Layer | Fill | Outline |
---|
Map layers
Theme | Visible | Selectable | Appearance | Zoom Range (now: 0) |
---|
Fill | Stroke |
---|---|
Collaborating Authors
ABSTRACT This paper summarizes the geologic knowledge of the Foz do Amazonas basin in Northern Brazil, which has been investigated by Petrobras through geophysics and exploratory drilling. The basin covers an area of about 200,000 km, including the present coastal zone, continental shelf, and. Amazon submarine fan. This potentially prospective basin has been filled from Albian to Recent; may contain 14 km of sediments along the present-day shelf edge; and consists of a central deep basin flanked by two marginal platforms. The basin has passed through three tectonic stages since its beginning in the Albian; its main structural trends are related to fracture zones and ridges of the equatorial Atlantic Ocean. INTRODUCTION This paper describes the structural and stratigraphic framework of the Foz do Amazonas basin and integrates it with the northern Brazilian continental margin. The basin under the mouth of the Amazon River in northern Brazil, known as the Foz do Amazonas basin, comprises an area of about 200,000 km, including a coastal zone, continental shelf, and a submarine fan. Presently two main rivers reach the basin, the Amazon and the Tocantins (Fig. 1). The channels of both rivers become shallow where they reach the coastline and here they have tidal ridges typical of tide-dominated deltas. Mud brought by these rivers is deflected northwestward by the strong Guiana current and is deposited on the inner shelf almost all the way to the Orinoco delta in northeastern Venezuela. The recent sedimentation does not reach the outer shelf and slope because of the recent high stand of sea level (Fig. 1). Petroleo Brasileiro S.A. (Petrobras), the Brazilian national company for oil exploration, has investigated the basin with both geophysics and exploratory drilling. Seismic records of good quality permit the use of seismic stratigraphy for faciologic-structural mapping, identification of shelf margins, and the configuration of on and offlapping units. STRUCTURAL FRAME WORK The Foz do Amazonas basin has a sedimentary section over 5 km thick onshore and may be as thick as 14 km along the present-day shelf edge. The age of the sediments in the basin ranges from Middle Cretaceous (Albian?) to Quaternary. The main structural provinces are two onshore grabens, Limoeiro and Mexiana, which extend to the continental shelf, and the "Amazon Deep" (Rezende) which continues into the modern submarine fan (Amazon Cone) off the Amazon River (Fig. 2). The Limoeiro graben extends southeastward into the Paleozoic Maranhao basin, while the Mexiana graben is aligned northeastward. The Mexiana graben continues to the continental shelf, where geophysics suggests that it bifurcates into the Mexiana West and Mexiana East grabens (Rezende). Thus tectonics were very active during Upper Cretaceous, when terrigenous sedimentation prevailed in the basin. This tectonic activity was reduced during Paleogene times so that a wide carbonate platform developed over most of the modern continental shelf.
- South America > Ecuador > Orellana Province (1.00)
- South America > Brazil (1.00)
- Oceania > Australia > Victoria > Bass Strait (1.00)
- Phanerozoic > Mesozoic > Cretaceous > Upper Cretaceous (0.76)
- Phanerozoic > Mesozoic > Cretaceous > Lower Cretaceous > Albian (0.54)
- Geology > Structural Geology > Tectonics > Extensional Tectonics (1.00)
- Geology > Structural Geology > Fault > Dip-Slip Fault > Normal Fault (1.00)
- Geology > Geological Subdiscipline > Stratigraphy (1.00)
- (2 more...)
