Mapping geology beneath volcanics using magnetic data

2018 ◽  
Vol 58 (2) ◽  
pp. 821
Author(s):  
Irena Kivior ◽  
Stephen Markham ◽  
Leslie Mellon ◽  
David Boyd
Keyword(s):  
South Australia ◽  
Sedimentary Basins ◽  
Seismic Signal ◽  
Petroleum Exploration ◽  
Seismic Survey ◽  
Source Distribution ◽  
Magnetic Data ◽  
Large Area ◽  
Magnetic Susceptibilities ◽  
Passive Seismic

Volcanic layers within sedimentary basins cause significant problems for petroleum exploration because the attenuation of the seismic signal masks the underlying geology. A test study was conducted for the South Australia Government to map the thickness of volcanics and sub-volcanic geology over a large area in the Gawler Range Volcanics province. The area is covered by good quality magnetic data. The thickness of volcanics and basement configuration was unknown as there has only been a limited amount of drilling. The Automatic Curve Matching (ACM) method was applied to located magnetic data and detected magnetic sources within different rock units, providing their depth, location, geometry and magnetic susceptibility. The magnetic susceptibilities detected by ACM allowed the differentiation of the volcanics and the underlying basement. The base of volcanics and the depth to the top of basement was mapped along 75 km NS profiles, that were spaced 1 km apart over a distance of 220 km. The volcanic and basement magnetic susceptibilities and the magnetic source distribution pattern were used as key determinants to interpret the depth to the two interfaces. The results for each interface were gridded, and images of the base of volcanics and depth to basement were generated. The mapped volcanics thickness was validated by comparison with the results from drilling, with the volcanics thickness matching very well. After project completion, a passive seismic survey was conducted in part of the test area, indicating a base of volcanics of ~4 km, which further confirmed the results.

APPLICATION OF SEMI-AUTOMATED AND INTERACTIVE MAGNETIC INTERPRETATION TECHNIQUES IN PETROLEUM EXPLORATION

1977 ◽  
Vol 17 (1) ◽  
pp. 85
Author(s):  
Robert J. Whiteley ◽  
Barry F. Long ◽  
David A. Pratt
Keyword(s):  
Sedimentary Basin ◽  
Sedimentary Basins ◽  
Magnetic Anomalies ◽  
Petroleum Exploration ◽  
Magnetic Data ◽  
Magnetic Method ◽  
Magnetic Interpretation ◽  
Geological Information ◽  
Detailed Interpretation ◽  
Insight Into

The magnetic method is used at many stages of a modern petroleum exploration program. Effective interpretation techniques are required to extract maximum geological information from magnetic data. Those techniques which provide the greatest flexibility and make full use of the talents of experienced interpreters are generally of a semi-automated and interactive nature.There are several practical methods for semi-automated quantitative magnetic interpretation in sedimentary basins. Initial interpretation can be achieved by automatic calculation of characteristic anomaly parameters continuously along original or processed magnetic data profiles. Detailed interpretation of more subtle magnetic features can then follow by theoretical anomaly comparison with field anomalies using interactive portfolio modelling or by direct computation.Examples of the use of these semi-automated techniques in the interpretation of basement and intra-sedimentary magnetic anomalies show that combined magnetic and seismic interpretations can provide considerable insight into the structural processes which have operated in a sedimentary basin.

