STRUCTURE AND HYDROCARBONS IN THE SHIPWRECK TROUGH, OTWAY BASIN: HALF-GRABEN GAS FIELDS ABUTTING A CONTINENTAL TRANSFORM

2004 ◽  
Vol 44 (1) ◽  
pp. 417 ◽  
Author(s):  
D. Palmowski ◽  
K.C. Hill ◽  
N. Hoffman
Keyword(s):  
Lateral Displacement ◽  
Seismic Survey ◽  
Early Eocene ◽  
Regional Study ◽  
Large Structures ◽  
Hydrocarbon Maturation ◽  
Half Graben ◽  
Hinge Zone ◽  
Gas Fields ◽  
Great Australian Bight

As part of a regional study of the evolution of the Otway Basin, the Investigator 3D seismic survey has been structurally analysed, using 11 extracted 2D sections and 3D interpretations of key horizons. South-southwest directed extension was widespread in the Turonian forming the Shipwreck Trough, coincident with uplift of the Otway Ranges to the northeast. The Turonian extension, at ~1.5 myrs, resulted in planar faults in the northeastern part of the Trough, but large half-graben above south-southwest dipping listric master faults in the southwest, both fault sets soling into an Early Cretaceous shale detachment. The half-graben propagated north from the Mussel-Tarpwaup Hinge-Zone by footwall collapse and accommodated deposition of reservoir rocks for the known hydrocarbon accumulations. The half-graben die out along strike to the east at tip-points against an accommodation zone that developed into a continental transform (the Shipwreck Fault).Santonian breakup in the Great Australian Bight coincided with considerable south-southwesterly extension in the Otway Basin juxtaposed against the failed Bassian rift across the Shipwreck Fault. Extension of ~1.21 km to the west of the Shipwreck Fault contrasts with ~0.42 km on the eastern side accommodated by ~0.79 km left-lateral displacement along the Shipwreck Fault. The Belfast Mudstone was deposited during this time, forming the regional seal for the known hydrocarbon accumulations.Limited slow extension during the Campanian to Early Eocene resulted in a further 0.33 km sinistral slip along the Shipwreck Fault. Late Early Eocene Breakup in the Otway Basin ended the transitional phase, terminating extensional and Shipwreck Fault offset. The breakup caused local uplift and ~1 km erosion of Wangerrip Group sediments. The post breakup phase is characterised by prograding sequences indicating progressive-regressive cycles.The Thylacine and La Bella gas fields occur in large tilted fault-blocks near the Hinge-Zone. These successful large structures lie along a longstanding High probably sourced from south of the Hinge-Zone. Key elements for a successful hydrocarbon play are deposition of the Turonian Waarre Formation sandstone reservoirs at rift onset and of a thick Belfast Mudstone seal during continuous Coniacian-Santonian extension. Footwall collapse north of the Hinge-Zone, bound by the deepwater Otway Basin and the continental transform, controlled the distribution of traps, regional seal and hydrocarbon maturation.

The Halladale and Black Watch gas fields—drilling AVO anomalies along Victoria's Shipwreck Coast

2009 ◽  
Vol 49 (1) ◽  
pp. 101 ◽  
Author(s):  
Andrew Constantine ◽  
Glenn Morgan ◽  
Randall Taylor
Keyword(s):  
Joint Venture ◽  
Seismic Survey ◽  
Amplitude Variation With Offset ◽  
Development Scenarios ◽  
Fault Block ◽  
Close Proximity ◽  
Strong Amplitude ◽  
Water Gradient ◽  
Seismic Amplitudes ◽  
Gas Fields

The Halladale and Black Watch fields are adjacent fault-dependent gas accumulations at the Turonian Waarre Formation level situated in the eastern Otway Basin, about 4–5 km from shore in VIC/RL2(v). The two fields were first identified in 2002 when anomalous seismic amplitudes were observed on the tail-ends of several 90s-vintage 2D lines that extended into what was then vacant acreage. After being awarded the block as VIC/P37(v) Origin Energy Limited and its joint venture (JV) partner, Woodside Energy Limited, acquired a 211 km2 full-fold 3D seismic survey over the anomalous amplitudes in late 2003. Subsequent analysis of the seismic volume revealed two tilted fault blocks with strong amplitude variation with offset (AVO) anomalies in the Waarre A and Waarre C units that conformed to structure and appeared to shut off at the same depth. A similar AVO anomaly was also observed in the overlying Santonian Nullawarre Formation, raising the possibility that Halladale and/or Black Watch had leaked or were leaking. In early 2005, the VIC/P37(v) JV drilled two exploration wells targetting the key Waarre C reservoir on the eastern flank of Halladale and eastern crest of Black Watch. Both wells encountered live gas columns in the Waarre C but no GWCs were observed on logs and wireline pressure data indicated the two fields were not in pressure communication. A third well was then drilled down-dip of the Waarre C AVO shut off on the Halladale fault block to obtain a water gradient from the Waarre C. This well proved invaluable in determining the height of the gas columns in the Waarre C at both fields as it showed the gas-water contacts (GWCs) at Halladale (1,760 mSS) and Black Watch (1,770 mSS) were shallow to their respective AVO shut offs by about 20 m and 10 m respectively. Subsequent analysis of shear wave sonic data from the third well indicated there is a 17 m residual gas column at the base of the Halladale Field. This suggests Halladale either leaked slightly at some time in the past or is still leaking. A similar scenario may also occur at Black Watch. Given the close proximity of the two fields to the coast, development scenarios from onshore are now being considered.

