Australian School of Petroleum
Permanent URI for this collection
This collection contains Honours, Masters and Ph.D by coursework theses from University of Adelaide postgraduate students within the Australian School of Petroleum. The material has been approved as making a significant contribution to knowledge.
Browse
Recent Submissions
Item Open Access Spectral gamma ray characterisation of the Dongara Sandstone, Perth Basin, W.A.: applications to high-resolution correlation(2004) Di Bacco, Mark Phillip; Australian School of PetroleumThe northern Perth Basin has been a proven hydrocarbon province since the 1960s, however, little is known about the internal stratigraphy of the primary reservoir target the late Permian Dongara Sandstone. Spectral gamma ray data has previously been used in the high - resolution correlation of sediments, but its potential in the Perth Basin has not been previously determined. The effectiveness of this technique is investigated here. Spectral gamma ray (SGR) data were acquired from cores of the Dongara Sandstone using a hand -held gamma ray spectrometer. These data were combined with the relatively sparse wireline log SGR data available for the Dongara Sandstone. A study of the ratios of K, Th and U concentrations was first undertaken to determine whether SGR analysis was applicable in high - resolution correlation in the Dongara Sandstone. Core data was proven to be adequately precise for the comparison with wireline SGR data. It was confirmed that rocktypes could be clearly differentiated from one another on the basis of their SGR signatures. It was also proven that intra- formational character of the Dongara Sandstone could be identified from the SGR signatures, and that this character may have application in high - resolution correlation. Once the effectiveness of the SGR data for correlation had been demonstrated, the data were analysed with a suite of petrophysical software, creating a series of SGR composite logs for each well. There was a good similarity between the SGR composite logs from rocks that had both wireline and core SGR measurements taken. This indicates that the core SGR can be confidently integrated with the wireline SGR data for use in interpretation. These SGR composite logs were used in high - resolution correlation of the Dongara Sandstone. Composite logs effectively display specific SGR signatures as a distinct colour, thus indicating the bulk mineralogy of the sediment and giving indications of distinct depositional facies. In particular, high- thorium intervals were interpreted as representative of beach facies due to the likely presence of the heavy mineral monazite. These facies were recognised in the composite logs, and in many cases, facies could be correlated between wells in neighbouring fields. The stratigraphic and lateral extents of these facies were defined, enabling the construction of palaeogeographic maps for three chronologically separate Late Permian sediment packages. From these maps, the paleogeographic evolution was inferred. These maps indicate that the Dongara Sandstone is interpreted as having deposited on a series of back - stepping shorelines, depositing during a sea level transgression. The sequential changes in facies distributions identified from SGR data can assist in defining the sequence stratigraphy of the Dongara Sandstone. With the internal architecture of the Dongara Sandstone defined, accurate predictions of reservoir distribution and quality can be made. This has important implications in the future exploration and exploitation of hydrocarbon accumulations within the Dongara Sandstone.Item Open Access Geomechanical modelling of stress magnitude and orientation across fault and its relation to hydraulic fracturing(2012) Karatela, Ehtesham; Australian School of PetroleumWith intense exploration around the world, easily extractable hydrocarbons are getting more and more difficult to find. Major conventional hydrocarbon accumulations have been targeted and are being produced; but increased world’s consumption has led petroleum exploration and production industry to consider exploiting targets that were not believed to be economical. Tight reservoirs include shale gas, shale oil, coal seam gas (CSG) and tight sands. This concept has changed the conventional view of shales from being source and seal rock to unconventional perception –as reservoir. These reservoirs have minimal porosity and permeability which is not sufficient to produce at economic rates. Developing these reserves may require hydraulic fracturing to create a predictable network of fractures with height of several hundred feet through which hydrocarbons can easily flow towards borehole. Even if these reservoirs are fracture stimulated at best of the knowledge and skills; production from two wells in the same field is never the same. For a successful fracturing treatment, it is necessary to understand impact of existing fractures, faults and stress regimes in the subsurface. Geologic structures influence the stress field locally and show deviation from the regional trend of stress pattern. This study utilizes geomechanical modeling with static elastic moduli to depict stress magnitude and orientation around faults. For the purpose, stress magnitudes estimated by Reynolds et al., (2006) are used. Strike-slip stress regime prevails in at the depth interval selected. A thorough study using different lithologies, σH azimuth and fault size is carried out. Stress concentrate at the fault tips on opposite quadrants of the fault tips. Fluctuation in stress magnitude increases with increase in fault size. However, the variation diminishes after fault size of 1500 meters. These models help in understanding the orientation of fractures during hydraulic fracturing and help to recognize stress barriers that may affect production from an unconventional reservoir.Item Open Access Controls on porosity in the Pab Sandstone, Kirthar Basin, Pakistan(1996) Enman, Travis; National Centre for Petroleum Geology and GeophysicsItem Open Access Reservoir characterisation of the Jurassic Springbok Sandstone, Surat Basin, Queensland(2012) Gallagher, Victoria; Australian School of PetroleumThe Late Jurassic Springbok Sandstone unconformably overlies the mid-Jurassic Walloon Subgroup in the northeastern region of the Surat Basin, Queensland. The Walloon Subgroup contains significant economic coal seam gas (CSG) reserves which are currently