3D Seismic Survey Research Articles

Oil Reservoir Detection Using Volume Attributes in Chia Surkh Area, Kurdistan Region, Iraq

This study includes picking seven reflectors from intense sampling of 3D Seismic survey composed of 40 inlines and 30 crosslines, the distance between the seismic lines is equal to 250m. The study deals with extracting and analysing volume seismic attributes of 3D seismic data of Chia Surkh area. The area is located east of Kalar City, Sulaimani Government, Kurdistan Region, Iraq. The main aim is to determine locations of hydrocarbon accumulation by picking seven horizons as well as studying and analysing both subsurface structure and direct hydrocarbon indicators. The seismic volume attributes are calculated from the original seismic data that consist of (400) inlines and (300) crosslines, and the distance between two adjacent lines is equal to (25m). The seismic attributes used in the current study are, variance edge, curvature, root mean square, envelope and sweetness. Revealed existence of a major anticline, a major fault. As well as two small faults were detected and running parallel to the major fault, while the envelope and sweetness attributes emphasized appearance of several bright spots within Lower Fars, Dhiban, Jeribe and Euphrates Formations, which give quite evidence for accumulation of hydrocarbon. The study concluded that the complete system requires for existence of petroleum is available such as the major anticlinal structure, carbonate rocks as an excellent reservoir rocks and gypsum or (anhydrite) as an optimal cap rock. The existence of hydrocarbon is confirmed by bright spots.

Identification of small-sized oil and gas deposits in the Pannonian Basin according to seismic data

The article presents the results of the practical application of an integrated approach to the study of small-sized oil and gas deposits in the interval of terrigenous deposits of the lower Pontus of the southeastern part of the Pannonian Basin using 3D seismic survey. Some geomorphological features of the structure of the pre-Neogene basement of the studied area of the Pannonian Basin of the Republic of Serbia are shown, the relationship between the position of local basement ledges and the localization of new oil and gas deposits in the overlying horizons is analyzed.Based on the work carried out, a number of signs and features of the seismic material were identified, thanks to which the location of promising structures and associated hydrocarbon deposits was substantiated and coordinates for drilling new wells were proposed. The subsequent implementation of the completed drilling recommendations was confirmed by the results of testing and discoveries of new oil deposits at the Kikinda North-West field.The discovered deposits of oil and gas at the Kikinda North-West field are associated with the "root" structures of the basement, areas of through faults and subvertical local seismic anomalies. The presented results indicate the need for further comprehensive analysis of 3D seismic survey, drilling data, core studies, well logging, well testing results in order to search for and discover new hydrocarbon deposits based on the identified patterns and approaches.

Acoustic monitoring and analyses of air gun, pile driving, vessel, and ambient sounds during the 2015 seismic surveys on the Sakhalin shelf

During the summer of 2015, four 4D seismic surveys were conducted on the northeastern Sakhalin shelf near the feeding grounds of the Korean-Okhotsk (western) gray whale (Eschrichtius robustus) population. In addition to the seismic surveys, onshore pile driving activities and vessel operations occurred. Forty autonomous underwater acoustic recorders provided data in the 2 Hz to15 kHz frequency band. Recordings were analyzed to evaluate the characteristics of impulses propagating from the seismic sources. Acoustic metrics analyzed comprised peak sound pressure level (PK), mean square sound pressure level (SPL), sound exposure level (SEL), T100%, T90% (the time intervals that contain the full and 90% of the energy of the impulse), and kurtosis. The impulses analyzed differed significantly due to the variability and complexity of propagation in the shallow water of the northeast Sakhalin shelf. At larger ranges, a seismic precursor propagated in the seabed ahead of the acoustic impulse, and the impulses often interfered with each other, complicating analyses. Additional processing of recordings allowed evaluation and documentation of relevant metrics for pile driving, vessel sounds, and ambient background levels. The computed metrics were used to calibrate acoustic models, generating time resolved estimates of the acoustic levels from seismic surveys, pile driving, and vessel operations on a gray whale distribution grid and along observed gray whale tracks. This paper describes the development of the metrics and the calibrated acoustic models, both of which will be used in work quantifying gray whale behavioral and distribution responses to underwater sounds and to determine whether these observed responses have the potential to impact important parameters at the population level (e.g., reproductive success).

