Three‐dimensional marine magnetotellurics for petroleum exploration

2003 ◽  
Author(s):  
Michael S. Zhdanov ◽  
Le Wan

Geophysics ◽  
1998 ◽  
Vol 63 (3) ◽  
pp. 826-840 ◽  
Author(s):  
G. Michael Hoversten ◽  
H. Frank Morrison ◽  
Steven C. Constable

In areas where seismic imaging of the base of salt structures is difficult, seaborne electromagnetic techniques offer complementary as well as independent structural information. Numerical models of 2-D and 3-D salt structures demonstrate the capability of the marine magnetotelluric (MT) technique to map the base of the salt structures with an average depth accuracy of better than 10%. The mapping of the base of the salt with marine MT is virtually unaffected by internal variation within the salt. Three‐dimensional anticlinal structures with a horizontal aspect ratio greater than two can be interpreted adequately via two‐dimensional inversions. Marine MT can distinguish between salt structures which possess deep vertical roots and those which do not. One measure of the relative accuracy of MT and seismic methods can be made by considering the vertical and lateral position errors in the locations of interfaces caused by neglecting velocity anisotropy in migration. For the shallow part of the section where two‐way travel times are on the order of 1 s, the vertical and lateral position errors in the locations of salt‐sediment interfaces from 2-D MT inversion is more than twice the expected migration error in reflectors in transversely isotropic sediments, such as those in the Gulf of Mexico. Deeper in the section where two‐way times are on the order of 4 s, lateral position errors in migration become comparable to those of the MT inverse, whereas seismic vertical position errors remain more than a factor of two smaller than MT errors. This analysis shows that structural mapping accuracy would be improved using MT and seismic together.



2004 ◽  
Vol 4 ◽  
pp. 53-56 ◽  
Author(s):  
Peter Japsen ◽  
Morten Sparre Andersen ◽  
Lars Ole Boldreel ◽  
Lars Ole Boldreel ◽  
Regin Waagstein ◽  
...  

Flood basalt-covered basins exist worldwide along continental margins and are now in focus as targets for future hydrocarbon exploration. It is generally difficult to image through the basalt cover by conventional seismic reflection methods, and this is a major challenge to future petroleum exploration offshore the Faroe Islands. Long-offset profiling has proven very successful (White et al. 2003). Surprisingly, however, it is possible to image through kilometre-thick basalt sequences on some conventional profiles. Details of basalt stratigraphy are revealed on old, reprocessed seismic profiles as well as on recently acquired profiles, even though the imaging may be unsuccessful on nearby profiles (e.g. Boldreel & Andersen 1993). This stresses the need for a better understanding of the acoustic and other physical properties of basalt as well as of the degree of three-dimensional heterogeneity. The SeiFaBa project (Seismic and petrophysical properties of Faroes Basalt, 2002–2005) is funded by the Sindri Group as part of the programmes for licensees within the Faroese offshore area, and addresses these issues with special focus on the subaerially extruded flood basalts of the Faroe Islands (cf. Japsen et al. in press).



Geology ◽  
2019 ◽  
Vol 47 (12) ◽  
pp. 1181-1184 ◽  
Author(s):  
Rosine Riera ◽  
Julien Bourget ◽  
Victorien Paumard ◽  
Moyra E.J. Wilson ◽  
Jeffrey Shragge ◽  
...  

Abstract Recognition of seismic unconformities is crucial for interpreting basin history from seismic reflection data sets in both siliciclastic and carbonate settings. While it is well established that non-erosional changes in sedimentary facies can create seismic reflections that mimic seismic unconformities (i.e., pseudo-unconformities), these features are generally considered to be localized and uncommon, and, therefore, are largely overlooked during interpretation. Diagenetic alteration of strata can also affect the morphology of seismic reflectors and mislead seismic interpreters. This study is based on a three-dimensional (3-D) seismic data set and documents a 400 km2 honeycomb structure (HS) masquerading as a regional erosional unconformity in the Oligocene–Miocene carbonate strata of Australia’s North West Shelf. This HS is located at the transition between the topsets and the foresets of clinoforms of carbonate to marly composition. The HS expression in 3-D seismic data cross sections is irregular, giving the HS the appearance of a truncated surface that could erroneously be interpreted as a regional seismic unconformity. Closer examination reveals that the HS crosscuts chronostratigraphic clinoform reflectors, and frequency extraction processing shows that the HS dominantly falls within a lower-frequency band than the clinoform reflectors. The morphology of the HS (i.e., continuous with densely packed cells) and its time-transgressive nature suggest that it has a burial diagenetic origin. This suggests that creation of pseudo-unconformities at basin scale by burial diagenesis may lead to surface misidentification, with negative consequences for paleoenvironmental studies and petroleum exploration activities.





1993 ◽  
Vol 11 (5) ◽  
pp. 414-422
Author(s):  
Adebayo Aina

Two key technological developments in petroleum exploration - three dimensional seismic survey (3-D Seismic) and integrated seismic interpretation workstations - have led to significant discoveries of oil and gas in the various Nigerian oil provinces where they have been introduced. These new technologies were introduced in Nigeria in the mid-1980s and have since resulted in significant additions to the country's proven crude oil and natural gas reserves.





2013 ◽  
Vol 734-737 ◽  
pp. 1144-1149
Author(s):  
Jian Ming Hao ◽  
Wei Zhao ◽  
Jian Guo Zhang ◽  
Zai Xing Jiang

Seismic exploration of petroleum is a kind of high technology which integrated hardware and software. The improvement of software engineering has produced an active influence on seismic exploration. The recent advance mainly expressed on acquisition, processing and interpretation of high frequency three dimensional seismic data. Application of new algorithm and super integrate large-scale software can improve the accuracy and efficiency of the petroleum discovery. Development seismic is new frontier of seismic application. Its a new branch of learning which makes full description and dynamic detection during petroleum exploration. It need use manners of oil and gas reservoir observation and information processing technique, combining with the data of drilling, geology and reservoir engineering etc. This can also take related hardware and software technological advances and development.



2021 ◽  
Vol 13 (1) ◽  
pp. 262-271
Author(s):  
Hakim Saibi ◽  
Diab Bakri Hag ◽  
Mohammed Saeed Mohammed Alamri ◽  
Hamdan Abdo Ali

Abstract The crustal structure beneath the United Arab Emirates (UAE) is still relatively unknown. Here, we use regional gravity data to constrain the subsurface density distribution and structure of the crust of the UAE by applying diverse gravity derivatives methods such as horizontal derivative (HDR), analytic signal (AS), and tilt angle (TA) to analyze the subsurface structure and perform three-dimensional (3D) gravity inversion for imaging crustal structure from the surface down to 35 km depth. The results are compared with known geological regional structures and the location of the petroleum fields. The Bouguer anomalies range from −100.8 to 113.5 mGal. The 3D gravity inversion results and the maximum Bouguer values coincide with the ophiolitic Hajar mountains in the east and the successive anticlines (uplifted basement rocks) and synclines in different parts of UAE, which could be promising sites for future mining and petroleum exploration. Also, the 3D density model results and the minimum Bouguer anomalies are located over the Aruma Basin, eastern UAE Platform, and Low Central UAE Platform, which can be the places for deep groundwater aquifers. These new results from HDR, AS, and TA successfully identify known geological structures, especially in the eastern part of UAE.



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