under significant development. Development of CSG for production requires the extraction of significant volumes of water from the coal seams to enable the gas to flow. The dewatering process has the potential to affect the Springbok Sandstone as it may be in hydraulic connection with the coal seams. The aim of this study is to characterise the reservoir quality, stratigraphic architecture and primary geologic controls on the Springbok Sandstone in order to gain an understanding of the potential for hydraulic interaction with the underlying coal measures. The depositional characteristics of the Springbok Sandstone were evaluated by analysing wireline line logs and the cored intervals of wells, and the petrology and reservoir quality of the lower section of the Springbok Sandstone was conducted through statistical analysis of thin sections, XRD data and RCA data. The Springbok Sandstone has been previously interpreted as a thick sequence of channel sands interbedded with relatively minor quantities of heterolithic sandstone, siltstone, mudstone and coal lithologies deposited in a vast intracratonic alluvial plain in warm temperate conditions. Core and wireline log analyses indicate that the Springbok Sandstone typically consists of a thin, low-permeability blocky basal sandstone and two major fining-upwards sequences, each consisting of channel sands at the base that fine-up into overbank and mire environments. An erosional unconformity exists at the base of the Springbok Sandstone and between each intraformational unit. The basal sandstone has been heavily eroded in the west of the study area by the later succession of channel sands. This lower section of the Springbok Sandstone appears to have been deposited in a high-energy braided stream environment, while the upper section of the Springbok Sandstone was deposited in a lower energy meandering stream environment. lsopach maps suggest that paleoflow was towards the centre of the basin and that there may have been syndepositional deformation of the basin during the Late Jurassic. The geologic controls on the detrital composition and diagenesis of the Springbok Sandstone are complex. Analysis of thin sections indicates that the sediment in the lower Springbok Sandstone section is generally medium grained, well sorted and mineralogically immature volcanogenic feldspathic litharenite to litharenite. The formation contains abundant well preserved lithic clasts, feldspars and biotite. The small sample size and mixed sediment composition of volcanic, plutonic and metamorphic fragments and post-depositional alteration precluded conclusive petrographic provenance analysis. High clay contents are present in the volcanic-rich sediments, predominantly including kaolin and highly smectitic mixed-layer illite interlayers, indicating that the formation may be freshwater sensitive. The reservoir quality of the lower section of the Springbok Sandstone is principally controlled by depositional environments, detrital mineralogy, clay alteration and cementation, and ranges from poor to excellent. These controls are highlighted by the relationship between lithofacies, grain size, grain composition and diagenetic alteration. The highly heterogeneous cyclic nature of the Springbok Sandstone has made correlation and prediction of reservoir properties difficult. Reseruoir quality tends to increase as grain size increases and is best developed in medium to coarse sandstones while lower energy depositional facies have substantially lower permeabilities. The basal calcite cemented sandstones potentially represent a sealing lithology however the unit is not laterally extensive across the study area. The areas with the highest risk of reseruoir connectivity between the Springbok Sandstone and Walloons Subgroup were identified where porous sands directly overlie the Walloon Subgroup, particulary in the west of the study region. Autocyclic processes were the primary driver for much of the local scale composition variation, which was largely a function of hydrodynamic softing. Tectonic and climatic influence is also evident in the stacking pattern of the Springbok Sandstone succession. Mechanical compaction reduced the porosity and permeabilty of sandstones containing high labile grain content. Cementation involved early stage glaucony, pyrite, chlorite and siderite mineralisation, followed by later stage dissolution and kaolinisation of labile grains, illitisation of clays, fracture formation and poikilotopic calcite mineralisation. Diagenetic processes have diminished the reseruoir quality of the deeper sandstone samples. Reservoir quality tends to reduce with increased burial, although moderate to high porosity and permeability are still observed at depth. The results of this study highlight the heterogeneous nature of the Springbok Sandstone. The formation comprises a series of heterogeneous sandstone and mudstone units with variable reservoir quality. The stratigraphic and depositional trends identified in the stratigraphy, sandstone composition and reservoir quality of the Springbok Sandstone can be used in future predictive reservoir modelling.Item Open Access Reservoir complexity in the Mid Jurassic J28-J30 Succession, North Carnarvon Basin, Northwest Shelf, Australia(2015) Anderson, Chloe; Kaldi, John George; Australian School of PetroleumThe Mid-Jurassic late J20 regional play interval is located within the North Carnarvon Basin, North West Shelf, Australia, and comprises syn-rift shallow marine reservoirs in a number of producing fields. Due to both the shallow marine systems’ depositional complexities and the influence of tectonically driven variation in accommodation space, the structure of the late J20 reservoirs is complex and there are many uncertainties in the models for this syn‐rift succession. The aim of this research is to interpret ‘well’ data in order to evaluate and interpret the complexity of the late J20 reservoir in the immediate area of the Perseus-2, Capella-1 and Persephone-1 wells. This complexity includes uncertainty of the depositional environments and the dominant depositional processes, the influence from syn‐rift tectonics and the impact of these on static and dynamic reservoir properties, and exploration prospectively. Three cores were described and interpreted (Perseus-2, Capella-1 and Persephone-1). These were then reviewed using the WAVE Descriptive Framework, and the resulting data were used to