WANDOO—A NEW TREND

1994 ◽  
Vol 34 (1) ◽  
pp. 586
Author(s):  
Ernie Delfos ◽  
Malcolm Boardman

In June 1991 a flow of 4 560 barrels of 19° API oil per day, from a depth of 600 m, heralded the discovery of a new hydrocarbon trend along the eastern margin of the Dampier Sub-basin on the North West Shelf of Australia. Wandoo–1 recovered oil and gas from lower Cretaceous sands associated with the M.australis dinoflagellate zone (Barremian), and gas from lower Jurassic Aalenian sands.The main reservoir at Wandoo is the M. australis Sandstone Member of the Muderong Shale. This is interpreted to be a shelfal shoal sand deposited in a minor regression phase during the regional transgression of the Muderong Shale. This reservoir is split into two main lithotypes, a glauconitic subarkose to subarenite, and an overlying greensand. Oil and gas have been recovered from both units, which are considered contiguous for reservoir definition. General reservoir parameters are exceptional. Since the initial discovery a 3D seismic survey has been acquired and appraisal drilling has proven approximately 250 MMSTBOIP.The unusual features of the field necessitated innovative exploration techniques and the need for a strong appraisal program. These techniques included a six streamer, high resolution, three dimensional seismic survey and its associated processing; development of methods to recover and preserve core in extremely unconsolidated sediments; use of non destructive core analysis methods such as nuclear magnetic resonance; and petrophysical analysis that incorporates the resistivity suppression problems of glauconite. Without core a very pessimistic view would have been taken of the M. australis Sandstone reservoir.The Wandoo discovery is on an exciting new trend previously overlooked due to the shallowness of reservoirs, lack of locally recognised source rocks and the dominance of other oil and gas trends in the Dampier Sub-basin and Barrow Sub-basin to the south.

1986 ◽  
Vol 26 (1) ◽  
pp. 375
Author(s):  
N.B. Beston

The North Rankin Field off northwestern Australia provides the major part of the gas reserves for the North West Shelf Project, one of the largest and most ambitious natural resource developments yet undertaken in Australia. Detailed reservoir geological modelling coupled with a three dimensional reservoir simulator have strongly enhanced development planning of the field.The North Rankin structure is a large horst feature of Upper Triassic to Lower Jurassic fluvial and marginal marine sediments unconformably overlain by Cretaceous claystones and marls. The sequence is comprised of braided stream 'sheet like' sandstones, fluvial meandering stream and floodplain sediments, and mixed marginal marine and fluvial channel sandstones.Comprehensive reservoir geological studies involving the examination of reservoir quality, distribution, and continuity were undertaken and combined with an extensive three dimensional seismic survey to provide improved structural definition. The resultant reservoir geological model, which required close interaction and integration of all petroleum engineering disciplines, provided not only the geological basis for improving the estimate of field reserves but also formed the geological input for a reservoir simulation model to optimise the development planning of the North Rankin Field and to predict the reservoir performance of this internally faulted field.The completion of the Domestic Gas Phase of the Project, which involved the drilling of seven development wells, has confirmed the reservoir geological/structural model thus providing a firm basis for the future development planning of the gas recycling and liquefied natural gas phases of the North West Shelf Project.


2018 ◽  
Vol 58 (2) ◽  
pp. 871 ◽  
Author(s):  
Melissa Thompson ◽  
Fred Wehr ◽  
Jack Woodward ◽  
Jon Minken ◽  
Gino D'Orazio ◽  
...  

Commencing in 2014, Quadrant Energy and partners have undertaken an active exploration program in the Bedout Sub-basin with a 100% success rate, discovering four hydrocarbon accumulations with four wells. The primary exploration target in the basin, the Middle Triassic Lower Keraudren Formation, encompasses the reservoirs, source rocks and seals that have trapped hydrocarbons in a self-contained petroleum system. This petroleum system is older than the traditional plays on the North-West Shelf and before recent activity was very poorly understood and easily overlooked. Key reservoirs occur at burial depths of 3500–5500 m, deeper than many of the traditional plays on the North-West Shelf and exhibit variable reservoir quality. Oil and gas-condensate discovered in the first two wells, Phoenix South-1 and Roc-1, raised key questions on the preservation of effective porosity and productivity sufficient to support a commercial development. With the acquisition and detailed interpretation of 119 m of core over the Caley Member reservoir in Roc-2 and a successful drill stem test that was surface equipment constrained to 55 MMscf/d, the productive potential of this reservoir interval has been confirmed. The results of the exploration program to date, combined with acquisition of new 3D/2D seismic data, have enabled a deeper understanding of the potential of the Bedout Sub-basin. A detailed basin model has been developed and a large suite of prospects and leads are recognised across a family of hydrocarbon plays. Two key wells currently scheduled for 2018 (Phoenix South-3 and Dorado-1) will provide critical information about the scale of this opportunity.


