN PLATFORM

In the Earth studies, discoveries and investigations of impact craters buried beneath thick sediments are sporadic so far and may still remain inefficient, unless geophysical surveys of the areas of interest are initiated. Such studies can provide useful data to develop the knowledge about cosmic events of the past geological eras, as well as contribute to industrial development of the areas. It is known that an impact crater is filled with layered deposits that create specific sequences and are generally thicker that deposits outside the crater. We have investigated a Precambrian crater located in the southern part of the Nepa-Botuoba anteclise of the Siberian platform. This impact crater called Nepsky-1 was discovered by seismic surveys using the common depth point method (CDPM). In our study, we used the geological and geophysical deep-drilling data of three wells, including gamma-ray and neutron logs and lithological core descriptions. With reference to the concepts of regional geological conditions, we reconstructed the conditions of sedimentation in the study area based on a comprehensive analysis of the structural and textural features of the rocks, and logging and seismic survey data. By processing and interpretation of the CDPM 3D seismic survey data, we obtained the structural images and cross-sections of the impact crater and analysed the thickness of its fill deposits. The Nepsky-1 crater is a bowl-shaped structure with a rim composed of allogenic breccia. In the area around the crater, fault systems are detected. Based on the core sample analysis, we identified the lithological members of the crater and its rim and described them in detail. Active compensation with lacustrine-delta sediments took place in the Nepa period of the late Vendian. By the end of the Tira time, the crater was completely leveled up. In our study, we obtained the first data on the structure of the crater section of the Vendian deposits. Sedimentation in the study area was controlled by the sea level changes. The main terrigenous productive horizons are confined to sandstones that accumulated during the sea level low stand, and found at the bottoms of the lower and upper Nepa subsuites, as well as at the bottoms of the lower and upper Tira subsuites. It is established that the study area was tectonically active in the late Tira time. As a result, the sediments filling the crater were removed to subaerial conditions, and the edges of the allogenic breccia rim were partially destroyed and formed granite breccia outgrowths observed in the rim’s cross-section. We conclude that in the Nepa and Tira times, tectonic vertical movements initiated relatively fast weathering and transportation of the terrigenous material from the adjacent hills into the sedimentation basin. The Nepsky-1 crater gives evidence of meteorite bombing of the Siberian paleocontinent in Precambrian. Finding similar crater structures can be reasonably expected in the study region. Considering the increased thicknesses of crater fill deposits, buried craters are promising potential for discovering oil-source and overlying seal rocks, which is important for petroleum industry.

3D Seismic Reflection Study of Al-Akhadeir Area, Southwestern Iraq

This study includes structural and stratigraphic interpretation of 3D seismic reflection data for Zubair Formation (L. Cretaceous) within Al-Akhadeir area, southwestern Iraq (Karbala Governorate). Depending on the 3D seismic reflection interpretation process, and based on the synthetic seismogram and well logs data, two horizons were identified and selected (top and base Zubair reflectors). These horizons were followed up over the entire area in order to obtain structural and stratigraphic settings. TWT, depth, and velocity maps for the base and top Zubair Formation were constructed. From the interpretation of these maps and based on the seismic section, the study concluded that there are some enclosures that represent anticline in the NW of the horizon and syncline in the NE, while the nose structure appears in the middle of the horizon and trends N-S. The horizon represents a progradational with sigmoid configuration.. Other seismic structural phenomena were recognized in this part of the area, such as flat spot, down lap, and top lap, which give indicators of potential hydrocarbon accumulations

Structural style of buried Ediacaran basins in Saudi Arabia on seismic reflection data

Several isolated Ediacaran basins subcrop Phanerozoic strata in Saudi Arabia. The structural styles of these subcropping basins are reviewed here based on interpretation of 2D and 3D seismic reflection data and comparison with Arabian Shield outcrops. The basins are distinguished by layered seismic reflectors that are interpreted as sedimentary and volcanic strata. Due to limited well penetrations these packages cannot be directly dated but a relative chronology is established, anchored by constraints from the Arabian Shield and regional studies. Most of the basins are bound by extensional faults and the basin fills show growth architectures and angular unconformities. The bounding faults trend broadly north–south and are interpreted to be late to post-orogenic reactivations of oceanic terrane margins. Based on their structural characteristics in comparison with sub-basins exposed on the shield, the basin fills are correlated with the Ediacaran Jibalah Group, an equivalent of the Omani Nafun Group. These sub-basins experienced inversion and exhumation prior to ongoing volcanism and unconformable deposition of late Ediacaran to earliest Cambrian Kurayshah Group sediments. The Kurayshah Group is disconformably overlain by the widespread Tayma Group siliciclastics. This disconformity correlates to the Angudan Unconformity in Oman. The Kurayshah Group includes a late Ediacaran stratovolcano over 40 km in diameter. In the eastern basins, evaporitic structural styles indicate the presence of Hormuz / Ara evaporites, with local igneous intrusions, that correlate at least in part to the Kurayshah Group. The Tayma Group infills significant accommodation space variations and was affected by ongoing but declining differential subsidence and reactivation of the underlying basin-bounding faults.

Basin modeling of Late Cretaceous / Mio-Pliocene (.) petroleum system of the deep-water eastern Colombian Basin and South Caribbean Deformed Belt

Previous interpretation of 2D and 3D seismic reflection data have shown widespread, direct hydrocarbon indicators from deep-water successions of the eastern Colombian Basin (ECB) and adjacent South Caribbean Deformed Belt (SCDB) that suggest the presence of an extensive - but poorly defined - petroleum system. We integrate Rock-Eval analysis, seismic interpretation, and 1D/2D thermal and basin modeling to better understand the origin of gas chimneys and bright spots identified in the ECB. Our dataset consists of 36 Rock-Eval samples of Coniacian to Santonian source rocks from the DSDP well sites 153, 151, and 146 located in the Beata Ridge tied to a 270 km-long composite 2D seismic line covering the ECB. Rock-Eval analyses reveal intervals of immature source rocks containing 1) kerogen types II and III; 2) an average TOC of 3.70% with a maximum TOC of 11.4%; 3) an average HI of 241; and 4) an average OI of 124. Seismic interpretation reveals: 1) wedging of post-Coniacian, organic-rich successions from the Beata Ridge (35–73 m thick) towards the ECB (500–1700 m thick); 2) Late Cretaceous to Eocene slow sedimentation rate of 38 m/my, followed by faster Oligocene to Recent sedimentation rate of 149 m/my from the Magdalena River; and 3) Late Oligocene to Recent thrusting and propagation of the SCDB. Thermal and basin modeling show: 1) mature Cretaceous source rocks in the SCDB and ECB; 2) Miocene to Pliocene, Magdalena Fan-derived deltaic and turbiditic reservoir and seal rocks, and Plio-Pleistocene sealing mass transport deposits.; 3) Late Oligocene to present-day trap formation related to thrust front structures, compaction folds, and stratigraphic traps; 4) hydrocarbon expulsion since Pliocene times; 5) vertical and lateral up-dip seaward migration occurs in the ECB while a secondary landward migration takes place toward the SCDB; and 6) hydrocarbon accumulation and preservation may be affected by remobilization due to biodegradation in the ECB and trap breaching in the SCDB.