discuss the complexity of the reservoir. The results show that waves and a fluvial interval were the dominant depositional processes influencing the reservoirs, and the interpreted depositional sequence boundaries correlate strongly with the pressure data in the late J20 reservoir, which show five sub-divisions. This suggests that the sedimentary sequences resulted in layering and vertical permeability barriers. Later tectonics further complicated these layers and their connectivity. This complexity has influenced the reservoirs properties and behaviour, as well as exploration prospectively and production.Item Open Access Controls on shallow marine reservoir development, Jansz-IO Field, Northern Carnarvon Basin(2015) Plotnek, Elizabeth K.; Kaldi, John George; Rarity, Frank; Australian School of PetroleumThe Jansz-Io field is a gas-bearing sandstone reservoir in the Northern Carnarvon basin off the North West Shelf of Australia. The field is part of the prolific Greater Gorgon gas field and has an exploration history dating back to 1953. The aim of this study is to log the available core and integrate other datasets such as wireline and biostratigraphy to establish geological and stratigraphic models that can give fresh perspectives and insights into this field and develop these learnings to apply to other shallow marine clastic reservoirs. The results of the study show a coarsening upwards package of siltstones and sandstones that indicate an increase in energy and shallowing water depths. The WAVE classification was used to define the respective wave, tidal and fluvial influences, in combination with ichnology, to produce a range of possible depositional environment outputs. The proposed model for the deposition of the Jansz sandstone reservoir is an offshore transition at the most distal, above storm wave base (50-75 meters) and below fair-weather wave base (5-15 meters). The most proximal deposition was in the upper shoreface to foreshore where waves broke on the beach in water depths less than 5 meters. The level of uncertainty associated with the geologic model for the reservoir has implications for future development and production.Item Open Access A facies atlas for the wave to tide-dominated Gulf St Vincent (South Australia)(2015) Swiatek, David; Nanson, Rachel; Rarity, Frank; Australian School of PetroleumMarginal marine depositional systems represent a significant proportion of the world’s known and exploitable hydrocarbons; however, they are complex environments containing varying modes of deposition and heterogeneity. Marginal marine process classifications have historically lacked adequate interpretation of the variability in mixed-process systems. Modern analogues provide the most accurate planform geometries of marginal marine elements for input into reservoir models. Observations made during deposition of similar systems can supplement seismic, core and geological outcrop datasets, thus improving 3D models. This research develops a facies atlas for Gulf St Vincent as a modern analogue, examining process variability of marginal marine elements resulting from wave and tide-dominant processes. Gulf St Vincent is a shallow, inverse estuary in South Australia that connects to the Southern Ocean. Gulf St Vincent was flooded by the most recent Holocene post-glacial marine transgression. The sediments that form the marginal marine deposits accumulated along the eastern coast of Gulf St Vincent are interpreted to be derived from the reworking of the gulf floor as the sea level transgressed to its present location. Analysis of data collected along the eastern coast of Gulf St Vincent displayed evidence that wave height and energy, along with tidal range, control the geomorphology of the shoreline and sediment heterogeneity. Depositional environments changed as the shoreline transitioned from wave to tide-dominated processes. The carbonate-rich sediments in the tide-dominated northern region indicate they were very different depositional environments from the homogeneous quartz-rich medium-grained sands produced in the wave-dominated areas to the south. The dominant process controls vary from wave through tide in a northerly direction.This research has determined that four types of depositional environments dominate the eastern coastline of Gulf St Vincent, which were linked to process controls and characterised by their shore face slope, sedimentary deposits and architecture. They were linked to distinct arrangements of depositional elements with their own sedimentary signatures. This study also suggests that the observed carbonate sediments can be classified using the Ainsworth et al. (2011) and Vakarelov and Ainsworth (2013) marginal marine mapping and classification systems. The facies atlas presented herein has the potential to inform hydrocarbon reservoir modellers by providing data on the internal architecture of 2D mapped depositional elements.Item Open Access A 3-D seismic interpretation of the Palaeo-Fluvial geomorphology of the off-shore Gippsland Basin utilising seismic attibutes(2015) Neden, Luke; Bunch, Mark; Australian School of PetroleumThe stratigraphy of the offshore Gippsland Basin exhibits extensive channelization features which developed during periods of lowstand that lowered base level causing incision and sediment bypass. These features are well documented at shallow depths but deeper in the stratigraphy the extent and geometry are less well defined. Traditional structural traps in the basin are becoming depleted and these features represent possible new targets. Equally their presence where down-cut into sealing lithologies represent a risk to the seal integrity/capacity overlying potential reservoirs concerned with CO2 storage. Seismic attributes, specifically coherence (variance) and sweetness, are co-rendered and mapped on stratal slices of the Gippsland Megasurvey 3D seismic dataset to enhance seismic images and establish the extent and geometry of channelisation in the offshore Gippsland Basin. These findings may help to identify new targets and determine potential for greenhouse gas storage, as well as helping to account for seismic anomalies that have been responsible for the misplacement of drilling targets in the past.Item Open Access A regional study of the Toro and Imburu Formation aquifers in the Papuan Basin, Papua New Guinea.