Real-time acoustic monitoring with telemetry to mitigate potential effects of seismic survey sounds on marine mammals: a case study offshore Sakhalin Island

Exxon Neftegas Ltd. (ENL) carried out three 4D seismic surveys during the summer of 2015. Seismic operations in two of these fields (Odoptu and Chayvo) ensonified the nearshore feeding area of Korean-Okhotsk (western) gray whales (Eschrichtius robustus), potentially disturbing feeding activities. Following model-based optimization of the source design to minimize its lateral acoustic footprint, pre-season modeling was used to compute the acoustic exposure along each survey line. Real-time acoustic data facilitated implementation of mitigation measures aimed to minimize disturbance of whales. Acoustic data originated from underwater recorders deployed on the seafloor. Two complementary approaches were used to transmit recorded sound data to a computer housed at the Central Post (CP), where decisions regarding mitigation shut downs were made. In the first approach, a limited bandwidth (2–2000 Hz) sampling of the data was transmitted via cable to a surface buoy, which relayed these data to a shore station up to 15 km away via digital VHF telemetry. At the shore station, acoustic impulses from the seismic surveys were processed to compute impulse characteristics in the form of estimates of sound exposure level and peak sound pressure level, as well as one-minute-average 1/3-octave power spectral density coefficients, which were then transmitted to the CP via the internet. In the second, the pulse characteristics were computed through algorithms running on an onboard processor in each recorder’s surface buoy and sent directly to the CP computer via an Iridium satellite uplink. Both methods of data transfer proved viable, but Iridium transmission achieved the goal without the need for any shore based relay stations and is therefore more operationally efficient than VHF transmission. At the CP, analysts used the real-time acoustic data to calibrate and adjust the output of pre-season acoustical model runs. The acoustic footprint for the active seismic source, advancing synchronously with the motion of the seismic vessel and changing as the sound propagation environment changed, was computed from the calibrated and adjusted model output and integrated through the software Pythagoras with locations of gray whales provided by shore-based observers. This enabled analysts to require air gun array shutdowns before whales were exposed to mean square sound pressure levels greater than the behavioral response threshold of 163 dB re 1 μPa2. The method described here provides a realistic means of mitigating the possible effects of air guns at a behavioral response level, whereas most seismic surveys rely on pre-established mitigation radii to manage the risk of injury to a whale.

Prediction of petrophysical characteristics of deposits in Kurovdagh field by use of attribute analysis of 3D data