- Energy > Oil & Gas > Upstream (1.00)
- Government > Regional Government > South America Government > Brazil Government (0.76)
- South America > Brazil > Maranhão > South Atlantic Ocean > Maranhao Basin (0.99)
- South America > Brazil > Amapá > North Atlantic Ocean > Foz do Amazonas Basin (0.99)
Abstract. The gulf of Suez represents a unique structural Résumé. Le golfe de Suez représente une unité structuunit in the major Red Sea tectonic framework of which it relle unique dans la structure tectonique de la mer Rouge is today a part. It differs from this latter system with dont il fait part aujourd'hui. II se distingue de cette derregard to structure, geologic evolution, and history. The nière, par la structure, l'évolution géologique et son Red Sea graben proper lies in the middle of the Arabo- histoire. Le graben de la mer Rouge se trouve au milieu du Nubian massif and its origin is most probably connected massif arabo-noubien et son origine est probablement with tensional forces that resulted from the stretching of relié à des forces tensionales résultant de l'expansion du the massif in mid-Tertiary time (Cloos, 1939). The Gulf massif au Tertiaire moyen (Cloos, 1939). Le golfe de Suez of Suez, on the other hand, was formed originally as a d'autre part, se formait en temps paléozoïques en demi half graben on the flankmf an interbasinal arch in Palaeo- graben sur le flanc d'un ploiement interbasinal. II y a des zoic time. There is indication that the Gulf of Suez was indications que le golfe de Suez était inondé par la mer overlapped by seas throughout almost all geologic time. pendant presque tous les temps géologiques. L'accumu-The cumulative thickness of the sedimentary section is lation des sédiments monte à plus de 10.000 m et le golfe over 10,000 m and the Gulf is essentially a taphro-geo- est vraiement une taphrogéosynclinale (Said, 1962). syncline (Said, 1962). In contrast, the Red Sea forms La mer Rouge fait part, au contraire, du massif rigide arapart of the rigid Arabo-Nubian massif having been over- bo-noubien, qui était inondé seulement après le Miocène lapped only (with the exception of its northernmost part inférieure (à l'exception de la partie du nord jusqu'à la u p to lat. 25 N) in post-Lower Miocene tirrie. The sedi- latitude 25 o N). La section sédimentaire de la mer Rouge mentary section in the Red Sea is nowhere more than présente en aucun lieu une épaisseur plus de 800 m, 800 m thick while in its northern part it reaches 1,700 m in cependant la partie du nord parvient à une épaisseur cumulative thickness. cumulative de 1.700 m. In a recent attempt by this author4) to integrate been the site of immense accumulation of Sediments. within a system the mass of scattered information on By contrast, the Red Sea proper is of a much later Egyptian geology, several interesting results regard- date, having taken shape only in late lower Miocene ing the origin and the evolution of the Gulf of Suez time. This unique history is believed to be a reflection were reached. This region possesses a unique sedi- of the structural setting of the region. mentary history when compared with the bordering A
- Asia > Middle East > Yemen (1.00)
- Asia > Middle East > Saudi Arabia (1.00)
- Africa > Middle East > Egypt (1.00)
- Africa > Middle East > Djibouti (1.00)
- Phanerozoic > Cenozoic > Paleogene (1.00)
- Phanerozoic > Cenozoic > Neogene > Miocene > Lower Miocene (0.46)
- Geology > Structural Geology > Tectonics > Extensional Tectonics (1.00)
- Geology > Structural Geology > Fault > Dip-Slip Fault > Normal Fault (1.00)
- Asia > Middle East > Saudi Arabia > Red Sea > Red Sea Basin (0.99)
- Asia > Thailand > Gulf of Thailand > Western Basin (0.94)
- Asia > Middle East > Yemen (0.89)
