13 research outputs found
Subsurface lithofacies mapping from geophysical logs in Kansas
Stratigraphic tops picked from geophysical logs are basic data in the preparation of regional subsurface maps of structure and thickness. These maps are topological-they are restricted to the display of the shape and size of stratigraphic units. However, the quantitative variation of logs with depth can be analyzed in terms of mineralogy and porosity which express the internal composition of these units. Use of computer-mapping packages in a novel way allows this information to be interpolated from available well control in the generation of lithofacies maps. As a practical example, the composition of the Viola Limestone was mapped in a four-county area in southern Kansas through transformation of data from neutron, density, and sonic logs into estimations of calcite, dolomite, chert, and pore volume. Available cuttings and core information were used both to monitor the result and to provide detailed meaning to observed variation. The map shows facies patterns which are readily related to depositional, diagenetic, and erosional trends. In a second example, the statistical moments of the gamma-ray log were used by a computer program to generate three-dimensional trend maps and cross section slices of shale-sand variation in the Simpson Group of the same area. The results give an immediate picture of the shapes and dispositions of major sandstone and sandy carbonate bodies, as well as outlining the areal pattern of a basal transgressive sand
Lithofacies and geochemical facies profiles from nuclear wire-line logs: New subsurface templates for sedimentary modeling
The use of wire-line logs in subsurface studies is all too often restricted to the correlation of selected stratigraphic horizons. There is an increasing content of valuable geologic information in modern wire-line logs that can be extracted by simple computer processing. The resulting log transformations provide lengthy and continuous records of sections of interest. Examples of these methods, as applied to Cretaceous and Permian stratigraphic case studies, are described here. The log data can be incorporated in either forward- or reverse-modeling modes in the simulation and analysis of sedimentary sequences. In addition to their geologic information content, wire-line logs are quantitative, and so their data can be entered easily into numerical modeling programs. Analysis can be made in either the stratigraphic time or frequency domain. The power spectra of logs give key insights into the nature and scale of sedimentary depositional mechanisms
Subsurface lithofacies mapping from geophysical logs in Kansas
Stratigraphic tops picked from geophysical logs are basic data in the preparation of regional subsurface maps of structure and thickness. These maps are topological-they are restricted to the display of the shape and size of stratigraphic units. However, the quantitative variation of logs with depth can be analyzed in terms of mineralogy and porosity which express the internal composition of these units. Use of computer-mapping packages in a novel way allows this information to be interpolated from available well control in the generation of lithofacies maps. As a practical example, the composition of the Viola Limestone was mapped in a four-county area in southern Kansas through transformation of data from neutron, density, and sonic logs into estimations of calcite, dolomite, chert, and pore volume. Available cuttings and core information were used both to monitor the result and to provide detailed meaning to observed variation. The map shows facies patterns which are readily related to depositional, diagenetic, and erosional trends. In a second example, the statistical moments of the gamma-ray log were used by a computer program to generate three-dimensional trend maps and cross section slices of shale-sand variation in the Simpson Group of the same area. The results give an immediate picture of the shapes and dispositions of major sandstone and sandy carbonate bodies, as well as outlining the areal pattern of a basal transgressive sand
Lithofacies and geochemical facies profiles from nuclear wire-line logs: New subsurface templates for sedimentary modeling
The use of wire-line logs in subsurface studies is all too often restricted to the correlation of selected stratigraphic horizons. There is an increasing content of valuable geologic information in modern wire-line logs that can be extracted by simple computer processing. The resulting log transformations provide lengthy and continuous records of sections of interest. Examples of these methods, as applied to Cretaceous and Permian stratigraphic case studies, are described here. The log data can be incorporated in either forward- or reverse-modeling modes in the simulation and analysis of sedimentary sequences. In addition to their geologic information content, wire-line logs are quantitative, and so their data can be entered easily into numerical modeling programs. Analysis can be made in either the stratigraphic time or frequency domain. The power spectra of logs give key insights into the nature and scale of sedimentary depositional mechanisms
Latent Facies Mapping from Binary Geological Data
This is the published version. Copyright University of Chicago PressMany geological observation sets contain discrete-state data, which can be encoded as binary patterns. When there are conditional relationships between the variables, latent class analysis may be applied to subdivide the total sample into latent facies associations, which have local independence in the probability sense. Probabilities of latent facies assignments can be mapped areally as continuous surfaces of implied geological facies. Latent class analysis is rooted in simple probabilityt heory and can be a useful technique in geological applications where observations are descriptive or weakly numerical. The method is illustrated by a latent facies mapping of the Morrison Formation (Upper Jurassic) in the subsurface of west Kansas
All Models Are Wrong, but Some Models Are Useful: "Solving" the Simandoux Equation
Abstract Log analysis solutions for water saturation in shaly sandstone hydrocarbon reservoirs are elaborations of the Archie equation, with extra terms that accommodate volumes of shale or bound water and their associated electrical properties. There are a large number of alternative shaly sandstone equations that are used today because no uniquely satisfactory solution has been reached. Simpler equation forms run the danger of becoming simplistic, but are robust, comprehensible, and can perform surprisingly well when applied thoughtfully. More complex equations are better functional representations, but involve additional terms which are often difficult to estimate, while introducing more error interactions. With the typical situation of limited subsurface information and the variety of shaly sandstones, the comparative performance of any equation model is debatable. However, if models are used from the point of view of utility, then the calibration within a shaly sandstone reservoir can be made as an optimization problem based on a (provisional) recognition of water zones. By this means, a petrophysical optimum is honored rather than a purely mathematical one. The approach applies a statistical derivation of parameter values from the shaly sandstone reservoir under analysis within the framework of classic shaly sandstone equations that have been proposed from theoretical and laboratory considerations. Prolog: The Archie Equation From empirical observations, where m took different values according to the relative consolidation of the sandstone sample. Unconsolidated sandstones showed low values of m, as contrasted with higher values in consolidated sandstones. This observation led to the informal name for m as the "cementation factor". In later work, particularly following the lead of In the same paper
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GEMINI (Geo-Engineering Modeling through Internet Informatics) is a public-domain web application focused on analysis and modeling of petroleum reservoirs and plays (http://www.kgs.ukans.edu/Gemini/index.html). GEMINI creates a virtual project by ''on-the-fly'' assembly and analysis of on-line data either from the Kansas Geological Survey or uploaded from the user. GEMINI's suite of geological and engineering web applications for reservoir analysis include: (1) petrofacies-based core and log modeling using an interactive relational rock catalog and log analysis modules; (2) a well profile module; (3) interactive cross sections to display ''marked'' wireline logs; (4) deterministic gridding and mapping of petrophysical data; (5) calculation and mapping of layer volumetrics; (6) material balance calculations; (7) PVT calculator; (8) DST analyst, (9) automated hydrocarbon association navigator (KHAN) for database mining, and (10) tutorial and help functions. The Kansas Hydrocarbon Association Navigator (KHAN) utilizes petrophysical databases to estimate hydrocarbon pay or other constituent at a play- or field-scale. Databases analyzed and displayed include digital logs, core analysis and photos, DST, and production data. GEMINI accommodates distant collaborations using secure password protection and authorized access. Assembled data, analyses, charts, and maps can readily be moved to other applications. GEMINI's target audience includes small independents and consultants seeking to find, quantitatively characterize, and develop subtle and bypassed pays by leveraging the growing base of digital data resources. Participating companies involved in the testing and evaluation of GEMINI included Anadarko, BP, Conoco-Phillips, Lario, Mull, Murfin, and Pioneer Resources