Revisions to the chronostratigraphic framework of the Upper Jurassic Walloon Coal Measures of the Surat Basin, Australia

2019 ◽  
Vol 59 (2) ◽  
pp. 965
Author(s):  
Carmine Wainman ◽  
Peter McCabe
Keyword(s):  
Sea Level ◽  
Upper Jurassic ◽  
Coal Seam Gas ◽  
Flow Simulations ◽  
Reservoir Models ◽  
Stratigraphic Framework ◽  
Ionisation Mass Spectrometry ◽  
Time Gap ◽  
Coal Accumulation ◽  
Coal Measures

The Upper Jurassic Walloon Coal Measures (WCM) in the Surat Basin host the largest coal seam gas (CSG) resource in Australia. Despite this, a poorly defined lithostratigraphic framework hinders the development of reservoir models and groundwater flow simulations. Correlations in the WCM are challenging, owing to the complex arrangement of facies over short distances and the absence of a reliable regional stratigraphic datum. To better correlate the strata, 26 tuff beds were dated using the U–Pb chemical abrasion thermal ionisation mass spectrometry methodology across the Surat Basin CSG fairway. This initially suggested that coal-bearing strata in the basin were diachronous. However, the acquisition of a new date from the Surat Basin has identified a five million year time gap between dated tuffs ~20 m apart. This suggests the presence of an unconformity and that there were two independent episodes of coal accumulation in the basin. Above the unconformity, there are incised valleys with a sedimentary infill that transitions from fluvial- to tidal-influenced facies, as indicated by dinoflagellate cysts and tidal sedimentary structures, including double mud drapes. The cause of the unconformity is likely to be tectonic, as eustatic sea-level was rising during the Kimmeridigian. The marine incursion into the basin is the consequence of a highstand of sea-level during the early Tithonian. The application of the new chronostratigraphic framework should elucidate the evolution of fluviolacustrine systems in the basin and aid in resource prediction. Further dating of tuffs in the basin could refine the stratigraphic framework.

Using precise CA-TIMS ages of volcanic air-fall tuff beds in correlating the Walloon Coal Measures of the Surat Basin, Australia

2017 ◽  
Vol 57 (2) ◽  
pp. 810 ◽  
Author(s):  
Carmine Wainman ◽  
Peter McCabe
Keyword(s):  
High Precision ◽  
Sedimentary Facies ◽  
Time Frame ◽  
Upper Jurassic ◽  
Marine Strata ◽  
Stratigraphic Framework ◽  
Lithostratigraphic Units ◽  
Spectrometry Technique ◽  
Discontinuous Nature ◽  
Coal Measures

The Upper Jurassic Walloon Coal Measures of the Surat Basin is one of Australia’s largest and most productive gas provinces. Despite the drilling of over 8500 wells and numerous publications, the stratigraphic framework is poorly defined. The laterally discontinuous nature of the sedimentary facies, including coals and fluvial channel sandstones, makes correlation difficult. The abundance of volcanic air-fall tuff beds within strata across the basin provides a unique opportunity to independently verify existing stratigraphic frameworks. Using the high-precision chemical abrasion thermal ionisation mass spectrometry technique, zircon grains from 28 tuff beds have been successfully dated within an error margin of less than 100 kyr. These dates substantially revise biostratigraphic and lithostratigraphic frameworks. Lithostratigraphic units are diachronous across the basin. In addition, the sparsity of key spore–pollen taxa limits the application of biostratigraphy. The complex interplay of climate and subsidence on facies distributions can now be documented over a time frame of ~4 Ma. Syntectonism played an important role in variable palaeodrainage patterns across the basin, the frequency of fluvial avulsions and preferential sites of peat accumulation through time. The new stratigraphic framework should aid in future exploration for coal seam gas in the area. Dating tuff beds using high-precision dating techniques should also assist in correlation of non-marine strata elsewhere in the world.

