Paleotectonic control of reservoir facies

The basement structural fabric of the Paradox basin affected sedimentary facies throughout Phanerozoic time. Continental-scale basement wrench-fault zones were rejuvenated repeatedly throughout the Paleozoic. The Paradox pull-apart evaporite basin was formed along the northwest-southeast-trending Paradox-Wichita lineament in Middle Pennsylvanian time, facilitated by basement faults of the northeast-southwest-trending Colorado lineament. Structurally controlled shoaling conditions, formed by reactivation of basement faults, fostered marine sandstone reservoirs in Late Devonian time, crinoidal buildups in the Early Mississippian, and phylloid-algae mounds in Middle Pennsylvanian time. Apparently similar basement wrench-fault zones are present in Kansas. The midcontinent rift system is a north-northeast-south-southwest-trending fault zone that was reactivated during the Paleozoic. Northwest-southeast-trending faults along the Central Kansas-Bourbon arch complex appear to have offset structures of the midcontinent rift. Both trends are interpreted to be continental-scale conjugate wrench-fault zones with sinistral displacement along the midcontinent rift and dextral displacement along the Central Kansas-Bourbon arch complex. Stratigraphic relationships suggest repeated reactivation before Pennsylvanian uplift and erosion along the major structures. In both regions major structural lineaments are associated with smaller-scale fault patterns. Reactivation of these structures through time created paleotectonic trapping conditions at several stratigraphic intervals. Evidence is accumulating in Kansas that tectonically controlled paleotopography and paleobathymetry are major predictable factors in reservoir localization. Recognition of reactivated basement structural fabrics can provide* significant constraints on reservoir characterization and modeling

Paleotectonic control of reservoir facies

The basement structural fabric of the Paradox basin affected sedimentary facies throughout Phanerozoic time. Continental-scale basement wrench-fault zones were rejuvenated repeatedly throughout the Paleozoic. The Paradox pull-apart evaporite basin was formed along the northwest-southeast-trending Paradox-Wichita lineament in Middle Pennsylvanian time, facilitated by basement faults of the northeast-southwest-trending Colorado lineament. Structurally controlled shoaling conditions, formed by reactivation of basement faults, fostered marine sandstone reservoirs in Late Devonian time, crinoidal buildups in the Early Mississippian, and phylloid-algae mounds in Middle Pennsylvanian time. Apparently similar basement wrench-fault zones are present in Kansas. The midcontinent rift system is a north-northeast-south-southwest-trending fault zone that was reactivated during the Paleozoic. Northwest-southeast-trending faults along the Central Kansas-Bourbon arch complex appear to have offset structures of the midcontinent rift. Both trends are interpreted to be continental-scale conjugate wrench-fault zones with sinistral displacement along the midcontinent rift and dextral displacement along the Central Kansas-Bourbon arch complex. Stratigraphic relationships suggest repeated reactivation before Pennsylvanian uplift and erosion along the major structures. In both regions major structural lineaments are associated with smaller-scale fault patterns. Reactivation of these structures through time created paleotectonic trapping conditions at several stratigraphic intervals. Evidence is accumulating in Kansas that tectonically controlled paleotopography and paleobathymetry are major predictable factors in reservoir localization. Recognition of reactivated basement structural fabrics can provide* significant constraints on reservoir characterization and modeling

The Permian System in Kansas

Rocks of Permian age in Kansas were first recognized in 1895, and by the early 21st century the internationally accepted boundary between the Permian and the Carboniferous (Pennsylvanian Subsystem) was recognized in Kansas at the base of the Bennett Shale Member of the Red Eagle Limestone. The upper boundary of the Permian is an erosional unconformity that is overlain by rocks of Cretaceous age. Currently accepted stratigraphic nomenclature for the Permian of Kansas recognizes the Wolfcampian, Leonardian, and Guadalupian Series, and the lithostratigraphic formations within each of these series reflect a wide spectrum of depositional environments. Summaries of the lithofacies, thicknesses, depositional environments, and source areas of, and for, the rocks in each series provide a basis for inferring the history of the Permian in Kansas as currently understood. Fluctuations from shallow-marine to terrestrial environments associated with climate change as a result of the waning of Gondwana glaciers and latitudinal shifts are recorded in the Permian rocks of Kansas. Economically these Permian rocks have been, and are, an important source of hydrocarbons, salt, gypsum, building stone, aggregate, and ground water. This report on the Permian System in Kansas is "a work in progress" and future multi-disciplinary studies of chrono- and sequence stratigraphy, climate history, structural aspects, sediment transport, and diagenesis will further enhance our understanding of the end of the Paleozoic in Kansas. Cover photo--The broad, flat surface in the center of the photo is the top of the Glenrock Limestone Member of the Red Eagle Limestone and the Carboniferous-Permian boundary at Tuttle Creek Lake Spillway in Pottawatomie County, Kansas

