Peter Lemiszki - Academia.edu (original) (raw)
Papers by Peter Lemiszki
Gas Shale Capillary Pressure - Saturation Relations Determined using a Water Activity Meter
Journal of Natural Gas Science and Engineering, 2016
Hydraulic fracturing of gas shale formations involves pumping a large volume of fracking fluid in... more Hydraulic fracturing of gas shale formations involves pumping a large volume of fracking fluid into a hydrocarbon reservoir to fracture the rock and thus increase its permeability. The majority of the fracking fluid introduced is never recovered and the fate of this lost fluid, often called "leak off," has become the source of much debate. Information on the capillary pressuresaturation relationship for each wetting phase is needed to simulate leak off using numerical reservoir models. The petroleum industry commonly employs airwater capillary pressuresaturation curves to predict these relationships for mixed wet reservoirs. Traditional methods of measuring this curve are unsuitable for gas shale's due to high capillary pressures associated with the small pores present. A possible alternative method is the water activity meter which is used widely in the soil sciences for such measurements. However, its application to lithified material has been limited. This study utilized a water activity meter to measure airwater capillary pressures (ranging from 1.3-219.6 MPa) at several water saturation levels in both the wetting and drying directions. Water contents were measured gravimetrically. Seven types of gas producing shale with different porosities (2.5-13.6%) and total organic carbon contents (0.4-13.5%) were investigated. Nonlinear regression was used to fit the resulting capillary pressurewater saturation data pairs for each shale type to the Brooks and Corey equation. Data for six of the seven shale types investigated were successfully fitted (median R 2 = 0.93), indicating this may be a viable method for parameterizing capillary pressuresaturation relationships for inclusion in numerical reservoir models. As expected, the different shale types had statistically different Brooks and Corey parameters. However, there were no significant differences between the Brooks and Corey parameters for the wetting and drying measurements, suggesting that hysteresis may not need to be taken into account in leak off simulations.
Portions of this document may be illegible in electronic image products. Images are produced from... more Portions of this document may be illegible in electronic image products. Images are produced from the best available original document. I IUER-259 Environmental Restoration Division K-25 Environmental Restoration Program Mesoscopic Structural Analysis of Bedrock Exposures at the Oak Ridge K-25 Site,
and Waste Management under budget and reporting codes CD 10 72 and EW 20 ' Oak Ridge K-25 Site Oa... more and Waste Management under budget and reporting codes CD 10 72 and EW 20 ' Oak Ridge K-25 Site Oak Ridge, Tennessee 37831-7101 managed by MARTIN MARIETTA ENERGY SYSTEMS, INC. for the U.S. DEPARTMENT OF ENERGY under contract DE-AC05-840R2 1400 I 4 DECLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process dwlosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufactufcr, or otherwise does not necessarily constitute or imply its endorsement, m o mmendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.
Regional Polyphase Deformation on the Nashville and Jessamine Domes, Tennessee and Kentucky I: Far-Field Effects of the Acadian-Neoacadian and Alleghanian Orogenies
Geological Society of America Abstracts with Programs, 2017
Multidisciplinary research and education with open tools
Proceedings of the 2015 XSEDE Conference on Scientific Advancements Enabled by Enhanced Cyberinfrastructure - XSEDE '15, 2015
ABSTRACT Modern scientific research is often multidisciplinary, involving scientists from two or ... more ABSTRACT Modern scientific research is often multidisciplinary, involving scientists from two or more backgrounds. A multidisciplinary approach is frequently necessary to advance our knowledge in a diverse range of fields, from genomics to climate change. Many of the projects undertaken in these areas involve a combination of field, lab, and computational analysis components. Our research initiatives demonstrate how the principles of active learning – performing tasks while engaging in analysis, synthesizing and evaluating the tasks being performed [10] – can be applied to undergraduate science education using 16S rRNA metagenomics as the basis. Beginning with development of the scientific questions, students work through the entire process of designing, testing and implementing physical and digital sampling protocols, hardware and software platforms for collecting geographically coded (geocoded) environmental metadata, and lab protocols; they work in the field taking samples and in the lab preparing them; they perform the computational analysis of the sequencer output and synthesis of metadata and metagenomic data; and finally they disseminate the results. The students come primarily from backgrounds in computer science, biology, geology, and physics. This broad range makes it possible to select teams that cover many of the traditionally underrepresented groups in science. Working together for a year or more, the students learn the science, vocabularies, skill sets, etc. of all the disciplines, as well as how their own discipline, in conjunction with others, contributes to addressing large, complex questions.
