scholarly journals Five buried crater structures imaged on reflection seismic data in Saudi Arabia

GeoArabia ◽  
2014 ◽  
Vol 19 (1) ◽  
pp. 17-44
Author(s):  
Allen S. Neville ◽  
Douglas J. Cook ◽  
Abdulkader M. Afifi ◽  
Simon A. Stewart
Keyword(s):  
Saudi Arabia ◽  
Seismic Data ◽  
Surface Expression ◽  
Hydrocarbon Exploration ◽  
Magnetic Data ◽  
Recent Sediment ◽  
Upper Ordovician ◽  
Middle Ordovician ◽  
Reflection Seismic ◽  
Future Work

ABSTRACT Reflection seismic data acquired for hydrocarbon exploration in Saudi Arabia have revealed five buried crater structures ranging in diameter from 5 km to 34 km. These structures have little or no present-day surface expression and span a range of ages from Ordovician to Cenozoic. The Saqqar structure (29°35′N, 38°42″E) is 34 km in diameter and is formed in Devonian siliciclastics. The structure is partially eroded and is unconformably overlain by Upper Cretaceous and Paleogene strata up to 400 m thick. The Jalamid structure (31°27′N, 39°35″E) is 19 km in diameter at Lower Ordovician level and is infilled by Middle Ordovician sediments, at a present-day depth of 4,500 m. The Banat Baqar structure (29°07′N, 37°36″E) is 12 km in diameter at Middle Ordovician level and infilled by Upper Ordovician sediments, at a depth of 2,000 m. The Hamidan structure (20°36′N, 54°44″E) is 16 km in diameter at Paleogene level and is overlain by a thin veneer of Recent sediment. The Zaynan structure (20°23′N, 50°08″E) is 5 km in diameter and affects Triassic sediments at depth of 3,800 m, and is infilled by Jurassic strata. In addition to reflection seismic imaging, various amounts of gravity and magnetic data and drilled wells are available in or near these structures. Various models including impact cratering are discussed here for each structure. One structure (Saqqar) has yielded quartz grains with possible shock metamorphic features that, contingent on future work, may support a meteorite impact crater interpretation.

New geophysical and geological results in frontier basins along the southwest Australian continental margin

2009 ◽  
Vol 49 (2) ◽  
pp. 587
Author(s):  
Chris Nicholson ◽  
Edward Bowen ◽  
George Bernardel ◽  
Barry Bradshaw ◽  
Irina Borissova ◽  
...  
Keyword(s):  
Continental Margin ◽  
Seismic Data ◽  
Seismic Survey ◽  
Magnetic Data ◽  
Geological Samples ◽  
Potential Field Data ◽  
Swath Bathymetry ◽  
Reflection Seismic ◽  
Industry Standard ◽  
Areas Of Interest

Under the Australian Government’s Energy Security Program, Geoscience Australia is conducting a seismic survey and a marine reconnaissance survey to acquire new geophysical data and obtain geological samples in frontier basins along the southwest Australian continental margin. Specific areas of interest include the Mentelle Basin, northern Perth Basin, Wallaby Plateau and the southern Carnarvon Basin. The regional seismic survey will acquire 8,000–10,000 km of industry-standard 2D reflection seismic data using an 8 km solid streamer and a 12 second record length, together with gravity and magnetic data. These new geophysical datasets, together with over 7,000 km of reprocessed open-file seismic, will facilitate more detailed mapping of the regional geology, determination of total sediment thickness, interpretation of the nature and thickness of crust beneath the major depocentres, modelling of the tectonic evolution and an assessment of the petroleum prospectivity of frontier basins along the southwest margin. The overall scientific aim of the marine survey is to collect swath bathymetry, potential field data, geological samples and biophysical data. Together with the new seismic data, samples recovered from frontier basins will assist in understanding the geological setting and petroleum prospectivity of these little known areas. Preliminary results from both surveys will be presented for the first time at this conference.

scholarly journals Stratigraphic Interpretation of Magnetotelluric Data in Central Saudi Arabia

GeoArabia ◽  
1996 ◽  
Vol 1 (1) ◽  
pp. 52-63
Author(s):  
Ian C.F. Stewart ◽  
Thomas C. Connally ◽  
Jeffrey H. Copley
Keyword(s):  
Saudi Arabia ◽  
Seismic Data ◽  
Hydrocarbon Exploration ◽  
Well Log ◽  
Precambrian Basement ◽  
Magnetotelluric Data ◽  
Model Studies ◽  
Structural Relief ◽  
Basement Structures ◽  
The Relationship

ABSTRACT The pre-Khuff interval of the Paleozoic sediments in central Arabia is poorly defined by conventional seismic techniques, although this layer has significant potential for hydrocarbon exploration. Model studies indicated that magnetotelluric methods could outline the regional changes expected in the pre-Khuff in the area, which are largely dependent on the topography of the Precambrian basement. The Hercynian orogenic event created an extensive block-faulted terrane of half-grabens and horsts. The Hercynian structural relief was infilled in the Permo-Carboniferous and faulting reactivated in Triassic and later time, but the relationship between pre-Khuff and post-Khuff structure was impossible to understand using seismic data alone. In this survey of almost 500 magnetotelluric (MT) stations, essential control on the shallower section was provided by seismic interpretations, in addition to well log data for depths and resistivities. The MT method was very successful in confirming the presence of significant pre-Khuff section over some basement structures, as well as defining areas where the section is thin or absent which may be suitable for further exploration for stratigraphic traps.