1994 ◽  
Vol 34 (1) ◽  
pp. 297
Author(s):  
E.L. Horstman

The oil potential of rocks containing inertinite is systematically underestimated by chemical or programmed pyrolysis techniques. Inertinite is measured as organic carbon, but does not contribute to the hydrocarbons produced during pyrolysis. When maceral data is available the measured amount of organic carbon can be recalculated to establish an Hydrogen Index based only on the kerogen which might contribute to oil and gas generation. Inertiniterich rocks that were previously discounted as being only gas prone should be reviewed.Recalculated HI:OI plots prepared from samples from the North West Shelf of Australia indicate the presence of significant amounts of oil-prone kerogen in source rocks previously evaluated as being predominantly gas-prone, upgrading the oil potential of the area.


1985 ◽  
Vol 25 (1) ◽  
pp. 235 ◽  
Author(s):  
A.F. Williams ◽  
D.J. Poynton

The South Pepper field, discovered in 1982, is located 30 km southwest of Barrow Island in the offshore portion of the Barrow Sub-basin, Western Australia. The oil and gas accumulation occurs in the uppermost sands of the Lower Cretaceous Barrow Group and the overlying low permeability Mardie Greensand Member of the Muderong Shale.The hydrocarbons are trapped in one of several fault closed anticlines which lie on a high trend that includes the North Herald, Pepper and Barrow Island structures. This trend is postulated to have formed during the late Valanginian as the result of differential compaction and drape over a buried submarine fan sequence. During the Turonian the trend acted as a locus for folding induced by right-lateral wrenching along the sub-basin edge. Concurrent normal faulting dissected the fold into a number of smaller anticlines. This essentially compressional tectonic phase contrasted with the earlier extensional regime which was associated with rift development during the Callovian. A compressional tectonic event in the Middle Miocene produced apparent reverse movement on the South Pepper Fault but only minor changes to the structural closure.Geochemical and structural evidence indicates at least two periods of hydrocarbon migration into the top Barrow Group - Mardie Greensand reservoir. The earlier occurred in the Turonian subsequent to the period of wrench tectonics and involved the migration of oil from Lower Jurassic Dingo Claystone source rocks up the South Pepper Fault. This oil was biodegraded before the second episode of migration occurred after the Middle Miocene tectonism. The later oil is believed to have been sourced by the Middle to Upper Jurassic Dingo Claystone. Biodegradation at this stage ceased or became insignificant due to temperature increase and reduction of meteoric water flow. Gas-condensate, sourced from Triassic or Lower Jurassic sediments may have migrated into the structure with this second oil although a more recent migration cannot be ruled out.The proposed structural and hydrocarbon migration history fits regional as well as local geological observations for the Barrow Sub-basin. Further data particularly from older sections of the stratigraphic column within the area are needed to refine the interpretation.


2019 ◽  
pp. 9-15
Author(s):  
Ya. I. Gladysheva

Discovered hydrocarbon deposits in a number of fields are the characteristic of the industrial productivity of Jurassic sediments in the north of Western Siberia. Most of the deposits are in the Middle Jurassic sediments, the signs of hydrocarbons have been obtained in the Lower Jurassic sediments, single deposits have been obtained in the Upper Jurassic sediments. This uneven distribution of deposits in the Jurassic oil and gas bearing facility is associated with the complexity of its structure. Therefore, there is a need to conduct a comprehensive analysis of the geological structure of Jurassic sediments, to identify geological parameters to predict commercial oiland-gas content zones in the investigated territory.Based on the results of the study of deep drilling data, seismic survey in the north of Western Siberia, schematic maps of the depth zones of Jurassic sediments have been constructed, the author of the article determines the parameters of industrial productivity zones. The most significant parameter is abnormally high formation pressure. Based on the conducted researches, the author notes the prospective commercial oil-and-gas content zones for Jurassic sediments within NadymPur watershed.


Minerals ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 75
Author(s):  
Meihua Yang ◽  
Yinhui Zuo ◽  
Xiaodong Fu ◽  
Lei Qiu ◽  
Wenzheng Li ◽  
...  

The quality of hydrocarbon source rocks is affected by the sedimentary paleoenvironment. A paleoenvironment with anoxia and a high paleoproductivity is beneficial to source rocks. The paleoenvironment of the Lower Ordovician Meitan Formation of the Sichuan Basin and its adjacent areas is lacking, restricting the oil and gas exploration of the Ordovician in the Sichuan Basin and its adjacent areas. In this paper, the content of major and trace elements of 50 samples was tested to clarify the paleoenvironment of the Meitan Formation. The paleoclimate, paleosalinity, paleoredox, and paleoproductivity during the deposition of the Meitan Formation were analyzed. The control effect of the paleoenvironment on the development of source rocks was clarified, and the favorable paleoenvironment for source rock development was pointed out. The results show that the paleoenvironment of the Meitan Formation has the following characteristics: humidity, brackish water, oxygen depletion, anoxia environment, and high paleoproductivity. These characteristics are conducive to the development of poor and moderate source rocks. The source rocks of the Meitan Formation were developed in the north, west, and south of the Sichuan Basin and its adjacent areas. The organic matter of the source rocks is mainly typed II1 kerogen, and the quality is evaluated as poor-medium source rocks having the potential of generating oil and gas. This study can provide fundamental parameters for the further exploration of Ordovician petroleum.