(2014) Hopwood, Blair; Bunch, Mark; Australian School of PetroleumThis study represents a regional review of the Toro and Imburu Formation aquifers in the fold belt and foreland regions of the Papuan Basin, Papua New Guinea (PNG). This study extends previous Toro aquifer studies in the Papuan Basin (Eisenberg 1993; Eisenberg et al., 1994; Kotaka 1996). A comprehensive data set was assembled containing all currently available well formation fluid pressure, salinity and temperature data. These data were used to calculate hydraulic potential (Hw) values, which were subsequently used to generate a regional potentiometric map for the Toro Sandstone reservoir and semi-regional maps for the Digimu, Hedinia and Iagifu Sandstone reservoirs of the Imburu Formation. The Toro potentiometric surface map generated in this study is consistent with an extensive hydrodynamic Toro aquifer system existing in the Papuan Basin Fold Belt. The Toro aquifer likely flows northwest to southeast parallel to the fold belt, from the Lavani Valley Toro outcrop (likely recharge region) in the Highlands, through to the Kutubu Complex, potentially via Hides, (possibly Angore) and the Mananda/South East Mananda Fields. The evidence for Toro aquifer hydrodynamic flow is strongest through the Kutubu Complex of fields, with water flow, entering via Agogo and exiting the fold belt, at the southern end of the Usano Field into the foreland of the basin. However, it should be noted that gas water contacts (GWCs) for Hides and Angore Fields are not yet available. These have been estimated in this study from Hides and Angore gas pressure gradient intersections with water pressure gradients identified from nearby wells (Lavani-1 and Egele-1). Therefore it is not currently possible to unequivocally identify a connected Toro aquifer system between Lavani Valley, (possibly Angore) and Hides. Nevertheless, the Lavani Valley-Hides-Mananda/South East Mananda system (LV-H-M/SEM) represents the most likely flow path for a Toro hydrodynamic aquifer model in the fold belt. Evidence for hydrodynamic Toro aquifer flow was identified in the opposite direction, in a southeast to northwest direction, in the South East Hedinia Field. Significant compartmentalisation of the Toro reservoir was identified in several Hinterland Fields and anticline structures (Egele, Angore, Moran, and Paua Fields along with the Kutubu and Makas Anticlines) and in the southeast region of the central fold belt (Gobe/South East Gobe Fields). Likely Toro aquifer flow exit points from fold belt into foreland were identified at the southern end of Usano at Iorogabaui-1 and at southern end of South East Mananada Field at Libano-1 involving the Bosavi Lineament. Possible northwest to southeast Toro aquifer flow was identified in the foreland region of the basin from the Stanley Field in the northwest to the sea in the southeast. The Komewu and Darai Fault systems appear to operate as barriers to northeast to southwest Toro aquifer flow in the foreland. Considerably less data were obtained in this study for the Digimu, Hedinia, Iagifu Sandstone reservoir aquifers compared to the Toro reservoir unit. However, key findings include; (1) for the Digimu Sandstone, hydrostatic and compartmentalised aquifer behaviour in the Agogo, Hedinia/Iagifu and Moran Fields, (2) for the Hedinia Sandstone, hydrodynamic aquifer behaviour in the Hedinia/Iagifu and South East Hedinia Fields and (3) for the Iagifu Sandstone, hydrodynamic aquifer behavior in the Hedinia/Iagifu Fields, a significant Hw step between the Agogo and Hedinia/Iagifu Fields (not seen with any of the other reservoir sandstones) and a compartmentalised aquifer in the Gobe/South East Gobe Fields (where it acts as the main hydrocarbon reservoir). The updated regional data and potentiometric maps generated in this study will assist subregional and field scale modelling of the Toro and Imburu Formation aquifers, future hydrodynamic trapping studies and provide increased confidence for hydrocarbon reserve determination in the Papuan Basin Fields.Item Open Access Depositional environments of 3D surveys for potential CO2 sequestration in the Northern Caswell Sub-basin, Browse Basin, North West Shelf, Australia(2014) Thurlow, Brenden James; Australian School of PetroleumThe Browse Basin is a northeast-trending, Palaeozoic depocentre on Australia’s North West Shelf. It covers an area of approximately 140,000km², contains in excess of 15km of Palaeozoic to Cenozoic sediments and host significant gas and condensate reserves. Reactivation and inversion of older structures, as well as the generation of anticlines within the Browse Basin has occurred. The Browse Basin holds two very large Miocene inversion structures, the Lombardina and Lyner structures, interpreted to be transpressional anticlines that continued to grow throughout the Late Miocene (Keep, 1998). The reservoir/seal thicknesses are similar to what would be expected of those deposited in a regressive/lowstand environment, with thicker accumulations of strata most likely to be encountered basinward, or in this case to the west/northwest. The prospect that an adequate system exists for the capture and storage of CO₂ within all three surveys cannot be adequately determined from this study. All three of the 3D surveys showed valid reservoir and seal pairs exist, with the thicknesses varying greatly. The lack of any structural high within the Canis and North Browse 2 surveys despite the presence of a valid reservoir/seal pair automatically precludes these survey areas from being considered for a potential CCS project.Item Open Access Four-dimensional fracture distribution in the Cooper Basin using image logs(2014) Al Barwani, Khalda; Amrouch, Khalid; Kulikowski, David; Australian School of PetroleumAn understanding of four-dimensional fracture distribution in the Cooper Basin can be used to optimise the development of well placements and fracture stimulation treatments used in tight gas and shale gas reservoirs. Comprehension of the paleo-stress, current stress, natural fractures and tectonic history of the basin can facilitate the exploitation of hydrocarbon resources in the basin. Natural fracture distribution and orientation were analysed using borehole image logs of 13 wells in the NW of the Cooper Basin. Additionally, in situ stress was evaluated in these locations, and paleo-stress evolution was interpreted based on the structures analysed. Through drilling-induced tensiles fracture and breakouts observed in the image logs, the maximum