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Observations, Opportunities, and Risks of the Energy Transition
Green, Sidney, Enhanced Production, Inc. (2024)
Abstract
There are huge amounts of information available about the energy transition, including energy data of all kinds, lobbyist presentations, scientific updates, market analyses, and numerous opinions and editorials on specific parts of the energy transition. Unfortunately, objectively grasping the meanings of this information to create correct public perceptions and for wise policy making is not easy. This is made particularly difficult by widely varying future projections, which often include estimates based on “if this happens” scenarios and “aspirational desires”. This is a review considering facts and science. The review does not address details of the criticality of energy, or of the huge carbon dioxide emissions resulting from burning of fossil fuels, nor the intent of the energy transition to lower carbon dioxide (CO2) emissions.
Part One – The Energy Transition
Part Two – Observations That Have Emerged
Part Three – Opportunities of the Energy Transition
Part Four – Risks of the Energy Transition
Citation
Green, Sidney, (2024), “Observations, Opportunities, and Risks of the Energy Transition”, presentation to the US Congressional Research Service, 17 April, 2024
Geomechanical Lessons from Oil and Gas Produced Water Injection Towards Subsurface Carbon Dioxide Sequestration
Ramos, G. G., McLennan, J., Ispas, I., and Sidney Green (2024)
The petroleum sector, with its competencies in water flooding and produced-water re-injection, provides complementary technologies for carbon capture and sequestration (CCS). Our objective is to identify oil & gas technologies and procedures that would be beneficial to future CCS implementations...Read entire Abstract.
The petroleum sector, with its competencies in water flooding and produced-water re-injection (PWRI), provides complementary technologies for carbon capture and sequestration (CCS). Our objective is to identify oil & gas technologies and procedures that would be beneficial to future CCS implementations. We reviewed PWRI operations in 3 major petroleum basins. We then compared their geological and geomechanical settings, PWRI data, and induced seismicity. The most prominent impact is induced seismicity, as others have shown, the cause being the increase of pore pressure in faults. Contributing causes of rock failure and pressure communication are perturbation of the in-situ stresses, water-induced weakening, static creep, and fatigue-induced weakening. Measures for effective risk reduction are volume/pressure management, well placement, managed pumping schedules, high-resolution reservoir description, frequent monitoring coupled with laboratory programs, and strain-coupled reservoir simulation. We recommend adopting these practices learned from water-flood oil-gas operations. These would help promote gradual ramping of the reservoir pressure, a uniform CO2 flooding front, flooding profile control, and most importantly, rock stability.
INTRODUCTION - With growing public interest and government incentives for carbon capture, the oil and gas sectors are uniquely positioned in future implementation of large-scale carbon capture and sequestration as supercritical CO2 (sCO2 or "CCS"). The industry's experience, personnel, infrastructure, and core competencies in deep subsurface operations can immediately provide complementary technologies for subsurface Carbon Sequestration (CS).
As geo-engineers/scientists in the upstream petroleum sector, we offer practical lessons from our experience in large-scale water floods and Produced Water Re-Injection (PWRI), also called Salt Water Disposal. The multimillion-barrel daily produced water disposal operations in Texas and Oklahoma are very relevant to future high-tonnage injection of sCO2. The most prominent adverse impact is induced seismicity, because of its impact on structures and the general public. Another unfavorable effect is the contamination of freshwater aquifers. Lesser known and poorly understood effects are induced microseismicity, surface heave, loss of injectivity, and overestimation of reservoir capacity. All of these arise from combinations of factors such as: pore pressure rise, proximity to unmapped structures, perturbation of in-situ stresses leading to rock failure, injection fluids' geochemical effects, induced fatigue from pumping schedules, concentration of pressurized zones/bulbs, and perturbation of pre-existing geologic creep rate. This paper provides an overview of PWRI operations in 3 major oil and gas (O/G) fields in Texas and Oklahoma, and how seismicity may have developed. We identified other geomechanical processes that contribute to rock weakening and debilitation of rock interfaces.
Citation
Ramos, G. G., McLennan, John, Ispas, Ion, and Sidney Green (2024). "Geomechanical Lessons from Oil and Gas Produced Water Injection Towards Subsurface Carbon Dioxide Sequestration." Paper presented at the 58th U.S. Rock Mechanics/Geomechanics Symposium, Golden, Colorado, USA, June 2024.
Creating Micro Fractures in Rock Fragments for Blasting Efficiency Improvement
Yang, Ruilin, (杨瑞林) Orica Limited, Prof. Sidney Green, Enhanced Production Inc., (2024)
Blasting is a commonly used method for rock fragmentation in mining operations for mineral extraction. It involves breaking the rock mass into small pieces, and ideally creating micro fractures within the small pieces. Such micro fractures could significantly reduce the energy required for subsequent processes like crushing and comminution...
Read entire Abstract.
Blasting is a commonly used method for rock fragmentation in mining operations for mineral extraction. It involves breaking the rock mass into small pieces, and ideally creating micro fractures within the small pieces. Such micro fractures could significantly reduce the energy required for subsequent processes like crushing and comminution. Additionally, micro fractures would enhance the rock-fragments fluid permeability thereby enhancing desired chemical reactions during certain processing operations. This paper presents recent developments of the Multiple Blasthole Fragmentation (MBF) model, which simulates blasting rockmass fragmentation. The MBF model allows estimating rock strains experienced during the blast, for various blast design parameters and geometries. The intent is to correlate these strains with created micro fractures in the blast rock fragments.
Citation
Yang, R, (杨瑞林), Green, S., (2024), “Creating Micro Fractures in Rock Fragments for Blasting Efficiency Improvement”, International Society of Explosives Engineers, (isee.org) Atlanta, Georgia, Jan. 24-27 2024.
Peak Particle Velocity for Blasting Rock Modeling
Yang, Ruilin (杨瑞林), Green, S. (2023)
Blasting mechanisms are a complex coupling of the rock mass properties and the explosive detonation performance as well as the blast design parameters. Both rock mass and explosive properties have parameters that are inherently not well defined. Thus, blast modeling is greatly challenging to predict rock fragmentation, blast vibration, and the broken-rock mass movement...Read entire Abstract.
Blasting mechanisms are a complex coupling of the rock mass properties and the explosive detonation performance as well as the blast design parameters. Both rock mass and explosive properties have parameters that are inherently not well defined. Thus, blast modeling is greatly challenging to predict rock fragmentation, blast vibration, and the broken-rock mass movement. For blast modeling, previous work has shown that near-field signature-hole blast vibration monitoring is an effective method to obtain critical blast model input. In a blast field, multiple charges create nonlinear additive strains at a given point in the rock and time, which further complicates blast modeling. This paper shows how the measured peak particle velocity (“PPV”) from the signature-hole blast vibration serves as a key controlling parameter for modelling. Using PPV as the controlling parameter, pressures and strains can be approximated at a point of interest. Rock breakage is then related by simplified approximations to the pressures and strains. The modelling method described in the paper relates all blast design parameters to the PPV induced by multiple charges at a point in the rock. Therefore, using PPV as a key parameter allows blasting models to simulate all blast design parameters and significantly simplifies blast modeling.
Citation
Yang, Ruilin (杨瑞林), Green, S., 2023, “Peak Particle Velocity for Blasting Rock Modeling”, ARMA, presented at the 57th U.S. Rock Mechanics/Geomechanics Symposium, June 2023
or view on: ResearchGate
The Potential and Challenges of Expanded Nuclear Energy ⚛️
Green, Sidney – EPI & University of Utah, Glenn Sjoden – University of Utah, Steven Aumeier – Idaho National Laboratory, Kim McCarter – Retired, University of Utah, Gen Green – EPI & Environmental Consultant, John McLennan – University of Utah, (2023)
Nuclear fission reactors have long been part of the world energy supply, and provide about 2-percent of total annual world energy. The contribution as steam-produced grid electricity is about 10 percent of annual world electricity and over 20 percent of US annual grid electricity...Read entire Abstract.