THE INTERPRETATION OF AEROMAGNETIC SURVEYS FOR HYDROCARBON EXPLORATION

1999 ◽  
Vol 39 (1) ◽  
pp. 494
Author(s):  
I. Kivior ◽  
D. Boyd
Keyword(s):  
Spectral Analysis ◽  
Sedimentary Basins ◽  
Hydrocarbon Exploration ◽  
Petroleum Exploration ◽  
Magnetic Data ◽  
Curve Matching ◽  
Aeromagnetic Data ◽  
Profile Data ◽  
Aeromagnetic Survey ◽  
New Approach

Aeromagnetic surveys have been generally regarded in petroleum exploration as a reconnaissance tool for major structures. They were used commonly in the early stages of exploration to delineate the shape and depth of the sedimentary basin by detecting the strong magnetic contrast between the sediments and the underlying metamorphic basement. Recent developments in the application of computer technology to the study of the earth's magnetic field have significantly extended the scope of aeromagnetic surveys as a tool in the exploration for hydrocarbons. In this paper the two principal methods used in the analysis and interpretation of aeromagnetic data over sedimentary basins are: 1) energy spectral analysis applied to gridded data; and, 2) automatic curve matching applied to profile data. It is important to establish the magnetic character of sedimentary and basement rocks, and to determine the regional magnetic character of the area by applying energy spectral analysis. Application of automatic curve matching to profile data can provide results from the sedimentary section and deeper parts of a basin. High quality magnetic data from an experimental aeromagnetic survey flown over part of the Eromanga/Cooper Basin has recently been interpreted using this new approach. From this survey it is possible to detect major structures such as highs and troughs in the weakly magnetic basement, as well as pick out faults, and magnetic layers in the sedimentary section. The results are consistent with interpretation from seismic and demonstrate that aeromagnetic data can be used to assist seismic interpretation, for example to interpolate between widely spaced seismic lines and sometimes to locate structures which can not be detected from seismic surveys. This new approach to the interpretation of aeromagnetic data can provide a complementary tool for hydrocarbon exploration, which is ideal for logistically difficult terrain and environmentally sensitive areas.

Exploring New Zealand's marine territory

2011 ◽  
Vol 51 (1) ◽  
pp. 549 ◽  
Author(s):  
Chris Uruski
Keyword(s):  
New Zealand ◽  
Deep Water ◽  
Seismic Data ◽  
East Coast ◽  
Sedimentary Basins ◽  
Petroleum Exploration ◽  
Seismic Survey ◽  
Data Set ◽  
Eastern Australia ◽  
Deep Water Part

Around the end of the twentieth century, awareness grew that, in addition to the Taranaki Basin, other unexplored basins in New Zealand’s large exclusive economic zone (EEZ) and extended continental shelf (ECS) may contain petroleum. GNS Science initiated a program to assess the prospectivity of more than 1 million square kilometres of sedimentary basins in New Zealand’s marine territories. The first project in 2001 acquired, with TGS-NOPEC, a 6,200 km reconnaissance 2D seismic survey in deep-water Taranaki. This showed a large Late Cretaceous delta built out into a northwest-trending basin above a thick succession of older rocks. Many deltas around the world are petroleum provinces and the new data showed that the deep-water part of Taranaki Basin may also be prospective. Since the 2001 survey a further 9,000 km of infill 2D seismic data has been acquired and exploration continues. The New Zealand government recognised the potential of its frontier basins and, in 2005 Crown Minerals acquired a 2D survey in the East Coast Basin, North Island. This was followed by surveys in the Great South, Raukumara and Reinga basins. Petroleum Exploration Permits were awarded in most of these and licence rounds in the Northland/Reinga Basin closed recently. New data have since been acquired from the Pegasus, Great South and Canterbury basins. The New Zealand government, through Crown Minerals, funds all or part of a survey. GNS Science interprets the new data set and the data along with reports are packaged for free dissemination prior to a licensing round. The strategy has worked well, as indicated by the entry of ExxonMobil, OMV and Petrobras into New Zealand. Anadarko, another new entry, farmed into the previously licensed Canterbury and deep-water Taranaki basins. One of the main results of the surveys has been to show that geology and prospectivity of New Zealand’s frontier basins may be similar to eastern Australia, as older apparently unmetamophosed successions are preserved. By extrapolating from the results in the Taranaki Basin, ultimate prospectivity is likely to be a resource of some tens of billions of barrels of oil equivalent. New Zealand’s largely submerged continent may yield continent-sized resources.