2002 ◽  
Vol 8 (2-3) ◽  
pp. 206-208
Author(s):  
V.G. Osadchyi ◽  
◽  
O.A. Prykhod'ko ◽  
I.I. Hrytsyk ◽  
◽  
...  

GeoArabia ◽  
2009 ◽  
Vol 14 (3) ◽  
pp. 199-228 ◽  
Author(s):  
Mohammad Faqira ◽  
Martin Rademakers ◽  
AbdulKader M. Afifi

ABSTRACT During the past decade, considerable improvements in the seismic imaging of the deeper Paleozoic section, along with data from new well penetrations, have significantly improved our understanding of the mid-Carboniferous deformational event. Because it occurred at the same time as the Hercynian Orogeny in Europe, North Africa and North America it has been commonly referred to by the same name in the Middle East. This was the main tectonic event during the late Paleozoic, which initiated or reactivated many of the N-trending block uplifts that underlie the major hydrocarbon accumulations in eastern Arabia. The nature of the Hercynian deformation away from these structural features was poorly understood due to inadequate seismic imaging and insufficient well control, along with the tectonic overprint of subsequent deformation events. Three Hercynian NE-trending arches are recognized in the Arabian Plate (1) the Levant Arch, which extended from Egypt to Turkey along the coast of the Mediterranean Sea, (2) the Al-Batin Arch, which extended from the Arabian Shield through Kuwait to Iran, and (3) the Oman-Hadhramaut Arch, which extended along the southeast coast of Oman and Yemen. These arches were initiated during the mid-Carboniferous Hercynian Orogeny, and persisted until they were covered unconformably by the Khuff Formation during the Late Permian. Two Hercynian basins separate these arches: the Nafud-Ma’aniya Basin in the north and Faydah-Jafurah Basin in the south. The pre-Hercynian Paleozoic section was extensively eroded over the arches, resulting in a major angular unconformity, but generally preserved within the basins. Our interpretation suggests that most of the Arabian Shield, except the western highlands along the Red Sea, is the exhumed part of the Al-Batin Arch. The Hercynian structural fabric of regional arches and basins continue in northern Africa, and in general appear to be oriented orthogonal to the old margin of the Gondwana continent. The Hercynian structure of arches and basins was partly obliterated by subsequent Mesozoic and Cenozoic tectonic events. In eastern Saudi Arabia, Qatar, and Kuwait, regional extension during the Triassic formed N-trending horsts and graben that cut across the NE-trending Hercynian mega-structures, which locally inverted them. Subsequent reactivation during the Cretaceous and Neogene resulted in additional growth of the N-trending structures. The Hercynian Arches had major impact on the Paleozoic hydrocarbon accumulations. The Silurian source rocks are generally preserved in the basins and eroded over the arches, which generally confined Silurian-sourced hydrocarbons either within the basins or along their flanks. Furthermore, the relict Hercynian paleo-topography generally confined the post-Hercynian continental clastics of the Unayzah Formation and equivalents to the Hercynian basins. These clastics contain the main Paleozoic oil and gas reservoirs, particularly along the basin margins where they overlie the sub-crop of the Silurian section with angular unconformity, thus juxtaposing reservoir and source rock.


2018 ◽  
Vol 36 (5) ◽  
pp. 1229-1244
Author(s):  
Xiao-Rong Qu ◽  
Yan-Ming Zhu ◽  
Wu Li ◽  
Xin Tang ◽  
Han Zhang

The Huanghua Depression is located in the north-centre of Bohai Bay Basin, which is a rift basin developed in the Mesozoic over the basement of the Huabei Platform, China. Permo-Carboniferous source rocks were formed in the Huanghua Depression, which has experienced multiple complicated tectonic alterations with inhomogeneous uplift, deformation, buried depth and magma effect. As a result, the hydrocarbon generation evolution of Permo-Carboniferous source rocks was characterized by discontinuity and grading. On the basis of a detailed study on tectonic-burial history, the paper worked on the burial history, heating history and hydrocarbon generation history of Permo-Carboniferous source rocks in the Huanghua Depression combined with apatite fission track testing and fluid inclusion analyses using the EASY% Ro numerical simulation. The results revealed that their maturity evolved in stages with multiple hydrocarbon generations. In this paper, we clarified the tectonic episode, the strength of hydrocarbon generation and the time–spatial distribution of hydrocarbon regeneration. Finally, an important conclusion was made that the hydrocarbon regeneration of Permo-Carboniferous source rocks occurred in the Late Cenozoic and the subordinate depressions were brought forward as advantage zones for the depth exploration of Permo-Carboniferous oil and gas in the middle-northern part of the Huanghua Depression, Bohai Bay Basin, China.


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