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Collaborating Authors
Results
Summary Marine controlled-source electromagnetic (MCSEM) surveys have become an important part of offshore hydrocarbon (HC) exploration. Marine sediments may exhibit strong anisotropy of electrical conductivity. Ignoring anisotropy may lead to er- roneous interpretation of MCSEM data. This paper introduces a 3D inversion of MCSEM data for anisotropic distribution of conductivity based on integral formulation of the EM field equations. Simple modification of the Fr´echet derivative ex- pression allows inversion for both horizontal and vertical con- ductivities. This inversion method has been successfully ap- plied to synthetic data computed for a realistic model of the Harding field.
- Europe > United Kingdom > North Sea (0.36)
- North America > United States > North Dakota > McKenzie County (0.35)
- North America > United States > Gulf of Mexico > Central GOM (0.35)
- Africa > South Africa > Western Cape Province > Indian Ocean (0.26)
- Geology > Rock Type > Sedimentary Rock (0.46)
- Geology > Sedimentary Geology > Depositional Environment (0.35)
- Geophysics > Electromagnetic Surveying (1.00)
- Geophysics > Seismic Surveying (0.94)
- North America > United States > Gulf of Mexico > Central GOM > East Gulf Coast Tertiary Basin > Main Pass > Block 287 > Harding Field (0.99)
- Europe > United Kingdom > North Sea > Central North Sea > Crawford Spur > Duplicate field name in UK/GOM. > Block 9/23b > Harding Field (0.99)
- Africa > South Africa > Western Cape Province > Indian Ocean > Bredasdorp Basin > Block 9 > EM Field (0.99)
Summary The structural factor is not decisive in the detection of hydrocarbon deposits within the Jurassic formations of the southern parts of the West Siberian province. A principal possibility of Direct Hydrocarbon Detection (DHI) and mapping of oil-saturated zones within the Middle Jurassic reservoirs is investigated. As a result the DHI methodology including quantitative criterion of separation between oil-saturated and water-saturated zones is discussed. The methodology is based on the amplitude analysis of the 3D seismic data and the information obtained from the log data and well testing.
- North America > United States > California > Sacramento Basin > 4 Formation (0.99)
- Asia > Russia > Siberian Federal District > Tomsk Oblast > West Siberian Basin > Central Basin > Bazhenov Formation (0.99)
- Asia > Middle East > Kuwait > Jahra Governorate > Arabian Basin > Widyan Basin > North Kuwait Jurassic (NKJ) Fields > Marrat Formation > Upper Marrat Formation (0.98)
- Asia > Middle East > Kuwait > Jahra Governorate > Arabian Basin > Widyan Basin > North Kuwait Jurassic (NKJ) Fields > Marrat Formation > Sargelu Formation (0.98)
Summary Electrical resistivity tomography (ERT) as a tool for monitoring the processes and time-related changes in geological environments has made great progress in recent years and has become standard for observing natural phenomena. This method is simple to use and it often provides high-quality results that are well interpreted. Our research is based on observing time-lapse changes of the physical parameters (conductivity, for instance) of joints systems (mostly in crystalline massifs). The primary aim is to develop a monitoring system mostly for the needs of deep repositories of nuclear waste. Geophysical research of such repositories has so far dealt only with one-off research (no time-monitoring) of potential host rock´s properties. Contrary to this, our developed system and methodology is unique in continuously measuring the physical properties (in this case, electrical resistivity) of the rock massif. This system will be permanently fixed in the field and by observing changes in measured data reports if any remarkable occurrence in the EDZ zone is or was happening (for example, opening or closing of the joints or micro-fractures). Today, our monitoring system is being developed and tested at the field base in Bedrichov (northern Bohemia). The Bedrichov gallery is approximately 2.5 km long and continuously leads through one type of granite massif. Point 792, where a significant geological fracture zone goes through, was chosen as an ideal place for taking repeated measurements via our ERT system. Currently, we test the measurement quality, such as whether our system provides real data and is able to reliably observe resistivity changes measured at ERT profiles.