Several episodes of uplift have occurred along the Cincinnati arch. These periods of uplift are l... more Several episodes of uplift have occurred along the Cincinnati arch. These periods of uplift are likely a result of several orogenic events although the exact timing of the uplift in relation to these orogenic events is not fully understood. One reason for this has been the lack of accessible structural data over this region. The southern end of the Cincinnati arch and the Nashville and Jessamine domes occur along the arch in Kentucky, Tennessee, and northern Alabama. These states have very different levels of data availability, but potentially enough to identify more subtle, second- and third-order folds and faults along and on the flanks of the arch. These structures may be the key to unraveling the pre-Devonian tectonic history of the two domes, and can be identified in structure contour maps with sufficient data. The goal of this study was to perform a preliminary assessment of the viability of constructing a complete series of structure contour maps of several geologic units acr...
Initial Assessment of the Pre-Chattanooga Tectonic History Along the Southern Cincinnati Arch Using Automated Gis Tools
529 Out of 804 and Counting: recent 7.5-MINUTE Quadrangle Scale Geologic Mapping by the Tennessee Geological Survey
Semi-Automated Approach to Mapping Small Scale Structures for Oil and Gas Exploration Along the Southern Cincinnati Arch Using Python and Gis Applications
Analysis of Polyphase Deformation of the Southern Cincinnati Arch Using Python and Gis Applications
Crustal structure of the Basin and Range–Sierra Nevada Transition from COCORP deep seismic-reflection profiling
Geological Society of America Bulletin, 1987
Strategy for definition and protection of east Tennessee karst groundwater basins
This paper describes and gives suggestions for protecting the bedrock geology of eastern Tennesse... more This paper describes and gives suggestions for protecting the bedrock geology of eastern Tennessee which is typical of the southern Appalachian Valley and Ridge province. Carbonate beds (limestones and dolomites) of the Knox and Chickamauga Groups are bounded by non-carbonate beds, most of which strike northeast and dip steeply (10°--45°) to the southeast. The carbonate aquifers are maturely karstified and are extremely vulnerable to contaminant infiltration, thus necessitating appropriate land use planning focused on their environmental sensitivity. Urban expansion is resulting in greater land development in karst regions. Planned and existing activities produce wastes that may potentially leach into underlying karst systems. This waste may flow rapidly and untreated for many miles along strike. The potential degradation of aquifers and receiving streams due to the cumulative waste loading of numerous small enterprises may be more environmentally destructive than a few hazardous waste sites. Costs to remediate contaminated water supplies and streams can be in the millions of dollars versus the substantially lower costs of prudent land use planning.
Geologic characteristics of permeable groundwater intervals defined by electromagnetic borehole flowmeter surveys on the Oak Ridge Reservation
ABSTRACT
Structural and stratigraphic controls on cave development in the Oak Ridge area, Tennessee
The Oak Ridge Reservation (ORR) is located in the northwestern part of the Valley and Ridge provi... more The Oak Ridge Reservation (ORR) is located in the northwestern part of the Valley and Ridge province in east Tennessee. The Valley and Ridge province is the topographic expression of the southern Appalachian foreland fold-thrust belt, which formed during the late Paleozoic Alleghanian orogeny. In the Oak Ridge area, three major northwest verging thrust faults (Kingston, Whiteoak Mountain, and Copper Creek) imbricate and juxtapose carbonate and clastic stratigraphic units that range in age from the lower Cambrian to the lower Mississippian. The carbonate stratigraphic units range in thickness from 1278 to 1748 m and include the Maynardville Limestone in the Conasauga Group (hereby included as part of the Knox Group), the Knox Group, and the Chickamauga Group. Stratigraphic relationships and repetition of units by thrust faulting has produced three northeast striking and southeast dipping carbonate bands bounded to the northwest and southeast by noncarbonate units. Preliminary results indicate that within two of these carbonate bands, formations composed of mudstone and argillaceous limestone appear to further subdivide groundwater basins. Our efforts have focused on relating the stratigraphic and structural characteristics of these rock units with cave development in the region.