horizontal stress is oriented WNW-ESE in Patchawarra Trough and Sub-Patchawarra Trough. It has been observed that older and deeper buried formations have a higher number of fractures per thickness ratio (fracture density) than shallow formations. Stress history is recorded in ancient formations; therefore, the age of the formation may affect the number of fractures per thickness. However, the contribution of lithology must be taken into consideration. Rocks with low tensile strength have a more common rock failure than stiffer lithologies. Correspondingly, fine-grained lithologies such as siltstone, shale and mudstone have more natural fractures than sandy lithologies. Various fracture sets were determined in the analysed wells. The NW-SE extension fracture sets of Adelaidean rifting were observed in two wells. This was followed by a compression of Kanimblan/Alice Springs, which is proposed to accompany the WNW-ESE strike-slip regime. The NW-SE compression fracture sets of Permian formations were related to the Sakmarian uplift. The Daralingie uplift is also proposed to be evident in the analysed image logs. Local heterogeneous kinematics are suggested to affect the Daralingie uplift, and it is associated with an extension event. The Hunter Bowen Orogeny ended the deposition of Cooper Basin formations. It has been suggested that E-W compression events affected the basin during the Late Cretaceous. During the Cenozoic Era, E-W to N-S compression might have affected the basin, as shown by the N-S and NE-SW compression fracture system in the analysed image logs. Present-day maximum horizontal stress is attributed to the NW-SE compression and extension fracture sets of the Eromanga Formations.Item Open Access The unconventional petroleum potential of the Officer Basin, Australia(2013) Revie, Daniel J.; Holford, Simon Paul; Amrouch, Khalid; Australian School of PetroleumThe Officer Basin is a Neoproterozoic Basin located in Central Australia. This study looks at the unconventional prospectivity of the source rocks in the depocentres of the Officer Basin. The Savory, Gibson, Yowalga, Gibson and Lennis sub-basins are located in the Western Australian section of the Officer Basin. The Birksgate Trough, and the Munyarai, Tallaringa, and Manya Troughs, are located in the South Australian section of the Officer Basin. The Munyarai Trough contains the Observatory Hill Formation, the most prospective source rock in the Officer Basin. In the region of the Marla Overthrust Zone on the northern margin of the Munyarai Trough, the Observatory Hill Formation is the most prospective region for shale gas continuous accumulations. The thrust faulting in the Marla Overthrust Zone, and also in the Yowalga Sub-Basin, in combination with salt diapirism in these zones, poses a risk to the lateral continuity of a continuous accumulation of shale gas in these regions. The Officer Basin contains pre-Devonian source rocks which are devoid of plant material, containing algal-sourced hydrocarbons. Triaromatic hydrocarbons such as methylphenanthrene can be exploited as a measure of maturity and distribution, and have been used to map the maturity of the source rocks in the basin. The sampled data available in the underexplored Officer Basin indicates that the basin is a high risk exploration target for continuous gas accumulations. The sampled data indicates that the Officer Basin shale formations do not meet the minimum requirements outlined by the U.S. Geological Survey (USGS) for highly productive shale gas. However due to the limited sampling and exploration undertaken in the Officer Basin, there may exist other regions outside of those sampled that have the characteristics that do meet the USGS minimum requirements for highly productive shale gas systems. Three key findings of this investigation include: • The Officer Basin is a very high risk exploration target for shale gas continuous petroleum accumulations, and sampling has not been shown to meet all of the USGS minimum requirements for a highly productive shale gas system. • The Yowalga Sub-basin and the Marla Overthrust Zone contain thrust faulting and salt piercement structures related to halotectonics, affecting the lateral distribution of any continuous accumulations that may occur in the region. • The Officer Basin is underexplored, particularly in the Savory, Lennis, Gibson, Waigen and Birksgate Sub-basins, and should not be excluded from potentially hosting formations which may meet the USGS minimum requirements of a shale gas system.Item Open Access Controls on the morphology of fluvial and tidal influenced channels in the Gulf of Carpentaria, Australia.(2013) Okafor, Rosemary N.; Nanson, Rachel; Rarity, Frank; Australian School of PetroleumThe influence of wave, tide and fluvial processes interact to control sediment erosion, transport and deposition in clastic coastal environments. This results in mixed-process coastal systems, which can form good quality, yet geometrically complex reservoir deposits. Channels in modern analogue mixed process environments provide useful insights into how wave, tide and fluvial processes affect paleochannels and can aid subsurface stratigraphic correlation and palaeoenvironmental reconstruction. The Gulf of Carpentaria is an epicontinental sea which formed as a result of sea level rise during the last marine transgression. Holocene deposits have prograded over low gradient bathymetry and display a range of channel forms. The channels that traverse these coastal plains cannot be satisfactorily characterised by simple morphological classification. They have morphologically complex patterns which have developed in response to the seasonal variations in fluvial, tide and wave energy. A numerical examination of the effects of fluvial, tidal and wave energy on the geometry and morphology of 70 single and distributary channels in the Gulf Carpentaria was undertaken using desktop based statistical analyses. Catchment area was used as a proxy for fluvial discharge in these largely ungagged catchments while wave height and tidal range was applied directly from available gauged data. These channels were divided into two subsets based on whether their channel mouths were best described by linear or exponential trends and by the channels being either distributary or single channels. These four groups were then tested separately to assess their geometrical characteristics, including the rate of decrease