Nuclear fission reactors have long been part of the world energy supply, and provide about 2-percent of total annual world energy. The contribution as steam-produced grid electricity is about 10 percent of annual world electricity and over 20 percent of US annual grid electricity. This overview-summary speaks to the potential and challenges of much-expanded nuclear energy deployment. Shippingport, PA. – May 1958
The potential and challenges for nuclear energy – for electricity and more broadly heat for industry – are considered in light of the worldwide energy transition that is focusing heavily on solar and wind primary energy sources to reduce greenhouse gas emissions. Nuclear energy – although less promoted in the on-going energy transition – has an opportunity to contribute much toward reducing emissions. Expanded nuclear energy is advocated by many, but often without complete consideration of the challenges that must be overcome to enable such expansion.
The overview-summary discusses the opportunities and challenges and draws on numerous previous publications and presentations, and most importantly on experience with nuclear technology. It seems clear that nuclear energy is a key part of the energy transition. Better public understanding based on facts can help to remove misconceptions and negative concerns and advance nuclear energy; nuclear energy is indeed important.
Citation
Green, Sidney, Sjoden, Glenn, Aumeier, S., McCarter, K., Green, G., McLennan, J., 2023, "The Potential and Challenges of Expanded Nuclear Energy", Pre-print, 2023.
What has been learned about Hydraulic Fracturing from Calculations, Laboratory Experiments, Field Observations? a question from ARMA Hydraulic Fracturing Community
Green, Sidney, (2021)
Abstract
A perspective is presented of important observations from many referenced calculations, laboratory experiments, actual field experience combined with comments and perceptions from industry experts.
Citation
Green, Sidney, (2021), “What has been learned about Hydraulic Fracturing from Calculations, Laboratory Experiments, Field Observations?”, ARMA, Hydraulic Fracturing Technical Community Seminar, 11 November, 2021.
Geothermal Battery as Energy Storage, Large-scale Subsurface Seasonal Solar Heat Storage for Future Value
Green, Sidney, McLennan, J., Palash P., Kitz, K., Allis R., and Moore, J., (2021)
Abstract
The Geothermal Battery Energy Storage (“GB”) concept has been proposed as a large-scale renewable energy storage method. This is particularly important as solar and wind power are being introduced into electric grids, and economical utility-scale storage has not yet become available to handle the variable nature of solar and wind.
Citation
Green, Sidney, McLennan, J. D., Palash P., Kitz, K., Allis R., and Moore, J., (2021), “Geothermal Battery Energy Storage”, Renewable Energy, v 164: 777-790, February, 2021.
Presentation
US Congressional Research Service, U.S. Oil and Natural Gas Production: Ramifications for the U.S. of Volatile Oil Reserve & Natural Gas Prices
Green, Sidney (2020)
Abstract
Abundant, low-cost, reliable, and secure energy continues to be critical to the US. Oil will continue as a prominent transport fuel and for chemical feedstock and natural gas will continue to replace coal for electricity for the decades ahead. The unconventional shale oil and gas production is greatly important for the US as the Nation continues as a world-wide technology and commercial leader for such unconventional oil/gas energy production.
Citation
Green, Sidney, (2020), “U.S. Oil and Natural Gas Production: Ramifications for the U.S. of Volatile Oil Reserve & Natural Gas Prices”, Statement for Congressional Research Service (CRS), webinar presentation, 17 September, 2020
U.S. Shale Oil/Gas Recovery: A Drastic Change is Required,
Hydraulic Fracturing Community (HFC) "Robe Talk" series. Presented by, Dr. Gang Han, Aramco.
Green, Sidney (2020)
Abstract
Abundant and low cost energy are essential for economic development and improved quality of life; the US unconventional shale gas and oil recovery has greatly changed the US and the world. And, there are significant social and environmental consequences of the shale gas and oil recovery, as there is “no free lunch”...
Citation
Green, Sidney, (2020), “U.S. Shale Oil/Gas Recovery: A Drastic Change is Required”, Hydraulic Fracturing Community of ARMA, HFC ‘Robe’ Talk, WebEx hosted by Gang Han, 3 April, 2020.
Early Time Fracture Growth and Cluster Spacing Effects
Green, S., Xu, G., Forbes, B., Green, G., McLennan, J. et al (2018)
Abstract
The injection of large quantities of treating fluid and proppants during fracture stimulation of low permeability formations causes local insitu stress changes, sometimes referred to as stress shadowing or stress interference. Recent procedures for improving production have led to closer spacing of clusters, from approximately 80 feet spacing a few years ago to about 20 feet spacing now, or less in some cases. That is, there are now about four times the number of potential fracture initiation locations (clusters) per foot of lateral well, while the sand pumped per foot of lateral continues at about 1700-1800 pounds per foot. With four times the number of clusters and the same mass of sand pumped, the stress disturbance of one cluster to another cluster has changed. This paper addresses the near wellbore stress interference effects for close cluster spacing. Numerical simulations are presented using a robust linear-elastic 3-D hydraulic fracturing computer code that calculates fracture ‘bending’ and fracture width change due to stress interference. The stress interference that changes the fracture width is the most significant because the resistance to fracture fluid flow at high velocities in these narrow channels is the primary driver of stress shadowing fracture geometry changes.
Citation
Green, S., Xu, G., Forbes, B., Green, G., McLennan, J., and D. Work. "Early Time Fracture Growth and Cluster Spacing Effects." Paper presented at the 52nd U.S. Rock Mechanics/Geomechanics Symposium, Seattle, Washington, June 2018
Cracking the Code in Tight Shale an interview from Upstream Technology Magazine
Green, Sidney (2017)
Abstract
UNLOCKING THE POTENTIAL: Despite not fully understanding the basic physics of fluid flowing through shale rocks, industry has nonetheless found a way to recover the oil. Cracking the code in tight shale.
Oil moves through shale rocks, even though the physical structure of such rocks suggests it should not. That is only one of the confusing aspects to consider when developing the shale oil plays, according to a rock mechanics expert…
Citation
Green, S., Jennifer Pallanich editor (2017), “Cracking the code in tight shale”, Upstream Technology Magazine, upstreamonline.com, 9 August, 2017
Hydraulic Fracture Propagation in Steps Considering Different Fracture Fluids
Green, S., Walsh, J., McLennan, J., and Forbes, B. (2017)
Abstract
Hydraulic fracture propagation under high compressive stresses in rock is considered. An ideal case of a Griffith crack propagating in an ideal material has been calculated by Dr. Joseph Walsh. This ideal case is used to estimate stepwise or continuous fracture propagation for different fracture fluids for a rock with stiffness and strength simulating a shale at a depth of about 6000 feet. More compressible fluids such as CO2 and nitrogen foam show larger stepwise propagation with steps of possibly tens of feet. Indeed rocks are not ‘ideal’ materials, nor are insitu stress magnitudes uniform and continuous. Nevertheless, the calculations here present interesting perceptions of the role of the compressibility of fracture fluids on hydraulic fracture propagation.