Walker Creek fault zone, central Rocky Mountains, British Columbia-southern continuation of the Northern Rocky Mountain Trench fault zone

2000 ◽  
Vol 37 (9) ◽  
pp. 1259-1273 ◽  
Author(s):  
M E McMechan
Keyword(s):  
Fault Zone ◽  
Late Cretaceous ◽  
Lateral Displacement ◽  
Shear Bands ◽  
Rocky Mountain ◽  
Strike Slip ◽  
Fault System ◽  
Early Eocene ◽  
Fold And Thrust Belt ◽  
Slip Displacement

Walker Creek fault zone (WCFZ), well exposed in the western Rocky Mountains of central British Columbia near 54°, comprises a 2 km wide zone of variably deformed Neoproterozoic and Cambrian strata in fault-bounded slivers and lozenges. Extensional shear bands, subhorizontal extension lineations, slickensides, mesoscopic shear bands, and other minor structures developed within and immediately adjacent to the fault zone consistently indicate right-lateral displacement. Offset stratigraphic changes in correlative Neoproterozoic strata indicate at least 60 km of right-lateral displacement across the zone. WCFZ is the southern continuation of the Northern Rocky Mountain Trench (NRMT) fault zone. It shows a through going, moderate displacement, strike-slip fault system structurally links the NRMT and the north-central part of the Southern Rocky Mountain Trench. Strike-slip motion on the WCFZ occurred in the Late Cretaceous to Early Eocene at the same time as northeast-directed shortening in the fold-and-thrust belt. Thus, oblique convergence in the eastern part of the south-central Canadian Cordillera was apparently resolved into parallel northwest-striking zones of strike-slip and thrust faulting during the Late Cretaceous to Early Eocene. The change in the net Late Cretaceous to Early Eocene displacement direction for rocks in the Rocky Mountain trenches from north (56-54°N) to northeast (52-49°N) suggests that the disappearance of strike-slip displacement and increase in fold-and-thrust belt shortening in the eastern Cordillera between 56° and 49°N is largely the result of a north-south change in relative plate motion or strain partitioning across the Cordillera, rather than the southward transformation of right-lateral strike-slip displacement on the Tintina - NRMT fault system into compressional deformation.

ANALYSIS OF COLLISION BETWEEN DRILLSTRING AND WELL SIDEWALL

2008 ◽  
Vol 22 (31n32) ◽  
pp. 5459-5464 ◽  
Author(s):  
G.H. ZHAO ◽  
Z. LIANG
Keyword(s):  
Stress Wave ◽  
Lateral Displacement ◽  
Borehole Wall ◽  
Frequency Method ◽  
Element Analysis ◽  
Premature Failure ◽  
Middle Cross Section ◽  
Fixed End ◽  
Gas Fields ◽  
Wave Induced

Drillstring is the most important tool in petroleum drilling engineering. Alternating stress has been found to be responsible for the premature failure of drillstring. Propagation of stress wave, induced by collision between tool-joints of drillstring and borehole wall, is studied in this paper. The condition that all the tool-joints of drill pipes (DPs) strike borehole wall at the same time has been considered. Because of symmetry, the middle cross section of the DP is simplified as fixed end, and mechanical model is established as the beam with both ends fixed. Propagation of lateral displacement wave and stress wave in the DP is investigated by means of Eigen-frequency method and the Finite Element Analysis software ANSYS. The theoretic results coincide with those obtained from numerical modeling very well and also explain the drillstring accidents in gas fields.