Geological interpretation of a high resolution reflection seismic survey at the Buchans mine, Newfoundland

1992 ◽  
Vol 29 (9) ◽  
pp. 2022-2037 ◽  
Author(s):  
J. G. Thurlow ◽  
C. P. Spencer ◽  
D. E. Boerner ◽  
L. E. Reed ◽  
J. A. Wright
Keyword(s):  
High Resolution ◽  
Seismic Data ◽  
Surface Expression ◽  
Seismic Survey ◽  
Geological Interpretation ◽  
Reflection Seismic ◽  
Underground Workings ◽  
Cost Efficient ◽  
Drill Holes ◽  
Structural Base

Sixteen kilometres of high resolution Vibroseis reflection seismic data have been acquired in the vicinity of the former Buchans mine. Direct identification of the cause of several reflectors is possible because the geology is tightly constrained by underground workings and drill holes both of which locally exceed 1 km depth. Many of the mine-scale thrust faults are imaged as reflectors but conformable and intrusive contacts generally responded poorly. A significant shallow-dipping thrust, the Powerline Fault, is recognized below the orebodies and traced throughout the Buchans area, primarily as a result of the seismic survey. It truncates ore stratigraphy and forms the floor thrust of a large duplex–stack, which hosts all the orebodies. Its presence has negative implications for exploration in the immediate mine area. Several lines of evidence suggest that this fault has a significant component of out-of-sequence movement. A strong reflector 4.5 km below Buchans is correlated with the surface expression of the Victoria River Delta Fault, an important regional structure, newly recognized southeast of Red Indian Lake. This shallow, north-dipping sole thrust forms the structural base of the Buchans Group and brings it above a younger fossiliferous Llanvirn volcanic sequence. This fault is not itself the Red Indian Line but is one of a series of faults that collectively effect substantial geological contrasts in central Newfoundland. The seismic survey was a cost-efficient means of gaining knowledge of Buchans structure, which might otherwise have been acquired at much higher cost and over a longer period of time.

New insights into the deep-water Otway Basin – Part 2. Tectonostratigraphic framework revealed by new seismic data

2021 ◽  
Vol 61 (2) ◽  
pp. 657
Author(s):  
Alex Karvelas ◽  
Tekena West ◽  
Chris Nicholson ◽  
Steve Abbott ◽  
George Bernardel ◽  
...  
Keyword(s):  
Deep Water ◽  
Seismic Data ◽  
Structural Complexity ◽  
Water Area ◽  
Petroleum Systems ◽  
Reflection Seismic ◽  
Clear Insight ◽  
Deep Water Area ◽  
Seismic Reflectors ◽  
Future Work

The inboard areas of the Otway Basin, particularly the Shipwreck Trough, are well explored and a petroleum-producing province. However, outboard in water depths greater than 500m, the basin is underexplored with distant well control and sparse 2D reflection seismic data coverage. The presence of a successful petroleum province onshore and in shallow waters raises the question as to whether these plays may extend further outboard into the deep-water areas. In the deep-water area, structural complexity and poor imaging of events in the legacy seismic data have resulted in interpretation uncertainty and consequentially a high-risk profile for explorers. The 2020 Otway Basin seismic program acquired over 7000-line km of 2D reflection seismic data across the deep-water Otway Basin. In addition, over 10000km of legacy 2D seismic data were reprocessed to improve the tie between the inboard wells and the new seismic grid. This new dataset provides the first clear insight into the structural and stratigraphic framework of this frontier area, including better imaging of the sedimentary section and the lower crust, increased structural resolution and improved calibration of the outboard seismic reflectors via ties to the inboard wells. Interpretation of the new data has led to an improved assessment of the structural elements and the extension of regional supersequences into the deep-water areas. These refinements have been used as input into petroleum systems modelling work and will provide a foundation for future work to understand petroleum prospectivity, including the distribution of source, reservoir and seal facies.