HYDROCARBON POTENTIAL OF THE ARCKARINGA REGION, CENTRAL SOUTH AUSTRALIA

1982 ◽  
Vol 22 (1) ◽  
pp. 237 ◽  
Author(s):  
P. S. Moore
Keyword(s):  
Source Rock ◽  
South Australia ◽  
Petroleum Exploration ◽  
Hydrocarbon Generation ◽  
Large Area ◽  
Entire Area ◽  
Central Platform ◽  
Active Exploration ◽  
Central South ◽  
Eromanga Basin

The Arckaringa region is a large area which lies between the Officer Basin and the Peake and Denison Ranges in central South Australia. It includes sedimentary rocks of Jurassic-Cretaceous, Permo-Carboniferous and ?Cambrian ages. The thickest sequence of sediments (about 2000m) occurs in the Boorthanna Trough, located immediately to the west of the Peake and Denison Ranges. Cretaceous sediments of the Eromanga Basin form a veneer over much of the area. Oil shows at very shallow depths in immature sediments at Oodnadatta 1 raise speculations about the possibility of shallow generation of hydrocarbons in the Eromanga Basin. However, most of the petroleum exploration in the region has been aimed at delineating the underlying Permo-Carboniferous Arckaringa Basin sequence. The Arckaringa Basin is not a simple sedimentary depression but rather a series of peripheral depressions surrounding a central platform region. Unlike the Cooper and Pedirka Basins, it contains some marine sediment, suggesting the possibility of an oil-prone rather than a predominantly gas-prone province. Due to the thin nature of the sequence and its shallow depth of burial, most of the Arckaringa Basin is predicted to be immature for hydrocarbon generation in traditional terms. However, source-rock and vitrinite studies in the Boorthanna Trough indicate that the basal units are marginally mature to mature in this area. Early Cambrian carbonates are interpreted to extend southeastwards in an arc from Byilkaoora 1 in the Officer Basin, through the Boorthanna Trough, and onto the Stuart Shelf. In the Boorthanna Trough these carbonates are named the Cootanoorina Formation. They are of varied lithology and are associated with terrigenous clastics and minor evaporites. Vugular porosity occurs sporadically in the sequence, which may be thicker than 1000m in some of the deeper parts of the trough. Source-rock studies suggest that the sequence is immature to marginally mature in Weedina 1 and Cootanoorina 1.It is emphasised that the Arckaringa region is largely unexplored for hydrocarbons, with only two wells drilled on structural targets in the entire area of about 60 000 sq km. This report presents source-rock and maturation data which suggest that the sequence is more mature than originally predicted, and that the deeper parts of the Boorthanna Trough may have a modest potential for oil, both in the basal Permo-Carboniferous and in the ?Cambrian Cootanoorina Formation. An active exploration programme has begun, with several hundred kilometres of seismic surveys planned for 1982.

EXPLORATION AND ITS RESPONSE TO DIVERGENT INFLUENCES

1975 ◽  
Vol 15 (1) ◽  
pp. 153
Author(s):  
W. G. H. Maxwell
Keyword(s):  
Technological Factor ◽  
South Australia ◽  
Sedimentary Basins ◽  
Social Background ◽  
Petroleum Exploration ◽  
Social Trends ◽  
Oil Boom ◽  
Third Phase ◽  
Political Events ◽  
Fluctuating Course

Petroleum exploration in Australia has evolved through three distinct phases and is now entering a fourth. It began with the wild, speculative flurries that culminated in drilling on the Coorong, South Australia in 1892, it was revived by the accidental discovery of gas near Roma at the turn of the century leading to the oil boom from 1926 to 1933, and it reached its peak in 1962-72 in the third phase, after which exploration activity has gone into decline. Examination of the economic, political and social background to the industry reveals that, on the national scene, political events rather than economic and social trends have had greater impact on the fluctuating course of its development. International influences also appear, in many instances, to be of greater significance than domestic factors. Much time and effort have been devoted by industry, government and academics to the analysis of economic, political and social influences on Australia's petroleum exploration but it is quite obvious that the basic determinant Is still the oft-forgotten geologic-technological factor. The condition of the domestic industry depends primarily on the potential of Australia's sedimentary basins and the quality of the technology used to explore them. In the long term, all other influences are temporary in their impact and subordinate in their ultimate effect.

