3D Seismic Survey Research Articles

П Р И М Е Н Е Н И Е Т Р Е Х М Е Р Н О Й С Е Й С М О Р А З В Е Д К И Д Л Я М О Д Е Л И Р О В А Н И Я Р У Д Н Ы Х З А Л Е

The article deals with the possibility of using seismic exploration in solving problems of ore geology in complex mining and geological conditions of Kazakhstan. The substantiation and characterization of geological and geophysical conditions for conducting experimental 3D seismic surveys at the deposits of the Zhilandinsky group of copper sandstones located in the Karaganda region of Central Kazakhstan are presented. The tasks are defined and the technique of conducting high-resolution 3D seismic exploration is developed, accompanied by modern processing and interpretation complexes for obtaining high-quality seismic materials for solving geological problems: studying the structural and tectonic structure of ore areas, identifying and refining ore-controlling structures, detecting and deep mapping of tectonic faults, volumetric mapping of intrusive massifs. The directions and technology of the process of modeling ore horizons and tracing them in space based on the results of a comprehensive interpretation of three-dimensional seismic exploration and geological and geophysical data, which will significantly increase the reliability coefficient of forecasting ore deposits, are indicated.

Numerical Investigation of Geophysical Monitoring Based Upon Co2 Geological Storage and Leakage

In this study, we conducted numerical simulations on long-term behaviour of CO2 injected into a saline aquifer and resulting changes of geophysical data to investigate which combination of the methods and measurement locations will be effective for the CCS monitoring based upon hypothetical CO2 geological storage and leakage calculations. Predicted geophysical data include seismic reflection, microgravity, and seafloor surface displacement. Simulated results indicated that time-lapse 3D seismic reflection surveys will be a primarily reliable tool for the CCS monitoring, while other methods also can provide additional and/or complementary data which will be helpful for a decision of whether to conduct a close investigation using methods with more cost. These investigations will be useful for constructing efficient and effective monitoring network for the future planning of CCS project.

CO2 storage monitoring using 3-axis borehole gravity

Carbon capture and storage underground (CCS) is now regarded as a vital and significant means to achieve 3 of the 4 IPCC pathways necessary to limit global warming to 1.5degC. Our internal analysis indicates the number of wells required to facilitate the levels of CO2 capture to meet these objectives are numerous over the next 30 years. An understanding of containment is essential for CO2 storage, but few options exist to monitor a CO2 plume growth 100's of metres away from a well. Gravity is a direct measurement of density, through substitution of water by CO2. The gravity measurement detects changes in mass in the subsurface, such that time-lapse wireline-based surveys may be taken to build up a picture of fluid movements at 100’s of meters from the wellbore. By measuring gravity in all three-axis it is possible to determine directional information about the spatial movement of fluid, even when acquired from just a single borehole. We present emerging 3-axis borehole gravity technology that enables the recording of gravitational acceleration at very high sensitivity (targeted at ≈ 5 µGal) using an innovation in resonant Microelectromechanical system (MEMS) vibrating beam technology with the aim of making small, cheap, but highly stable and highly sensitive field and borehole-deployable relative gravimeters. The vibrating beam gravimeter consists of a suspended mass connected to a vibrating beam, such that the inertial force experienced by the mass in gravitational field is communicated as an axial load on the beam. The technology is currently undergoing field trials as part of the CCP* and we show the results of a feasibility study aimed at monitoring CO2 in a deep storage reservoir in Canada which shows the gravity variation likely to be seen due to density changes during a period of CO2 injection. The displacement and substitution of the aquifer water at the storage site over time is referred to as a 4D gravity survey. The cost effectiveness of a 4D wireline gravity survey compared to 4D seismic survey is highly attractive in smaller carbon storage programs. Where the project size or complexity allow both to be run, the complementary nature of the measurements has been noted by several operators. Survey feasibility modelling and a workflow are presented that together provide important information for planning and acquiring a successful gravity survey, as well as the best time interval (given the planned injection rate), and which well location is most suitable to use. The workflow for conducting borehole gravity simulations from time-lapse reservoir models starts with a 3D model of reservoir porosity, saturation and fluid constituent density, which is used to generate a time-lapse density model from the provided set of reservoir simulation data. Vector gravity anomaly responses (gz, gx, and gy) along the wellbore in a variety of well locations are then predicted through forward modelling. The density changes due to fluid substitution are measured by the vertical, gz, gravity anomaly with respect to the reference gravity field. The fluid front progress through the field is assessed through the horizontal gravity anomalies (gx, and gy). Modelling shows plume growth is detectable even over a period of 1 year (Figure 1) and with MEMS technology lifetime monitoring is possible. We conclude that this emerging technology has the potential to provide a solution for long term monitoring of CO2 plume growth within the likely numerous wells that may be needed to fill the CO2 storage requirements resulting from the IPCC pathway scenarios to 1.5degC.

