Тип бассейна: Платформ
Подтип бассейна: Пассивных окраин (перикратонно-океанический)
Класс бассейна: Периокеанический
Возраст бассейна: Зрелый - Мезозойский
Тип полезных ископаемых:
Геологический возраст начало:
Геологический возраст конец:
Площадь: 409775.6 км²
Geology
The Guyana-Suriname Basin is a passive margin basin formed by Triassic to Jurassic rifting and separation of South America from Africa (Fig.1).
Fig. 1. Paleotectonic Map Showing the Location of Guyana and Plate Tectonics in the Late Cretaceous
This basin is primarily offshore and is bounded to the south by crystalline basement and to the east by the Demerara High, a remnant of continental crust from the separation. The basin fill includes clastic deposits from the South American continent, which formed deltas along a passive margin shelf and slope (Fig. 2). Carbonate depositional settings were located on the shelf edge. Miocene uplift changed the drainage of the continent and reduced the clastic sedimentation from the continent replacing the coarse-grained clastics and shelf edge carbonates with fine-grained clastics such as turbidites and seafloor fans. More than 7,000 meters of sedimentary fill has occurred in certain areas of the Guyana Basin.
Fig. 2. Stratigraphic Column for the Guyana - Suriname Basin
Regional Geologic Setting
The offshore Suriname is a part of the Suriname-Guyana basin, covering an area of about 230,000 square kilometers (Fig .3). It can be divided into three tectonic units: the shelf, the deep sea subbasin and the Demerara Plateau. In recent years, a number of turbidite sandstone oil and gas fields have been discovered in the deep sea of the basin, and C & T heavy oil field has been discovered onshore. The exploration Wells in the shallow sea area have good oil and gas shows, which has a certain exploration potential.
Fig. 3.Oil and gas fields and the location of study area in Suriname-Guyana Basin
The Demerara plateau is caused by the African Plate counterclockwise rotation and rifting away from South America, dividing the basin into the Central Atlantic passive margin to the west and the Equatorial Atlantic Transform margin to the east. the African Plate counterclockwise rotation to South America is recorded by smaller compressional structures, resulting in up to 50 km of NE-SW shortening and 6 km of erosion.
The Suriname-Guyana basin was formed as part of the tectonic evolution of the Central, Equatorial and South Atlantic Oceans which can be subdivided into four major stages according to the research of this paper: Break up of Pangea phase, intracontinental rift phase, regional uplift phase, and drifting over the South Atlantic phase.
Triassic break up of Pangea phase (~200 Ma)
The initiation of the Guiana Basin was caused by the breakup of Pangea around 200 million years ago and the subsequent drift between Gondwanaland & Laurasia which is recognized in the acreage on offer as the Nickerie Graben, part of a failed arm of the Central Atlantic. This is reflected in the fact that the Nickerie Graben is part of the failed branch of the mid-Atlantic.
Fig. 4.A comprehensive stratigraphic column map of Suriname-Guyana basin
Mid-Late Jurassic intracontinental rift phase (200Ma-150Ma)
This phase created a syn-rift sequence of Lower Jurassic sediments, while the Upper Jurassic drift phase created a passive margin with a moderate to high fluvial/deltaic discharge rapidly deposited in an inner neritic environment (Fig. 4). The principal structural elements of the Suriname-Guyana Basin that were created during this period include the Jurassic syn-rift grabens underlying the shelf, the shelf itself, a deep marine basin and the Demerara Plateau. Remnants of earliest rifting are present in the form of the Nickerie and the Commewijne Grabens, and their onshore equivalent Takutu Graben on the border between Guyana and Brazil which has a proven Jurassic Petroleum System. The end of this period is marked by the Break – up Un-conformity.
Early-Late Cretaceous regional uplift phase (150 Ma-95 Ma)
The South Atlantic rift and drift phase cause dramatic compression of the Jurassic section within the Suriname-Guyana basin due to rotational tectonic movement between South America and Africa which created major uplift and subsequent erosion leading to the basin-wide Break-up Unconformity. The compressional features are recognized at the north-eastern edge of the Suriname-Guyana Basin (Fig. 4). The reactivation is characterized by rather steep dipping normal faults in the Shallow offshore.
Late Cretaceous to recent Atlantic drifting phase (95 Ma-0 Ma)
The fourth major phase of the development of Guiana Basin occurred following the complete rifting of Gondwanaland and the opening of the Equatorial Atlantic rift which connected the South Atlantic and Central Atlantic oceans. Associated large igneous province volcanism and an ocean predisposed to anoxia and euxinia led to global Oceanic Anoxic Event which created the world class Cenomanian-Turonian Canje formation source rock which has been identified as one of the main sources for the oil found in the basin so far (Fig. 4). The drift phase of this tectonic chapter also marked the transition from a tectonically active basin to a passive margin.
The Equatorial Atlantic drift phase is characterized in the Guiana Basin as a passive margin sedimentary setting albeit with evidence of strike-slip tectonics observable in the sedimentary column.