Estimating porosity and permeability in the Springbok Sandstone, Surat Basin (Queensland), using new wireline log-based workflow

2021 ◽  
Vol 61 (2) ◽  
pp. 720
Author(s):  
Kasia Sobczak ◽  
Heinz-Gerd Holl ◽  
Andrew Garnett
Keyword(s):  
Upper Jurassic ◽  
Coal Seams ◽  
Impact Prediction ◽  
Reservoir Models ◽  
Resistivity Logs ◽  
Porosity And Permeability ◽  
Sandstone Formation ◽  
Definition Of ◽  
Coal Measures

The Upper Jurassic Walloon Coal Measures of the Surat Basin (Queensland) host some of the most prominent coal seam gas (CSG) resources in Australia. The Walloon Coal Measures are directly overlain by the Springbok Sandstone formation, historically referred to as a regional aquifer. An increasing number of studies and industry models suggest relatively limited hydraulic connectivity within the formation and between it and the underlying coal measures, due to extreme lithological heterogeneity. Accurate evaluation of the permeability, as well as lateral and vertical continuity of the lithological units within the Springbok Sandstone, is critical in reservoir models that form the basis of reasonable aquifer protection practices and impact prediction. This study presents a wireline log-based workflow applied to identify permeable zones within the Springbok Sandstone in 31 CSG wells across the Surat Basin that allows robust estimations of porosities and Klinkenberg permeabilities. The workflow primarily utilises spontaneous potential, density, neutron and resistivity logs, and was developed by integrating current industry practices implemented by operators on a local scale to identify risk (permeable) zones in the vicinity of targeted coal seams. The results of this case study indicate that permeable zones within the interval are volumetrically minor (on average 25% N/G) and likely isolated, with Klinkenberg permeabilities rarely exceeding 10–20mD. This evidence for low hydraulic connectivity, as well as significant local variations in the character of the Springbok Sandstone, suggests that the definition of the formation as a regional, continuous aquifer and the way it is modelled needs to be revised.

Fluvial architecture of the Burro Canyon Formation using unmanned aerial vehicle-based photogrammetry and outcrop-based modeling: Implications for reservoir performance, Escalante Canyon, southwestern Piceance Basin, Colorado

2018 ◽  
Vol 6 (4) ◽  
pp. T1117-T1139
Author(s):  
Sarah A. Clark ◽  
Matthew J. Pranter ◽  
Rex D. Cole ◽  
Zulfiquar A. Reza
Keyword(s):  
Fluid Flow ◽  
Unmanned Aerial Vehicle ◽  
Geometric Mean ◽  
Piceance Basin ◽  
Sweep Efficiency ◽  
Flow Simulations ◽  
Reservoir Performance ◽  
Reservoir Models ◽  
Sandstone Body ◽  
Aerial Vehicle

The Cretaceous Burro Canyon Formation in the southern Piceance Basin, Colorado, represents low sinuosity to sinuous braided fluvial deposits that consist of amalgamated channel complexes, amalgamated and isolated fluvial-bar channel fills, and floodplain deposits. Lithofacies primarily include granule-cobble conglomerates, conglomeratic sandstones, cross-stratified sandstones, upward-fining sandstones, and gray-green mudstones. To assess the effects of variable sandstone-body geometry and internal lithofacies and petrophysical heterogeneity on reservoir performance, conventional field methods are combined with unmanned aerial vehicle-based photogrammetry to create representative outcrop-based reservoir models. Outcrop reservoir models and fluid-flow simulations compare three reservoir scenarios of the Burro Canyon Formation based on stratigraphic variability, sandstone-body geometry, and lithofacies heterogeneity. Simulation results indicate that lithofacies variability can account for an almost 50% variation in breakthrough time (BTT). Internal channel-bounding surfaces reduce the BTT by 2%, volumetric sweep efficiency by 8%, and recovery efficiency by 10%. Three lateral grid resolutions and two permeability-upscaling methods for each reservoir scenario are explored in fluid-flow simulations to investigate how upscaling impacts reservoir performance. Our results indicate that coarsely resolved grids experience delayed breakthrough by as much as 40% and greater volumetric sweep efficiency by an average of 10%. Permeability models that are upscaled using a geometric mean preserve slightly higher values than those using a harmonic mean. For upscaling based on a geometric mean, BTTs are delayed by an average of 17% and the volumetric sweep efficiency is reduced by as much as 10%. Results of the study highlight the importance of properly incorporating stratigraphic details into 3D reservoir models and preserving those details through proper upscaling methods.