The tectono-magmatic and subsidence evolution during lithospheric breakup in a salt-rich rifted margin: Insights from a 3D seismic survey from southern Gabon

In this study, we present an interpretation of a 3D depth-migrated dataset imaging the Ocean Continent-Transition (OCT) of the southern Gabon margin. Located in an area where salt is not strongly overflowing the OCT, it allows the geometrical relationships of salt deposition and its relative timing to breakup to be determined. The OCT is formed by extensional propagators floored by exhumed mantle limited by either fault-bounded upper-crustal or pre-salt sediments and/or magmatic additions. Based on our interpretations, we conclude that the pre-salt sequence was deposited over a wide area spanning crustal thinning to the onset of hyperextension and exhumation. The relative timing of salt deposition is constrained by the observations that detachment faults break away in the pre-salt sequence and that some of these faults also strongly offset the base salt and are linked to the creation of accommodation space in the salt. This is direct proof that salt was deposited during mantle exhumation. Salt deposition is interpreted to have occurred at variable depths. Evaporites formed approximately 1 km below sea level in the north, above a 4–6 km thick pre-salt sequence, and as deep as 2 km in the south. In this area, salt is interpreted to directly overlie exhumed mantle, but whether it was deposited on mantle or juxtaposed during exhumation remains more debatable. Space created in the faulted outer trough was filled partly by autochthonous salt and possibly also by downslope flow. Rifting continued after the cessation of salt deposition, followed by magmatic additions in the outer high and ultimately the onset of seafloor spreading and the formation of Penrose oceanic crust.

Characterization of a Karst Site using Electrical Resistivity Tomography and Seismic Full Waveform Inversion

Karst geology is characterized by the presence of sinkholes and voids, which may pose significant risk to existing infrastructure. Sinkhole formation is often observed near active quarries, where dewatering operations can alter regional groundwater flow patterns leading to subsidence and increased void formation. In these areas, identifying locations which may be susceptible to sinkhole formation requires an ability to map dissolution features within the rock. Traditional geotechnical explorations alone are not well-suited to this effort as they only provide subsurface information at discrete points and therefore may miss voids within the rock. Geophysical methods offer a means to produce continuous profiles of the rock surface and possible locations for voids but interpreting the results of these tests in karstic geology can be challenging. This study uses 2D electrical resistivity and seismic surveys at a site with previous sinkhole activity along an interstate in central Alabama. The site is adjacent to a limestone quarry. Resistivity data is collected using 2D dipole-dipole and strong-gradient arrays. The seismic data is processed using a full waveform inversion (FWI) technique. Subsurface profiles interpreted from the geophysical surveys are then compared to borehole data from previous site investigations. Results from the geophysical surveys are found to be consistent with borehole data regarding variation of bedrock depth and identification of possible sinkhole features. Potential limitations and sources of error pertaining to each survey type are considered.

Introduction to this special section: Basin exploration

Originally, explorers relied on hydrocarbon seeps and 2D seismic lines to define a basin's petroleum potential and to identify its best part. Due to dramatic improvements in seismic technology, today's explorers have access to a vast seismic tool kit, from basin-scale regional 3D seismic surveys to neural network techniques that directly derive reservoir properties from seismic volumes. However, in frontier or mature exploration, geoscientists are often limited by the amount of well data and rock properties information available, and they may deal with poor(er) seismic that makes seismic calibration difficult. Successful explorers will require a lot of knowledge-based creativity to derive meaningful geologic and reservoir properties models to reduce exploration risk. By embracing uncertainties, explorers develop “outside-the-box” thinking to help them chase the hydrocarbon molecules and unlock the prize. With their knowledge in rock physics, subsurface deformation, and wave propagation, geoscientists are deploying new methodologies and tools to fill the data gap and produce an improved description of the subsurface.

