Hydrocarbon Prospect of Block VI, East Gobi Basin

2013 ◽  
Vol 827 ◽  
pp. 148-152
Author(s):  
Lian Jin Wang ◽  
Yan Jun Chen ◽  
Chou Chou Yang

2D seismic reflection data and magnetism data, gravity data and electrical data together define the overall subsurface structure of the East Gobi basin (EGB), and reflect Jurassic-Cretaceous intracontinental rift evolution through deposition of at least five distinct stratigraphic sequences. Three major NE-SW trending fault zones divide the basin[. In the paper, through strata sequence description and sedimentary facies analysis, as well as zone appraisal for the oil and gas in the study area, we conclude that western step-fault zone of the block VI of EGB was most favorable pay, then the reverse faulted-nose structure in the east, while in the western slope and eastern fault zone, their hydrocarbon prospect need further proved.

Solid Earth ◽  
2019 ◽  
Vol 10 (3) ◽  
pp. 851-869 ◽  
Author(s):  
Salomé Mignard ◽  
Thierry Mulder ◽  
Philippe Martinez ◽  
Thierry Garlan

Abstract. The effects of changes in slope gradient on deposition processes and architecture have been investigated in different deep-sea systems both in modern and ancient environments. However, the impact of subtle gradient changes (< 0.3∘) on sedimentary processes along deep-sea fans still needs to be clarified. The Ogooue Fan, located in the northeastern part of the Gulf of Guinea, extends over more than 550 km westwards of the Gabonese shelf and passes through the Cameroon volcanic line. Here, we present the first study of acoustic data (multibeam echosounder and 3.5 kHz, very high-resolution seismic data) and piston cores covering the deep-sea part of this West African system. This study documents the architecture and sedimentary facies distribution along the fan. Detailed mapping of near-seafloor seismic-reflection data reveals the influence of subtle slope gradient changes (< 0.2∘) along the fan morphology. The overall system corresponds to a well-developed deep-sea fan, fed by the Ogooue River sedimentary load, with tributary canyons, distributary channel–levee complexes and lobe elements. However, variations in the slope gradient due to inherited salt-related structures and the presence of several seamounts, including volcanic islands, result in a topographically complex slope profile including several ramps and steps. In particular, turbidity currents derived from the Gabonese shelf deposit cross several interconnected intra-slope basins located on the low gradient segments of the margin (< 0.3∘). On a higher gradient segment of the slope (0.6∘), a large mid-system valley developed connecting an intermediate sedimentary basin to the more distal lobe area. Distribution and thickness of turbidite sands is highly variable along the system. However, turbidite sands are preferentially deposited on the floor of the channel and the most proximal depositional areas. Core description indicates that the upper parts of the turbidity flows, mainly composed of fine-grained sediments, are found in the most distal depocenters.


1992 ◽  
Vol 63 (3) ◽  
pp. 249-262 ◽  
Author(s):  
Anthony J. Crone

Abstract A preliminary interpretation of about 135 km of seismic-reflection data provides new information on the structural relations between the the Crittenden County fault zone and the subjacent rift-bounding faults along the southeastern margin of the Reelfoot rift in the New Madrid seismic zone. On the reflection data, the rift boundary is marked by a 4- to 8-km-wide zone of incoherent reflected energy and disrupted reflectors in the lower part of the well-stratified, lower Paleozoic sedimentary rocks and in the underlying Precambrian crystalline basement. In places, the zone of disrupted reflectors extends into the upper part of the Paleozoic rocks, and, on some lines, disrupted reflectors and distinct faults are present in the Upper Cretaceous and Tertiary rocks of the Mississippi Embayment. The Crittenden County fault zone is interpreted as a northwest-dipping, high-angle reverse fault with an up-to-the-northwest throw, which is opposite to the net structural relief in the subjacent graben. The fault zone is at least 32 km long and coincides with the rift margin in southwestern Crittenden County, but to the northeast, it diverges away from the aeromagnetically defined margin of the rift by almost 4 km. Most faults in the Crittenden County fault zone are apparently ancient rift-bounding normal faults that were reactivated with a significant amount of reverse slip during the Mesozoic and Cenozoic. On the basis of its apparent connection with the rift-bounding faults, the evidence of its long history of recurrent movement, and its orientation with respect to the modern stress field, the Crittenden County fault zone might be considered to potentially generate major earthquakes. In contrast, the possibility that the Crittenden County fault zone could be a bending-moment fault argues against it being extremely hazardous. Precambrian crystalline basement interpreted on the profiles is commonly deeper than magnetic basement by as much as 2.5 km. This discrepancy between shallow magnetic basement and deeper crystalline basement could be explained by the presence of igneous intrusions in the Paleozoic strata immediately above Precambrian basement.