in channel width downstream of equi-width (fluvial) reaches, and the wave, tide and fluvial ratios. Of the analysed channels 65% where found to have a linear width profile, and their parallel banked profile was further enhanced by a strong positive correlation with catchment which exhibited very low slope of distance to equi-width. These parallel banked (linear) channels were found to be fluvial dominated while the other 35% had an exponential width profile with their entrance width visually exhibiting a strong funnelling characteristic, and the channels having a wider entrance width and a longer distance to equi-width. These exponential channels are more tidally dominated. There was a general decrease in tidal energy and wave influence with increase in distance to equivalent width in the channels, this relationship implies that a channel's distance to equivalent width can be used to identify where the fluvial energy is least effective moving downstream indicating that another process is dominant which is usually tidal or in some cases wave energy. It is also shown that there are characteristic relationships between geometric variables like entrance width at the channel mouth and the rate of decrease in channel width downstream of equivalent - width (slope) with proxies of fluvial influences and tidal range. These relationships may overlap as a result of the complex morphodynamic feedbacks between fluvial discharge, tidal propagation and wave height in this tropical monsoonal environment.Item Open Access Palaeogeographic mapping and depositional trends of the Patchawarra Formation within the Tenappera Region, Cooper Basin(2014) Kobelt, Sam J.; Amrouch, Khalid; McCabe, Peter; Australian School of PetroleumThe Patchawarra Formation is a coal dominated fluvio-lacustrine environment. These environments have complex geometries and facies distribution is difficult to predict spatially. This study defined palaeogeographic reconstructions using log-signature responses from equivalent chronostratigraphic intervals, modern fluvial analogues and regional TWT isochrons. This resulted in the definition of spatial distribution of fluvio-lacustrine facies throughout the Tenappera region, Cooper Basin, South Australia. 379 wells were correlated into 21 chronostratigraphic intervals wireline log responses. 6 electrofacies were identified from the gamma ray and sonic velocity log motifs. These were combined with modern fluvial analogues to yield 4 facies assemblages. Multiple modern analogues were considered suitable for the Patchawarra Formation in the Tenappera Region. The Ob River, Siberia is considered more suitable for depositional facies whereas the McKenzie River, Northwest Territories demonstrated the influence of a compressional stress regime on fluvial avulsion patterns and styles. In order to map channel belt width within a chronostratigraphic interval empirical relationships from previous studies were applied. By measuring bankfull depth from well data an estimate of channel belt width is obtained. 532 bankfull measurements were taken giving a maximum bankfull depth of 8.2m, a minimum of 1.4m and a mean value of 5.1m. Channel belt width ranges were then estimated by applying bankfull population statistics to applicable linear regression curves. Channel belt width calculations gave a range of variability from 76m to 3625m, with an average channel belt width range from 1639-1908m. For the interpreted Patchawarra Formation intervals there were eight populations with similar channel belt ranges. High resolution palaeogeographic reconstruction of the Patchawarra Formation within the Tenappera Region allows for better prediction of facies distribution. There are two distinguishable periods of fluvial deposition deposition in the upper and lower Patchawarra Formation. Ultimately, the paleogeographic maps aid assessment of field prospects by defining depositional channel fairways which control reservoir distribution. These techniques could be applied to other fluvial dominated petroleum systems.Item Open Access Characterisation of carbonate cemented zones in the Paaratte Formation of the Victorian Otway Basin and Bass Megasequence of the Bass Basin using wireline log data(2014) Armener, Kapila J.M.; Daniel, Richard Francis; Bunch, Mark; Australian School of PetroleumThe identification and modelling of carbonate cemented zones represents one of the many challenges facing the world leading Carbon Capture and Storage (CCS) CO2CRC Otway Project in Victoria. Carbonate cemented zones are low permeability dolomite-dominated zones that form at the meteoric-saline water interface within winnowed tidal bar sandstones deposited in deltaic-marginal marine environments. Successful identification of these zones from wireline log data requires the creation of empirical tools that combine statistical analysis with geological interpretation. The Mean-Probability Log and the Vshale Facies Log are two empirical tools that, when combined, can successfully identify carbonate cemented zones from well log data. The Mean-Probability Log is derived from available well data contained at CRC-2 which includes the CCA_20 log (Elemental Capture Spectroscopy) and CarbCmnt log (carbonate cemented zones prediction log). These logs, combined with conventional raw and derived logs (Gamma, Sonic, Neutron, Density, Shallow Resistivity, Deep Resistivity, and Ratio) were used to create binned distributions required for a probability distribution model. Probability values from the model were incorporated into individual carbonate cement predictions logs for each of the raw and derived logs. An average of these logs resulted in the creation of a carbonate cemented prediction Mean-Probability Log. Flexibility of the Mean-Probability Log revealed only a variance of 13 samples when compared to Mean-Probability Logs lacking one of the key logs (e.g. Gamma). Calculation of a statistically derived cutoff was incorporated using the mode, standard deviation and a fixed spread (variance). Creation of a Vshale Facies Log was undertaken to assist accuracy of the Mean-Probability Log in predicting carbonate cemented zones within winnowed sandstones. The facies component of the log was derived from reclassification of an existing core-derived facies log used at CRC-2, whilst the clay-content (Vcl) of the log was derived from an existing Petrolog algorithm used in the Darling Basin of NSW. A cutoff value for CRC-2 (Vcl value