The paper is devoted to predicting petrophysical parameters of productive series of Kurovdagh field by use of attribute analysis of seismic data to define the direction of reconnaissance works in this field. The paper considers geographical position of the study area, its cover by geological and geophysical studies and underlines, in particular, the importance of 3D seismic data acquisition for more detailed study of Kurovdagh structure. Lithological and stratigraphic characteristics of the section is also given in the paper with detailed description of Productive Series deposits. In addition, tectonics of the area is considered in more detail. It is noted that the area is attributed to the Low Kur basin — the compound of the large tectonic unit. The tectonic zone of the south-eastern Shirvan is embracing four anticlinal zones: Pirsaat-Khamamdagh; Kharami—Mishovdag—Kalmas—Khydirly—Aghaevir-Byandovan; Kursangya; Padar—Kurovdagh—Karabaghly—Babazanan—Duzdagh-Neftchala. The latter anticlinal zone is characterized by a significant length. In the north-western part between the folds of Padar and Karabaghly the brachyanticline of Kurovdagh is located. In the north it has the border with M. Kharami uplift, in the north-east with Mishovdagh fold, it borders with Kursyanga anticline in the south-east and in the south-west with wide Salyan trough. In the Near-Kur depression the existence of two tectonic stripes has been established. One of them embraces the south-eastern Shirvan, the other covers the eastern Mughan and the western portion of Salyan steppe. The detailed description of fold setting is given on the basis of 3D seismic survey data. It has been indicated that the results of 3D data interpretation made it possible to study in more detail and make changes in the scheme of faults location accepted earlier. The other problem considered in the paper is the oil-and-gas presence in Kurovdagh field, which is related to the Absheron stage of Pleistocene, Akchagyl stage and Productive series (horizons of PS01—PS20) of Neogene, with lithology represented by sandy-clay rocks with various degrees of calcareousness. The structure of each of indicated horizons is rather complicated and variable in lateral. The most complicated of them is the Middle Absheron sub-stage, with identified 11 oil-bearing layers. Study results are given in the end of the paper. For prediction purposes within the study area we have prepared normalized curves of relative parameter of SP-ASP, gamma-log — dGR and resistivity by use of well logging data. The analysis of dependence of seismic attributes on petrophysical parameters within target interval, identified the low information bearing ability of SP method and gamma-log across the study area and established a good correlation between resistivity curve and instantaneous amplitudes, frequencies and dip angles. The clay cubes have been designed. To outline productive layers, we have applied multidimensional filters with cut offs for reservoir and as a result we have acquired a cube for supposed distribution of productive layers. It is emphasized that the conducted studies led to the conclusion that due to the complexity and interference nature of the observed wave pattern in some parts of the Kurovdagh structure, it was not possible to reliably convert the attributes of the seismic wave field into petrophysical parameters.

3D reflection seismic imaging of the Zinkgruvan mineral‐bearing structures in the south‐eastern Bergslagen mineral district (Sweden)

AbstractMineral exploration is facing greater challenges nowadays because of the increasing demand for raw materials and the lesser chance of finding large deposits at shallow depths. To be efficient and address new exploration challenges, high‐resolution and sensitive methods that are cost‐effective and environmentally friendly are required. In this work, we present the results of a sparse 3D seismic survey that was conducted in the Zinkgruvan mining area, in the Bergslagen mineral district of central Sweden. The survey covers an area of 10.5 km2 for deep targeting of massive sulphides in a polyphasic tectonic setting. A total of 1311 receivers and 950 shot points in a fixed 3D geometry setup were employed for the survey. Nine 2D profiles and a smaller 3D mesh were used. Shots were generated at every 10 m, and receivers were placed at every 10–20 m, along the 2D profiles, and 40–80 m in the mesh area. An analysis of the seismic fold coverage at depth was used to determine the potential resolving power of this sparse 3D setup. The data processing had to account for cultural noise from the operating mine and strong source‐generated surface waves, which were attenuated during both pre‐ and post‐stack processing steps. The processing workflow employed a combination of 2D and 3D refraction static corrections, and post‐stack FK filters along inlines and crosslines. The resulting 3D seismic volume is correlated with downhole data (density and P‐wave, acoustic impedance, reflection coefficient), synthetic seismograms, surface geology and a 3D model of mineral‐bearing horizons in order to suggest new exploration targets at depth. The overall geological architecture at Zinkgruvan is interpreted as two EW overturn folds, an antiform and a synform, affected by later NS‐trending folding. Two strong sets of shallow reflections, associated with the Zn–Pb mineralization, are located at the hinge of an EW‐trending antiform, while a strong set of reflections, associated with the main mineralization, is located at the overturned apex of the EW synform. The NS Knalla fault that crosses the study area terminates the continuation of the mineral‐bearing deposits at depth towards the west, a conclusion solely based on the reflectivity character of the seismic volume. This study illustrates that sparse 3D data acquisition, while it has its own challenges, can be a suitable replacement for 2D profiles while line cutting, and environmental footprints can totally be avoided.