The transform fault systems associated with this drift can be traced on the present-day sea floor. The transform fault lineaments connecting the Demerara Plateau to Equatorial Guinea Bissau Plateau in West Africa.
The Identification and Characterization of Submarine Fan
Sedimentary Facies and Sequence
The sedimentary section in the onshore to shallow offshore is underlain by the Gui-ana shield. The Guiana shield is Precambrian aged crystalline basement consisting of volcanic, granitoid and metamorphic rocks.
Permo-Triassic dykes indicate the onset of rifting within the Suriname-Guyana basin. The initial provenance of the sediment of the basin is the Guiana shield which has undergone intense weathering and erosion. River systems which developed through major faults/rifts acted as the transportation and depositional systems which ultimately created the sedimentary section as described in this report. The Precambrian basement is evident on 2D seismic data from the onshore and southern part of the shallow offshore.
The Jurassic Rift Grabens in the shallow offshore area are little explored. The rift was first penetrated in 1983 by the I/23-1X well where ~400 meters of alternating silt and volcanic material were penetrated in the Nickerie Graben. Recent evaluation indicates that the thickness of the Rift is more than 10km thick below the Cretaceous and Tertiary section. The stratigraphy of the Nikerie Rift basin is in part inferred from the Takutu Graben where lithologies include Triassic/Jurassic volcanics to Jurassic shale, salt, and sands. 40-degree API oil was tested from Jurassic fault systems.
Jurassic sequence is unconformably overlain by the Berriasian-Albian sequence, where it progressively onlaps the older sequence in an up-dip southerly direction and consequently the earliest Cretaceous section is absent in the most southerly near-shore acreage. The sedimentary record of this sequence is related to tectonic evolution when compression caused major inversion of the pre- Aptian/Albian sediments and created a regional peneplanation with the break in stratigraphy evident through-out the basin. The gross depositional environments transits from continental, delta plain, neritic to shelf margin in the shallow offshore. The extend in the deep water is characterized by bathyal to abyssal deposits.
The Albian-Cenomanian-Turonian sequence marks the onset of the passive margin with the basin and is subdivided into two distinct stratigraphic play intervals: Albian bounded by Mid Cretaceous flooding surface and top Albian unconformity and Cenomanian-Turonian bounded by top Albian unconformity and top Turonian un-conformity. The Albian interval is deposited during the equatorial Atlantic rifting and drifting phase when the African plate was still close to South America with sediment input still dominantly from the east. Seismic observations also indicate well developed delta in the east of the shallow offshore area. The Cenomanian-Turonian comprises the Cenomanian and Turonian interval (source rock equivalent interval) and is also characterized by a relative sea level rise. The sequence was deposited towards the end of the Equatorial Atlantic Rifting and Drifting phase. The deposited environment reflects a retreat of the Continental and the Delta plain zone relatively to the underlying Albian interval. The south exhibits a transition from delta plain to neritic environments, while a neritic environment dominates towards the north.
The Upper Cretaceous Coniacian-Mid Campanian marks the transition of a transgressive to a regressive system with increasing sediment input from the south west, creating a broad delta plain environment across the shallow offshore area. A shelf margin zone could not be identified for this sequence as no clear clinoforms/foresets were evident on the seismic data, possibly because they have been removed by the Cretaceous Mega erosional event which created a cut and fill system in this area (Fig. 5). The shallow offshore area is dominated by a delta plain environment and gradually transitioning to a neritic environment. The regression continued during Mid Campanian-Maastrichtian which is characterized by tremendous sediment input in the west creating a broad delta plain across the shallow offshore area. Overall, this sequence is characterized by a transition from delta plain to neritic environments similar to the underlying Mid Campanian-Maastrichtian.
Fig. 5.Seismic interpretation profile and submarine fan erosion characteristics in Suriname (see seismic location in Figure 3)
From the Upper Cretaceous to present, the coast of Suriname has remained a passive margin. The basin was, however, affected during the Tertiary by the eastward movement of the Caribbean plate, which resulted in a series of strike-slip faults parallel to the Surinamese coast.
During the Miocene, the Pacific plate started to under-thrust the South American continent, causing it to tilt to the east. The Amazon river’s lower tributaries consequently shifted to the south, beheading the big rivers that were draining in the Guiana basin and changed the basin from a sand dominated system to a clay-dominated system. It also ended the carbonate growth on the shelf due to the mud carried from the present Amazon river mouth along the coast of the Guyana.
Petroleum Systems
Oil production from the onshore Tambaredjo, Tambaredjo Northeast and Calcutta fields and that of the newly discovered Liza field indicate that a proven active petroleum system (Magoon, 1988) or systems are present in the Guyana-Suriname Basin.
