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

Improving Geologic and Engineering Models of Midcontinent Fracture and Karst-Modified Reservoirs Using New 3-D Seismic Attributes

Our project goal was to develop innovative seismic-based workflows for the incremental recovery of oil from karst-modified reservoirs within the onshore continental United States. Specific project objectives were: (1) to calibrate new multi-trace seismic attributes (volumetric curvature, in particular) for improved imaging of karst-modified reservoirs, (2) to develop attribute-based, cost-effective workflows to better characterize karst-modified carbonate reservoirs and fracture systems, and (3) to improve accuracy and predictiveness of resulting geomodels and reservoir simulations. In order to develop our workflows and validate our techniques, we conducted integrated studies of five karst-modified reservoirs in west Texas, Colorado, and Kansas. Our studies show that 3-D seismic volumetric curvature attributes have the ability to re-veal previously unknown features or provide enhanced visibility of karst and fracture features compared with other seismic analysis methods. Using these attributes, we recognize collapse features, solution-enlarged fractures, and geomorphologies that appear to be related to mature, cockpit landscapes. In four of our reservoir studies, volumetric curvature attributes appear to delineate reservoir compartment boundaries that impact production. The presence of these compartment boundaries was corroborated by reservoir simulations in two of the study areas. Based on our study results, we conclude that volumetric curvature attributes are valuable tools for mapping compartment boundaries in fracture- and karst-modified reservoirs, and we propose a best practices workflow for incorporating these attributes into reservoir characterization. When properly calibrated with geological and production data, these attributes can be used to predict the locations and sizes of undrained reservoir compartments. Technology transfer of our project work has been accomplished through presentations at professional society meetings, peer-reviewed publications, Kansas Geological Survey Open-file reports, Master's theses, and postings on the project website: http://www.kgs.ku.edu/SEISKARST

FIELD DEMONSTRATION OF CARBON DIOXIDE MISCIBLE FLOODING IN THE LANSING-KANSAS CITY FORMATION, CENTRAL KANSAS

A pilot carbon dioxide miscible flood was initiated in the Lansing Kansas City C formation in the Hall Gurney Field, Russell County, Kansas. Continuous carbon dioxide injection began on December 2, 2003. By the end of December 2004, 11.39 MM lb of carbon dioxide were injected into the pilot area. Carbon dioxide injection rates averaged about 242 MCFD. Vent losses were excessive during June as ambient temperatures increased. Installation of smaller plungers in the carbon dioxide injection pump reduced the recycle and vent loss substantially. Carbon dioxide was detected in one production well near the end of May and in the second production well in August. No channeling of carbon dioxide was observed. The GOR has remained within the range of 3000-4000 for most the last six months. Wells in the pilot area produced 100% water at the beginning of the flood. Oil production began in February, increasing to an average of about 2.35 B/D for the six month period between July 1 and December 31. Cumulative oil production was 814 bbls. Neither well has experienced increased oil production rates expected from the arrival of the oil bank generated by carbon dioxide injection

Field Demonstration of Carbon Dioxide Miscible Flooding in the Lansing-Kansas City Formation, Central Kansas

Progress is reported for the period from January 1, 2002 to March 31, 2002. Technical design and budget for a larger (60-acre, 24.3 ha) CO2 demonstration project are being reviewed by the US DOE for approval. While this review process is being conducted, work is proceeding on well testing to obtain reservoir properties and on the VIP reservoir simulation model to improve model prediction and better understand the controls that certain parameters exert on predicted performance. In addition, evaluation of the economics of commercial application in the surrounding area was performed. In a meeting on January 14, 2002 the possibility of staging the demonstration, starting with a 10-acre sub-pattern flood was raised and the decision made to investigate this plan in detail. The influence of carbon dioxide on oil properties and the influence of binary interaction parameters (BIP) used in the VIP simulator were investigated. VIP calculated swelling factors are in good agreement with published values up to 65% mole-fraction CO2. Swelling factor and saturated liquid density are relatively independent of the BIP over the range of BIPs used (0.08-0.15) up to 65% mole-fraction CO2. Assuming a CO2 EOR recovery rate projected as being most likely by current modeling, commercial scale CO2 flooding at $20/BO is possible in the leases in Hall-Gurney field. Relatively small floods (240-320 acres, 4-6 patterns) are economically viable at$20/BO in areas of very high primary and secondary productivity (>14 MBO/net acre recovery). Leases with moderately high primary and secondary productivity (> 10 MBO/net acre recovery) can be economic when combined with high productivity leases to form larger floods (>640 acres, 9 or more patterns)

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