Fracture toughness testing of core from the Cambro-Ordovician Section on the Oak Ridge Reservation
... This has lead to the site being the focus of numerous studies aimed at delineating the geolog... more ... This has lead to the site being the focus of numerous studies aimed at delineating the geology and the processes that control groundwater flow and contaminant transport (eg, Hatcher and others 1992; Solomon and others 1992). ...
Digital geologic maps and airborne geophysical maps: Applications to environmental restoration on the Oak Ridge Reservation, Tennessee
The US Department of Energy Oak Ridge Reservation (ORR) is a 143 km[sup 2] area in the western pa... more The US Department of Energy Oak Ridge Reservation (ORR) is a 143 km[sup 2] area in the western part of the southern Appalachian foreland fold-thrust belt. As a result of activities at the site, nonhazardous, hazardous, radioactive, and mixed wastes have been stored, treated, and disposed of at various locations. Restoration plans for both known and potential areas of groundwater contamination require an understanding of groundwater flow pathways, flow rates, and discharge points. The area has thus been the focus of numerous geologic, geophysical, and hydrologic studies designed to characterize the groundwater flow system. Here the authors present results and some applications of geologic mapping and an airborne geophysical survey of the ORR.
Character of rigid boundaries and internal deformation of the southern Appalachian foreland fold-thrust belt
Special Paper 433: Whence the Mountains? Inquiries into the Evolution of Orogenic Systems: A Volume in Honor of Raymond A. Price, 2007
ABSTRACT
Journal of Geophysical Research, 1994
The stress history results from a published viscous layer folding solution are used as the basis ... more The stress history results from a published viscous layer folding solution are used as the basis for a fracture mechanics analysis of the factors that control hinge-parallel extension fracturing in tangential-longitudinal strain folds. The analysis incorporates published results for the change in sedimen• rock mode I fracture toughness at increasing confining stress to examine the relationship between regional strain rate, depth of burial, pore fluid pressure, initial crack size, layer viscosity, and the amount of fold shortening required for the propagation of a bed-perpendicular, hinge-parallel extension fracture. Tangential-longitudinal strain folding of layers can occur at all scales in a foreland thrust system and is the result of the buckling and bending of stratigraphic units during the development of d6collement, fault bend, and fault propagation folds. Hinge-parallel extension fractures orientexl perpendicular to bedding are a common fracture set observed in tangential-longitudinal strain folds. The fractures propagate as a result of local tensile stresses that develop by the stretching of layers in the outer arc of fold hinges during bending. We considered a range of geologically reasonable boundary conditions to show that at one extreme, fracturing can occur as a result of only minor shortening by folding to the other extreme where a fight fold can form with no associated extension fracturing. For folds formed at shallow depths, where the confining stress on the system is less than the bending stresses in the layer and where the confining stress has not greatly increased the fracture toughness of the rock, hinge-parallel extension fractures can grow under hydrostatic fluid pressure conditions. As depth increases, however, much higher pore fluid pressures are required to cause fracturing under similar strain rates. The observed controls are used to hypothesize how hingeparallel extension fracturing in fault bend folds can vary spatially and temporally across a thrust belt as a function of strain (thrusting) rate, the amount of bending at thrust ramps, and the depth of folding. Introduction It has long been recognized that understanding the relationship between folding and fracture development has important implications for exploration and recovery of hydrocarbons [e.g., Kostura and Ravenscroft, 1977]. The site of the most productive wells is commonly related to the greater frequency of fracturing that occurs within fold hinges [Murray, 1968; Garfield et al., 1992]. As a result, numerous field studies have documented the fracture sets in folds formed by buckling and bending processes and have interpreted various fracture characteristics with respect to position in the 22,027 22,028 LEMISZKI ET AL.: FOLD HINGE-PARALLEL EXTENSION FRACTURING fold and the stress history during folding [e.g., Price and Cosgrove, 1990]. Macroscopic buckling and bending of strata in foreland fold-thrust belts is manifested by the development