of 0.6) was established for sandstones that are hosts for known carbonate cemented zones. Both the Mean-Probability Log and the Vshale Facies Log were successfully applied to both selected Otway Basin (onshore and offshore) and Bass Basin wells. Carbonate cemented zone analysis revealed a total of 126 carbonate cemented zones in onshore Otway Basin, 53 in offshore Otway Basin, and 7 in the Bass Basin. Interpretation of carbonate cemented zone results revealed a decrease in thickness and increase in clay-content from the Port Campbell Embayment to Shipwreck Trough in the Otway Basin, and a localised accumulation along the Pelican and Dondu Troughs within the Bass Basin.Item Open Access Geocellular modelling and connectivity analysis of a tide-influenced channel belt system: example from the Mitchell River Delta, Gulf of Carpentaria, Australia(2014) Al Quwaitii, Reham Said; Amos, Kathryn; Holford, Simon Paul; Australian School of PetroleumThe interaction of tidal and fluvial processes in marginal marine settings, particularly tidally influenced channel systems, can produce profound lateral and vertical facies heterogeneity, in forms such as Lateral Accretion Packages (LAPs) and Inclined Heterolithic Stratification (IHS). LAPs form at the convex banks of sinuous channels, and can be composed of either homogeneous or heterogeneous deposits. Within tidal reaches, they are often comprised of IHS deposits. IHS deposits are inclined alternating shale and sand layers that form by laterally accreting fluvial-estuarine point bars. Understanding the 3D distribution of tidally influenced channel architectures in modern channel systems has important implications for the effective modelling of subsurface channel reservoir distribution, connectivity and fluid flow. In this research, 3D geocellular modelling of a selected modern point bar from the Mitchell River system, Gulf of Carpentaria (GoC), Queensland, Australia, is used to predict heterogeneity and connectivity associated with a tidally influenced channel reservoir system. The modelling workflow consisted of four main stages: (a) data integration, (b) mapping, (c) geocellular modelling and (d) connectivity assessment. Analysis of high-resolution satellite imagery merged with Shuttle Radar Topography Mission Digital Elevation Models data for an area of 14.57 km × 2.34 km allowed direct mapping and measurement of dimensions and orientation of the stratigraphic architecture of the selected point bar geometry. Core and auger well log data and a stratigraphic cross section oriented perpendicular to the channel axis were used in order to constrain the stratigraphic architecture and the facies distribution. Five facies were identified in the studied point bar strata, including Lag Sand Deposits with rippled sandstone 2.5 m thick, which is common in upstream locations on the point bar, and heterogeneous sand and mud facies. Inclined heterolithic mud deposits (IHS) are confined to the upper 3 m of the point bar. As the focus of this project is the impact of IHS on reservoir connectivity, a new approach was proposed to resolve the heterogeneity associated with tidally influenced channel systems, by developing three geological models based on the presence and continuity of IHS deposits (the products of fluvial and tidal interaction processes). Connectivity analysis of the three realisations showed marked contrast between models using point bar geobodies. The tide-dominated, fluvial-influenced channel system represents the worst reservoir connectivity in the subsurface, as the volume contains considerable bodies of mainly mud facies. Although there are significant objects in this point bar model, the majority of these bodies are very small and supposedly form 75% mudstone of the total volume. In scenario two (Ft channel system; fluvial dominated, tidally influenced channel system), the model suggests fluid flow will preferentially concentrate in the lower part of the point bar, where clean sand sediments form a continuous body. The geo-volume in realization three (F channel system; fluvial dominated channel system) reflects the connectivity of the channel comprised of just the point bar object, which can represent best reservoir continuity and limited compartmentalization. Thus, reservoir quality increases as the fluvial process in the channel system becomes more dominant. We recommend that further field work, such as a new stratigraphic cross sections, should be obtained parallel to the channel axis in order to capture 3D heterogeneity within tidally influenced channel systems, and that the Fullbore Formation Microimager tool should be used to obtain the corrected inclination of IHS deposits.Item Open Access Stratigraphy and sedimentology of the Late Neoproterozoic Bonney Sandstone, Northern Flinders Ranges, South Australia(2014) Liu, Limeng; Amos, Kathryn; Counts, John; Australian School of PetroleumThe Adelaide Geosyncline is considered as a deformed sedimentary basin located between the Paleoproterozoic Gawler and Curnamona crystalline basement complexes. A suite of Late Neoproterozoic clastic sediments are widely deposited in the Flinders Ranges, South Australia. From the Proterozoic to the Cambrian, this area was a passive margin system. The outstanding exposures in this region allow detailed study of the sedimentary structures of analogous basins around the world, which often contain similar styles of source rocks and petroleum reservoirs. The Bonney Sandstone in the Northern Flinders Ranges is the lower part of the coarser, shallow-marine Pound Subgroup. This project provides an opportunity to examine relatively undescribed strata in this area. During the fieldtrip, my investigation consists of two detailed measured stratigraphic sections, which reveal a few well-preserved primary sedimentary structures. Many detailed sedimentological analysis were done during the study, including the measurement of strata and petrography. Several lithofacies were summarized and the associations of them were discovered. The characteristics of sedimentation are influenced by the paleocurrent, sediment supply and basin development. Both the modelling of this sedimentary process and the palaeogeography of the Neoproterozoic of South Australia are required to better understand the sedimentary character in the Northern Flinders Ranges.Item Open Access Detecting the occurrence of dolomite cemented zones in the Otway Gippsland