Aeromagnetic regional survey of onshore Australia

Geophysics ◽  
1988 ◽  
Vol 53 (2) ◽  
pp. 254-265
Author(s):  
D. H. Tucker ◽  
I. G. Hone ◽  
D. Downie ◽  
A. Luyendyk ◽  
K. Horsfall ◽  
...  
Keyword(s):  
Data Base ◽  
Mineral Resources ◽  
Sedimentary Basins ◽  
Petroleum Exploration ◽  
Quality Data ◽  
Magnetic Data ◽  
Regional Survey ◽  
Wide Range ◽  
Line Spacing ◽  
Airborne Magnetic

The Australian Bureau of Mineral Resources (BMR) is responsible for the National Airborne Magnetic Database. This data base consists of results from approximately 3 500 000 line‐km of regional survey flying carried out over 35 years, recording total magnetic intensity. The magnetic data base is one of the most important geophysical data bases for Australia and is used extensively by the minerals and petroleum exploration industries. First‐pass coverage of onshore Australia is aimed for completion in 1992. This coverage contains data from surveys with a wide range of specifications, resulting in a wide range of data quality; some of the areas covered by poorer quality data may be reflown later. For the most part, the intention has been to acquire data at a continuous ground clearance of 150 m and with a line spacing of 1500 m. However, over some sedimentary basins, the line spacing is in excess of 3200 m. New color and grey‐scale (image processed type) digital magnetic maps (pixel maps) are in preparation; these will supersede the 1976 digital magnetic map of Australia, which was gridded on a 1.2 minute mesh (2000 m) mostly by digitizing contours on maps. The new map, produced from flight‐line data, will have a grid size of 0.25 minutes. Initially, a series of maps will be produced with each one covering a block of 4 degrees latitude by 6 degrees longitude, coinciding with standard 1 : 1 000 000 map sheets. An example included for the Adelaide 1 : 1 000 000 map sheet in Southern Australia shows a dramatic increase in the number of anomalies over those that were evident in earlier contour presentations.

Petroleum geological summary of the 2012 offshore acreage release for petroleum exploration

2012 ◽  
Vol 52 (1) ◽  
pp. 7 ◽  
Author(s):  
Thomas Bernecker
Keyword(s):  
South Australia ◽  
Data Availability ◽  
Petroleum Exploration ◽  
Free Access ◽  
Australian Government ◽  
Large Area ◽  
Offshore Area ◽  
North West ◽  
The North ◽  
Gippsland Basin

The Australian Government formally releases new offshore exploration areas at the annual APPEA conference. In 2012, 27 areas in nine offshore basins are being released for work program bidding. Closing dates for bid submissions are either six or twelve months after the release date, i.e. 8 November 2012 or 9 May 2013, depending on the exploration status in these areas and on data availability. As was the case in 2011, this year’s Release again covers a total offshore area of about 200,000 km2. The Release Areas are located in Commonwealth waters offshore Northern Territory, Western Australia, South Australia, Victoria and Tasmania (Fig. 1). Areas on the North West Shelf feature prominently again and include under-explored shallow water areas in the Arafura and Money Shoal basins and rank frontier deep water areas in the outer Browse and Roebuck basins as well as on the outer Exmouth Plateau. Following the recent uptake of exploration permits in the Bight Basin (Ceduna and Duntroon sub-basins), Australia’s southern margin is well represented in the 2012 Acreage Release. Three new areas in the Ceduna Sub-basin, four areas in the Otway Basin, one large area in the Sorell Basin and two areas in the eastern Gippsland Basin are on offer. Multiple industry nominations for this Acreage Release were received, confirming the healthy status of exploration activity in Australia. The Australian government continues to support these activities by providing free access to a wealth of geological and geophysical data.