of d6collement folds, fault bend folds, and fault propagation folds [Suppe, 1985; Jamison, 1987; Mitra, 1990]. Fracture characteristics in folded layers will vary, however, based on whether the strain distribution is the result of flexural slip or tangential-longitudinal strain [e.g., Ramsay and Huber, 1987]. During folding, strength contrasts associated with sedimentary layering causes the flexural slip mechanism to be active within weak layers, such as shale, and at the contacts between weak and strong layers [Donath and Parker, 1964; Chapple and Spang, 1974; Tanner, 1989]. Within strong layers, however, the absence of a preexisting bed-parallel fabric usually prevents the flexural slip mechanism from operating during folding, resulting in tangential-longitudinal strain [e.g., Beer and Johnston, 1981]. Although other fracture sets occur, one commonly observed fracture set in tangential-longitudinal strain folds consists of bed-normal, hinge-parallel extension fractures (Figure 1), which are considered to be the result of stretching in the outer arcs of layers during bending [Stearns and Friedman, 1972; Hancock, 1985; Srivastava and Engelder, 1990]. Based on fracture mechanics theory, extension fracture (mode I) propagation is dependent on the magnitude of the principal stresses, the fracture toughness (strength) of the layer, and initial flaw size. Finite element models that use a linear viscous rheology to form tangential-longitudinal strain folds by buckling indicate that the magnitude and orientation of the principal stresses are partly dependent on the strain rate and viscosity contrast between the layer and surrounding matrix [Dieterich and Carter, 1969; DeBremaecker and Becker, 1978; Williams, 1980]. Therefore, assuming that the layer Hinge-Parallel B Extension Fractures .... ::!:::::• .,,•.•. Hinge-Perpendicular •.•,.• Extension Fractures shaeeadr I Surface Figure 1. (a) Mesoscopic buckle fold of a thin bedded siltstone from the Nolichucky Shale in the southern Appalachian fold-thrust belt, Tennessee. A set of hinge-parallel, bed-normal extension fractures are concentrated near the outer arc of the fold hinge within the upper half of the layer. (b) Sketch of bed-normal extensional and bed-parallel shear fracture sets that can develop as a result of flexural slip between layers and tangential-longitudinal strain within the layer during buckling and bending [e.g., Price and Cosgrove, 1990]. LEMISZKI ET AL.: FOLD HINGE-PARALLEL EXTENSION FRACTURING 22,029
Gas Shale Capillary Pressure - Saturation Relations Determined using a Water Activity Meter
Journal of Natural Gas Science and Engineering, 2016
Hydraulic fracturing of gas shale formations involves pumping a large volume of fracking fluid in... more Hydraulic fracturing of gas shale formations involves pumping a large volume of fracking fluid into a hydrocarbon reservoir to fracture the rock and thus increase its permeability. The majority of the fracking fluid introduced is never recovered and the fate of this lost fluid, often called "leak off," has become the source of much debate. Information on the capillary pressuresaturation relationship for each wetting phase is needed to simulate leak off using numerical reservoir models. The petroleum industry commonly employs airwater capillary pressuresaturation curves to predict these relationships for mixed wet reservoirs. Traditional methods of measuring this curve are unsuitable for gas shale's due to high capillary pressures associated with the small pores present. A possible alternative method is the water activity meter which is used widely in the soil sciences for such measurements. However, its application to lithified material has been limited. This study utilized a water activity meter to measure airwater capillary pressures (ranging from 1.3-219.6 MPa) at several water saturation levels in both the wetting and drying directions. Water contents were measured gravimetrically. Seven types of gas producing shale with different porosities (2.5-13.6%) and total organic carbon contents (0.4-13.5%) were investigated. Nonlinear regression was used to fit the resulting capillary pressurewater saturation data pairs for each shale type to the Brooks and Corey equation. Data for six of the seven shale types investigated were successfully fitted (median R 2 = 0.93), indicating this may be a viable method for parameterizing capillary pressuresaturation relationships for inclusion in numerical reservoir models. As expected, the different shale types had statistically different Brooks and Corey parameters. However, there were no significant differences between the Brooks and Corey parameters for the wetting and drying measurements, suggesting that hysteresis may not need to be taken into account in leak off simulations.