Citation
Green, Sidney, Walsh, Joseph, McLennan, John, and Bryan Forbes. "Hydraulic Fracture Propagation in Steps Considering Different Fracture Fluids." Paper presented at the 51st U.S. Rock Mechanics/Geomechanics Symposium, San Francisco, California, USA, June 2017
Understanding the Subsurface
Green, Sidney (2017)
Abstract
Understanding the subsurface better is on many grand challenges lists. The interest is not new, and much progress has been made over the decades to better see into the earth. Nevertheless, the perception continues to be that only through actual drilling or excavation can one for sure know the subsurface in detail. Such drilling and excavation leads to exceptional expense, disruptions, and often environmental impacts. This author believes that understanding the heterogeneity of the rock mass physical and chemical complexity including discontinuities such as layer interfaces, fractures, and inclusions is the highest priority for better understanding of the subsurface. The need for better understanding of the subsurface is driven by economic, environmental, and public perception considerations. Better subsurface characterization is important.
Citation
Green, S., (2017), “Understanding the Subsurface”, Hydraulic Fracturing Journal, March 2017, Volume 4 Number 2: 24-26.
Properties and Formation of Mineralized Veins in an Organic-Rich Shale Formation
Małachowska, Aleksandra, Green, Sidney, and Jan Hupka (2017)
Abstract
An earlier paper defined mineral and organic matter constituents in weak interfaces in shale formations (Ptaszynska, et. al., 2016). The formation studied in the earlier work and here is the Jurassic, early-Cretaceous Vaca Muerta formation in the Neuquen basin in Argentina. In this earlier work, mineralized "veins" were noted to be prevalent and complicated, sometimes being shear weak interfaces while in other cases they were not. This work looks specifically at the formation mechanisms and composition chemistry of the veins, to better understand why some are planes of weakness. This work shows how observations from core samples of the direction of crystal growth and the vein composition can help predict weak or strong interfaces, and suggests that ultimately high-resolution borehole logs may be better able to predict interfaces. The research focuses on understanding the planes of weakness, as it is now well accepted that such planes of weakness can significantly affect hydraulic fracture propagation during well completions.
Citation
Małachowska, Aleksandra, Green, Sidney, and Jan Hupka (2017). "Properties and Formation of Mineralized Veins in an Organic-Rich Shale Formation." Paper presented at the 51st U.S. Rock Mechanics/Geomechanics Symposium, San Francisco, California, USA, June 2017.
Mineral and Organic Matter Constituents in Weak Interfaces in Shales
Ptaszynska, Aleksandra, Green, Sidney, Hupka, Jan, and Roberto Suarez-Rivera (2016)
Abstract
This paper identifies formation interfaces that would appear to be “weak interfaces”, in the Jurassic, Early-Cretaceous Vaca Muerta formation, in the Neuquén Basin, Argentina. Significant distribution of the weak interfaces was observed including contacts between volcanic ash layers of varying thicknesses, calcite-filled veins, and contacts between lithology changes, such as between argillaceous mudstone and mottled carbonates. The paper shows mineral and organic matter constituents of selected interfaces and suggests that interface weakness depends on certain composition and morphology of mineral and organic constituents associated with the interfaces. The understanding presented in this paper of the composition of interfaces is a first step toward both identifying the location and frequency of the weak interfaces throughout the formation and ultimately of determining the shear strength of these interfaces. These interfaces have a significant effect on hydraulic fractures used for completion stimulation.
Introduction - Hydraulic fracturing is required to create large surface area to allow oil or gas to be extracted from unconventional formations, and particularly mudstone reservoirs. Recent work has shown the importance of rock fabric and particularly weak interfaces on hydraulic fracture propagation and geometry (Detournay, 2004; Dargaud et al., 2005; Jeffrey et al., 2009; Suarez-Rivera et al. 2006; Lecampion et al., 2013; Green, 2013). Early analysis and observations suggested that hydraulic fracture growth is affected by weak interfaces and other localized heterogeneities in the formation. They promote the development of complex fracture networks, may restrict the propped fracture surface area in contact with the reservoir, and thus influence the production potential of the play (Warpinski, 1987; Suarez-Rivera, 2011 & 2013; Green, 2013 & 2014).
The weak interfaces as discussed here tend to have low shear strength, and are thus more susceptible to local shear deformation as the fracture intersects the interface during the fracture propagation (Suarez-Rivera, 2013). The propagating fracture can either be arrested at the interface or can reorient and propagate in a different direction along the weak interface or may branch into two fractures (Thiercelin, 2005, Suarez-Rivera et al., 2006 & 2013; Green, 2014)
Citation
Ptaszynska, Aleksandra, Green, Sidney, Hupka, Jan, and R. Suarez-Rivera (2016). "Mineral and Organic Matter Constituents in Weak Interfaces in Shales." Paper presented at the 50th U.S. Rock Mechanics/Geomechanics Symposium, Houston, Texas, June 2016.
CT X-Ray Observations after Hydraulic Fracturing of Large Rocks Samples
Wickham, Don, Green, S., Surdi, A. (2011)
Abstract
Presentation on the unique work that is performed to resolve geometry of hydraulic fractures. Large-scale polyaxial stress rock tests (one sample about one meter3) are used to simulate hydraulic fracturing in complex rock. These tests are aimed to study the role of the rock fabric under high stress conditions simulating real field-scale hydraulic fracturing in gas or oil wells. This work has worldwide importance and no other facility has conducted such tests. Discussion includes TerraTek’s polyaxial vessels [as seen on this downloadable announcement].
Citation
Wickham, Don, Green, S., Surdi, A., (2011), “CT X-Ray Observations after Hydraulic Fracturing of Large Rocks Samples”, Graduate Seminar, Department of Chemical Engineering, University of Utah, November 20, 2011
Numerical Modeling of Quasi-Static Rock Testing
Bhide, R. J., Mclennan, J. D., Guilkey, J. E., Green, S. J. (2011)
Abstract
Quasi-static mechanical testing of granular structures (representing rock) is simulated using a Generalized Interpolation Material Point method (GIMP). The numerical analysis is carried out by representing the rock as a dense packing of non-uniformly-sized particles that are cemented in the vicinity of points of contact. Mechanical behavior of the cement is imparted by cohesive zone elements. With progressively increasing application of far-field stresses, local stresses increase to the point where the cohesive zone elements lose load-bearing capacity. The sensitivity of this decohesion to the number of cohesive zone segments was investigated (i.e., the discretization of cemented zones into conjoined cohesive elements). A parametric study also varied the traction strengths for these cohesive features. Cementitious micro-properties were estimated to represent cohesive characteristics of typical porous rock materials and to result in representative peak-loading behavior for the aggregate sample. Uniaxial compression and Brazilian tests were numerically performed on granular assemblies with rock-like properties.
Citation
Bhide, R. J., Mclennan, J. D., Guilkey, J. E., Green, S. J., (2011), “Numerical Modeling of Quasi-Static Rock Testing”, ARMA, 45th U.S. Rock Mechanics/Geomechanics Symposium, San Francisco CA, 2011.
Full-Scale Deep Well Drilling Simulation
全尺寸深井钻井模拟装置对钻井技术发展的影响
Green, Sidney (2011)
Abstract
Deep-well drilling is essential for oil and gas recovery, and in many ways drives the advancement in energy recovery for unconventional and difficult reservoirs. Furthermore, as the world moves more toward unconventional oil and to gas, more and more reliance is place on drilling. This is particularly true for gas, as more length of drilled hole – much greater lengths- will be required for the same amount of BTU’s recovered. Drilling is often the key to economic success and risk reduction. Advancements are being made in drill bits, in drilling muds, and drilling techniques. Unfortunately we cannot “see” the drilling operation at great depths, and must rely on experimentation trial-and-error to a large extent. The field drilling is to some extent a “free” laboratory, and indeed advancements are being made via this field laboratory and trial-and-error experimentation. There are limitations with this approach, and the introduction of new innovations tends to be slow and limited. However, the Schlumberger TerraTek Drilling and Completions Laboratory offers an opportunity for quantitative measurements that greatly add to the field laboratory observations. The TerraTek Drilling and Completions Laboratory is the most advanced facility in the world for full-scale drilling experimentation, simulation great depths. The TerraTek facility has been operated for nearly three decades and is well recognized for its contributions to drilling advancements. This paper reviews this world recognized facility, and notes some important observations.