Indications of sandstone-type uranium mineralization from 3D seismic data: a case study of the Qiharigetu deposit, Erenhot Basin, China

The primary exploration objective of Qiharigetu Sandstone-type Uranium (SU) deposit in the Erenhot Basin of China is to understand the stratigraphy, lithology and fault distribution of the target layer. Various geophysical techniques including gravity, magnetic, electromagnetic and 2D seismic have been proved not very effective due to its shallow depth of burial and small geophysical differences between layers. A specific 3D seismic survey of the Qiharigetu SU deposit has been carried out, and the inferred geological features of the uranium mineralization could provide important references for subsequent drilling programs. It is deduced that the target layer in the central part of the study area has a local "depression" through 3D seismic imaging and interpretation, which is conducive to river runoff and formation of sand body, as the sand body is a necessary precondition for mineralization. There are faults (5–50 m in throw) striking north–south for around 2 km, and it is an important ore-controlling factor, which could provide channels for the rise of reducing agents (such as gas, H2S, and coalbed methane) at depth as they can promote the redox reaction for mineralization. The 3D seismic inversion is used to estimate the impedance, lithology, sand content and porosity of the target layer. With the help of drilling verification, it is found that the area with sand content over 75% and porosity over 10% is favorable for the SU deposit. Compared with other geophysical techniques, 3D seismic method is able to provide high-resolution images for unraveling SU mineralization and thereby reduce the drilling risk of the SU deposit.

Sparse 3D reflection seismic survey for deep-targeting iron oxide deposits and their host rocks, Ludvika Mines, Sweden

Abstract. Many metallic mineral deposits have sufficient physical property contrasts, particularly density, to be detectable using seismic methods. These deposits are sometimes significant for our society and economic growth and can help to accelerate the energy transition towards decarbonization. However, their exploration at depth requires high-resolution and sensitive methods. Following a series of 2D seismic trials, a sparse, narrow source–receiver azimuth, 3D seismic survey was conducted in the Blötberget mine, in central Sweden, covering an area of approximately 6 km2 for deep-targeting iron oxide deposits and their host rock structures. The survey benefited from a collaborative work by putting together 1266 seismic recorders and a 32 t vibrator, generating 1056 shot points in a fixed geometry setup. Shots were fired at every 10 m where possible, and receivers were placed at every 10–20 m. Notable quality data were acquired despite the area being dominated by swampy places as well as by built-up roads and historical tailings. The data processing had to overcome these challenges for the static corrections and strong surface waves in particular. A tailored for hardrock setting and processing workflow was developed for handling such a dataset, where the use of mixed 2D and 3D refraction static corrections was relevant. The resulting seismic volume is rich in terms of reflectivity, with clear southeast-dipping reflections originating from the iron oxide deposits extending vertically and laterally at least 300 m beyond what was known from available boreholes. As a result, we estimate potential additional resources from the 3D reflection seismic experiment on the order of 10 Mt to be worth drilling for detailed assessments. The mineralization is crosscut by at least two major sets of northwest-dipping reflections interpreted to dominantly be normal faults and to be responsible for much of the lowland in the Blötberget area. Moreover, these post-mineralization faults likely control the current 3D geometry of the deposits. Curved and submerged reflections interpreted from folds or later intrusions are also observed, showing the geological complexity of the study area. The seismic survey also delineates the near-surface expression of a historical tailing as a by-product of refraction static corrections, demonstrating why 3D seismic data are so valuable for both mineral exploration and mine planning applications.

Characteristics and origins of ridges and troughs on the top of the Middle Miocene strata in the Beijiao Sag of the Qiongdongnan Basin, northern South China Sea