- Water & Waste Management > Solid Waste Management (0.51)
- Energy > Oil & Gas > Upstream (0.47)
- Energy > Power Industry > Utilities > Nuclear (0.36)
- Law > Environmental Law (0.34)
Summary Shale gas is becoming increasingly important exploration and production targets. Geological study has showed that the rich shale in southern China has good quality for exploitation. Due to the unique storage condition and continuous complicated accumulation pattern of shale gas, it is difficult to use conventional geophysical method to predict sweet spots. Complex resistivity (CR) method has been used to detect hydrocarbon for more than ten years, because laboratory studies of measureable induced polarization(IP) effects associated with non-metallic minerals(such as oil and gas), and two IP models were proposed for conventional oil and gas exploration, but this is not the case for shale gas prospecting with CR. In this paper we have found that pyrite plays an important role in the prediction for total organic content (TOC) of shale, and an IP model based on lots of complex resistivity measurements and composition analyses for cores and samples collected from southern China was proposed. The model features that the rich organic shale itself is a strong IP body with low resistivity. With this model CR data can be interpreted effectively in the exploration for shale gas. Application showed that chargeability and resistivity anomalies inverted by CR were in good agreement with the seismic prediction for sweet spots.
- Asia > China > Sanshui Basin (0.99)
- Asia > China > Qinghai > Qaidam Basin (0.99)
- Africa > South Africa > Western Cape Province > Indian Ocean > Bredasdorp Basin > Block 9 > EM Field (0.99)
Summary Many oilfields are in the development stage at present, it has important significance to monitor oil and gas reservoirs using time-lapse electromagnetic. Four continuous electromagnetic profiling (CEMP) lines with 199 stations have been acquired in the Sebei gas field. Remote reference is used to suppress noise during field data acquisition. Data format of 4 frequencies per octave is output to improve the resolution and information of the filed data. High precision two-dimensional magnetotelluric (MT) inversion is adopted to process the data. The inversion results show that, the resolution has been improved with high sampling rate of CEMP data and high precision processing method. It provides technical support for time-lapse MT monitoring. The high resistance characteristic is very clear shown in the inversion profiles of Sebei gas filed. It provides important basis for time-lapse MT monitoring oil and gas reservoir. The inversion results are consistent with the logging curves, and the predicted reservoir area and thickness are consistent with the known wells and the collected data.
- Europe > Norway > Norwegian Sea > Vøring Basin > License 218 > Block 6707/10 > Aasta Hansteen Field > Luva Field > Nise Formation (0.99)
- Europe > Norway > Norwegian Sea > Vøring Basin > License 218 > Block 6706/12 > Aasta Hansteen Field > Luva Field > Nise Formation (0.99)
- Europe > Norway > Norwegian Sea > Vøring Basin > License 218 B > Block 6707/10 > Aasta Hansteen Field > Luva Field > Nise Formation (0.99)
- (2 more...)
- Reservoir Description and Dynamics > Reservoir Characterization (1.00)
- Data Science & Engineering Analytics > Information Management and Systems (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Cross-well tomography (0.71)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Open hole/cased hole log analysis (0.49)
Complex Resistivity Characteristics of High TOC Marine Shale Core Samples and its Applications
Yu, Gang (BGP Inc.) | Hu, Wenbao (Yangtze University) | He, Zhenxiang (BGP Inc.) | Xiang, Kui (Yangtze University) | Hu, Hua (Yangtze University) | He, Lanfang (BGP Inc.) | Wang, Tianping (BGP Inc.) | Li, Pengfei (Yangtze University)
Summary Total Organic Content (TOC) is one of the key and important parameters to effectively evaluate the shale gas formation production potential. According to geological deposition theory, the TOC is the basic key element that controls the form of pyrite in the marine sediment under deep water strong reducing deposition environment. There is a close relationship between the TOC and pyrite in such deep water reducing deposition environment. Through the laboratory measurement and analysis of the complex resistivity on marine shale formation core samples from South China, the high TOC shale reservoir core samples contain more pyrite, and they show clearly low resistivity and high polarization anomaly. In comparison with well log data, the laboratory measurements of TOC and pyrite are closely related to the results from the log data analysis. We concluded that high TOC marine shale formation has the characterization of low resistivity and high induced polarization (IP) anomaly. Based on the research results, the application of the induced polarization or complex resistivity method to measure the subsurface resistivity and polarization anomaly is a new approach to effectively evaluate the TOC content within the shale gas formation, and it has high potential value for future shale gas reservoir evaluation and characterization.