Citation
Green, Sidney, (May, 2011), “Full-Scale Deep Well Drilling Simulation”, Petroleum Drilling Techniques, 2011, 39(3): 1-5.
Investigating the Efficacy of Seismic Air Guns for Coalbed Fracturing
Guilkey, Jim, Suarez-Rivera, R., Green, S. (2011)
Abstract
A numerical analysis has been conducted using the Uintah numerical code to simulate the dynamics of water and air pressurization and flow during air gun operation, and their effect on weak interfaces (cleats and butts) in coal seams. The study evaluates the extent of the disturbance away from the wellbore and the type of failure along these interfaces as a function of changes in the air gun and the interfaces (including: loading rates, gun cross sectional area, cleat spacing and friction angle). A model was developed based on available information of wellbore geometry, rock facies distribution, thickness and properties, the distribution and type of interfaces (cleats, butts, bed boundaries etc.), and the mechanical properties of the interfaces (friction angle and cohesion).
Because of the complexity associated with the numerical simulations of fracturing on media with heterogeneous distributions of weak interfaces, we conducted the study with a simplified geometry and a simplified characterization of the interfaces (dominant features only). The shear behavior of the cleats was also simplified by assuming a negligible cohesion (i.e. they are weak interfaces). Results from this initial analysis may motivate the implementation of additional complexity to the model, and better characterization of the material properties (matrix and interfaces).
Citation
Guilkey, Jim, Suarez-Rivera, R., Green, S. (2011), “Investigating the Efficacy of Seismic Air Guns for Coalbed Fracturing”, company paper, 2011.
A Parametric Analysis of Deep Injection for Waste Disposal using a 3-D Hydraulic Fracturing Simulator
Bai, Mao, Green, S., van den Hoek, P. (2002)
Abstract
Deep injection for disposal of drill cuttings, produced water, or drill site, cleanup waste is of great importance. Details of the injection capacity of a given injection well and of the containment within a given horizon are critical, and both economic and environmental needs must be met. This paper presents a parametric examination and comparison with actual field injections, using the TerraFRAC 3-D hydraulic fracture simulator. The paper focuses on the critical issues of the waste disposal, where efficiencies of deep injections are a function of key parameters, including injection rate, slurry concentration and rheology, and formation leakoff characteristics. Analysis shows that fracture storage capacity and waste containment are strongly driven by these parameters. And that the slurry dehydration may be controlled by proper slurry rheology.
Citation
Bai, M., Green, S., van den Hoek, P., (2002), “A Parametric Analysis of Deep Injection for Waste Disposal using a 3-D Hydraulic Fracturing Simulator”, North American Rock Mechanics, Tunnelling Association of Canada, North American Rock Mechanics symposium, Toronto, Canada, 2002, 577-584.
Simultaneous Determination of Two-Phase Relative Permeability and Capillary Pressure of Porous Rocks from Steady-State Flow Experiments: Accounting for Gravitational Forces and Fluid Compressibility
Mitlin, Vladimir, McLennan, J., Green, S. (1998)
Abstract
A methodology for simultaneously measuring two-phase relative permeability and capillary pressure of porous rock samples from steady-state flow experiments, reported by Virnovsky et al. in 1995, is considered. The method requires measuring pressure drops in individual fluid phases across a rock sample. This paper studies the role of gravitational forces, neglected in the original derivation of the method. Direct numerical simulations of steady-state vertical flow experiments, performed over a typical range of rocks and flow parameters, show that the error caused by neglecting gravitational forces in the original method, is acceptable even for extremely high (approximately 10-10 m2) permeability samples. Thus, if multiphase flow measurements are performed on vertical samples, the gravitational force can be neglected for estimating relative permeability and capillary pressure. An extension of this method to the case of compressible fluids is presented.
Citation
Mitlin, Vladimir, McLennan, J., Green, S., (August, 1998), “Simultaneous Determination of Two-Phase Relative Permeability and Capillary Pressure of Porous Rocks from Steady-State Flow Experiments: Accounting for Gravitational Forces and Fluid Compressibility”, Journal of Colloid and Interface Science, 1998, 204, (1):205-213.
Grain Density Measurements on Zeolitized Tuff
Martin, J. W., Felice, C. W., DeVan, R. T., Green, S. J. (1991)
Abstract
Due to their hygroscopic mineralogic characteristics, zeolites, an alteration product of volcanic glass, present problems in determining grain density. Grain densities measured by gas pycnometry varied with the gas used due to a difference in their adsorption by zeolite. Grain densities measured with atmospheric air were substantially higher than grain densities measured with helium. Also, grain densities measured with water pycnometry were typically higher than grain densities measured with helium gas pycnometry. Both techniques were strongly affected by drying temperatures. An overview of zeolite properties and experimental procedures used to measure grain density of zeolite bearing material are discussed. Traditional techniques of water and gas pycnometry have been modified in an attempt to account for zeolite moisture adsorption when attempting to measure grain density. Errors resulting from technique and procedural handling are documented. Estimated grain densities from X-Ray Diffraction (XRD) techniques have been used to check values obtained by conventional measurements. The XRD estimates are predominantly lower than conventional values.
Citation
Martin, J. W., Felice, C. W., DeVan, R. T., Green, S. J., (September, 1991), “Grain Density Measurements on Zeolitized Tuff”, 6th Symposium on Containment of Underground Nuclear Explosions, September 24-27, 1991, Nevada, 203-226
Experimental Observations Regarding Strain Softening
Green, Sidney, Zheng, Z., Jones, A., Tester, V. (1990)
Abstract
This paper addresses the issue of strain softening, a phenomenon where stress is decreasing in magnitude and strain is increasing in magnitude. Primary emphasis is how strain softening may be experimentally measured, as opposed to simply noting an artifact of the particular test.
Citation
Green, S., Zheng, Z., Jones, A., Tester, V., (1990), “Experimental Observations Regarding Strain Softening”, SECTAM XV Mini-symposium on Theoretical, Experimental, and Computational, Problems Related to Concrete, Rock and Soil, Georgia, March 22-23, 1990.
Effects of Bit Hydraulics on Full-Scale Laboratory Drilled Shale
Tibbitts, Gordon A., Sandstrom, J. L., Black, A. D., Green, S. J. (1981)
Abstract
Summary- The effects of bit hydraulics while drilling shale with a standard three-cone bit are examined in this paper. Tests were conducted by drilling into large-diameter, intact shale samples at simulated downhole conditions in Drilling Research Laboratory's wellbore simulator. The shale samples were recovered from massive surface outcroppings and preserved for laboratory use. The effects of hydraulic horsepower from 20 to 400 hhp and bit weights from 20,000 to 50,000 lbm on rate of penetration are presented.
Introduction- Most deep shales and some intermediate shales found in the U.S. are typically "slow" drilling formations. Efforts to improve rate of penetration in shale have been performed in both field tests and small-scale laboratory investigations. Until recently, laboratory drilling studies on shale have been confined to microbit1 or single-cutter2 studies because the ability to obtain and preserve large, intact shale samples had not been developed. In addition, laboratory facilities where full-scale drilling tests could be conducted at simulated deep-well conditions did not exist.