ABSTRACT: Cheliff basin is an intra-mountainous basin concealing two oil fields and hydrocarbon shows in Oligocene and Miocene reservoirs. The sedimentary cover consists mainly of marl deposits associated with limited sand bodies of lower and upper Miocene. Three main formations have been sampled through ten wells for geochemical evaluation, Oligocene, Middle and Upper Miocene. Although Oligocene is not widespread in the basin, it shows mean potential (type II, TOC=0.5− 1%) and a maturity level of an oil window (Tmax= 430− 455°C). The Middle Miocene marls does not have the characteristic of a source rock which could generate commercial quantities of hydrocarbon, because of the weak organic richness (TOC generally lower than 0.5 %) and the lack of preservation of the organic matter. The marls of upper Miocene have mean to good potential, the TOC range from 0.5 to 1.2 % with type II marine organic matter. However, they still immature in the analysed well, Tmax< 430°C. Nevertheless, if a kinetic model reveals a type II S kerogen (like Ain Zeft oils); this horizon could be considered as a mature source rock. The offshore is also studied through the only one well located near Habibas Islands (northern Oran). The Middle Miocene is mature whereas, the source rock potential is weak (TOC<0.5 %). The Upper Miocene is relatively rich (TOC>1%) but it still immature. The Ain Zeft heavy oil (high NSO, 23 ° API) located in the northern part of the basin is probably sourced from Messinian which is an hyper saline deposit. Tliouanet oils (light) were more likely generated from the basement, a higher maturity source rock (Cretaceous). The hydrocarbon generation from the Middle Miocene occurred at 13 my, 10 to 50 % of oil was expelled since 11 my. Using type II S kinetic model (assumption) for the upper Miocene, the model shows oil generation period of Pleistocene. There are similarities in terms of organo-facies and conditions of preservation of the organic matter between Cheliff basin and Offshore. For predicting prospective zones of potential source rock in Algerian-provincial basin, we need to study source rocks distribution and occurrence regarding the organic matter preservation and supply at a whole Mediterranean scale
- Asia > Middle East > Yemen (0.93)
- Asia > Middle East > Saudi Arabia (0.93)
- Africa > Sudan (0.93)
- (4 more...)
- Phanerozoic > Cenozoic > Neogene > Miocene > Upper Miocene (1.00)
- Phanerozoic > Cenozoic > Neogene > Miocene > Middle Miocene (0.91)
- Geology > Geological Subdiscipline > Geochemistry (1.00)
- Geology > Geological Subdiscipline > Economic Geology > Petroleum Geology (1.00)
- Africa > Middle East > Algeria > Relizane Province > Chelif Basin > Tliouanet Field (0.99)
- Africa > Middle East > Algeria > Relizane Province > Chelif Basin > Ain Zeft Field (0.99)
- South America > Bolivia > Beni Basin (0.97)
ABSTRACT The Algerian offshore is situated in the southern part of Western Mediterranean sea. From East to the West, It extends over 1200 Km with an area of 93500 Km2, corresponding to the basins of Alboran into the West and Algero-Provencal into the center and the East. The exploration of the Algerian offshore began during the sixties, with a 2D seismic acquisition concentrated mainly on bays. Currently, a volume of about 34.500 km of 2D seismic is available. In 2011, more than 5000 Km were acquired, in addition to the gravity and magnetic data. One deep well (HBB-1; 4496.5m) and two cores drill (ARZ-1; 1304m and ALG-1; 1205m) were drilled in the Algerian offshore which still under explored. The interpretation of the HBB-1 well data shows the possibility of existence of petroleum system; with source rock related to Miocene (TOC could reach 1.5%). Concerning the reservoirs, HBB-1 well crossed 03 interesting sandy levels with good porosities (5–18%) within the Miocene and lower Pliocene highlighted on Gamma Ray and Sonic logs. Other reservoirs could be interesting and are related to the Numidian sandstones which exist to the Eastern part. The messinian evaporitic sequence could be a regional seal in addition to the interbedded clays and marls. The interpretation of all the seismic data, let to establish different structural maps, with several area of interest. The first one is situated in Eastern part between Béjaia and Annaba, and the second one is situated in the Western part between Mostaganem and Ténès. Different kind of traps (anticlines, faulted and tilted blocks) have been identified on the seismic lines acquired in 2000 and 2002. The well definition of the traps will be possible with a detailed 3D seismic acquisition in order to plan a new exploration well in the Algerian offshore basin.