Techniques for Fast Screening of 3D Heterogeneous Shale Barrier Configurations and Their Impacts on SAGD Chamber Development

SPE Journal ◽  
2021 ◽  
pp. 1-25
Author(s):  
Chang Gao ◽  
Juliana Y. Leung
Keyword(s):  
Distance Measure ◽  
Flow Simulation ◽  
Training Data ◽  
Distance Measures ◽  
Data Driven ◽  
Data Set ◽  
Flow Simulations ◽  
Steam Chamber ◽  
Reservoir Models ◽  
Tracking Model

Summary The steam-assisted gravity drainage (SAGD) recovery process is strongly impacted by the spatial distributions of heterogeneous shale barriers. Though detailed compositional flow simulators are available for SAGD recovery performance evaluation, the simulation process is usually quite computationally demanding, rendering their use over a large number of reservoir models for assessing the impacts of heterogeneity (uncertainties) to be impractical. In recent years, data-driven proxies have been widely proposed to reduce the computational effort; nevertheless, the proxy must be trained using a large data set consisting of many flow simulation cases that are ideally spanning the model parameter spaces. The question remains: is there a more efficient way to screen a large number of heterogeneous SAGD models? Such techniques could help to construct a training data set with less redundancy; they can also be used to quickly identify a subset of heterogeneous models for detailed flow simulation. In this work, we formulated two particular distance measures, flow-based and static-based, to quantify the similarity among a set of 3D heterogeneous SAGD models. First, to formulate the flow-based distance measure, a physics-basedparticle-tracking model is used: Darcy’s law and energy balance are integrated to mimic the steam chamber expansion process; steam particles that are located at the edge of the chamber would release their energy to the surrounding cold bitumen, while detailed fluid displacements are not explicitly simulated. The steam chamber evolution is modeled, and a flow-based distance between two given reservoir models is defined as the difference in their chamber sizes over time. Second, to formulate the static-based distance, the Hausdorff distance (Hausdorff 1914) is used: it is often used in image processing to compare two images according to their corresponding spatial arrangement and shapes of various objects. A suite of 3D models is constructed using representative petrophysical properties and operating constraints extracted from several pads in Suncor Energy’s Firebag project. The computed distance measures are used to partition the models into different groups. To establish a baseline for comparison, flow simulations are performed on these models to predict the actual chamber evolution and production profiles. The grouping results according to the proposed flow- and static-based distance measures match reasonably well to those obtained from detailed flow simulations. Significant improvement in computational efficiency is achieved with the proposed techniques. They can be used to efficiently screen a large number of reservoir models and facilitate the clustering of these models into groups with distinct shale heterogeneity characteristics. It presents a significant potential to be integrated with other data-driven approaches for reducing the computational load typically associated with detailed flow simulations involving multiple heterogeneous reservoir realizations.

Sequence stratigraphic analysis and sea-level history of the Upper Jurassic deposits (Mozduran Formation), south of Aghdarband, NE Iran

2018 ◽  
Vol 31 (8) ◽  
pp. 1097-1114 ◽  
Author(s):  
Ali Aghaei ◽  
Hamed Zand-Moghadam ◽  
Reza Moussavi-Harami ◽  
Asadollah Mahboubi
Keyword(s):  
Sea Level ◽  
Upper Jurassic ◽  
Sequence Stratigraphic ◽  
Stratigraphic Analysis ◽  
History Of ◽  
Ne Iran ◽  
And Sea Level

BREATHING NEW LIFE INTO THE EASTERN DAMPIER SUB-BASIN: AN INTEGRATED REVIEW BASED ON GEOPHYSICAL, STRATIGRAPHIC AND BASIN MODELLING EVALUATION

2004 ◽  
Vol 44 (1) ◽  
pp. 123 ◽  
Author(s):  
G.P. Thomas ◽  
M.R. Lennane ◽  
F. Glass ◽  
T. Walker ◽  
M. Partington ◽  
...  
Keyword(s):  
Seismic Data ◽  
Joint Venture ◽  
Velocity Model ◽  
Upper Jurassic ◽  
Source Rocks ◽  
Third Order ◽  
Geochemical Fingerprinting ◽  
Stratigraphic Framework ◽  
Seismic Image ◽  
Hydrocarbon Charge

