The Latrobe Group and the 90-million-year beach

2013 ◽  
Vol 53 (2) ◽  
pp. 460
Author(s):  
Nick Hoffman ◽  
Natt Arian

Carbon dioxide geosequestration requires a detailed understanding of the whole sedimentary section, with particular emphasis on topseals and intraformational seals. Hydrocarbon exploration is more focused on reservoirs but requires a similar basin understanding. This extended abstract reviews the knowledge gained from petroleum exploration in the Gippsland Basin to The CarbonNet Project’s exploration program for CO2 storage. The Ninety Mile Beach on the Gippsland coast is a prominent modern-day sand fairway where longshore drift transports sediments north-eastwards along a barrier-bar system, trapping lake systems behind the coastal strip. This beach is only 10,000 years old (dating to the last glacial rise of sea level) but is built on a platform of earlier beaches that can be traced back almost 90 million years to the initiation of Latrobe Group deposition in the Gippsland Basin. Using a recently compiled and open-file volume of merged 3D seismic surveys, the authors show the evolution of the Latrobe shoreline can be mapped continuously from the Upper Cretaceous to the present day. Sand fairways accumulate as a barrier-bar system at the edge of a steadily subsiding marine embayment, with distinct retrogradational geometries. Behind the barrier system, a series of trapped lakes and lagoons are mapped. In these, coal swamps, extensive shales, and tidal sediments were deposited at different stages of the sea-level curve, while fluvial systems prograded through these lowlands. Detailed 3D seismic extractions show the geometry, orientation and extent of coals, sealing shales, fluvial channels, and bayhead deltas. Detailed understanding of these reservoir and seal systems outlines multi-storey play fairways for hydrocarbon exploration and geosequestration. Use of modern basin resource needs careful coordination of activity and benefits greatly from established data-sharing practices.

2019 ◽  
Vol 59 (2) ◽  
pp. 493
Author(s):  
D. Lockhart ◽  
D. Spring

Available data for 2018 indicates that exploration activity is on the rise in Australia, compared to 2017, and this represents a second year of growth in exploration activity in Australia. There has been an increase in area under licence by 92 000 km2, reversing the downward trend in area under licence that commenced in 2014. Since 2016, exploratory drilling within Australia has seen a continued upward trend in both the number of wells drilled and the percentage of total worldwide. Onshore, 77 conventional exploration and appraisal wells were spudded during the year. Offshore, exploration and appraisal drilling matched that seen in 2017, with five new wells spudded: two in the Roebuck Basin, two in the Gippsland Basin and one in the North Carnarvon Basin. Almost 1500 km of 2D seismic and over 10 000 km2 of 3D seismic were acquired within Australia during 2018, accounting for 2.4% and 3.9% of global acquisition, respectively. This represents an increase in the amount of both 2D and 3D seismic acquired in Australia compared with 2017. Once the 2017 Offshore Petroleum Acreage Release was finalised, seven new offshore exploration permits were awarded as a result. A total of 12 bids were received for round one of the 2018 Offshore Petroleum Exploration Release, demonstrating an increase in momentum for offshore exploration in Australia. The permits are in Commonwealth waters off Western Australia, Victoria and the Ashmore and Cartier islands. In June 2018, the Queensland Government announced the release of 11 areas for petroleum exploration acreage in onshore Queensland, with tenders closing in February/March 2019; a further 11 areas will be released in early 2019. The acreage is a mix of coal seam gas and conventional oil and gas. Victoria released five areas in the offshore Otway Basin within State waters. In the Northern Territory, the moratorium on fracking was lifted in April, clearing the way for exploration to recommence in the 2019 dry season. With the increase in exploration has come an increase in success, with total reserves discovered within Australia during 2018 at just under 400 million barrels of oil equivalent, representing a significant increase from 2017. In 2018, onshore drilling resulted in 18 new discoveries, while offshore, two new discoveries were made. The most notable exploration success of 2018 was Dorado-1 drilled in March by Quadrant and Carnarvon Petroleum in the underexplored Bedout Sub-basin. Dorado is the largest oil discovery in Australia of 100 million barrels, or over, since 1996 and has the potential to reinvigorate exploration in the region.