Application of 3D Optical Fibre Reflection Seismic in Challenging Surface Conditions

Distributed Acoustic Sensing (DAS), which uses strain-induced optical distortion effects to use optical fibres as multi-channel seismic arrays, enable efficient and inexpensive high-resolution seismic surveying in the challenging surface conditions, such as salt lakes. In this study, we present a first published 3D seismic survey completed with a fibre optic network. Since DAS cables freely deployed on surface can be sensitive to ambient noise such as strong wind, which is common in many field conditions, we developed an efficient methodology for cable burring by fast ploughing it in both soft and hard ground conditions. Even a standard telecommunication fibre optic cable deployed beneath the surface by this ploughing method delivers reflection seismic recording performance comparable to conventional geophone systems, offering substantial cost savings in practice. Combined with light and mobile seismic sources such as Betsy gun, DAS technology deployed in 3D surface reflection configuration across a hyper-saline salt-lake environment delivered a performance akin to modern nodal seismic systems. We show that the introduction of DAS technology into seismic surveying practice in the mineral sector could deliver an order of magnitude saving, while substantially increasing the data density and hence allowing optimum performance of modern seismic imaging algorithms.

Surface wave tomography using dense 3D data around the Scrovegni Chapel in Padua, Italy

A dense single-node 3D seismic survey has been carried out around the Scrovegni Chapel in Padua (Italy), in order to give new insights about the archaeological setting of the area. The survey made use of nearly 1500 vertical nodes deployed over two rectangular grids. 38 shot positions were fired all around the two receiver patches. The fundamental mode Rayleigh wave signal is here analysed: traveltimes are directly inferred from the signal phases, and phase velocity maps are obtained using Eikonal tomography. Also surface wave amplitudes are used, to produce autospectrum gradient maps. The joint analysis of phase velocity and autospectrum gradient allowed the identification of several buried features, among which possible remains of radial walls of the adjacent Roman amphitheater, structures belonging to a medieval convent, and the root area of an eradicated tree. Finally, depth inversion of 1D dispersion curves allowed the reconstruction of a quasi-3D shear-wave velocity model.

Porosity estimation of a geothermal carbonate reservoir in the German Molasse Basin based on seismic amplitude inversion

The Molasse Basin is one of the most promising areas for deep geothermal exploitation in Germany and the target horizon is the aquifer in the Upper Jurassic carbonates. Carbonate deposits can be very heterogeneous even over a small area due to diagenetic processes and varying depositional environments. The preferential targets for geothermal exploitation in carbonate deposits are fault zones, reef facies and karstified areas, since they are expected to act as hydraulically permeable zones due to high porosity and high permeability. Therefore, identifying these structures and characterizing, e.g., their internal porosity distribution are of high importance. This can be accomplished using 3D reflection seismic data. Besides structural information, 3D seismic surveys provide important reservoir properties, such as acoustic impedance, from which a porosity model can be derived. In our study area in Munich we carried out a seismic amplitude inversion to get an acoustic impedance model of the Upper Jurassic carbonate reservoir using a 3D seismic data set, a corresponding structural geological model, and logging data from six wells at the ‘Schäftlarnstraße’ geothermal site. The impedance model and porosity logs were than used to calculate a porosity model. The model shows a wide porosity range from 0 to 20% for the entire reservoir zone and the lithology along the wells reveals that dolomitic limestone has the highest porosities and calcareous dolomite has the lowest porosities. The study area is cut by a large W–E striking fault, the Munich Fault, and the footwall north of it shows higher porosities and more intense karstification than the hanging wall to the south. Considering the entire study area, an increase in porosity from east to west is observed. Furthermore, we identified a complex porosity distribution in reef buildups and pinnacle reefs. The reef cores have mostly low porosities of, e.g., < 3% and the highest porosities of up to 7 to 14% are observed at the reef caps and on the reef slopes. The reef slopes show a characteristic interfingering of the reef facies with the surrounding bedded facies, which indicates a syn-sedimentary reef development with slightly varying build up growth rates. We also assessed the reservoir quality with regard to porosity distribution and determined areas with moderate to good quality for geothermal exploitation by defining porosity evaluation levels. The porosity evaluation maps show that the carbonate rocks of Berriasian to Malm zeta1 are preferential targets for exploitation, especially in the footwall of the Munich Fault and to the west of the hanging wall, because these areas are characterized by high porosities due to intense karstification of bedded and massive facies, although the latter is mainly restricted to reef caps and reef slopes.