The Permian System in Kansas

Rocks of Permian age in Kansas were first recognized in 1895, and by the early 21st century the internationally accepted boundary between the Permian and the Carboniferous (Pennsylvanian Subsystem) was recognized in Kansas at the base of the Bennett Shale Member of the Red Eagle Limestone. The upper boundary of the Permian is an erosional unconformity that is overlain by rocks of Cretaceous age. Currently accepted stratigraphic nomenclature for the Permian of Kansas recognizes the Wolfcampian, Leonardian, and Guadalupian Series, and the lithostratigraphic formations within each of these series reflect a wide spectrum of depositional environments. Summaries of the lithofacies, thicknesses, depositional environments, and source areas of, and for, the rocks in each series provide a basis for inferring the history of the Permian in Kansas as currently understood. Fluctuations from shallow-marine to terrestrial environments associated with climate change as a result of the waning of Gondwana glaciers and latitudinal shifts are recorded in the Permian rocks of Kansas. Economically these Permian rocks have been, and are, an important source of hydrocarbons, salt, gypsum, building stone, aggregate, and ground water. This report on the Permian System in Kansas is "a work in progress" and future multi-disciplinary studies of chrono- and sequence stratigraphy, climate history, structural aspects, sediment transport, and diagenesis will further enhance our understanding of the end of the Paleozoic in Kansas. Cover photo--The broad, flat surface in the center of the photo is the top of the Glenrock Limestone Member of the Red Eagle Limestone and the Carboniferous-Permian boundary at Tuttle Creek Lake Spillway in Pottawatomie County, Kansas

Suitability of high-resolution seismic method to identifying petroleum reservoirs in Kansas--a geological perspective

Kansas has been a part of a stable craton since at least the beginning of the Paleozoic some 550 m. y. ago. The majority of the sedimentary rocks deposited during the last 550 m. y. are products of numerous inundations by shallow seas. Interspersed with these transgressions were periods of erosion, many coinciding with widespread uplift. The distribution of reservoir-quality rocks has been controlled by the varying structural and depositional settings in both time and space. The identification of these reservoirs begins with a knowledge of the geologic history as detailed by the vast subsurface information base, mainly wire line logs and completion records, that is available for Kansas. Seismic profiling has been and will continue to be used effectively to resolve structural traps. The trend in exploration in the midcontinent has been to strengthen the search for reservoirs associated with more subtle structures and difficult-to-find stratigraphic traps. Stratigraphic traps will become increasingly important, particularly within established production trends. The many unconformities in the midcontinent stratigraphic column afford numerous types of trapping geometry such as truncation beneath an unconformity, traps associated with buried valleys, discontinuous onlap onto erosion surfaces, and porosity pinchouts due to changes in original depositional conditions and diagenetic alteration. The most widespread petroleum accumulations in Kansas occur in structural and stratigraphic traps associated with the pre-Pennsylvanian unconformity. Production associated with the unconformity includes numerous lower Paleozoic pay zones which subcrop directly beneath the unconformity in the Sedgwick, Salina, and Anadarko basins; the Arbuckle production on the Central Kansas uplift; and numerous fields which payout from either conglomerates or weathered zones along the unconformity. Considerable production also occurs farther up-section with the Cherokee and Lansing-Kansas City groups, and down-section in the Viola Formation and Simpson Group. In order to demonstrate the potential use of the seismic method in defining subtle traps, synthetic seismograms were produced for selected strata in central Kansas. Critical attributes of reservoir rock and associated strata conducive to seismic stratigraphic processing include the thickness of a potential reservoir bed and its velocity and density contrast with adjacent strata. Thicker strata such as the Morrow and most lower Paleozoic formations may be more easily defined by seismic-stratigraphic methods. In contrast, the stratigraphy of the Pennsylvanian and Permian cyclothems may not be amenable to definition by seismic methods because these units contain heterogenous reservoirs interbedded with other thin strata of similar composition