Two source rock intervals have been identified in the Guyana-Suriname Basin, the Upper Albian to Santonian Canje Formation and an unnamed Jurassic interval (Fig.2). Oils in the Tambaredjo, Tambaredjo Northwest, and Calcutta fields located onshore in Suriname have been sourced from rocks in the Canje Formation.Figure 6). Significant oil generation from this source rock began during the Late Paleocene and continues. 4 The Canje Formation is presently in the oil window in the offshore Guyana and Suriname area Figure 6. Significant oil generation from this source rock began during the Late Paleocene and continues.
The Canje Formation source rock (Fig. 2) consists dominantly of organic-rich black mudstones with Total Organic Carbon (TOC) contents ranging from 2% to 5%. Values as high as 20% have been measured in equivalent Cenomanian to Santonian age black mudstones drilled during ODP Leg 207 (Erbacher, 2004) on the Demerara Plateau. Source rocks are dominantly algal Type II marine organic material with increasing terrestrial components in nearshore locations. Equivalent age source rocks of the Guyana Suriname Basin are now within the oil generation window with many ‘shows’ of oil and gas from several wells indicating the presence of hydrocarbons (Ginger, 1990). In this portion of the Guyana Suriname basin, the top of the oil window may be near 3,500 meters based on a locally higher thermal gradient than other areas in the basin. The mature pod of Cretaceous source rocks is located offshore in an area of the basin along the Guyana and Suriname coast (Fig. 6). This source rock is up to 550 meters thick. Migration to the producing oil fields onshore has been primarily lateral and updip for 100 to 150 kilometers (Ginger, 1990; Staatsolie.com, 2016).
Fig. 6 Map of Offshore Suriname Showing Mature Canje Formation Source Rock Maturation Level
Evidence of Jurassic source rocks in the basin comes from analysis of oil in Suriname that is unlike the Cretaceous sourced oil (Bihariesingh, 2014). These Jurassic source rocks are interpreted to have been deposited in pre-rift and rift depositional environments. These rocks include lacustrine shales with Type I oil-prone organic material. More than one rift half-graben may be present under the basin where lacustrine or restricted marine source rocks are mature and generating oil.
Exploration History for the Offshore of Guyana
Exploration activity in the offshore of Guyana began in 1958 when the California Oil Company conducted seismic surveys but did not drill a well. The first wells in the Guyana offshore area was drilled by Conoco and Tenneco in 1967. The Guyana Offshore #1 well encountered gas shows while the subsequent Guyana Offshore #2 well was a dry hole. Shell and Conoco drilled the Berbice #1 well in 1971 that had oil and gas shows in the Miocene but was abandoned after a gas kick at 2,171 meters (7,124 feet) in the Eocene. The Berbice #2 well found minor gas shows and oil stains in the Pliocene and Oligocene. Shell drilled the Mahaica #1 and #2 wells in 1974 with no success. In 1975, Shell drilled the Abary #1 well which found oil and gas shows and flowed 37o API oil from a turbidite at a depth of 3,990 meters (13,091 feet). Deminex drilled the Essequibo #1 well which had several oil and gas shows in the Miocene and Upper Cretaceous in 1977 but the subsequent well, the Essiquibo #2 drilled nearby had only minor shows of methane in the Upper Cretaceous. The Essiquibo wells and the Berbice wells were located on the extreme southern part of the Orinduik Block. The Arapaima #1 was drilled by Total in 1992 with gas tested in the Lower Cretaceous. In mid-2000, CGX Energy was prepared to drill the Eagle #1 well but the rig had to abandon the location because a Surinamese gunboat threatened to fire on it. The rig was moved to the Horseshoe West #1 location closer to shore which was abandoned as a dry hole. Drilling activity resumed in 2012, after the 2007 agreement between Guyana and Suriname to resolve the border dispute, with the drilling of the Eagle #1 and Jaguar #1 wells. The Eagle well found reservoir quality sands with shows of hydrocarbons in the Eocene and Upper Cretaceous while the Jaguar well was abandoned due to unexpected high pressures encountered in the well. Exxon then drilled the Liza #1 well which discovered commercial quantities of oil and gas in 2015 in the Stabroek Block, which is adjacent to the Orinduik Block. This discovery was followed by several additional successes which resulted in an estimated recoverable resource of 4 billion oil-equivalent barrels. Exxon has drilled over 15 wells to date on the Stabroek Block including the Hammerhead #1 well and has plans to develop the discovered fields and continue exploratory drilling.
Data source: Competent Persons Report for Certain Assets in Offshore Guyana. Kevin S. Weller, Jan J. Tomanek, 2019
Seismic Identification and Hydrocarbon Accumulation Characteristics of Submarine Fan in offshore Suriname. Hai-guang Bian, Zhi-xin Wen , Zhao-ming Wang, Zheng-jun He, Chengpeng Song, Zuo-dong Liu, Xue-ling Wang, Heng-xuan Li, Tian-yu Ji. The International Petroleum & Petrochemical Technology Conference 2023
Следующий Бассейн: Barbados