Artificial Intelligence for Automating Seismic Horizon Picking

Fully-automated seismic horizon picking dramatically shortens the time between acquiring seismic data and picking drilling targets. Oil and gas exploration companies worldwide spend millions of tedious man-hours picking horizons on seismic data to produce inventories of drilling targets. Freeing up that time to better incorporate the geologic and geophysical properties within mapped structures guarantees more drilling success. Artificial intelligence is frequently mentioned in today’s news: self-driving cars, vehicle identification, robot vacuums, fingerprint identification, facial recognition and Alexa are just a few examples. Why not seismic data interpretation? Here, it is proven that automated seismic horizon picking is possible. From a two-column text file of time-amplitude pairs my algorithm produces a reflection-time-ordered text file of all continuous series of connected pixel coordinates easily-read by mapping software. These connected pixels are plotted separately on the input seismic test line’s peaks and troughs. More than 10,000 connected segments were written in less than a minute of computer time, saving many hours of manual labour. This time-saving extrapolated to 3D seismic surveys will reduce the time it takes to find drilling targets by months.

Study of the Geological Structure and Prediction of the Oil and Gas Potential of the Zardab-Shikhbagi Field

The Zardab – Shikhbagi area is located on the northeastern slope of the Yevlag – Agjabedi depression and on the southeastern wing of the Saatli – Goychai uplift zone. Based on the conducted geological and geophysical, research and data from exploration drilling, it was established that in the geological structure of the Zardab-Shykhbagi area, deposits from Quaternary to Lower Cretaceous inclusive are involved. The article commented on some data from 3D seismic surveys carried out at Zardab - Shykhbagi and related fields. The changes in the parameters of seismic waves are analyzed on the basis of time and dynamic depth sections drawn up in different directions. In accordance with various stratigraphic sections, intervals were identified and they were interpreted. Based on the performed studies, the presence of favorable geological conditions for the formation of anticline and non–anticline traps, which can be considered promising from the point of view of oil and gas potential at the Zardab - Shikhbagi field, was predicted. Keywords: Seismic exploration; Oil and gas potential; Time section; Dynamic and deep section; Anticline and non-anticline traps.

Backthrust play of the Chernyshev swell, Timan-Pechora Basin: Reentry into a legacy exploration site based on multidisciplinary study

We have developed a new interpretation of the Povarnitsa High, located in the southern part of the transition zone between the Chernyshov swell and the Kosyu-Rogov trough in the Polar Urals foreland. Petroleum exploration in this area took place in the 1980s and resulted only in an uneconomical oil deposit. Reprocessing and reinterpretation of vintage data and a newly acquired 3D seismic survey along with nonseismic geophysical data provided new insight into the geologic setting of the area. It found a subthrust extension of the Povarnitsa High, overlain by a backthrust sheet floored by upper Ordovician evaporites. This backthrust sheet interpretably resulted from the squeezing of the salt diapir during the late Permian contraction. Stratal patterns of the Silurian-Carboniferous section adjacent to the salt structures suggest early precontraction initiation of the halokinetic deformation, which influenced the distribution of reservoirs such as reefs and oolites. We consider the salt-cored subthrust structural culmination a principal hydrocarbon prospect. It includes multiple reservoir-seal pairs in the Silurian-Permian section at depths ranging from 1 to 4 km. The updated structural model of the Povarnitsa High area suggests that the vintage wells penetrated prospective intervals at the periphery of the closure approximately 1 km downdip from the subthrust crest of the prospect.