- Africa > Middle East > Algeria > Béjaïa Province > Bejaia (0.27)
- Africa > Middle East > Algeria > Mostaganem Province > Mostaganem (0.26)
- Africa > Middle East > Algeria > Annaba Province > Annaba (0.25)
- Geology > Geological Subdiscipline (1.00)
- Geology > Structural Geology > Tectonics > Compressional Tectonics > Fold and Thrust Belt (0.72)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock (0.70)
Depositional Pattern and Diagenesis of Neogene Resedimented Carbonates of Sunda Shelf in Banyumeneng Area, Western Kendeng Basin, Indonesia
Ridha, Muhammad (Universitas Diponegoro) | Nurdiansyah, Mukhammad (Universitas Diponegoro) | Zamili, Jonathan Sofiawan (Universitas Diponegoro) | Triwigati, Purnaning Tuwuh (Universitas Diponegoro) | Muslih, Yan Bachtiar (Universitas Pertamina) | Farida, Widiastuti Nur (Pertamina Hulu Energi)
Abstract This study area is located on Dolok River, Banyumeneng, Western Kendeng Basin, which has a direct relation to the Sunda Shelf as the largest sediment supply for Kendeng Basin. The study aims to determine the changes of depositional succession on Late Neogene in the Western Part of Kendeng Basin and identify the diagenesis process and the implication to the physical properties of Calciclastic Submarine Fan (CSF) Deposits. The methods used in this study are field observation which was used to gather the stratigraphic record of deposits and rock samples analysis through petrography, microfossil, diagenesis, porosity and permeability. Measured stratigraphic section was used to determine the depositional pattern, facies and processes. Petrography analysis was used to determine the composition and diagenetic features. Moreover, the microfossil analysis was used to determine the relative age and the bathymetry of deposits, while the porosity was calculated using the mass-weighted method and permeability was calculated using the permeameter gas method to determine the quality of deposits as the hydrocarbon reservoir. Generally, the section shows the progradation sequence characterized by the Lobe Fringe deposits which gradationally change to the Outer Shelf deposits. The lower part was characterized by thick Hemipelagic Mudstone and Thin-bedded Calciturbidite Facies, showing the part of Lobe Fringe Deposits. The second part was divided into MTD type 1 and 2, MTD type 1 consist of Conglomeratic Calciturbidite, Clast-Supported Debrites, and Graded Calciturbidite, then the MTD type 2 is slumped levee deposits, showing the high-density turbidity current channel complexes on the Gullied Upper Slope. The third part was characterized by conglomeratic calciturbidite, graded calciturbidite, clast supported debrites, and hemipelagic mudstone, included into Braided Axis Channel facies. The fourth part was characterized by the interbedded of Thin-Bedded Calciturbidite, Laminated Calciturbidite and Hemipelagic Mudstone Facies, showing the Levee facies. The upper part was characterized by thick Cross-Bedded Calciclastic deposit, showing the Outer Shelf depositional environment. Furthermore, the Flute Cast shows the NW-SE paleocurrent direction which indicates that the Sunda Shelf Paleo-Environment was considered as the major sediment supply for this area. Moreover, the Foraminifera analysis shows the Lower Bathyal - Middle Neritic bathymetry on Middle - Late Miocene (N9 N18). The porosity and permeability quality ranged from 2.13 - 6.38% and 7.54 - 86.38 mD. Combined with petrography analysis, it can be analyzed that the diagenesis processes of Banyumeneng CSF deposits are micritization or grain-coating clays, compaction, cementation, neomorphism, and dissolution. The poorly-sorted materials and highly-cementation process may restrict the pore-throat and reduce the permeability as well. As the outcrop exposed, the meteoric water acts to dissolve the cement, leaving the small porosity inside. Therefore, the pores tend to be the secondary pores which are formed by the post depositional dissolution.
- Asia > Indonesia (1.00)
- North America (0.94)