Portions of this document may be illegible in electronic image products. Images are produced from... more Portions of this document may be illegible in electronic image products. Images are produced from the best available original document. I IUER-259 Environmental Restoration Division K-25 Environmental Restoration Program Mesoscopic Structural Analysis of Bedrock Exposures at the Oak Ridge K-25 Site,
and Waste Management under budget and reporting codes CD 10 72 and EW 20 ' Oak Ridge K-25 Site Oa... more and Waste Management under budget and reporting codes CD 10 72 and EW 20 ' Oak Ridge K-25 Site Oak Ridge, Tennessee 37831-7101 managed by MARTIN MARIETTA ENERGY SYSTEMS, INC. for the U.S. DEPARTMENT OF ENERGY under contract DE-AC05-840R2 1400 I 4 DECLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process dwlosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufactufcr, or otherwise does not necessarily constitute or imply its endorsement, m o mmendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.
Regional Polyphase Deformation on the Nashville and Jessamine Domes, Tennessee and Kentucky I: Far-Field Effects of the Acadian-Neoacadian and Alleghanian Orogenies
Geological Society of America Abstracts with Programs, 2017
Multidisciplinary research and education with open tools
Proceedings of the 2015 XSEDE Conference on Scientific Advancements Enabled by Enhanced Cyberinfrastructure - XSEDE '15, 2015
ABSTRACT Modern scientific research is often multidisciplinary, involving scientists from two or ... more ABSTRACT Modern scientific research is often multidisciplinary, involving scientists from two or more backgrounds. A multidisciplinary approach is frequently necessary to advance our knowledge in a diverse range of fields, from genomics to climate change. Many of the projects undertaken in these areas involve a combination of field, lab, and computational analysis components. Our research initiatives demonstrate how the principles of active learning – performing tasks while engaging in analysis, synthesizing and evaluating the tasks being performed [10] – can be applied to undergraduate science education using 16S rRNA metagenomics as the basis. Beginning with development of the scientific questions, students work through the entire process of designing, testing and implementing physical and digital sampling protocols, hardware and software platforms for collecting geographically coded (geocoded) environmental metadata, and lab protocols; they work in the field taking samples and in the lab preparing them; they perform the computational analysis of the sequencer output and synthesis of metadata and metagenomic data; and finally they disseminate the results. The students come primarily from backgrounds in computer science, biology, geology, and physics. This broad range makes it possible to select teams that cover many of the traditionally underrepresented groups in science. Working together for a year or more, the students learn the science, vocabularies, skill sets, etc. of all the disciplines, as well as how their own discipline, in conjunction with others, contributes to addressing large, complex questions.
Several episodes of uplift have occurred along the Cincinnati arch. These periods of uplift are l... more Several episodes of uplift have occurred along the Cincinnati arch. These periods of uplift are likely a result of several orogenic events although the exact timing of the uplift in relation to these orogenic events is not fully understood. One reason for this has been the lack of accessible structural data over this region. The southern end of the Cincinnati arch and the Nashville and Jessamine domes occur along the arch in Kentucky, Tennessee, and northern Alabama. These states have very different levels of data availability, but potentially enough to identify more subtle, second- and third-order folds and faults along and on the flanks of the arch. These structures may be the key to unraveling the pre-Devonian tectonic history of the two domes, and can be identified in structure contour maps with sufficient data. The goal of this study was to perform a preliminary assessment of the viability of constructing a complete series of structure contour maps of several geologic units acr...
Initial Assessment of the Pre-Chattanooga Tectonic History Along the Southern Cincinnati Arch Using Automated Gis Tools
529 Out of 804 and Counting: recent 7.5-MINUTE Quadrangle Scale Geologic Mapping by the Tennessee Geological Survey
Semi-Automated Approach to Mapping Small Scale Structures for Oil and Gas Exploration Along the Southern Cincinnati Arch Using Python and Gis Applications
Analysis of Polyphase Deformation of the Southern Cincinnati Arch Using Python and Gis Applications
Crustal structure of the Basin and Range–Sierra Nevada Transition from COCORP deep seismic-reflection profiling
Geological Society of America Bulletin, 1987
Strategy for definition and protection of east Tennessee karst groundwater basins
This paper describes and gives suggestions for protecting the bedrock geology of eastern Tennesse... more This paper describes and gives suggestions for protecting the bedrock geology of eastern Tennessee which is typical of the southern Appalachian Valley and Ridge province. Carbonate beds (limestones and dolomites) of the Knox and Chickamauga Groups are bounded by non-carbonate beds, most of which strike northeast and dip steeply (10°--45°) to the southeast. The carbonate aquifers are maturely karstified and are extremely vulnerable to contaminant infiltration, thus necessitating appropriate land use planning focused on their environmental sensitivity. Urban expansion is resulting in greater land development in karst regions. Planned and existing activities produce wastes that may potentially leach into underlying karst systems. This waste may flow rapidly and untreated for many miles along strike. The potential degradation of aquifers and receiving streams due to the cumulative waste loading of numerous small enterprises may be more environmentally destructive than a few hazardous waste sites. Costs to remediate contaminated water supplies and streams can be in the millions of dollars versus the substantially lower costs of prudent land use planning.