3D high-resolution seismic imaging of the iron oxide deposits in Ludvika (Sweden) using full-waveform inversion and reverse time migration

Abstract. A sparse 3D seismic survey was acquired over the Blötberget iron oxide deposits of the Ludvika Mines in south-central Sweden. The main aim of the survey was to delineate the deeper extension of the mineralisation and to better understand its 3D nature and associated fault systems for mine planning purposes. To obtain a high-quality seismic image in depth, we applied time-domain 3D acoustic full-waveform inversion (FWI) to build a high-resolution P-wave velocity model. This model was subsequently used for pre-stack depth imaging with reverse time migration (RTM) to produce the complementary reflectivity section. We developed a data preprocessing workflow and inversion strategy for the successful implementation of FWI in the hardrock environment. We obtained a high-fidelity velocity model using FWI and assessed its robustness. We extensively tested and optimised the parameters associated with the RTM method for subsequent depth imaging using different velocity models: a constant velocity model, a model built using first-arrival travel-time tomography and a velocity model derived by FWI. We compare our RTM results with a priori data available in the area. We conclude that, from all tested velocity models, the FWI velocity model in combination with the subsequent RTM step provided the most focussed image of the mineralisation and we successfully mapped its 3D geometrical nature. In particular, a major reflector interpreted as a cross-cutting fault, which is restricting the deeper extension of the mineralisation with depth, and several other fault structures which were earlier not imaged were also delineated. We believe that a thorough analysis of the depth images derived with the combined FWI–RTM approach that we present here can provide more details which will help with better estimation of areas with high mineralisation, better mine planning and safety measures.

Prospects of hydrocarbon exploration in the Laptev sea basin

Background. The geological structure of the Laptev Sea basin is characterized by a rift nature, thus providing no favorable conditions for the presence of hydrocarbon accumulations. However, the lack of seismic information and the absence of well drilling indicate an incomplete stage of the basin exploration.Aim. To analyze the results of geological modeling based on structural mapping and to identify promising areas of hydrocarbon exploration. A geological hydrocarbon study of the Laptev Sea basin was carried out in order to recommend areas for licensing, as well as to identify exploration drilling sites and estimate the total initial prospective geological resources according to the conducted numerical basin modeling. To design sedimentation models and predict reservoir properties in the Laptev Sea basin.Materials and methods. The analysis was based on the data retrieved from production reports for individual large objects in the water area. A model developed by Equinor specialists was used for the basin analysis. The results of hydrocarbon system modeling, the prediction of hydrocarbon saturation obtained from sections of two sample profiles while structural mapping of the basement and top of Oligocene-Miocene sediments were used.Results. Prospective areas of accumulation of hydrocarbons and their confinement were determined. The probability of hydrocarbons in non-anticlinal traps was estimated. Priority areas of hydrocarbon exploration within the unallocated subsoil area were identified. Recommendations for further geological exploration across the license area were formulated.Conclusion. Further exploration of the Yuzhno-Laptevomorsky promising area is recommended by means of analyzing the available data, processing of new geophysical data, updating the geological model and designing 3D seismic surveys within the identified promising areas. In addition, 2D seismic surveys at the regional level should be carried out to define the sedimentary boundaries of the Eastern Artic water area.

Concurrent 15. Presentation for: INPEX-led Ichthys Joint Venture – developing a dynamic adjustment area to identify, time, duration and potential exposure periods related to a 2D seismic survey offshore Western Australia

Presented on Wednesday 18 May: Session 15 The oil and gas industry is striving for effective consultation between titleholders and commercial fishing stakeholders. Recent developments in cross-industry consultation have resulted in frameworks to provide an adjustment (compensation) claim process, where short-term displacement of fishers and reduction of catch coincident and following marine seismic survey activities may occur. 3D seismic surveys are undertaken more intensively, in geographically smaller areas and shorter time periods. This allows for discreet areas and periods to be defined for the applicability of a claim when fishing catch rates or displacement may occur. By contrast, 2D seismic surveys can be undertaken at regional scales with long sail line transects. These result in a survey vessel being active in an area of potential acoustic influence for infrequent and short periods of time, thus making justification for claims, for loss of catch or displacement, over the full survey area and full acquisition period challenging. To address this challenge a novel approach was developed to determine a dynamic area, based on where and when a survey vessel was operating the seismic source. INPEX utilised the 10 nautical miles (nm) × 10 nm geospatial grid data set provided by Department of Primary Industries Resources and Development, for commercial fishers to report catch effort. The methodology used modified navigation files, to determine the frequency, duration and number of times a fishing block was intersected during the survey. The resulting data provided an ‘adjustment area’ and ‘exposure date’ which could then be referred to as a basis for claim. To access the presentation click the link on the right. To read the full paper click here