A NEW SEQUENCE FRAMEWORK FORTHE GREAT AUSTRALIAN BIGHT: STARTING WITH A CLEAN SLATE

2000 ◽  
Vol 40 (1) ◽  
pp. 95 ◽  
Author(s):  
J.M. Totterdell ◽  
J.E. Blevin ◽  
H.I.M. Struckmeyer ◽  
B.E. Bradshaw ◽  
J.B. Colwell ◽  
...  
Keyword(s):  
Source Rocks ◽  
Petroleum Exploration ◽  
Blue Whale ◽  
Growth Strata ◽  
Sequence Stratigraphic ◽  
Petroleum Systems ◽  
Lithospheric Extension ◽  
Stratigraphic Model ◽  
Half Graben ◽  
Great Australian Bight

The 1999 release of offshore petroleum exploration acreage in the Great Australian Bight and the acquisition of high quality seismic datasets covering the Bight and Duntroon Basins, have provided a timely opportunity to reassess the stratigraphic and tectonic evolution of the area. A sequence stratigraphic framework for the Great Australian Bight region has been developed based on the interpretation of exploration wells in the Bight and Duntroon basins and a grid of new and reprocessed seismic data in the Bight Basin. Previous formation-based nomenclature has emphasised lithostratigraphic correlations rather than the chronostratigraphic relationships. The new sequence framework underpins an analysis of play elements and petroleum systems and is helping to identify new exploration opportunities.Deposition in the Bight and Duntroon Basins commenced in the Late Jurassic during a period of lithospheric extension. Extensive half graben systems were filled with fluvial and lacustrine clastic sediments (Sea Lion and Minke supersequences). Potential source rocks within these supersequences are immature at Jerboa-1 in the Eyre Sub-basin, however higher maturities are expected within adjacent half graben and in the Ceduna and Recherche Sub-basins. The syn-rift successions are overlain by widespread Berriasian to Albian fluvio-lacustrine to marine sediments of the Southern Right and Bronze Whaler supersequences. The onlapping sag-fill geometry of these Early Cretaceous packages in the Eyre, Ceduna and inner Recherche Sub-basins suggests that they were deposited during a period of thermal subsidence.Accelerated subsidence commencing in the late Albian led to the deposition of the marine shales of the Blue Whale supersequence, followed by a period of gravity-controlled faulting and deformation in the Cenomanian. The White Pointer supersequence is characterised by growth strata associated with a series of listric faults that sole out in underlying ductile shales of the Blue Whale supersequence. Open marine conditions during the Turonian-Santonian (Tiger supersequence) were followed by the development of massive shelf margin delta complexes in the late Santonian-Maastrichtian (Hammerhead supersequence). The progradational to aggradational stratal geometries within the Hammerhead supersequence suggest initial high rates of sediment input that subsequently waned during this period. An overall transgressive phase of sedimentation in the Early Tertiary (Wobbegong supersequence) was followed by the establishment of open marine carbonate shelf conditions from the Early Eocene onward (Dugong supersequence). Organic geochemical studies show that the Bronze Whaler to White Pointer supersequences have good source rock potential in the relatively proximal facies intersected by existing petroleum exploration wells. Our sequence stratigraphic model predicts the likelihood of widespread late Aptian, Albian, Cenomanian-Santonian, and Campanian marine shales, which underpin four potential marine petroleum systems.

Pluto gas field: Successful placement of an infill well based on 4D seismic monitoring

2020 ◽  
Vol 39 (7) ◽  
pp. 464-470
Author(s):  
Benjamin Peterson ◽  
André Gerhardt
Keyword(s):  
Feasibility Studies ◽  
Gas Production ◽  
Seismic Survey ◽  
Gas Field ◽  
Water Contact ◽  
North West ◽  
Water Ingress ◽  
Gas Fields ◽  
4D Seismic ◽  
Gas Expansion

Seismic 4D monitoring technology has not been as widely employed for gas fields as it has for oil. Many gas fields rely on depletion drive, which has a 4D seismic response that can be uncertain and difficult to predict. On the other hand, aquifer-supported gas fields with measurable water ingress have a reasonable chance of success in terms of generating an interpretable 4D amplitude signal. Pluto gas field in the North West Shelf of Australia falls into this category. Following discovery in 2005, Pluto was appraised by five wells, which found a consistent gas gradient and gas-water contact across the entire field and its various reservoirs. Gas production began in 2012. Time-lapse seismic feasibility studies concluded that gas-saturation changes could be observed with a monitor seismic survey acquired three to four years after first gas. The Pluto 4D Monitor 1 survey was acquired at the start of 2016 and revealed both hardening and softening anomalies. Hardening is interpreted as water ingress (expected) and softening as gas expansion (unexpected). The Pluto 4D results provided important insights into reservoir connectivity and discontinuities. Large hardening anomalies at the TR27 (lower) level can be clearly seen in the data, showing avenues for water ingress. More importantly, a large softening anomaly below the original gas-water contact in the TR29 (upper) reservoir is interpreted to be gas expansion into the aquifer created by a U-tubing effect around a possible barrier in the gas leg. This suggests that the entire TR29 reservoir may not be accessed by the producing PLA04 well. Based on this 4D interpretation, the PLA07 well was drilled and completed in 2019 to produce the TR29 gas updip from the gas expansion anomaly and to increase Pluto field recovery.