Suitability of high-resolution seismic method to identifying petroleum reservoirs in Kansas--a geological perspective

Kansas has been a part of a stable craton since at least the beginning of the Paleozoic some 550 m. y. ago. The majority of the sedimentary rocks deposited during the last 550 m. y. are products of numerous inundations by shallow seas. Interspersed with these transgressions were periods of erosion, many coinciding with widespread uplift. The distribution of reservoir-quality rocks has been controlled by the varying structural and depositional settings in both time and space. The identification of these reservoirs begins with a knowledge of the geologic history as detailed by the vast subsurface information base, mainly wire line logs and completion records, that is available for Kansas. Seismic profiling has been and will continue to be used effectively to resolve structural traps. The trend in exploration in the midcontinent has been to strengthen the search for reservoirs associated with more subtle structures and difficult-to-find stratigraphic traps. Stratigraphic traps will become increasingly important, particularly within established production trends. The many unconformities in the midcontinent stratigraphic column afford numerous types of trapping geometry such as truncation beneath an unconformity, traps associated with buried valleys, discontinuous onlap onto erosion surfaces, and porosity pinchouts due to changes in original depositional conditions and diagenetic alteration. The most widespread petroleum accumulations in Kansas occur in structural and stratigraphic traps associated with the pre-Pennsylvanian unconformity. Production associated with the unconformity includes numerous lower Paleozoic pay zones which subcrop directly beneath the unconformity in the Sedgwick, Salina, and Anadarko basins; the Arbuckle production on the Central Kansas uplift; and numerous fields which payout from either conglomerates or weathered zones along the unconformity. Considerable production also occurs farther up-section with the Cherokee and Lansing-Kansas City groups, and down-section in the Viola Formation and Simpson Group. In order to demonstrate the potential use of the seismic method in defining subtle traps, synthetic seismograms were produced for selected strata in central Kansas. Critical attributes of reservoir rock and associated strata conducive to seismic stratigraphic processing include the thickness of a potential reservoir bed and its velocity and density contrast with adjacent strata. Thicker strata such as the Morrow and most lower Paleozoic formations may be more easily defined by seismic-stratigraphic methods. In contrast, the stratigraphy of the Pennsylvanian and Permian cyclothems may not be amenable to definition by seismic methods because these units contain heterogenous reservoirs interbedded with other thin strata of similar composition

Configuring the PrEP user: Framing Pre-exposure Prophylaxis in UK newsprint 2012 – 2016

Pre-exposure prophylaxis (PrEP) has been hailed as a revolutionary intervention for HIV prevention. PrEP’s controversial status in the UK has generated significant media coverage. It is important to understand what role the media plays in framing PrEP policy issues. We undertook a qualitative analysis of UK newsprint articles between 2012 and 2016 to examine how PrEP was framed as a public health intervention up until a controversial policy decision not to provide PrEP in England. We identified how scientific evidence was deployed to shape two narratives: ir/responsible citizens focused on imagined PrEP users and their capacity to use PrEP effectively; and the public health imperative, which described the need for PrEP. Our analysis demonstrates the particular ways in which scientific evidence contributed to the certainty of PrEP as an effective intervention within UK newsprint. Scientific evidence also played a key role in framing PrEP as an intervention specifically for cis-gendered gay and bisexual men, playing into wider debates about who is a deserving patient and the appropriate use of public resources. Practitioners in the UK and elsewhere should be aware of these constructions of the PrEP user to ensure equitable access to PrEP beyond gay and bisexual men

Mississippian Stratigraphic Nomenclature Revisions in Kansas

This paper reviews proposed Mississippian nomenclature changes in Kansas and outlines the changes to Zeller (1968) that have been adopted by the Kansas Geological Survey. The Sedalia Dolomite is changed to the Sedalia Formation and the Northview Shale is changed to Northview Formation due to lateral lithology changes. The Short Creek Oolite Member as originally defined and described by Smith and Siebenthal (1907) at the type section in Kansas is reinstated. The Cowley Formation as originally defined and described by Lee (1940) in Kansas is reinstated. The Ste. Genevieve Limestone is placed as the basal formation of the Chesteran Stage