Concurrent 5. Presentation for: Pluto 4D Monitor Two – a second outstanding success

Presented on Tuesday 17 May: Session 5 A second 4D seismic monitor survey acquired over the Pluto gas field has been an outstanding success despite three tropical cyclones, the start of a global pandemic, and technical subsurface risks. At the time of the Pluto 4D Monitor Two (M2) survey (December 2019 till February 2020), the Pluto field had been in production for 7 years and 9 months and had produced approximately 2 Tcf of gas. The M2 4D survey was acquired between December 2019 and February 2020 over a 20 × 30 km area, on a 12.5 m square grid. Data was processed by CGG to pre-stack depth migration, took 6 months to deliver, and required considerable collaboration with Woodside geoscientists. Use of modern processing technologies, including least squares migration, full waveform inversion and wave equation based amplitude versus offset inversion facilitated a high quality interpretation. On the 4D difference volumes, hardening responses were interpreted as water ingress. Hardening responses were seen in multiple Triassic reservoirs. A pronounced response was seen in a large Triassic valley within a predominantly mudstone background unit, which showed continued water ingress into the valley, upwards from the gas water contact towards the producing well. This confined hardening response contrasted with unconfined, water flood front responses seen in other reservoirs. Both responses enabled detailed interpretation of geological features and provided useful control points for history matching. Interpreted water ingress also gave additional depth control. To access the presentation click the link on the right. To read the full paper click here

Geoscience Poster G9: Optimising value in the mature Turrum Field: integrating modern seismic, high-resolution sequence stratigraphy and production data in a 3D geological model

Poster G9 The Turrum Field in the offshore Gippsland Basin has been a significant producing field since first development in 2004 and remains a keystone gas resource for the future as many of the Gippsland assets continue to deplete. The Turrum Field is a faulted anticlinal structure with multiple, stacked, Paleocene-aged fluvial to lagoonal reservoirs that stratigraphically sit below the overlying Marlin Field gas cap. This field was developed in two phases with drilling campaigns in 2004 and 2015 and includes a dedicated platform (Marlin B) for the higher pressure, higher CO2 gas. Leveraging the 2018 reprocessed Northern Margins 3D seismic survey with a modern broadband processing workflow and wider bandwidth and higher signal-to-noise ratio has led to a seismic image with greater resolution and allowed improved reservoir characterisation. The uplift in seismic data together with the colour blending capabilities in GeoTeric®, has led to the seismic identification of large-scale fluvial reservoir systems. These products have been integrated with a revised field-wide sequence stratigraphic framework, petrophysical analysis and incorporated into a full-field 3D geological model of the Turrum Field. The resultant geological model has improved our understanding of reservoir connectivity and will enable rapid integration of production and surveillance data to optimise gas deliverability. This will also provide increased confidence for future field depletion planning including the identification of potential bypassed gas opportunities prior to end of field life. To access the poster click the link on the right. To read the full paper click here

Concurrent 15. Presentation for: Impacts of exposure to a seismic source survey on silverlip pearl oysters (

Presented on Wednesday 18 May: Session 15 Between 2018 and 2021, AIMS and its partners conducted a large-scale experiment to investigate the effect of exposure to a 3D seismic survey on pearl oysters. In August 2018, ≈11 000 adult wild silverlip pearl oysters (Pinctada maxima) were collected and attached to bottom culture lines to acclimatise for 1 month at a holding lease site, 40 km off Broome, WA. These oysters were split across rows configured parallel to each other at seven horizontal distances up to 6000 m from a ‘zero line’. In September 2018, we sailed a commercial seismic vessel along one 20 km-long inactive (vessel control) sail line along the zero line, followed by six operational (exposure) sail lines, at increasing distances from the zero line, with each line separated in time by either 12 or 24 h. This design resulted in groups of pearl oysters with 35 different exposure histories (seven distances, five exposure distances) that were then transferred to undergo either lethal biophysical sampling or pearl seeding for a ‘grow-out’ study of pearl production. Biophysical sampling included immunology tests, primarily using flow cytometry and gene expression changes in nacre- and stress-associated genes. Audits of oyster growth and condition were conducted at various time points between the exposure period and harvesting of the seeded oysters. The number and quality of pearls produced by each exposure group was assessed 2 years after exposure (December 2020). The results of these analyses are being finalised for presentation. To access the presentation click the link on the right. To read the full paper click here