SEISMIC TO SIMULATION: INTEGRATED RESERVOIR MODEL FOR THE PATRICIA BALEEN GAS FIELD

2002 ◽  
Vol 42 (1) ◽  
pp. 83
Author(s):  
P. Fink ◽  
M. Adamson ◽  
F. Jamal ◽  
C. Stark
Keyword(s):  
Water Saturation ◽  
Subsequent Development ◽  
Seismic Survey ◽  
3D Seismic ◽  
Reservoir Model ◽  
Gas Field ◽  
Facies Model ◽  
Time Migration ◽  
Gas Fields ◽  
Elastic Impedance

The Patricia and Baleen offshore gas fields are located in the northeastern part of the Gippsland Basin in southeast Australia. Although discovered by two exploration wells almost a quarter of a century ago, the two gas fields only recently have again become the focus of appraisal and subsequent development activity through OMV’s acquisition of Cultus in 1999.After the drilling of a successful appraisal well in late 1999, a high resolution 3D seismic survey was acquired in early 2000. No further data acquisition will be undertaken. Special emphasis was therefore put on maximising the value of the 3D dataset by integrating the PreSTM (Pre. Stack Time Migration) seismic and several Elastic Impedance attributes with all other available subsurface data prior to building a sophisticated stochastic reservoir model for simulation.This paper describes how the integration of leading edge seismic technology with unconventional geological modelling was used to overcome a number of major challenges in order to build a coherent static reservoir model and constrain resource uncertainty given the limited amount of wireline and core data:A large proportion of the gas fields is strongly affected by seismic tuning which would introduce significant uncertainties on GRV and GWC estimations from seismic, if not accounted for properly. Likewise all seismic and to a somewhat lesser extent basic inversion based attributes used for reservoir property determination are strongly affected by this geophysical artefact: These challenges (and seismic pitfalls) were met by inverting the conventional 3D seismic for Pand S- wave impedances and generating a set of Elastic Impedance Cubes, difference cubes and LRM Cubes (standing for the elastic constants Lambda (λ), Rho (ρ) and Mhu (μ)), defining petroacoustic properties of the reservoir rocks. These cubes were tested for mathematical dependency and used for the conditioning of the facies and porosity models.The glauconitic Gurnard reservoir contains a high fraction of conductive minerals and is almost completely bioturbated. Conventional saturation estimations based on wireline-logs and conventional sequence stratigraphic facies description did not deliver a reliable picture: Instead a facies model based on ichnofabric analysis was built and constrained with data available at the three well locations. Saturation height functions were applied separately for each facies type. The Rho-Lambda (ρλ) cube was used to condition facies distribution away from the wells.More specifically, the results presented in the paper are:Elastic Impedance inversion provided vertical seismic resolution in the order of 4 m to 10 m, thereby allowing a more accurate seismic estimation of GRV and the GWC. Lamesf Constants were extracted from seismic in order to classify lithology.A realistic facies model was built utilizing the Rho- Lambda (ρλ) cube combined with ichnofabric analysis tied to permeability and water saturation distributions.Elastic Impedance Difference cubes were successfully calculated to eliminate tuning even further and condition the stochastic porosity model.Connected volume maps were used to optimise the production well pathsThe GIIP upside volume has been upgraded compared to that based on an earlier simplistic geological reservoir model used for simulation. A more realistic P10/P90 reserves range is now supported by a number of deterministic and stochastic reservoir models.