Sedimentary structures generated by (deepwater) bottom currents are of interest to geologists. Based on the root mean square, coherence attribute, and 3D representations, ridges and troughs are imaged for the first time using 3D high-resolution seismic data and confirmed by a well, YL19-1-1, in the Beijiao Sag of the Qiongdongnan Basin. Combined with 2D seismic profiles, we define the flow direction of bottom currents resulting in ridges and troughs. The results indicate that ridges and troughs occur on the top of the Middle Miocene strata and dominantly present wave-shaped structures. Their magnitudes decrease toward the upper and lower slopes. They extend for tens of kilometers, dominantly parallel to one another, with an evenly spaced distribution, some of which locally merge and bifurcate. They are aligned obliquely to the regional slope. The internal ridges are characterized by internal mounded reflections and/or parallel underlying-strata reflections. The presence of polygonal faults and weak to moderate amplitudes within the ridges and troughs suggests that they consist of fine-grained mudstones, as confirmed by the well YL19-1-1. High amplitudes filled within troughs are probably composed of coarse-grained turbidite materials, where polygonal faults are inhibited. Truncations and onlaps occur along the thalweg of a trough and are also clearly observed on the flanks of ridges and the walls of troughs. We infer that the troughs are a product of the erosion of bottom currents and the ridges are remnant underlying (sediment waves) strata as a result of the redeposition of eroded sediments. In addition, troughs are filled by turbidite materials with high amplitudes in the southwestern area of the 3D seismic survey, where ridges and troughs are a combined result of the early erosion by bottom currents and the later reworking by turbidity flows. We have developed conceptual schematic models to indicate the evolutionary history of the ridges and troughs. It provides new insights into the further understanding of the erosional and depositional impacts of bottom currents.

Technologies for efficient development of hydrocarbon resources on the Arctic and sub-Arctic shelf of Russia

This article discusses the technical capabilities and results of the application of modern technologies for geological exploration, well drilling, development and operation of offshore oil and gas fields on the Arctic and sub-Arctic shelf of Russia. Based on the scientific and production experience of the authors, analysis of the results of search and exploration in the seas of the Arctic and the Far East, a consistent system of technologies for geological exploration is proposed. The use of such an integrated set made it possible to discover large and unique oil and gas fields in the Barents-Kara region (Medynskoe-more, Dolginskoe, Varandey-more, Kamennomysskoe and others). The features of geophysical work and technologies for achieving high quality seismic material the transition zone (land-sea) in the Ob bay, where due to the presence of permafrost in the upper part of the geological section, there is a significant change in the velocities and absorbing properties of rocks, are shown. Using the example of the Varandey-more field, a technology for integrating 3D deep-sea seismic data and seismic surveys in the land-sea transition zone is described, which made it possible to update the geological model of the field, detail the structural plans of oil-bearing horizons. As a result, after the completion of the interpretation of the survey data in the transit zone, it was recommended to drill an exploration well in the southern part of the field. It has been substantiated that the efficient shelf field exploitation is ensured through the use of new technologies (drilling of long horizontal wells; 4D seismic surveys at the Piltun-Astokhskoye and Lunskoye fields; well designs providing high gas production rates; subsea production at the Kirinskoye field).

Seismic Signature of Transition Zone (Wolf Ramp) in Shale Deposits with Application of Frequency Analysis

The concept of a transition zone, known as Wolf ramp, was incorporated into the seismic interpretation of a 3D seismic survey situated within the Baltic Basin (Northern Poland). Within the survey area, there exists one formation, the Pasłęk Formation, (Lower Silurian—Llandovery), that exhibits a linear change of velocity. This characteristic—linear change of velocity—causes a reflection coefficient (i.e., seismic amplitude) produced at such a boundary to be frequency dependent. The Pasłęk Formation was considered to be a potential shale gas reservoir and it was necessary to determine its structural position and thickness. The formation is challenging for robust seismic interpretation on the migrated seismic section—it does not manifest a stable reflection coefficient, and the amplitude contrast associated with the borders of the formation is low. There is no impedance contrast that would produce a reflection of high amplitude at the top or base of the formation which excludes determination of the formation thickness, hence the estimation of reservoir volume. Within a 3D dataset, there exists only one well with complete logs that were used for the analysis. The Pasłęk Formation is a flat-lying layer that continues itself far beyond the 3D survey. It is present in wells in the vicinity of the study area. These wells lay within other 3D or 2D datasets, but the quality of the seismic is poor, and similar seismic analysis is not possible. Nevertheless, these wells were incorporated in the research to reason about the possible link between the existence of transition zone and mineral content. The method used for recognition of transition zone is spectral decomposition and spectral analyses. The integrated studies enabled us to find a link between the Wolf ramp and mudstone-claystone interval of the Silurian age and give a new example of a transition zone which is present in shale plays. The transition zone concept might be applied for shale plays identification and analysis.