Oxygen isotope (δ18O) trends measured from Ordovician conodont apatite using secondary ion mass spectrometry (SIMS): Implications for paleo-thermometry studies

2021 ◽  
Author(s):  
Cole T. Edwards ◽  
Clive M. Jones ◽  
Page C. Quinton ◽  
David A. Fike
Keyword(s):  
Mass Spectrometry ◽  
Secondary Ion Mass Spectrometry ◽  
Matrix Effects ◽  
Analytical Techniques ◽  
Upper Ordovician ◽  
Bulk Analysis ◽  
Middle Ordovician ◽  
Ion Mass Spectrometry ◽  
Oxygen Isotopic ◽  
Secondary Ion

The oxygen isotopic compositions (δ18O) of minimally altered phosphate minerals and fossils, such as conodont elements, are used as a proxy for past ocean temperature. Phosphate is thermally stable under low to moderate burial conditions and is ideal for reconstructing seawater temperatures because the P-O bonds are highly resistant to isotopic exchange during diagenesis. Traditional bulk methods used to measure conodont δ18O include multiple conodont elements, which can reflect different environments and potentially yield an aggregate δ18O value derived from a mixture of different water masses. In situ spot analyses of individual elements using micro-analytical techniques, such as secondary ion mass spectrometry (SIMS), can address these issues. Here we present 108 new δ18O values using SIMS from conodont apatite collected from four Lower to Upper Ordovician stratigraphic successions from North America (Nevada, Oklahoma, and the Cincinnati Arch region of Kentucky and Indiana, USA). The available elements measured had a range of thermal alteration regimes that are categorized based on their conodont alteration index (CAI) as either low (CAI = 1−2) or high (CAI = 3−4). Though individual spot analyses of the same element yield δ18O values that vary by several per mil (‰), most form a normal distribution around a mean value. Isotopic variability of individual spots can be minimized by avoiding surficial heterogeneities like cracks, pits, or near the edge of the element and the precision can be improved with multiple (≥4) spot analyses of the same element. Mean δ18O values from multiple conodonts from the same bed range between 0.0 and 4.3‰ (median 1.0‰), regardless of low or high CAI values. Oxygen isotopic values measured using SIMS in this study reproduce values similar to published trends, namely, δ18O values increase during the Early−Middle Ordovician and plateau by the mid Darriwilian (late Middle Ordovician). Twenty-two of the measured conodonts were from ten sampled beds that had been previously measured using bulk analysis. SIMS-based δ18O values from these samples are more positive by an average of 1.7‰ compared to bulk values, consistent with observations by others who attribute the shift to carbonate- and hydroxyl-related SIMS matrix effects. This offset has implications for paleo-temperature model estimates, which indicate that a 4 °C temperature change corresponds to a 1‰ shift in δ18O (‰). Although this uncertainty precludes precise paleo-temperature reconstructions by SIMS, it is valuable for identifying spatial and stratigraphic trends in temperature that might not have been previously possible with bulk approaches.

Deepwater reservoir prediction using broadband seismic-driven impedance inversion and seismic sedimentology in the South China Sea

2018 ◽  
Vol 6 (4) ◽  
pp. SO17-SO29 ◽  
Author(s):  
Yaneng Luo ◽  
Handong Huang ◽  
Yadi Yang ◽  
Qixin Li ◽  
Sheng Zhang ◽  
...  
Keyword(s):  
South China Sea ◽  
South China ◽  
Seismic Data ◽  
Seismic Velocity ◽  
The South China Sea ◽  
Hydrocarbon Exploration ◽  
The South ◽  
Low Frequencies ◽  
China Sea ◽  
Impedance Inversion

In recent years, many important discoveries have been made in the marine deepwater hydrocarbon exploration in the South China Sea, which indicates the huge exploration potential of this area. However, the seismic prediction of deepwater reservoirs is very challenging because of the complex sedimentation, the ghost problem, and the low exploration level with sparse wells in deepwater areas. Conventional impedance inversion methods interpolate the low frequencies from well-log data with the constraints of interpreted horizons to fill in the frequency gap between the seismic velocity and seismic data and thereby recover the absolute impedance values that may be inaccurate and cause biased inversion results if wells are sparse and geology is complex. The variable-depth streamer seismic data contain the missing low frequencies and provide a new opportunity to remove the need to estimate the low-frequency components from well-log data. Therefore, we first developed a broadband seismic-driven impedance inversion approach using the seismic velocity as initial low-frequency model based on the Bayesian framework. The synthetic data example demonstrates that our broadband impedance inversion approach is of high resolution and it can automatically balance between the inversion resolution and stability. Then, we perform seismic sedimentology stratal slices on the broadband seismic data to analyze the depositional evolution history of the deepwater reservoirs. Finally, we combine the broadband amplitude stratal slices with the impedance inversion results to comprehensively predict the distribution of deepwater reservoirs. Real data application results in the South China Sea verify the feasibility and effectiveness of our method, which can provide a guidance for the future deepwater hydrocarbon exploration in this area.

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