2006 ◽  
Vol 43 (4) ◽  
pp. 433-446 ◽  
Author(s):  
Nathan Hayward ◽  
Mladen R Nedimović ◽  
Matthew Cleary ◽  
Andrew J Calvert

The eastern Juan de Fuca Strait is subject to long-term, north–south-oriented shortening. The observed deformation is interpreted to result from the northward motion of the Oregon block, which is being driven north by oblique subduction of the oceanic Juan de Fuca plate. Seismic data, acquired during the Seismic Hazards Investigation in Puget Sound survey are used, with coincident first-arrival tomographic velocities, to interpret structural variation along the Devil's Mountain fault zone in the eastern Juan de Fuca Strait. The Primary fault of the Devil's Mountain fault zone developed at the northern boundary of the Everett basin, during north–south-oriented Tertiary compression. Interpretation of seismic reflection data suggests that, based on their similar geometry including the large magnitude of pre-Tertiary basement offset, the Primary fault of the Devil's Mountain fault west of ~122.95°W and the Utsalady Point fault represent the main fault of the Tertiary Devil's Mountain fault zone. The Tertiary Primary fault west of ~122.95°W was probably kinematically linked to faults to the east (Utsalady Point, Devil's Mountain, and another to the south), by an oblique north–northeast-trending transfer zone or ramp. Left-lateral transpression controlled the Quaternary evolution of the Devil's Mountain fault zone. Quaternary Primary fault offsets are smaller to the east of ~122.95°W, suggesting that stress here was in part accommodated by the prevalent oblique compressional structures to the north. Holocene deformation has focussed on the Devil's Mountain, Utsalady Point, and Strawberry Point faults to the east of ~122.8° but has not affected the Utsalady Point fault to the west of ~122.8°W.


Geosites ◽  
2019 ◽  
Vol 1 ◽  
pp. 1-6
Author(s):  
Robert Biek

The Sevier fault is spectacularly displayed on the north side of Utah Highway 12 at the entrance to Red Canyon, where it offsets a 500,000-year-old basaltic lava flow. The fault is one of several active, major faults that break apart the western margin of the Colorado Plateau in southwestern Utah. The Sevier fault is a “normal” fault, a type of fault that forms during extension of the earth’s crust, where one side of the fault moves down relative to the other side. In this case, the down-dropped side (the hanging wall) is west of the fault; the upthrown side (the footwall) lies to the east. The contrasting colors of rocks across the fault make the fault stand out in vivid detail. Immediately south of Red Canyon, the 5-million-year-old Rock Canyon lava flow, which erupted on the eastern slope of the Markagunt Plateau, flowed eastward and crossed the fault (which at the time juxtaposed non-resistant fan alluvium against coarse-grained volcaniclastic deposits) (Biek and others, 2015). The flow is now offset 775 to 1130 feet (235-345 m) along the main strand of the fault, yielding an anomalously low vertical slip rate of about 0.05 mm/yr (Lund and others, 2008). However, this eastern branch of the Sevier fault accounts for only part of the total displacement on the fault zone. A concealed, down-to-the-west fault is present west of coarse-grained volcaniclastic strata at the base of the Claron cliffs. Seismic reflection data indicate that the total displacement on the fault zone in this area is about 3000 feet (900 m) (Lundin, 1987, 1989; Davis, 1999).


2009 ◽  
Vol 470 (3-4) ◽  
pp. 319-328 ◽  
Author(s):  
Kyoko Kagohara ◽  
Tatsuya Ishiyama ◽  
Toshifumi Imaizumi ◽  
Takahiro Miyauchi ◽  
Hiroshi Sato ◽  
...  

2014 ◽  
Vol 962-965 ◽  
pp. 160-163
Author(s):  
Si Si Cai ◽  
Wen Hui Huang ◽  
Meng Gong ◽  
De Yu Yan

This document studies the deposition condition in northeast Jizhong depression by using relevant data of cores, logging and scanning electron microscope. The result indicates that the study area has 7 kinds of lithofacies, including conglomerate, sandstone, siltstone, mudstone, bauxite, carbonate rock and coal seam . Bottom-up development in the study area cover tidal flat, lagoon, delta, meandering river and braided river, a total of five kinds of sedimentary facies. Benxi Formation, Taiyuan Formation and Shanxi Formation deposited in transitional facies, which has high generation potential of Hydrocarbon. Lower and upper Shihezi Formation is mainly a set of river deposition as a good reservoir. The top of upper Shihezi Formation and Shiqianfen Formation are mainly mudstone, which is conducive to seal oil and gas.


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