МЕТОД РЕГИОНАЛЬНОГО ПРОГНОЗА НЕФТЕГАЗОНОСНОСТИ ТЕРРИТОРИЙ АЛГОРИТМАМИ МАШИННОГО ОБУЧЕНИЯ НА ПРИМЕРЕ ТЮМЕНСКОЙ СВИТЫ ЗАПАДНОЙ СИБИРИ

Актуальность исследования обусловлена сокращением фонда структурных ловушек и необходимостью расширения ресурсной базы углеводородов за счет повышения эффективности поиска и разведки месторождений в сложнопостроенных залежах нефти и газа. Цель: на примере прогноза нефтегазоносности территории исследования показать методику прогноза и набор применяемых технологических решений и алгоритмов. Объект: отложения средней юры (тюменская свита) Западной Сибири в пределах района (700×900 км), включающего в себя части Ямало-Ненецкого и Ханты-Мансийского административных округов и Томской области. Методы. С помощью алгоритмов машинного обучения и комплексирования технологического набора методов (геоинформатики, бассейнового моделирования, экспертных оценок) показаны следующие этапы реализации методики прогноза: 1) генерирование признакового пространства изучаемой территории на основе повышения пространственного разрешения структурных построений с применением алгоритмов генеративно-состязательной архитектуры нейронных сетей, где в качестве эталонных участков использованы результаты сейсморазведки 3D; 2) отбор признаков статистическим методом и методами машинного обучения; 3) создание подмножества моделей прогноза на основе градиентного бустинга над решающими деревьями; 4) объединение их в метамодель путем стекового обобщения логистической регрессией. Результаты. Формализован и апробирован подход к региональному прогнозу. Сделан прогноз вероятности нефтегазоносности тюменской свиты на изучаемой территории. На его основе и информации по открытым месторождениям оценена методом Монте-Карло ресурсная база УВ. Результаты представлены в виде суммарной таблицы геологических и извлекаемых ресурсов для вероятностей Р10, Р50, Р90 в сравнении с категориями запасов АВС1 и АВС1+С2 месторождений, числящихся на государственном балансе на территории исследования. В качестве примера приведены графические материалы результатов: работы алгоритма повышения пространственного разрешения; моделирования осадконакопления; моделирования миграции УВ; карта прогноза перспектив нефтегазоносности для северной части Надымского и Пуровского нефтегазовых районов.

Integrated reservoir characterization based on a comprehensive study of the geological structure using 3D seismic survey

The 3D seismic survey is the undisputed leader among tools of identifying potential exploration targets and reservoir characterization. This paper shows surveys that are crucial in the exploration and development of significant amounts of hydrocarbon resources, and enables operator companies to map complex geological structures and select better drilling locations. The purpose of the research is to have better understandings of formations and update previous studies in the oil field of Mangyshlak Basin, Western Kazakhstan. The Main results are the acoustic impedance, Vp/Vs ratio, lithological and reservoir properties data. The quality controls and analysis of results show a good match with well logs and good recovery of seismic signal in inversion, but it should be improved in some areas. The results, from a scientific point of view, expand the already known geological and geophysical studies of the reservoir and improve the quality of interpretation using seismic methods in studying the sedimentation environment.

Wyoming CarbonSAFE: Advancing Commercialization of Low-Carbon Energy Technologies in Fossil-Rich Wyoming