Geologic characteristics of permeable groundwater intervals defined by electromagnetic borehole flowmeter surveys on the Oak Ridge Reservation
ABSTRACT
Structural and stratigraphic controls on cave development in the Oak Ridge area, Tennessee
The Oak Ridge Reservation (ORR) is located in the northwestern part of the Valley and Ridge provi... more The Oak Ridge Reservation (ORR) is located in the northwestern part of the Valley and Ridge province in east Tennessee. The Valley and Ridge province is the topographic expression of the southern Appalachian foreland fold-thrust belt, which formed during the late Paleozoic Alleghanian orogeny. In the Oak Ridge area, three major northwest verging thrust faults (Kingston, Whiteoak Mountain, and Copper Creek) imbricate and juxtapose carbonate and clastic stratigraphic units that range in age from the lower Cambrian to the lower Mississippian. The carbonate stratigraphic units range in thickness from 1278 to 1748 m and include the Maynardville Limestone in the Conasauga Group (hereby included as part of the Knox Group), the Knox Group, and the Chickamauga Group. Stratigraphic relationships and repetition of units by thrust faulting has produced three northeast striking and southeast dipping carbonate bands bounded to the northwest and southeast by noncarbonate units. Preliminary results indicate that within two of these carbonate bands, formations composed of mudstone and argillaceous limestone appear to further subdivide groundwater basins. Our efforts have focused on relating the stratigraphic and structural characteristics of these rock units with cave development in the region.
Fracture toughness testing of core from the Cambro-Ordovician Section on the Oak Ridge Reservation
... This has lead to the site being the focus of numerous studies aimed at delineating the geolog... more ... This has lead to the site being the focus of numerous studies aimed at delineating the geology and the processes that control groundwater flow and contaminant transport (eg, Hatcher and others 1992; Solomon and others 1992). ...
Digital geologic maps and airborne geophysical maps: Applications to environmental restoration on the Oak Ridge Reservation, Tennessee
The US Department of Energy Oak Ridge Reservation (ORR) is a 143 km[sup 2] area in the western pa... more The US Department of Energy Oak Ridge Reservation (ORR) is a 143 km[sup 2] area in the western part of the southern Appalachian foreland fold-thrust belt. As a result of activities at the site, nonhazardous, hazardous, radioactive, and mixed wastes have been stored, treated, and disposed of at various locations. Restoration plans for both known and potential areas of groundwater contamination require an understanding of groundwater flow pathways, flow rates, and discharge points. The area has thus been the focus of numerous geologic, geophysical, and hydrologic studies designed to characterize the groundwater flow system. Here the authors present results and some applications of geologic mapping and an airborne geophysical survey of the ORR.