- Geophysics > Borehole Geophysics (1.00)
- Geophysics > Electromagnetic Surveying (0.94)
Summary A fast 1D electromagnetic modeling method for simulating electromagnetic (EM) field in biaxial anisotropic formation is applied to model a practical wireline triaxial induction tool response to fractured formation. The method is validated versus other independent modeling software. Multiple examples are presented to compare the apparent conductivity of transversely isotropic and biaxial anisotropic layered formation. Sensitivity to anisotropic conductivity, bed boundary, dip angle and layer thickness were observed, which implies that failure to consider the biaxial anisotropy would have great impact on interpretation of induction tool response. We discuss particular features which enable visual log interpretation for the presence of possible fractures.
- Africa > South Africa > Western Cape Province > Indian Ocean (0.24)
- Europe > Norway > Norwegian Sea (0.24)
Three-Dimensional Magnetotelluric Inversion and Petrophysical Interpretation of the Turquoise Ridge Gold Deposit, Nevada, USA
Howe, Brendan D. (Barrick Gold Exploration Inc) | Doerner, Bill (SourceOne Geophysical) | Townsend, Jared (Barrick Gold Exploration Inc.) | Patraskovic, Pamela (University of Toronto)
Summary With increasing computer power and the continual research into inversion algorithms and discretization methods, routine three-dimensional (3D) inversion of large, high- resolution magnetotelluric (MT) datasets is now possible. In this study, MT data from the Turquoise Ridge gold deposit has been inverted using the University of British Columbia, Geophysical Inversion Facility’s MT3D suite of algorithms. Resulting 3D models display a low resistivity anomaly spatially correlated with the deposit location. Petrophysical measurements performed on drill core samples, including galvanic resistivity and mass properties, as well as in situ electrical logs are compared with various geological and geochemical data including lithology, alteration, and multi- element geochemistry in order to determine the source of the geophysical anomalism observed in the 3D resistivity model. Comparison of the geological and petrophysical datasets demonstrate that no single variable can be invoked as a control on resistivity. Rather, multiple factors contribute to the apparent resistivity of any given volume of rock within the model. Porosity and specific types of alteration display the strongest correlations with resistivity and furthermore can be tied to gold distribution.
- Geology > Rock Type (1.00)
- Geology > Mineral > Native Element Mineral > Gold (1.00)
- Geology > Geological Subdiscipline (1.00)
- North America > United States > Wyoming > Great Basin (0.99)
- North America > United States > Utah > Great Basin (0.99)
- North America > United States > Oregon > Great Basin (0.99)
- (3 more...)
Summary In this study we demonstrate how incorporating controlled source electromagnetic (CSEM) and magnetotelluric (MT) data in the velocity model building improves seismic depth imaging in sub-basalt settings. We consider data acquired in the Faroe-Shetland basin. The resistivity model obtained from inversion of the electromagnetic (EM) data provides information about sub-basalt structure and resistivity. The EM data can image both the thickness and the extent of basalt layers, as well as the sediments underneath. We update the velocity model using a correlation between resistivity and seismic velocity derived from nearby well data. Our reverse-time migration (RTM) imaging improvements demonstrate the advantage of this integrated approach.
- Asia > Middle East > Yemen (0.94)
- Asia > Middle East > Saudi Arabia (0.94)
- Africa > Sudan (0.94)
- (4 more...)
- Geophysics > Seismic Surveying > Seismic Processing (1.00)
- Geophysics > Seismic Surveying > Seismic Modeling > Velocity Modeling (1.00)
- Geophysics > Electromagnetic Surveying (1.00)
Summary We propose a method for profiling soil permeability on a river embankment with multiple geophysical data. In this method, the unconsolidated sand model and the Glover’s model are employed for modelling seismic velocity - porosity and resistivity - porosity relationships, respectively, in order to obtain a seismic velocity – resistivity model. The clay content as a control parameter of mechanical property of the soil in these two models is used for soil classification with the seismic velocity and resistivity. The grain size representing soil type thus derived and porosity estimated from resistivity by the Glover’s model are input to the Kozeny-Carman equation for estimating permeability of the soil. The proposed method is applied to S-wave velocity and resistivity profiles acquired on an earthen levee to estimate its soil permeability profiles. Comparison of estimated permeability with actual measurements in the laboratory permeability test of the soil shows that permeability can be estimated in accuracy less than one order of magnitude. This result indicates that the proposed method is promising for permeability profiling of soils using geophysical data.