The eastern Dampier Sub-basin on Australia’s northwestern margin has been subject to intensive exploration activity since the early 1960s. The commercial success rate for exploration drilling, however, has been a disappointing 8%, despite numerous indications of at least one active petroleum system. During 2002–2003, Woodside and its joint venture partners undertook an integrated review of the area, aimed at unlocking its remaining potential. Stratigraphy, hydrocarbon charge and 3D seismic data quality were addressed in parallel.The eastern Dampier Sub-basin stratigraphy was upgraded from the existing, conventional, second-order tectono-stratigraphic framework to a third-order, exploration-scale, genetic stratigraphic framework. The new framework has regional predictive capability in terms of reservoir (and seal) presence and facies, and has led to recognition of new plays and an enhanced understanding of known plays. One new play involves shoreface sands within the Calypso Formation. New light has been shed on the known Lower Cretaceous M.australis sands play (K30), by the creation of gross depositional environment maps at third-order sequence scale. The Upper Jurassic deepwater clastics play of the Lewis Trough has also been developed, by recognition of four prospective, sand-rich gravity-flow intervals in the early Oxfordian (J42 play).A 3D charge modelling study, underpinned by new geochemical analysis, has allowed delineation of areas of higher and lower risk in terms of hydrocarbon charge and phase (oil versus gas). Key source rocks for oil are identified in the early Oxfordian W.spectabilis biozone, although they are also a likely source for gas in the southwest of the area. The Bathonian-Callovian Upper Legendre Formation is a major source for gas, but could also have contributed minor oil in the northeast of the area. By a combination of geochemical fingerprinting and 3D forward modelling, most hydrocarbon occurrences in the area have been tied to these source intervals, complete with a consistent view of maturities and migration pathways.Some 1,500 km2 of the Panaeus multi-client 3D survey were reprocessed, with close attention to multiple removal, velocities and imaging. A step-change improvement in seismic quality was obtained, together with improved velocities for depth conversion.The prospect portfolio has been polarised and much enhanced through these studies, and the results of several existing wells have become better understood. Some new prospects were identified by apparent direct fluid indications, detected in one case by 3D volume AVO screening. Other new prospects are the result of a clearer seismic image, or of the revised velocity model for depth conversion. New plays are still being followed up, while the fresh light cast on existing plays (e.g. K30 and J42), in combination with improved seismic data, has led to development of several interesting opportunities.

Regional parametric sensitivity analysis of Walloon Subgroup CSG production

2017 ◽  
Vol 57 (1) ◽  
pp. 277
Author(s):  
Daren Shields ◽  
Fengde Zhou ◽  
Joan Esterle
Keyword(s):  
Gas Production ◽  
Gas Content ◽  
Project Schedule ◽  
Coal Seam Gas ◽  
Simulation Experiments ◽  
Reservoir Performance ◽  
Well Completion ◽  
Reservoir Models ◽  
Single Well ◽  
Eastern Edge

Following two decades of intensive exploration, coal seam gas (CSG) production in the Surat Basin has begun to dramatically increase to meet the capacity of three newly completed CSG to liquefied natural gas (LNG) export projects. As the industry’s focus shifts from appraisal to exploitation, the production forecasts underpinning these LNG projects are being tested. In some cases predicted reservoir performance is found to be invalidated by observed production data, a condition that may require costly amendments to project schedule and scope. The deviation between actual and predicted reservoir performance can often be attributed to an incomplete understanding of parametric uncertainties present in static or dynamic reservoir models. To address this limitation, this study aims to explore the parametric controls upon CSG production behaviours with a series of simulation experiments. Distributions of reservoir parameters were compiled from 152 open-source well completion reports available in three areas along the eastern edge of the Surat Basin. These distributions were validated and then sampled to extract representative ranges for subsurface factors including gas content, permeability, net coal thickness, Langmuir pressure, Langmuir volume and drainage area. These inputs were used to construct single well radial models, which were then simulated to generate predictions of monthly and cumulative produced fluid volumes. The results of this study indicate that net coal thickness and lateral coal connectivity are the most sensitive factors with respect to cumulative gas production, while permeability was the single most influential parameter affecting the rate of gas production.

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