2020 ◽  
Vol 60 (2) ◽  
pp. 718
Author(s):  
Nick Hoffman

The CarbonNet project is making the first ever application for a ‘declaration of an identified greenhouse gas storage formation’ (similar to a petroleum location) under the Offshore Petroleum and Greenhouse Gas Storage Act. Unlike a petroleum location, however, there is no ‘discovery’ involved in the application. Instead, a detailed technical assessment is required of the geological suitability for successful long-term storage of CO2. The key challenges to achieving a successful application relate to addressing ‘fundamental suitability determinants’ under the act and regulations. At Pelican (Gippsland Basin), a new high-resolution 3D seismic survey and over 10 nearby petroleum wells (and over 1500 basinal wells) supplement a crestal well drilled in 1967 that proved the seal and reservoir stratigraphy. The GCN18A 3D marine seismic survey has the highest spatial and frequency resolution to date in the Gippsland Basin. The survey was acquired in water depths from 15 to 35 m with a conventional eight-streamer seismic vessel, aided by LiDAR bathymetry. The 12.5 m bin size and pre-stack depth migration with multiple tomographic velocity iterations have produced an unprecedented high-quality image of the Latrobe Group reservoirs and sealing units. The 3D seismic data provides excellent structural definition of the Pelican Anticline, and the overlying Golden Beach-1A gas pool is excellent. Depositional detail of reservoir-seal pairs within the Latrobe Group has been resolved, allowing a confident assessment of petroleum gas in place and CO2 storage opportunities. The CarbonNet project is progressing with a low-risk storage concept at intra-formational level, as proven by trapped pools at nearby oil and gas fields. Laterally extensive intra-formational shales provide seals across the entire structure, providing pressure and fluid separation between the overlying shallow hydrocarbon gas pool and the deeper CO2 storage opportunity. CarbonNet is assessing this storage opportunity and progressing towards a ‘declaration of an identified greenhouse gas storage formation’.


2012 ◽  
Vol 52 (1) ◽  
pp. 397 ◽  
Author(s):  
Bozkurt Ciftci ◽  
Laurent Langhi ◽  
Silvio Giger ◽  
Julian Strand ◽  
Louise Goldie-Divko ◽  
...  

The extensional architecture of the Gippsland Basin was modified by a phase of contractional deformation during the Oligocene—Pleistocene postdating the main subsidence phase of the basin. This deformation caused local inversion and folding, which modified the depocentre geometry and controlled deformation of the syn-kinematic regional top-seal—the Lakes Entrance Formation. Accordingly, there is spatial variation of deformation intensity and lithofacies distribution, the latter of which possibly affected the strain accommodation behaviour of the Lakes Entrance Formation. These factors are critical and locally detrimental to seal capacity. In this study, the volume of shale distribution of the Lakes Entrance Formation was modelled and various parameters of the seismic-scale faults were computed, including shale gouge ratio, slip tendency and dilation tendency. Sub-seismic deformation was captured by strain and curvature attributes at the Latrobe unconformity, which carries the most intense imprint of the deformation phase. These parameters were correlated to known hydrocarbon seepage and leakage indicators in the basin, which could be related either to: (i) localised deformation along fault zones; or, (ii) to distributed deformation separated from the fault zones. There is generally a good match between the anomalous values of the computed parameters and the location of leakage indicators. For fault-related localised deformation zones, the match of the parameters ranks in the following order: shale gouge ratio (95%), strain (84%), curvature (84%) and slip tendency (74%). By combining these four parameters, a fault-related leakage assessment factor (FLAF) was defined and mapped across the study area. Match ratio of the parameters used to capture distributed deformation separated from the fault zones are ranked in the following order: curvature (100%), strain (100%) and volume of shale (83%). These parameters were also combined to define an ‘other’ leakages assessment factor (OLAF) and mapped across the study area. FLAF and OLAF maps are consistent with known leakage/seepage indicators in the basin and are indicative of additional areas with potential risk for top seal bypass. These risk maps provide useful input to CO2 storage and hydrocarbon exploration efforts in the basin.


2012 ◽  
Vol 52 (2) ◽  
pp. 698
Author(s):  
Ernest Swierczek ◽  
Simon Holford ◽  
Guillaume Backé ◽  
Andy Mitchell

One of the main risks associated with the underground storage of CO2 is the possibility of leakage from the reservoir to the surface. Among the most likely pathways for CO2 migration are permeable fault systems and highly fractured caprocks. It is thus important to develop a detailed understanding of geometrical characteristics of fault systems to assess the long-term storage and reactivation potential of fault dependent reservoirs. This extended abstract describes the results from a detailed structural analysis of the Rosedale Fault System (RFS) in the Gippsland Basin, Victoria, which is undergoing assessment for CO2 storage, using high-fidelity 3D seismic data. The RFS is a long-lived fault system that has experienced significant reactivation since the late Miocene and continued activity on this fault. Conventional structural mapping has been supported by seismic attribute analyses using a dip-steering cube. The coupling of seismic attribute analysis with fault displacement analysis has enabled the geometry of the RFS to be defined and to delineate associated damage zone. This extended abstract's analysis shows that the RFS is an anastomosing normal fault system that displays lateral changes in the degree of late Miocene-onwards reverse reactivation, which has affected the Latrobe Group and older units. This analysis has also revealed an extensive polygonal fault-system confined to post-Top Latrobe (Eocene) sediments, showing that this component of the stratigraphy is structurally decoupled from the older sedimentary section. This extended abstract concludes by assessing the roles that both the RFS and the polygonal fault system play in fluid migration in the western Gippsland Basin.