RECONNAISSANCE GRAVITY SURVEY OF AUSTRALIA

Geophysics ◽  
1976 ◽  
Vol 41 (6) ◽  
pp. 1337-1345 ◽  
Author(s):  
A. R. Fraser ◽  
F. J. Moss ◽  
A. Turpie
Keyword(s):  
Bouguer Anomaly ◽  
South Australia ◽  
Mineral Resources ◽  
Sedimentary Basins ◽  
Petroleum Exploration ◽  
Aerial Photographs ◽  
Gravity Survey ◽  
State Governments ◽  
Anomaly Map ◽  
Considerable Benefit

The Australian Bureau of Mineral Resources, Geology and Geophysics, completed a 15 year systematic reconnaissance gravity survey of Australia in 1974. Using helicopters, gravity stations were established at 11 km spacing over most of the continent, and at 7 km spacing in South Australia and Tasmania. Station elevations were measured barometrically and station positions were marked on aerial photographs and transferred to 1:250,000 photocenter base maps. Gravity and elevation controls were maintained by ties to specially established control networks. A Bouguer anomaly map of Australia has been compiled from the reconnaissance data, and from information from other gravity surveys by state governments, petroleum exploration companies, and academic institutions which together cover about 15 percent of the total area. The compilation uses a total of about 170,000 gravity observations. The accuracy of Bouguer anomaly values, taking account of errors in the gravity, elevation, and position measurements, is estimated to be better than ± 2.0 mgal. The Bouguer anomaly fields over Australia are divided into nine regional gravity divisions, in each of which the gravity contour pattern has some degree of uniformity, or is such as to imply tectonic affinities between the sources of individual gravity features. The gravity divisions can be correlated with various metamorphic complexes and orogenic provinces, ranging in age from Archaean to Paleozoic, which also form the basements to extensive sedimentary platform covers. The reconnaissance gravity results have been made public as the survey has progressed to assist in regional geologic studies and the search for petroleum and minerals. They have proved to be of considerable benefit in delineating regional structures and in providing leads for more detailed geophysical investigations. Predictions of the structures of sedimentary basins have been made and possible extensions to mineral provinces have been indicated. The results have also been used in deep crustal and upper mantle studies and in geodesy.

NOISE AND TARGET SIGNALS SIMULATION IN PASSIVE SEISMIC LOCATION SYSTEMS

2018 ◽  
pp. 73-78
Author(s):  
Yu. V. Morozov ◽  
M. A. Rajfeld ◽  
A. A. Spektor
Keyword(s):  
Pulse Sequence ◽  
Signal To Noise Ratio ◽  
Seismic Signal ◽  
Seismic Signals ◽  
Simulation Procedure ◽  
Proposed Model ◽  
Seismic Location ◽  
Passive Seismic ◽  
System Characteristics ◽  
Primary Pulse

The paper proposes the model of a person seismic signal with noise for the investigation of passive seismic location system characteristics. The known models based on Gabor and Berlage pulses have been analyzed. These models are not able wholly to consider statistical properties of seismic signals. The proposed model is based on almost cyclic character of seismic signals, Gauss character of fluctuations inside a pulse, random amplitude change from pulse to pulse and relatively small fluctuation of separate pulses positions. The simulation procedure consists of passing the white noise through a linear generating filter with characteristics formed by real steps of a person, and the primary pulse sequence modulation by Gauss functions. The model permits to control the signal-to-noise ratio after its reduction to unity and to vary pulse shifts with respect to person steps irregularity. It has been shown that the model of a person seismic signal with noise agrees with experimental data.

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