Wyoming’s Powder River Basin (PRB) is the most prolific coal producer and exporter in the United States and the State of Wyoming’s largest oil-producing basin. In addition to being a leading energy producer, the PRB is the site of research programs whose aim is to develop and integrate low-carbon technologies into existing fossil fuel energy industries. Much of the PRB’s low-carbon research is focused around Dry Fork Station (DFS), which is the newest coal-fired power station in the western US. Currently, DFS hosts five carbon capture projects, including pilot-scale capture projects that utilize different capture technologies and a full front-end engineering and design (FEED) study, a commercial CO2 pipeline for nearby CO2-enhanced oil recovery industry, and is also co-located with the Wyoming Integrated Test Center, which is a host facility for unconventional carbon utilization research (i.e. flue gas carbon-to-products innovations). DFS is also the host site for the Wyoming CarbonSAFE project. Wyoming CarbonSAFE, funded by the Department of Energy/National Energy Technology Laboratory, is a multi-phased program (currently in Phase II) whose core objective is developing and validating storage sites within a complex capable of storing 50 million metric tonnes of CO2 over a 30 year project period using carbon capture, utilization and storage (CCUS). This paper will provide an overview of the project to-date, showing that CarbonSAFE goals are achievable with respect to geologic, environmental, regulatory, CO2 source and economic conditions, and why the State of Wyoming offers one of the more favorable environments to advance the commercialization studies. In 2019, the project team designed and completed a ~10,000 foot stratigraphic test well just south of DFS. From this well, the team collected over 600 feet of core, fluid samples from target injection zones, and a full petrophysical log suite. In addition, legacy 2D seismic lines were acquired and a 3D seismic survey was acquired in the fall of 2020. The objective of these field activities has been to identify and characterize target storage reservoirs and associated caprock. This complex has several reservoirs that could meet commercial injection goals, and over 4000 feet of associated caprock. Simulations of site performance suggest that stacked injection provides the most effective storage strategy, and would necessitate several sites within the greater complex to meet final project injection goals. Other work within this project includes the development of a business-case around proximal fields with CO2-enhanced oil recovery potential and existing tax credits, assessment of regulatory conditions, including pore space ownership and Class VI injection well permitting requirements, implementation of a robust public outreach program, and surface site characterization activities that have focused on environmental factors. In the PRB and at DFS, the State of Wyoming and other entities have made carbon management a priority of its future energy industry by providing a regulatory and business framework that is favorable to advancing these technologies. These endeavors will become more realistic with the successful implementation of Wyoming CarbonSAFE, and its ability to secure and validate commercial-scale CCUS at the center of Wyoming’s premier low-carbon research efforts.

Application of CO2 injection monitoring techniques for CO2 EOR and associated geologic storage

The Energy & Environmental Research Center (EERC), through its efforts leading the Plains CO2 Reduction (PCOR) Partnership, has successfully developed practices and technologies that can be used in future commercial-scale CO2 storage projects in different geologic formations, including both dedicated CO2 storage in saline formations and associated CO2 storage incidental to enhanced oil recovery (EOR). In this work, reservoir monitoring activities have been conducted in a large-scale CO2 EOR project to understand performance and associated storage. The activities include pulsed-neutron well logs (PNLs), 4D (time-lapse 3D) seismic surveys, and numerical simulation of injection and production. This enabled monitoring at different scales, from individual wells to field-scale reservoir assessments. The oil, water, and CO2 saturations were profiled to identify bypassed oil and high-conductivity CO2 migration pathways in the reservoir. These techniques provided actionable information, enabling better management of CO2 flooding, diagnosing performance and sweep efficiency while ensuring injected CO2 remained within the reservoir.

Controls on gravity-driven normal fault geometry and growth in stacked deltaic settings: a case study from the Ceduna Sub-basin

Kinematics of gravity-driven normal faults exerts a critical control on petroleum systems in deltaic settings but to date has not been extensively examined. The Ceduna Sub-basin (CSB) is a passive margin basin containing the White Pointer (Albian-Cenomanian) and Hammerhead (Campanian-Maastrichtian) delta systems that detach on shale layers of Albian-Cenomanian and Turonian-Coniacian ages, respectively. Here we present evidence for spatially variable fault growth styles based on interpretation of the Ceduna 3D seismic survey and fault kinematic analyses using displacement–distance, displacement–depth and expansion index methods. We identified faults that continuously grew either between the Cenomanian–Santonian or Santonian and the Maastrichtian located throughout the study area and faults that exhibit growth between the Cenomanian–Maastrichtian that are geographically separated into three areas according to their evolution histories: (i) Northern CSB faults exhibit constant growth between the Cenomanian and Maastrichtian. (ii) Central CSB faults show two dip-linkage intervals between (a) Cenomanian and Coniacian–Late Santonian, (b) Coniacian–Late Santonian and Late Santonian–Maastrichtian segments, respectively. (iii) Central and southern CSB faults exhibit dip-linkage intervals between Cenomanian–early Santonian and Late Santonian–Maastrichtian segments. Our study demonstrates a relationship between the location of the Cenomanian–Maastrichtian faults and their evolution history suggesting constant growth evolution at north and dip linkage at the central and south areas.