BASEMENT AND CRUSTAL CONTROLS ON HYDROCARBON MATURATION—LESSONS FROM BREMER SUB-BASIN FOR OTHER FRONTIER EXPLORATION AREAS

2006 ◽  
Vol 46 (1) ◽  
pp. 237 ◽  
Author(s):  
A. Goncharov ◽  
I. Deighton ◽  
P. Petkovic ◽  
H. Tassell ◽  
S. McLaren ◽  
...  
Keyword(s):  
Heat Flow ◽  
Surface Heat ◽  
Seismic Survey ◽  
Low Grade ◽  
Sea Floor ◽  
Rock Samples ◽  
Surface Heat Flow ◽  
Hydrocarbon Maturation ◽  
Refraction Seismic ◽  
Consistent Approach

A consistent approach to the assessment of basement and crustal controls on hydrocarbon maturation in the Bremer Sub-basin, offshore southwest Australia, has been undertaken as part of the Australian Government’s Big New Oil initiative. Geoscience Australia acquired marine reflection seismic survey in this area during late 2004 in conjunction with recording of refraction seismic data by sonobuoys at sea and by land stations in the onshore/offshore observation scheme. One of the key findings of the refraction seismic study is that velocities in the basement are generally in the 5.0–5.7 km/s range, indicating that, contrary to prior expectations, basement in the area is mostly not granitic in composition. Results from the conjugate margin in Antarctica also show low velocities in the basement on the inner side of Antarctic continent-ocean boundary, consistent with results from the Australian margin. It appears that a ~400-km-wide zone in Gondwana prior to break up had basement velocities significantly lower than the normal continental values of 6.0–6.2 km/s most commonly associated with granites and gneisses. Low-grade metasediments of the Albany-Fraser Orogen and its Antarctic equivalent is the preferred interpretation of this observation. Granites, dredged from the sea floor in the Bremer area, may represent only a small fraction of the basement, as within the basement highs where higher velocities have been detected by refraction work. As metasediments produce substantially less heat than granites, a different scenario for hydrocarbon maturation in the Bremer Sub-basin is possible. To quantify possible heat production in the Bremer basement and crust below it we have used contents of radioactive elements in rock samples taken from outcrops of Yilgarn Craton and Albany-Fraser Orogen onshore, as well as in rock samples dredged from the sea floor in the Bremer Sub-basin. Advanced burial and thermal geohistory modelling in this area was carried out using Fobos Pro modelling software for the first time in Australia without relying on default or inferred values (such as heat flow or geothermal gradient). Modelling showed that subsidence curves can be matched in various basement composition scenarios, but the high heat-producing granitic scenario leads to a present-day surface heat flow of 68 mW/m2 predicted by the model—unrealistically high given the context of heat flow measurements on the Australian Southern Margin. Other basement compositions (low heat- producing granite, metasediments, basalts) lead to a present-day surface heat flow of 46–57 mW/m2 and cannot be ruled out on the basis of heat flow modelling and data alone. This work details a methodologically consistent approach to burial and thermal geohistory modelling for other frontier areas where appropriate geophysical data have been collected.

THE THYLACINE AND GEOGRAPHE GAS DISCOVERIES, OFFSHORE EASTERN OTWAY BASIN

2004 ◽  
Vol 44 (1) ◽  
pp. 441 ◽  
Author(s):  
D.C.B. Cliff ◽  
S.C. Tye ◽  
R. Taylor
Keyword(s):  
Environmental Studies ◽  
Seismic Survey ◽  
Structural Imaging ◽  
3D Seismic ◽  
Surface Development ◽  
Gas Markets ◽  
Development Concept ◽  
Gas Fields ◽  
Water Depths

The Thylacine and Geographe gas fields were discovered in mid-2001 in the offshore Otway Basin, in permits T/30P and VIC/P43 respectively. Geographe is 55 km south of Port Campbell and Thylacine is a further 15 km offshore, in the depo-centre of the Shipwreck Trough, in water depths of 80 m to 100 m. The Thylacine–1 well intersected a 277 m gas column in Turonian to Santonian aged reservoirs. Geographe–1 intersected a 233 m gas column in a similar sedimentary section. Thylacine–2, 5.7 km west of Thylacine–1, confirmed the field extent, and flowed gas at 28 MMSCFD (0.79 Mm3/D). Critical to the discovery of these fields was the Investigator 3D seismic survey, which covered about 1,000 km2 of the central Shipwreck Trough. The pre-drill chance of success of both structures was high-graded as a result of excellent structural imaging and the conformance of amplitude and AVO anomalies to mapped closures. The interpretation of this survey and the subsequent drilling of the Thylacine and Geographe Fields have dramatically increased the understanding of the structure and stratigraphy of the offshore eastern Otway Basin particularly in relation to the Shipwreck Trough and the Sorell Fault Zone.Combined dry gas reserves at the proved and probable level stand at 0.85 TCF and condensate reserves at 10.7 MMBBL. The fields are undergoing integrated sub-surface, development and environmental studies with the aim of supplying the nearby southeastern Australian gas markets. The preferred development concept is a small jacket structure at Thylacine, followed by a subsea tie-in of the Geographe Field with onshore processing facilities near Port Campbell.

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