Massive surface shale formations have been located and techniques have been developed to extract and preserve large-diameter, intact samples. With these samples and the ability to simulate full-scale drilling conditions, a systematic, technical approach was taken where the effects of drill bit hydraulics were examined while drilling shale at simulated downhole conditions.
Background and Definitions- The in-situ conditions of a typical deep wellbore and surrounding rock formation are illustrated in Fig. 1. The formation is subjected to overburden stress, confining stress, wellbore pressure, and formation pressure. As previously demonstrated,3–5 rate of penetration is influenced strongly by the bottomhole conditions and appears to be most sensitive to the differential pressure between the wellbore and formation. These effects, however, can vary widely depending on rock properties such as rock type, strength, density, permeability, and mud properties such as composition, filtration rate, viscosity, solids content, and particle size.6 Bit hydraulics - i.e., the means of removing cuttings from the hole bottom and cleaning the bit with the drilling fluid - are a key factor in improved bit performance. Bottomhole cleaning theories,7 microbit studies,8 and full-scale laboratory drilling experiments in hard, impermeable rock9 have shown the need for adequate bit hydraulics to maximize rate of penetration and avoid bit balling. Field tests with extended nozzles10 also have demonstrated great potential for increasing rate of penetration in certain formations with improved bit hydraulics. Some nondrilling laboratory studies have shown the effects of nozzle size on pressure distribution at the hole bottom.11…
Citation
Tibbitts, G. A., Sandstrom, J. L., Black, A. D., Green, S. J., (July, 1981), “Effects of Bit Hydraulics on Full-Scale Laboratory Drilled Shale”, Journal of Petroleum Technology, 1981, 33 (07): 1180-1188
Development of Improved Rotary Seals for Downhole Motors in Geothermal Applications
Black, Alan D., Wilson, J. G., Green, S. J., Nixon, J. (1978)
Abstract
The major limitation of downhole mud motors for geothermal well drilling as well as straighthole and gas well drilling is the bearing section. Reduced bearing life has been a direct result of the inability to seal lubricant in the bearing section. Along with extending bearing life, a reliable rotary seal is needed to allow high pressure drops across the drill bit for improved bottomhole cleaning and increased drilling rate. A new approach to the development of an improved rotary seal is being carried out. The performance of candidate “high temperature” rotary seals compared with “standard” industry seals is being measured in a full-scale laboratory seal tester capable of simulating the temperatures, pressures and dynamic conditions of geothermal well drilling. A description of the candidate “high temperature” seals, the seal tester and current seal test results and findings are presented. Work performed for the U. S. Department of Energy/Division of Geothermal Energy, Contract No. EG-76-C-07-1581 with Terra Tek, prime contractor and Maurer Engineering, subcontractor.
Citation
Black, A. D., Wilson, J. G., Green, S. J., Nixon, J., (July 1978), “Development of Improved Rotary Seals for Downhole Motors in Geothermal Applications”, Presentation at Geothermal Resources Council Annual meeting in Hilo, Hawaii, July 25, 1978, Geothermal Resources Council Transactions, 1978, v. 2: 51-54
Laboratory Simulation of Deep Well Drilling
Black, Alan D., Green, S. J. (1978)
Abstract
Reduced penetration rates in deep wells strongly influence their economics, and have been a major concern to the oil and gas industry for decades. In addition to field observations of this phenomenon, therefore, the effects of deep well conditions on drill bit performance were studied in the laboratory. Parameters identified by these studies as affecting penetration rate include: Rock properties at depth (strength, porosity, permeability, modulus and ductility); drilling fluid properties (viscosity and filtrate characteristics); borehole mud pressure; bit type (design, hydraulics, and wear); differential pressure between the borehole and formation pressure; weight-on-bit; and rotary speed. Results of these laboratory tests are discussed.
Citation
Black, A. D., Green, S. J., (March 1978), “Laboratory Simulation of Deep Well Drilling”, Petroleum Engineer International, 50(3):40, 42, 46, 48
Drillability of a Sandstone and Dolomite at Simulated Depths
Black, Alan D., Green, S. J., and Williams, C. R. (1978)
Abstract
Drilling experiments were performed at the [Terra Tek] Drilling Research Laboratory, Salt Lake City, Utah, with full-scale rock bits under simulated deep well conditions. This paper describes the test facility, test set-up, rock and drill bit selection, experiment design, test results and conclusions for a laboratory drilling program funded by ERDA/Division of Oil, Gas and Shale Technology. Twenty rock samples of Colton Sandstone and Bonne Terre Dolomite were drilled under conditions simulating depth from 0 to 13,000’ with standard roller bits.
Citation
Black, A. D., Green, S. J., and Williams, C. R., (1978), “Drillability of a Sandstone and Dolomite at Simulated Depths”, Performed for ERDA Division of Oil, Gas and Shale Technology under Contract No. EY-76-02-4098.
Drilling and Production of Oil and Gas from an Offshore Tunnel and Chamber System
Lewis, John G., McDonald, W. J., Green, S. J. (1976)
Abstract
For at least 40 yrs the petroleum industry has operated offshore to recover oil and gas. First, by building piers out into the water and then by separate structures in shallow water. Subsequently, they have moved to deeper water with specially prepared offshore structures which often extend hundreds of feet to the ocean bottom. The most common type structure is the jacket-type, which is pile founded with one or more decks set on top of the jacket…
Citation
Lewis, J. G., McDonald, W. J., Green, S. J., (September, 1976), “Drilling and Production of Oil and Gas from an Offshore Tunnel and Chamber System”, 31st Petroleum Mechanical Engineering Conference, Mexico City, 1976
Determination of the Critical-stress-intensity factor Klc from Internally Pressurized Thick-walled Vessels
Download
Clifton, Rodney J., Simonson, E. R., Jones, A. H., and Green, S. J. (1976)
Abstract
Stable crack growth is obtained by subjecting prenotched thick-walled cylinders to internal pressure, with the bore jacketed to keep the crack faces traction free. The critical-stress-intensity factor Klc is determined from the pressure at failure. Results are presented for PMMA and a variety of rocks. 8 figures, 1 table.
Citation
Clifton, R. J., Simonson, E. R., Jones, A. H., and Green, S. J., (June, 1976), “Determination of the Critical-stress-intensity factor Klc from Internally Pressurized Thick-walled Vessels”, Presented SESA Spring meeting May 11-16 1975 and Experimental Mechanics, 16: 233-238.
High-strain-rate Tests on Titanium 6-6-2 Utilizing a Unique Rate-testing Machine
Luntz, R. D., Griffin, R. M., Green, S. J., Chou, S. C. (1975)
Abstract
A materials-test system employing both hydraulic and pneumatic modes of operation was developed for testing brittle materials from 10-4 to 102/s strain rates.
This paper presents the design of a unique materials-testing system capable of medium strain rates of from 10-4 to 102/s. The design incorporates both closed-loop hydraulic operation with that of open-loop pneumatic operation. A novel design permits accurate specimen alignment and a stiff frame which exceeds 17×106 lb/in. (11.7×104 MPa). The machine is able to perform conventional tension/compression tests, fatigue tests and, with slight modification, biaxial-stress-tube tests and triaxial-stress tests. The accurate alignment capability coupled with high frame stiffness and the pneumatic operation enables the testing of brittle materials with rigid grips. Titanium 6-6-2 was tested in both tension and compression at strain rates from 10-4 to about 10/s at four selected temperatures. The material showed a slight strain-rate sensitivity. Yield stress was shown to increase with strain rate while ductility decreased at each test temperature.