Geophysics ◽  
2009 ◽  
Vol 74 (2) ◽  
pp. B47-B59 ◽  
Author(s):  
Paul C. Veeken ◽  
Peter J. Legeydo ◽  
Yuri A. Davidenko ◽  
Elena O. Kudryavceva ◽  
Sergei A. Ivanov ◽  
...  

Delineation of hydrocarbon prospective areas is an important issue in petroleum exploration. The geoelectric method helps to identify attractive areas and reduces the overall drilling risk. For this purpose, induced polarization (IP) effects are mapped caused by the presence of epigenetic pyrite microcrystals in sedimentary rocks. These crystals occur in a shallow halo-shaped mineralogical alteration zone, often overlying a deeper-seated hydrocarbon accumulation. Local enrichment in pyrite results from reducing geochemical conditions below an impermeable layer. The imperfect top seal of the accumulation permits minor amounts of hydrocarbons to escape and migrate through the overlying rocks to shallower levels. During migration, hydro-carbons encounter an impermeable barrier, forming an altera-tion zone. Induced polarization logging and coring in wells confirm this working model. Geoelectric surveying visual-izes anomalies in electric potential difference measured be-tween receiver electrodes. The differentially normalized method (DNME) inverts the registered decay in potential differences, establishing a depth model constrained by seismic and petro-physical data. Diagnostic geoelectric attributes are proposed, giving a better grip on chargeability and resistivity distribution. Acquisition and processing parameters are adjusted to the target depth. Encouraging results are obtained in deeper [Formula: see text] as well as in very shallow water. Onshore, a grounded current transmitter is used. Geoelectric surveys cover different geologic settings with varying target depths. The success ratio for predicting hydrocarbon occurrences is high. So far, 40 successful wells have been drilled in Russia on mapped geoelectric anomalies. Out of 126 wells, the method produced satisfactory results in all but two cases. The technique reduces the risk attached to new hydrocarbon prospects and allows better ranking at a reasonable cost.


2021 ◽  
Author(s):  
Florence Letitia Bebb ◽  
Kate Clare Serena Evans ◽  
Jagannath Mukherjee ◽  
Bilal Saeed ◽  
Geovani Christopher

Abstract There are several significant differences between the behavior of injected CO2 and reservoired hydrocarbons in the subsurface. These fundamental differences greatly influence the modeling of CO2 plumes. Carbon capture, utilization, and storage (CCUS) is growing in importance in the exploration and production (E&P) regulatory environment with the Oil and Gas Climate Initiative (OGCI) making CCUS a priority. Companies need to prospect for storage sites and evaluate both the short-term risks and long-term fate of stored carbon dioxide (CO2). Understanding the physics governing fluid flow is important to both CO2 storage and hydrocarbon exploration and production. In the last decade, there has been much research into the movement and migration of CO2 in the subsurface. A better understanding of the flow dynamics of CO2 plumes in the subsurface has highlighted a number of significant differences in modeling CO2 storage sites compared with hydrocarbon reservoir simulations. These differences can greatly influence reliability when modeling CO2 storage sites.


2022 ◽  
Vol 5 (1) ◽  
pp. 98
Author(s):  
Vagia Ioanna Makri ◽  
Spyridon Bellas ◽  
Vasilis Gaganis

Although subsurface traps have been regularly explored for hydrocarbon exploration, natural gas and CO2 storage has drawn industrial attention over the past few decades, thanks to the increasing demand for energy resources and the need for greenhouse gas mitigation. With only one depleted hydrocarbon field in Greece, saline aquifers, salt caverns and sedimentary basins ought to be evaluated in furtherance of the latter. Within this study the potential of the Greek subsurface for underground storage is discussed. An overview and re-evaluation of the so-far studied areas is implemented based on the available data. Lastly, a pragmatic approach for the storage potential in Greece was created, delineating gaps and risks in the already proposed sites. Based on the above details, a case study for CO2 storage is presented, which is relevant to the West Katakolo field saline aquifer.


2021 ◽  

The most utilized technique for exploring the Earth's subsurface for petroleum is reflection seismology. However, a sole focus on reflection seismology often misses opportunities to integrate other geophysical techniques such as gravity, magnetic, resistivity, and other seismicity techniques, which have tended to be used in isolation and by specialist teams. There is now growing appreciation that these technologies used in combination with reflection seismology can produce more accurate images of the subsurface. This book describes how these different field techniques can be used individually and in combination with each other and with seismic reflection data. World leading experts present chapters covering different techniques and describe when, where, and how to apply them to improve petroleum exploration and production. It also explores the use of such techniques in monitoring CO2 storage reservoirs. Including case studies throughout, it will be an invaluable resource for petroleum industry professionals, advanced students, and researchers.


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