Geoscience Poster G12: Old basins, new seismic data – architecture of Proterozoic basins in Northwest Queensland

Poster G12 As part of the Strategic Resources Exploration Program and to complement surveys acquired under Geoscience Australia’s Exploring for the Future (EFTF) initiative, the Geological Survey of Queensland acquired the Camooweal 2D seismic survey in 2019. This survey was designed to support exploration for hydrocarbons in the Georgina and South Nicholson Basins and Isa Superbasin in Northwest Queensland (NWQ) by providing precompetitive sub-surface data to enable interpretation of basin and basement architecture and to examine structures interpreted in the 2018 North West Queensland SEEBASE Study. The Camooweal 2D seismic survey extends Geoscience Australia’s L210 South Nicholson Seismic Survey into an underexplored region of NWQ. It also ties into and complements the 1994 and 2004 Mount Isa seismic surveys, and the 2019 L212 Barkly Seismic Survey in the Northern Territory. The South Nicholson survey highlighted a significant thickness of sedimentary strata and identified a new depocenter of probable Proterozoic age, now referred to as the Carrara Sub-basin. The Camooweal and Barkly surveys extended the seismic coverage in this region and possibly increase the Carrara Sub-basin’s extent underneath the Georgina Basin. This work will present an interpretation of the basin architecture of the Camooweal 2D seismic in light of the recent drilling at NDI Cararra 1 and tie into interpretation of the Barkly Seismic Survey to provide a regional interpretation of NWQ’s Proterozoic basins in the region. To access the poster click the link on the right. To read the full paper click here

Attribute analysis as a tool for determining the areas of the late diagenetic Main Dolomite deposits and assessing the stability of the seismic signal parameters

The results of the lithofacial analysis of data from the Moracz 3D seismic survey were among the main premises leading to the positioning of the new petroleum exploration well in that area. Unfortunately, the reservoir properties of the drilled part of the Main Dolomite carbonates differed significantly from those anticipated by the analysis of the amplitudes of the seismic signal recorded. Such surprisingly negative results impelled the reinterpretation of 3D seismic data. Hence, a number of analyses of the amplitudes, the frequencies, and the variability of phase shift were carried out in order to determine the influence of these parameters on the lithofacial interpretation of seismic data. The results revealed a fundamental error of amplitude with the extraction maps. It appeared that the distribution of amplitudes is not essentially controlled by the reservoir properties of the Main Dolomite carbonates but by the fault shadow effect coming from Mesozoic graben in the overburden. In addition, a large diversity of frequency spectra was found, which, combined with the small thickness of the exploration level, could have contributed to incorrect identification of seismic reflections. There was also a change in seismic signatures from the same reflection in different parts of the survey, raising doubts about the distribution of the phase rotation. In order to recognize phase rotation diversity, a new seismic data analysis was based upon the selected Triassic sediments of high impedance. The obtained maps demonstrated significant variability within the data volume due to attenuation. The reinterpreted data from the Moracz 3D seismic survey proved the uneven and unstable distribution of amplitudes, frequencies, and phase which resulted in erroneous conclusions of petroleum exploration. After modeling with the use of different frequency ranges, an analysis of the amplitude extraction of the horizons related to the Main Dolomite was performed. Then the amplitude ratio attribute was selected which eliminated the influence of the regional amplitude and frequency distribution and showed the distribution of dolomite properties more reliably than the amplitude extraction maps.