Quaternary Stratigraphy and Stratigraphic Nomenclature Revisions in Kansas

This paper outlines Quaternary nomenclature changes to Zeller (1968) that have been adopted by the Kansas Geological Survey (KGS). The KGS formally recognizes two series/epochs for the Quaternary: the Holocene and Pleistocene. Pleistocene stage/age names Kansan, Aftonian, Nebraskan, and Yarmouthian are abandoned and replaced with the broader term "pre-Illinoian." Formation names Bignell, Peoria, Gilman Canyon, and Loveland are maintained for loess units. Formation names for the following alluvial lithostratigraphic units are abandoned: Crete, Sappa, Grand Island, Fullerton, and Holdrege. The Severance Formation is adopted as a new lithostratigraphic unit for thick packages of late Pleistocene alluvium and colluvium in Kansas. The DeForest Formation is accepted as a valid lithostratigraphic unit for deposits of fine-grained Holocene alluvium in Kansas. Formation names Iowa Point, Nickerson, and Cedar Bluffs for glacial tills and Atchison and David City for glaciofluvial deposits are abandoned. The Afton and Yarmouth Soils are abandoned as pedostratigraphic units, whereas the Sangamon Geosol and Brady Geosol are maintained

Improved Oil Recovery in Fluvial Dominated Deltaic Reservoirs of Kansas Near Term

The objective of this project is to address waterflood problems of the type found in Morrow sandstone reservoirs in southwestern Kansas and Cherokee Group reservoirs in southeastern Kansas. Two demonstration sites operated by different independent oil operators are involved in this project. The Stewart Field is located in Finney County, Kansas and is operated by North American Resources Company. The Nelson Lease is located in Allen County, Kansas, in the N.E. Savonburg Field and is operated by James E. Russell Petroleum, Inc. General topics to be addressed are (1) reservoir management and performance evaluation, (2) waterflood optimization, and (3) the demonstration of recovery processes involving off-the-shelf technologies which can be used to enhance waterflood recovery, increase reserves, and reduce the abandonment rate of these reservoir types. In the Stewart Project, the reservoir management portion of the project conducted during Budget Period I involved performance evaluation. This included (1) reservoir characterization and the development of a reservoir database, (2) volumetric analysis to evaluate production performance, (3) reservoir modeling, (4) laboratory work, (5) identification of operational problems, (6) identification of unrecovered mobile oil and estimation of recovery factors, and (7) identification of the most efficient and economical recovery process. To accomplish these objectives the initial budget period was subdivided into three major tasks. The tasks were (1) geological and engineering analysis, (2) laboratory testing, and (3) unitization. Due to the presence of different operators within the field, it was necessary to unitize the field in order to demonstrate a field-wide improved recovery process. This work was completed and the project moved into Budget Period 2. Budget Period 2 objectives consisted of the design, construction, and operation of a field-wide waterflood utilizing state-of-the-art, off-the-shelf technologies in an attempt to optimize secondary oil recovery. To accomplish these objectives the second budget period was subdivided into five major tasks. The tasks were (1) design and construction of a waterflood plant, (2) design and construction of a water injection system, (3) design and construction of tank battery consolidation and gathering system, (4) initiation of waterflood operations and reservoir management, and (5) technology transfer. In the Savonburg Project, the reservoir management portion involves performance evaluation. This work included (1) reservoir characterization and the development of a reservoir database, (2) identification of operational problems, (3) identification of near wellbore problems such as plugging caused from poor water quality, (4) identification of unrecovered mobile oil and estimation of recovery factors, and (5) preliminary identification of the most efficient and economical recovery process i.e., polymer augmented waterflooding or infill drilling (vertical or horizontal wells). To accomplish this work the initial budget period was subdivided into four major tasks. The tasks included (1) geological and engineering analysis, (2) waterplant optimization, (3) wellbore cleanup and pattern changes, and (4) field operations. This work was completed and the project has moved into Budget Period 2. The Budget Period 2 objectives consisted of continual optimization of this mature waterflood in an attempt to optimize secondary and tertiary oil recovery. To accomplish these objectives the second budget period was subdivided into six major tasks. The tasks were (1) waterplant development, (2) profile modification treatments, (3) pattern changes, new wells and wellbore cleanups, (4) reservoir development (polymer flooding), (5) field operations, and (6) technology transfer