Basins(2014) Al-Shukaili, Amira; Bunch, Mark; Daniel, Richard Francis; Australian School of PetroleumDolomite cemented zones have been recognized in both Otway and Gipssland Basins. These cemented zones have significant effects on the reservoir performance as they can degrade or enhance reservoir sweep. The CO2CRC CO₂ sequestration project in Otway Basin may be affected by these carbonate cemented zones, where it has been detected in CRC-2 and CRC-1. Therefore, the aim of this project is to generate an empirical model using well log data to detect the dolomite cemented zones in the Otway and Gippsland Basins. To achieve this goal, log data have been analyzed to firstly create a motif of cemented zones in the on-shore lower Paaratte Formation of Otway Basin. Then, verify cemented zones in the Casino Field of the Shipwreck Trough (offshore Paaratte Formation). As a result, the dolomitisation interval motifs will be generated from Paaratte Formation of Otway Basin and will be used to detect the cemented zones in the Gippsland basin.Item Open Access Pre-salt playing hydrocarbon trap evaluation within the Callanna Group in the eastern Officer Basin, South Australia, from recent drilling results(2014) Sahuri; Amrouch, Khalid; Mitchell, Andy; Australian School of PetroleumThe Officer Basin represents one of the last remaining onshore frontier exploration areas in Australia. It has potential to contain several very large oil fields within horsts capped by thick salt. The pre-salt trap within the Callanna Group in eastern Officer Basin has never been studied because of lack seismic coverage and deep well controls. The Callanna Group sequence upward consists of Pindyin Sandstone and Alinya shale-salt-dolomite. Some oil shows have been correlated to Alinya shale source rock. The full sequence was intersected by three wells drilled recently, one in the eastern and two wells in western parts of the basin. These intersected units are well-correlated with its type section based on lithology, superposition and wireline logs. The Pindyin Sandstone shows primary porosity and permeability and the overlying salts are thick and seismically mappable. Though these wells failed to find hydrocarbon accumulations, they have significantly improved the understanding the petroleum potential in the basin. The salt related structures in eastern Officer Basin are not as common as in Western Officer, Amadeus, Flinders Ranges, Eastern Siberia and South Oman Basins. The salt in eastern Officer Basin has been mobilized, while the salt in the western part of the basin is relatively stable. Salt features have been identified including salt anticlines, salt thickening and salt withdrawal collapse structures. At least seven salt anticlines are present but the outlines are uncertain because of poor seismic quality and coverage. They might have potential traps for the younger reservoir rocks e.g Murnaroo and Tarlina Sandstone. This study focuses on pre-salt hydrocarbon trap identification and evaluation (Pindyin Lead) through seismic mapping. Four structural time and depth maps have been generated and a total of 24 Pindyin Leads identified. The leads were classified into four groups: 1) a simple anticline, 2) drag rollover or anticline associated with reverse fault, 3) a gentle anticline or rollover associated with tilted graben due to an igneous intrusion or normal fault reactivation (reversed) and 4) Pindyin on-lapping against the sealing faults bounding the graben. The best pre-salt structural trap would be the simple anticline which has four way dip closure but it is not common in the basin and very deep to the target. The exploration should focus to identify this type of pre-salt play down dip the Murnaroo Platform where the depth to the Pindyin Sandstone is reachable. The second best Pindyin Lead is a gentle anticline in Manya and Wintinna Troughs, but it was defined by inadequate seismic controls. The most common pre-salt structural trap is a drag rollover or anticline associated with reverse faults, but it has high risk of the fault breach and poor reservoir rocks. Further study is needed to assess the trap closures, fault seal integrity, hydrocarbon generation and migration into trap.Item Open Access Sedimentology and stratigraphy of the Late Neoproterozoic Bonney Sandstone(2014) Koyejo, Oyinloye; Amos, Kathryn; Counts, John; Australian School of PetroleumThis study represents the first good detailed sedimentological and sequence stratigraphic analysis of the Bonney Sandstone exposed at the Arkaroola Syncline in the Northern part of Flinders Ranges, South Australia. The Bonney Sandstone is located between two prominent Late Neoproteozoic Formations, the underlying Wonoka Formation and overlying Rawnsley Quartzite. These rocks have become significant in recent years due to their importance in hydrocarbon exploration in salt withdrawal basins. However there are few published studies on the Bonney Sandstone. Ten lithofacies were identified which formed the five facies associations. These facies associations include Offshore deposits (FA 5), Offshore transition deposits (FA 4), Shoreface/Foreshore deposits (FA 3), Mixed Wave-Tidal delta deposits (FA 2) and Channel Deposits (FA 1). These facies association represent three major depositional environments, shallow marine, mixed wave-tidal delta and fluvial deposit. Sequence stratigraphically, there are shows two significate intervals. The lower transgressive interval which is made up of siltstone deposits with interbedded massive sandstones. Low stand system tract deposit which marked the boundary between the Wonoka Formation and the Bonney Sandstone. The middle to upper section essentially represents a highstand system tract with normal regression. The normal regressive interval was characterised by prograding delta and aggrading channel sandstone deposit. Cyclicity pattern within the Bonney Sandstone are made up of third and fourth order cycles. Eastern paleocurrent directions suggest palaeo flow towards the Arkaroola Syncline. Petrographic interpretation shows basement source rocks with deposition in a low topographic area with little or no exposure of sediments. Adverse effects of prevailing climatic conditions significantly affected sediment deposition as observed within the grain size, mineralogical composition and reservoir potential of the Bonney Sandstone. Reservoir quality of the Bonney Sandstone is essentially low due very poor porosity and permeability.