Citation
Luntz, R. D., Griffin, R. M., Green, S. J. et al., (October, 1975), “High-strain-rate Tests on Titanium 6-6-2 Utilizing a Unique Rate-testing Machine”, Experimental Mechanics, v. 15: 396–402
Mechanical Properties of Two Highly Porous Geologic Materials
Shipman, F. H., Johnson, J. N., Green, S. J. (1974)
Abstract
Hydrostatic pressure, compression under different confining pressures, proportional loading and uniaxial-strain tests were conducted on a dry tuff from the Nevada Test Site and dry Kayenta sandstone from the Mixed Company Site near Grand Junction, Colorado. Both rocks exhibit behavior which is characteristic of very porous geological materials; namely, increasing shear strength as a function of confining pressure, large volume compaction followed by volume dilatancy under selected loadings with enhanced compaction, over some pressure ranges, in the presence of shear deformation. Both materials also exhibit strain work-hardening. A “cap model” is applied to represent the mechanical behavior of these two materials. This model account for all of the aforementioned characteristics of both the tuff and the sandstone, and provides a means to represent the path dependence of their mechanical properties.
Citation
Shipman, F. H., Johnson, J. N., Green, S. J., (April, 1974), “Mechanical Properties of Two Highly Porous Geologic Materials”, Technical Report for Army Materials and Mechanics Research Center, AMMRC CTR-73-45
Static Constitutive Relations for Concrete
Green, Sidney J., Swanson, S. R. (1973)
Abstract
Static constitutive stress-strain relations are developed for concrete at intermediate pressure levels, up to 10-12 ksi mean normal stress. An elastic-plastic model is developed that quantitatively fits the loading features exhibited for a variety of controlled laboratory tests conducted in this program and found in the literature. Laboratory tests were conducted on several batches of concrete with 3/8 inch maximum aggregate. Considerable attention was paid to the casting of the concrete so that batch-to-batch repeatability could be obtained, and to specimen preparation. Some data are presented for aggregate variation form 3/16 inch to ¾ inch so that scaling to different aggregate could be performed. The laboratory tests presented represent a series of tests where all stresses and strains have been measured, thereby allowing the shear and dilatation stress-strain responses to be observed during a variety of load-unload paths.
Citation
Green, S. J., Swanson, S. R., (April, 1973), “Static Constitutive Relations for Concrete”, Technical Report for Air Force Weapons Laboratory, AFWL-TR-72-244
Stress-Strain and Failure Properties of a Porous Shale
Green, Sidney J., Griffin, R. M., and Pratt, H. R. (1973)
Abstract
Unconfined and triaxial stress tests were conducted on dry and saturated shale from El Paso's Wagon Wheel No. 1 well. The material tested is in general a very competent shale containing stringers of silt and sand, producing local inhomogeneities which effect unconfined fracture, but do not significantly effect the behavior at higher mean normal pressures. Strong sensitivity of deviatoric maximum stress to mean pressure is observed for dry material, while little increase in deviatoric strength with pressure occurs for the fully saturated material. Dilation accompanies distortional deformation; however, softening or ease of compaction occurs at small distortional strains, before substantial dilation begins. In detail, the deviatoric stiffness (apparent shear modulus) and the pressure-volume relation (compressibility) are stress state and stress path dependent, while the deviatoric strength path dependent, while the deviatoric strength is only stress state dependent.
Introduction
Mechanical properties of a shale material were obtained for El Paso Natural Gas Company to be used in shock calculations to determine rock breakage, and hence increased permeability, caused by nuclear explosion. The samples tested were taken from a core at the 10,215–10,216 foot depth in El Paso's Wagon Wheel No. 1 well, NW/4 Section 5, Township 30N, Range 108W, Sublette County, Wyoming. Small samples were dry cored from the large core provided by El Paso and tested unconfined and provided by El Paso and tested unconfined and confined to pressures of 6 kbars. Both dry and fully saturated samples were tested, parallel and perpendicular to the large core parallel and perpendicular to the large core axis. Petrofabric analysis was made and photomicrographic observations taken to photomicrographic observations taken to predict and better understand the mechanism predict and better understand the mechanism of fracture.
Similar tests were previously conducted for El Paso on a large core of sandstone from 10180.4–10181.0 foot depth. These results are reported in Terra Tek report "Testing Program Conducted for El Paso Natural Gas Company" August, 1970.
Citation
Green, Sidney J., Griffin, R. M., and Pratt, H. R., (1973), “Stress-Strain and Failure Properties of a Porous Shale”, 6th Conference on Drilling and Rock Mechanics SPE, Journal of Petroleum Technologyi>, January 1973: 118-128.
Triaxial Stress Behavior of Solenhofen Limestone and Westerly Granite at High Strain Rates
Green, Sidney J., Leasia, R. D., Perkins, R. D., Jones, A. H., Terra Tek, (1972)
Abstract
Constant strain rate tests were conducted on solid cylinders and thin-walled hollow cylinders of Solenhofen limestone and Westerly granite. Load and axial and transverse strains were measured to provide the stress-strain response and to define the brittle failure or ductile yield locus. Tests were conducted at confining pressures to 3 kb and strain rates to 103 /sec. The strength of the rocks is strain rate sensitive; i.e., somewhat increased strength with strain rate is shown. Stiffness and compressibility are stress state dependent and for Westerly granite, also strain rate dependent at low confining pressures.
Citation
Green, S. J., Leasia, R. D., Perkins, R. D., Jones, A. H., (1972), “Triaxial Stress Behavior of Solenhofen Limestone and Westerly Granite at High Strain Rates”, AGU, Journal of Geophysical Research, v 77, 20: 3711-3724.
Comparison of uniaxial deformation in shock and static loading of three rocks
Brace, W. F., Jones, A. H. (1971)
Abstract
Deformation of a granite, a tonalite, and a limestone in a plane shock wave is compared with triaxial deformation at 10−5 sec−1 under the constraint of uniaxial strain. For granite and for limestone at moderate pressure, the stress-strain relation is nearly identical in the two tests; strain under these conditions was elastically recoverable. For the limestone at high pressure and for the tonalite at all pressures, volume decreases permanently. This permanent deformation, compared here for shock and slow strain-rate tests, had approximately the same strain-rate dependence as has been observed typically in fracture of rocks under triaxial conditions.
Citation
Brace, W.F., Jones, A. H., (1971), “Comparison of uniaxial deformation in shock and static loading of three rocks”, AGU, Journal of Geophysical Research, v76, 20: 4913-4921. 10 July 1971
A Shock Wave Study on Coconino Sandstone
Shipman, F. H., Gregson, V. G., and Jones, A. H., General Motors (1971)
Abstract
Hugoniot equation of state measurements to 1400 kb were made on Coconino sandstone. This data is summarized with other quartz shock wave data and used to estimate isotherms for the three solid phases of quartz, coesite and stishovite. Calculations of shock temperature have been made based on these isotherms and lead to an estimation of the phase boundaries of quartz polymorphs under dynamic loading. The dynamic phase boundaries are shown to shift significantly compared to those determined statically.
Citation
Shipman, F. H., Gregson, V. G., and Jones A. H., (1971), “A Shock Wave Study on Coconino Sandstone”, Contracted report for National Aeronautics and Space Administration, NASA CR-1842, May 1971.