Character of rigid boundaries and internal deformation of the southern Appalachian foreland fold-thrust belt
Special Paper 433: Whence the Mountains? Inquiries into the Evolution of Orogenic Systems: A Volume in Honor of Raymond A. Price, 2007
ABSTRACT
Journal of Geophysical Research, 1994
The stress history results from a published viscous layer folding solution are used as the basis ... more The stress history results from a published viscous layer folding solution are used as the basis for a fracture mechanics analysis of the factors that control hinge-parallel extension fracturing in tangential-longitudinal strain folds. The analysis incorporates published results for the change in sedimen• rock mode I fracture toughness at increasing confining stress to examine the relationship between regional strain rate, depth of burial, pore fluid pressure, initial crack size, layer viscosity, and the amount of fold shortening required for the propagation of a bed-perpendicular, hinge-parallel extension fracture. Tangential-longitudinal strain folding of layers can occur at all scales in a foreland thrust system and is the result of the buckling and bending of stratigraphic units during the development of d6collement, fault bend, and fault propagation folds. Hinge-parallel extension fractures orientexl perpendicular to bedding are a common fracture set observed in tangential-longitudinal strain folds. The fractures propagate as a result of local tensile stresses that develop by the stretching of layers in the outer arc of fold hinges during bending. We considered a range of geologically reasonable boundary conditions to show that at one extreme, fracturing can occur as a result of only minor shortening by folding to the other extreme where a fight fold can form with no associated extension fracturing. For folds formed at shallow depths, where the confining stress on the system is less than the bending stresses in the layer and where the confining stress has not greatly increased the fracture toughness of the rock, hinge-parallel extension fractures can grow under hydrostatic fluid pressure conditions. As depth increases, however, much higher pore fluid pressures are required to cause fracturing under similar strain rates. The observed controls are used to hypothesize how hingeparallel extension fracturing in fault bend folds can vary spatially and temporally across a thrust belt as a function of strain (thrusting) rate, the amount of bending at thrust ramps, and the depth of folding. Introduction It has long been recognized that understanding the relationship between folding and fracture development has important implications for exploration and recovery of hydrocarbons [e.g., Kostura and Ravenscroft, 1977]. The site of the most productive wells is commonly related to the greater frequency of fracturing that occurs within fold hinges [Murray, 1968; Garfield et al., 1992]. As a result, numerous field studies have documented the fracture sets in folds formed by buckling and bending processes and have interpreted various fracture characteristics with respect to position in the 22,027 22,028 LEMISZKI ET AL.: FOLD HINGE-PARALLEL EXTENSION FRACTURING fold and the stress history during folding [e.g., Price and Cosgrove, 1990]. Macroscopic buckling and bending of strata in foreland fold-thrust belts is manifested by the development of d6collement folds, fault bend folds, and fault propagation folds [Suppe, 1985; Jamison, 1987; Mitra, 1990]. Fracture characteristics in folded layers will vary, however, based on whether the strain distribution is the result of flexural slip or tangential-longitudinal strain [e.g., Ramsay and Huber, 1987]. During folding, strength contrasts associated with sedimentary layering causes the flexural slip mechanism to be active within weak layers, such as shale, and at the contacts between weak and strong layers [Donath and Parker, 1964; Chapple and Spang, 1974; Tanner, 1989]. Within strong layers, however, the absence of a preexisting bed-parallel fabric usually prevents the flexural slip mechanism from operating during folding, resulting in tangential-longitudinal strain [e.g., Beer and Johnston, 1981]. Although other fracture sets occur, one commonly observed fracture set in tangential-longitudinal strain folds consists of bed-normal, hinge-parallel extension fractures (Figure 1), which are considered to be the result of stretching in the outer arcs of layers during bending [Stearns and Friedman, 1972; Hancock, 1985; Srivastava and Engelder, 1990]. Based on fracture mechanics theory, extension fracture (mode I) propagation is dependent on the magnitude of the principal stresses, the fracture toughness (strength) of the layer, and initial flaw size. Finite element models that use a linear viscous rheology to form tangential-longitudinal strain folds by buckling indicate that the magnitude and orientation of the principal stresses are partly dependent on the strain rate and viscosity contrast between the layer and surrounding matrix [Dieterich and Carter, 1969; DeBremaecker and Becker, 1978; Williams, 1980]. Therefore, assuming that the layer Hinge-Parallel B Extension Fractures .... ::!:::::• .,,•.•. Hinge-Perpendicular •.•,.• Extension Fractures shaeeadr I Surface Figure 1. (a) Mesoscopic buckle fold of a thin bedded siltstone from the Nolichucky Shale in the southern Appalachian fold-thrust belt, Tennessee. A set of hinge-parallel, bed-normal extension fractures are concentrated near the outer arc of the fold hinge within the upper half of the layer. (b) Sketch of bed-normal extensional and bed-parallel shear fracture sets that can develop as a result of flexural slip between layers and tangential-longitudinal strain within the layer during buckling and bending [e.g., Price and Cosgrove, 1990]. LEMISZKI ET AL.: FOLD HINGE-PARALLEL EXTENSION FRACTURING 22,029