The CarbonNet Pelican 3D seismic survey – A first for Australia’s offshore greenhouse gas storage

The CarbonNet Pelican 3D seismic survey – A first for Australia’s offshore greenhouse gas storage

Joint analysis of seismic and well log data applied for prediction of oil presence in Maykop deposits in Naftalan area

<abstract> <p>The paper is devoted to joint application of 3D seismic survey and well logging techniques to study oil and gas presence in Maykop deposits in Naftalan oil field. The field is located in Naftalan-Northern Naftalan area of Ganja oil and gas province, Azerbaijan. The paper brings data about Naftalan field, the ancient brachianticline type of field in Azerbaijan. The paper also considers the history of study of the field by use of geological and geophysical techniques. Despite the studies cover the area since 1873, the oil and gas presence in Maykop has not been studied sufficiently due to sparse network of wells and insufficient amount of core samples. To avoid this gap the results of previous studies have been revised. Joint interpretation of well logging data acquired from 22 wells and data of 3D seismic survey covering the area has been done. On the basis of oil-saturation cube, we have designed the map (the area between the top and the foot of I horizon of Maykop) and 3D model of target interval. It has been defined that uneven distribution of oil saturation and poor oil recovery depends also on sedimentation environment, characterized by rapid subsidence of the basin and increasing amount of clay in the process of sedimentation. Our studies revealed that the average value of oil saturation varies as 0.5–0.6 and increases towards the North-East of the study area. In the final stage of the study we have presented the oil saturation cube and the map drawn on the basis of this cube.</p> </abstract>

3D seismic survey data processing and interpretation by use of latest tools applied for discovery of new traps in Pleistocene deposits of Hovsan field

<abstract> The paper is devoted to outlining of hydrocarbon traps in Absheron suite by use of seismostratigraphy, standardless classification, taxonomy and attribute analysis. The paper gives a brief description of area under the study, its geographical position and research history. Correlation of seismic horizons traced within interval of seismic record embracing Absheron suite has been analyzed in detail. It has been noted that Absheron suite is rich with oil and gas deposits, which has been evidenced by discovery of fields located near to the study area. Six seismic horizons were picked off within the limits of target deposits. The described methodology of study reveals the essence of applied standardless classification and taxonomy. Analysis of dynamic parameters of seismic record led to outlining of amplitude anomalies related to zones of development of stratigraphic traps attributed to unconformity surfaces. Three such zones have been outlined. Classification and taxonomy cubes have been designed for the interval of Absheron suite. The internal structure of studied series is well traced in sections of "Classification" and "Taxonomy". Classification results allowed to outline traps characterized by abnormal grouping of some classes. Three "bright spot" anomalies are outlined in the Absheron deposits. Seismic anomalies are well correlated with sedimentation environment favorable for evolution of stratigraphic traps. The area of anomalies is 10.1 sq.km in summary. Burial depth of these anomalies is 450–950 m. Earlier drilled wells did not recover studied anomalies. </abstract>

New insights into the deep-water Otway Basin – Part 3. Petroleum system modelling

The Otway Basin is a broadly northwest–southeast trending basin and forms part of a rift system that developed along Australia’s southern margin. It represents an established hydrocarbon province with mostly onshore and shallow-water offshore discoveries. However, the outboard deep-water Otway Basin, with water depths up to 6300m, is comparatively underexplored and can be considered a frontier area. Following the completion of a basin-wide seismic depth-imaging program (Part 1) and insights from the revised seismic interpretation (Part 2), we have developed a comprehensive petroleum system modelling (PSM) study by integrating these data and findings (Part 3). Together, the studies have resulted in an improved understanding of the hydrocarbon prospectivity of the deep-water areas of the basin. Given the sparsity of data outboard, almost all legacy PSM studies have been focused either on the onshore or shallow-water areas of the basin and primarily on their thick Lower Cretaceous depocentres. The limitations of legacy seismic datasets resulted in a high degree of uncertainty in the derivative interpretations used as input into PSM studies. In addition, the paucity and poor quality of data in the deep-water area reduced confidence in the understanding of the basin evolution and spatial distribution of depositional environments through time. The newly acquired 2D seismic survey and reprocessed legacy data, with calibration via several wells across the basin, have improved confidence in our understanding of the tectonostratigraphic evolution of the basin (Part 2). The study presented herein integrates products from the work in Part 2 into a petroleum system model with the primary objective being to better understand the petroleum systems across the deep-water Otway Basin.