Observation of brittle-deformation features at the maximum stress of westerly granite and solenhofen limestone
Friedman, M., Perkins, R.D., Green, S. J. (May, 1970)
The nature and sequence of deformation in the region of the maximum stress were investigated in specimens deformed in uniaxial stress compression at room temperature and at constant strain rates from 10−4/sec to 103/sec. Microscopic observations show that no visible fracture (> 0·01 mm long) or other evidence of deformation takes place until > 99% of the average maximum stress at a strain rate of 10−4/sec is attained by the granite. Detailed examination of an incipient shear fracture in a granite specimen suggests that the fracture is formed by the coalescence of links between en echelon inclined grain boundaries and cleavages. Photographs taken during loading in the split-Hopkinson bar device illustrate that macroscopic shear fractures develop before extension fractures in the sequence of events leading to gross failure of the specimens.
Abstract
The nature and sequence of deformation in the region of the maximum stress were investigated in specimens deformed in uniaxial stress compression at room temperature and at constant strain rates from 10−4/sec to 103/sec. Microscopic observations show that no visible fracture (> 0·01 mm long) or other evidence of deformation takes place until > 99% of the average maximum stress at a strain rate of 10−4/sec is attained by the granite. Detailed examination of an incipient shear fracture in a granite specimen suggests that the fracture is formed by the coalescence of links between en echelon inclined grain boundaries and cleavages. Photographs taken during loading in the split-Hopkinson bar device illustrate that macroscopic shear fractures develop before extension fractures in the sequence of events leading to gross failure of the specimens. A PHENOMENOLOGICAL understanding of fracture in rock is one of the primary objectives
of rock mechanics research. Knowledge of the nature and sequence of events leading to
macroscopic rupture would be helpful in establishing (a) the locations of fracture initiation
relative to stress-strain distributions, grain boundaries, or imperfections within crystals,
(b) the scale on which fractures start, (c) the type of initial fracture-tensile or shear, and
(d) the dependence of the events on material properties.
Citation
Friedman, M., Perkins, R.D., Green, S. J., “Observation of brittle-deformation features at the maximum stress of westerly granite and solenhofen limestone”, International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts, V 7, Issue 3, 297-302, 1970.
Uniaxial Stress Behavior of Porphyritic Tonalite at Strain Rates to 10³/second
Perkins, R. D., Green, S. J., Friedman, M., (1970)
Abstract
Rock cores of a porphyritic tonalite composition have been loaded in uniaxial stress at strain rates from 10-4 to 10³/sec at temperatures of 25°C, -78°C and -191°C. The data presented include axial stress as a function of axial and transverse strain and volume change as a function of axial stress. For the conditions studied, the tonalite was found to exhibit increased stiffness and maximum stress with increasing strain rate and decreasing temperature. Anisotropy was studied by loading samples taken perpendicular and parallel to the bulk core axis. Specimens taken perpendicular to the bulk core axis were found to have increased initial stiffness and decreased maximum stress over specimens taken parallel to the core axis. A petrofabric analysis was made to aid in the interpretation of the experimentally observed behavior. From these data it has been determined that the unconfined behavior of the tonalite is controlled by the deformation of the fine-grained groundmass.
Citation
Perkins, R. D., Green, S. J., Friedman, M., (1970), “Uniaxial Stress Behavior of Porphyritic Tonalite at Strain Rates to 10³/second”, International Journal of Rock Mechanics and Mining Sciences and Geomechanics Abstracts, v7, 5: 527-535, 1970.
High-velocity Deformation Properties of Polyurethane Foams
Green, Sidney J., Schierloch, F. L., Perkins, R. D., and Babcock, S. G. (1969)
Abstract
Results of tensile and compressive tests at strain rates from 10-3 to 103 sec are presented for two kinds of polyurethane foam at various densities.
This paper presents the results of dynamic uniaxial-stress tests performed on polymer-foam material. A water-blown ester polyurethane foam designated as rigid and a castor-oil-base polyurethane foam designated as semirigid were tested in tension and compression at rates of loading from 10-3 in./in./sec. Tests at higher rates were performed on a split Hopkinson-bar device. High-speed photographic techniques were used to study dynamic fracture.
Citation
Green, S. J., Schierlock, F. L., Perkins, R. D., and Babcock, S. G. (1969), “High-velocity Deformation Properties of Polyurethane Foams”, Experimental Mechanics, March 1969: 103-109.
Uniaxial Compression Tests At Varying Strain Rates On Three Geologic Materials
Green, Sidney J., Perkins, R. D. (1968)
Little data exists on the high strain rate behavior of geologic materials. Uniaxial stress tests by Kumar1 and by Serdengecti and Boozer2 present some results to strain rates in the range 10 to 103 per sec. The two references cited are the only ones the authors found for high strain rates. Techniques for experiments at high strain rates are not well developed and, in general, leave questions with respect to interpretation of data when the material behaves in a brittle manner. The most reliable data at very high strain rates (104 to l06 per sec) are found in some recent flat-plate work 3-5 where experimenters have impacted one plate into another, thereby creating a uniaxial strain loading. The standard uniaxial stress-strain curves cannot be obtained directly from these tests; however, yield (or fracture) may be studied by measuring the "elastic" wave magnitude. These data then may be compared to uniaxial stress data by resorting to some preassumed yield/fracture criteria. Even with the most liberal interpretation of existing data, little can be said of the effects of high strain rate on stiffness, yield/fracture, and post-fracture behavior of geologic materials. It is the purpose of this work to begin to add to the understanding. The data presented here are intended to provide material information for use in calculating the response of geologic materials to high rate deformations. These data can be applied directly to determine parameters such as the elastic modulus and Poisson ratio as a function of stress. Furthermore, these data can be used to derive an understanding of yield/fracture and the effect of rate on the yield/fracture surface. The work presented is a first step, and is being extended to multiaxial stress states where by the yield/fracture surface can be mapped precisely over various strain and stress rates. Table 1. Description of Materials
MATERIAL DESCRIPTION TOWARDS MECHANICAL BEHAVIOR
Materials investigated were Solenhofen limestone, Westerly granite, and volcanic tuff. The grain size, porosity, and approximate composition of each material are given in Table 1. The Solenhofen limestone is very fine-grained, homogeneous, and isotropic in strength. The block of limestone from which test specimens were taken did have some stratification (sedimentary bedding) visible. Specimens were machined without regard to the stratification, and, therefore, loading was at various random angles to the stratification. Micrographic analysis indicated that fractures in all cases tended to transect the stratification, indicating that deformation was not influenced by the visible bedding.
The Westerly granite, obtained as a large block from Westerly, R.I., is relatively fine-grained and is composed of about one-third each quartz, potash feldspar, and plagioclase feldspar. Micas and accessory minerals compose a small percentage. Examination indicated that the aggregate appears homogeneous and that crystallographically and dimensionally the quartz and feldspar crystals are diffusely oriented in the aggregate. From these observations, isotropic strength behavior would be expected and was found to be the case.
Abstract
Little data exists on the high strain rate behavior of geologic materials. Uniaxial stress tests by Kumar 1 and by Serdengecti and Boozer 2 present some results to strain rates in the range 10 to 103 per sec. The two references cited are the only ones the authors found for high strain rates. Techniques for experiments at high strain rates are not we]] developed and, in general, leave questions with respect to interpretation of data when the material behaves in a brittle manner. The most reliable data at very high strain rates (104 to l06per sec) are found in some recent flat-plate work 3-5 where experimenters have impacted one plate into another, thereby creating a uniaxial strain loading. The standard uniaxial stress-strain curves cannot be obtained directly from these tests; however, yield (or fracture) may be studied by measuring the "elastic" wave magnitude. These data then may be compared to uniaxial stress data by resorting to some preassumed yield/fracture criteria.
Even with the most liberal interpretation of existing data, little can be said of the effects of high strain rate on stiffness, yield/fracture, and post-fracture behavior of geologic materials. It is the purpose of this work to begin to add to the understanding. The data presented here are intended to provide material information for use in calculating the response of geologic materials to high rate deformations. These data can be applied directly to determine parameters such as the elastic modulus and Poisson ratio as a function of stress. Furthermore, these data can be used to derive an understanding of yield/fracture and the effect of rate on the yield/fracture surface. The work presented is a first step, and is being extended to multiaxial stress states where by the yield/fracture surface can be mapped precisely over various strain and stress rates.
Table 1. Description of Materials (Available in full paper)
Citation
Green, S. J., Perkins, R. D., "Uniaxial Compression Tests At Varying Strain Rates On Three Geologic Materials", 10th U.S. Symposium on Rock Mechanics (USRMS), Austin, Texas, May, 1968.
Hugoniot Equation of State Measurements for Eleven Materials to Five Megabars
Isbell, W. M., Shipman, F. H., and Jones, A. H., (1968)
Abstract
An experimental technique is utilized in which a light-gas gun is used to launch flat impactor plates to high velocities approximately 8 km/sec at specimens suspended at the muzzle of the gun. Impact-induced shock waves at pressures to approximately 5 megabars are recorded and are used to determine the shock state in the specimen. The ability to launch unshocked, stress-free flat plates over a wide and continuous velocity range, coupled with the ability to launch impactor plates of the same material as the target, results in hugoniot measurements of relatively high precision. Measurements were made on Fansteel-77 a tungsten alloy, aluminum 2024-T4, copper OFHC, 99.99, nickel 99.95, stainless steel type 304, titanium 99.99, magnesium AZ31B, beryllium S- 200 and I-400, uranium depleted, plexiglas, and quartz phenolic. The results are compared with those of other researchers. Deviation from linear shock velocity - particle velocity was found in aluminum beginning at approximately 1.0 megabars, probably attributable to melting in the shock front.
Citation
Isbell, W. M., Shipman, F. H., and Jones, A. H., (1968), “Hugoniot Equation of State Measurements for Eleven Materials to Five Megabars”, General Motors Corporation Material and Structures Laboratory, MSL-68-13.
Prediction of Elastic-Plastic Wave Profiles in Aluminum 1060-0 Under Uniaxial Strain Loading
Jones, Arfon H., Maiden, C. J., and Green, S. J., Chin, H. (1968)
Abstract
In an ideally elastic-perfectly plastic material, in which the elastic moduli are constant, a high intensity wave propagating from the impact interface of two flat plates has a two-wave structure as shown in Fig. 1. The elastic wave propagates at velocity
√ ((λ + 2 μ )/ρ ) (1)
with intensity
((λ+2μ)/2μ)Y (2)
where Y is the yield stress of the material in a uniaxial stress test, λ and μ are Lame’s constants, and ρ is the material density. This is followed by the higher intensity plastic wave travelling at a slower velocity
√((λ+(2/3)μ)/ρ (3).
with intensity
((λ+2μ)/2μ)Y
where Y is the yield stress of the material in a uniaxial stress test, λ and μ are Lame’s constants, and ρ is the material density. This is followed by the higher intensity plastic wave travelling at a slower velocity
√((λ+(2/3)μ)/ρ (3).
Citation
Jones, A. H., Maiden, C. J., and Green, S. J., Chin, H. (September 6, 1967). "Prediction of Elastic-Plastic Wave Profiles in Aluminum 1060-0 Under Uniaxial Strain Loading" Pre-print from Symposium, Mechanical Behavior of Materials Under Dynamic Loads, p. 254-269, 1968.
The Strain-Rate Dependence of the Flow Stress in Some Aluminum Alloys
Holt, D. L., Babcock, S. G., Green, S. J., and Maiden, C. J. (1967)
Abstract
Flow stress at constant rates of strain, between 10-3 in./in./sec and 103 in./in./sec and up to strains of 8%, has been determined for 99.999% Al and the commercial alloys, 1060-O, 1100-O, 6061-O, 2024-O, 7075-O, 6061-T6 and 7075-T6. For materials in the O temper the principal effect of alloying is to raise the athermal (rate insensitive) component of the flow stress. Designating flow stress at a particular strain rate ϵ˙ (in./in./sec) (and fixed strain) as σϵ˙ while σ1000 – σ.001 is roughly the same for all materials, strain rate sensitivity as represented by (σ1000 – σ.001) / σ.001 decreases as alloying increases. Variation in activation volume changes rate sensitivity in only a minor way; furthermore, it may be that in all materials the activation barriers are forest dislocations. Rate sensitivity of the flow stress is negligible in alloys 6061-T6 and 7075-T6. The suggestions is that dislocation movement is controlled by the cutting of G. P. zones or coherent precipitates, so that activation volume is large.
Citation
Holt, D. L., Babcock, S. G., Green, S. J., and Maiden, C. J. (1967). “The Strain-Rate Dependence of the Flow Stress in Some Aluminum Alloys” ASM. Transactions of the ASM, 1967, v 60: 152-156.
Compressive Strain-Rate Tests on Six Selected Materials at Strain Rates From 10⁻³ to 10⁴ In/In/Sec
Maiden, Colin J., and Green, S. J. (1966)
Abstract
The results of compressive strain-rate tests on 6061-T6 aluminum, 7075-T6 aluminum, 6Al-4V titanium fully annealed, pyrolytic graphite, lucite, and micarta for rates of loading of 10⁻³ to 10⁴ in/in/sec are presented. A medium strain-rate machine and a split Hopkinson bar apparatus used to conduct these tests are described, and the principle of operation, data-reduction methods, and a critique of techniques are given for each machine. Results of the tests show that the two aluminums exhibit no strain-rate sensitivity over the rates tested. Titanium, lucite, and micarta are rate sensitive with the titanium exhibiting a delayed yield and the lucite and micarta showing viscoelastic behavior. The pyrolytic graphite shows little rate sensitivity below 10 in/in/sec and slight sensitivity above this rate.
Citation
Maiden, C. J., and Green, S. J. (September 1, 1966). "Compressive Strain-Rate Tests on Six Selected Materials at Strain Rates From 10⁻³ to 10⁴ In/In/Sec." ASME. J. Appl. Mech., September 1966; 33(3): 496–504.
An Investigation of the Protection Afforded a Spacecraft by a Thin Shield
Maiden, Colin J., and McMillan A. R. (1964)
Abstract
Results are presented from a theoretical and experimental program to investigate the damage that would be inflicted upon a missile, satellite, or space vehicle by a hypervelocity particle. Most of the work has been directed toward thin shield impacts. The problem is treated theoretically by examining the wave motion in an impacting projectile and shield, and consideration is given to heating effects. Theoretical considerations and experimental results lead to the following conclusions: 1) A thin shield is effective because it fragments and spreads the projectile and shield debris and, at high velocities, may melt or vaporize the fragments. 2) The optimum shield to minimize penetration is the one that melts or vaporizes the majority of debris coming through the shield. The shield thickness required to do this is found to decrease with increasing impact velocity. Total damage is not denned on this basis only, and failure may occur through momentum loading of the shielded structure. 3) Shield parameters such as strength and density, on an equiweight basis, are not important. 4) Hole diameter in a shield is proportional to impact velocity and to shield thickness to the two-thirds power.
Citation
Maiden, C. J., and McMillan A. R. (1964). “An Investigation of the Protection Afforded a Spacecraft by a Thin Shield.” American Institute of Aeronautics and Astronautics, AIAA Journal, November 1964; v. 2 n. 11: 1992-1998.
Additional various papers and presentations may be available on the ResearchGate / Google Scholar profiles for Sidney J. Green.
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