Sabina E. Deitrick and Ilia Murtazashvili
- Published in print:
- 2022
- Published Online:
- May 2022
- ISBN:
- 9781501760983
- eISBN:
- 9781501761003
- Item type:
- chapter
- Publisher:
- Cornell University Press
- DOI:
- 10.7591/cornell/9781501760983.003.0001
- Subject:
- Sociology, Urban and Rural Studies
This introductory chapter considers how communities have dealt with the shale boom, including its economic costs. The shale boom refers to the dramatic rise in U.S. shale gas production starting in ...
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This introductory chapter considers how communities have dealt with the shale boom, including its economic costs. The shale boom refers to the dramatic rise in U.S. shale gas production starting in the late 1990s and continuing into the 2020s. The focus is on how planners and government officials have responded to the challenges and opportunities from natural resource extraction. Many of these challenges may be exacerbated as state and local governments deal with the financial fallout from the COVID-19 pandemic, as well as the potential for increased pressure for shale gas development as a way to boost the economy and keep prices low as the curve flattens. The chapter attempts to provide insight into the specific legal, governance, planning, and economic challenges faced, as well as an understanding of how communities have responded when they often had no choice in the matter.Less
This introductory chapter considers how communities have dealt with the shale boom, including its economic costs. The shale boom refers to the dramatic rise in U.S. shale gas production starting in the late 1990s and continuing into the 2020s. The focus is on how planners and government officials have responded to the challenges and opportunities from natural resource extraction. Many of these challenges may be exacerbated as state and local governments deal with the financial fallout from the COVID-19 pandemic, as well as the potential for increased pressure for shale gas development as a way to boost the economy and keep prices low as the curve flattens. The chapter attempts to provide insight into the specific legal, governance, planning, and economic challenges faced, as well as an understanding of how communities have responded when they often had no choice in the matter.
Dieter Helm
- Published in print:
- 2012
- Published Online:
- October 2013
- ISBN:
- 9780300186598
- eISBN:
- 9780300188646
- Item type:
- chapter
- Publisher:
- Yale University Press
- DOI:
- 10.12987/yale/9780300186598.003.0011
- Subject:
- Environmental Science, Environmental Studies
This chapter focuses on the importance of a transition strategy—one that heads off the enormous projected expansion of coal-fired power stations and gets the existing ones closed as fast as possible. ...
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This chapter focuses on the importance of a transition strategy—one that heads off the enormous projected expansion of coal-fired power stations and gets the existing ones closed as fast as possible. The shale gas revolution has a particular resonance for the electricity market and for the options for new power stations. Gas-fired power stations have the peculiar economic merit of being comparatively quick to build, and have lower capital costs relative to coal, nuclear, and wind. Opponents of shale gas developments have a good case to make about specific locations, and about the general quality of the regulatory framework. Because none of the existing technologies can achieve decarbonization, new technologies are required, and the R&D will therefore have to be financed.Less
This chapter focuses on the importance of a transition strategy—one that heads off the enormous projected expansion of coal-fired power stations and gets the existing ones closed as fast as possible. The shale gas revolution has a particular resonance for the electricity market and for the options for new power stations. Gas-fired power stations have the peculiar economic merit of being comparatively quick to build, and have lower capital costs relative to coal, nuclear, and wind. Opponents of shale gas developments have a good case to make about specific locations, and about the general quality of the regulatory framework. Because none of the existing technologies can achieve decarbonization, new technologies are required, and the R&D will therefore have to be financed.
Michael Bradshaw, Murtala Chindo, Joseph Dutton, and Kärg Kama
- Published in print:
- 2015
- Published Online:
- September 2015
- ISBN:
- 9780198719526
- eISBN:
- 9780191788628
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198719526.003.0015
- Subject:
- Economics and Finance, Development, Growth, and Environmental
This chapter explores unconventional fossil fuels that are now seen as critical to meeting future energy demand. It explains the ‘conditional’ nature of these resources and identifies the various ...
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This chapter explores unconventional fossil fuels that are now seen as critical to meeting future energy demand. It explains the ‘conditional’ nature of these resources and identifies the various types of unconventional fossil fuel. The remainder of the chapter is given over to three case studies: oil shales, oil sands, and shale gas. Each case examines the history of development, the key technologies, and the current status of production. In conclusion, it is suggested that both oil and oil sands will continue to have a limited and localized impact. Shale gas and tight oil, by comparison, have the potential to have a significant impact due to their ubiquity and reliance upon proven and widely available technologies.Less
This chapter explores unconventional fossil fuels that are now seen as critical to meeting future energy demand. It explains the ‘conditional’ nature of these resources and identifies the various types of unconventional fossil fuel. The remainder of the chapter is given over to three case studies: oil shales, oil sands, and shale gas. Each case examines the history of development, the key technologies, and the current status of production. In conclusion, it is suggested that both oil and oil sands will continue to have a limited and localized impact. Shale gas and tight oil, by comparison, have the potential to have a significant impact due to their ubiquity and reliance upon proven and widely available technologies.
Christian de Perthuis and Pierre-André Jouvet
- Published in print:
- 2015
- Published Online:
- May 2016
- ISBN:
- 9780231171403
- eISBN:
- 9780231540360
- Item type:
- chapter
- Publisher:
- Columbia University Press
- DOI:
- 10.7312/columbia/9780231171403.003.0015
- Subject:
- Economics and Finance, Development, Growth, and Environmental
Chapters 14 looks in greater depth at the energy aspects of the transition to a green economy. First, various energy transition models are discussed: the U.S. energy revolution driven by the ...
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Chapters 14 looks in greater depth at the energy aspects of the transition to a green economy. First, various energy transition models are discussed: the U.S. energy revolution driven by the large-scale exploitation of oil and gas shale is a very different option than the low-carbon strategy adopted by Europe or the long-term diversification aimed at by oil-producing countries and the major emerging economies. Less
Chapters 14 looks in greater depth at the energy aspects of the transition to a green economy. First, various energy transition models are discussed: the U.S. energy revolution driven by the large-scale exploitation of oil and gas shale is a very different option than the low-carbon strategy adopted by Europe or the long-term diversification aimed at by oil-producing countries and the major emerging economies.
Ilia Murtazashvili and Ennio Piano
- Published in print:
- 2022
- Published Online:
- May 2022
- ISBN:
- 9781501760983
- eISBN:
- 9781501761003
- Item type:
- chapter
- Publisher:
- Cornell University Press
- DOI:
- 10.7591/cornell/9781501760983.003.0002
- Subject:
- Sociology, Urban and Rural Studies
This chapter offers several points that frame the analysis of governance, planning, and economic impacts associated with fracking in the rest of the book. It shows that some of the accounts of the ...
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This chapter offers several points that frame the analysis of governance, planning, and economic impacts associated with fracking in the rest of the book. It shows that some of the accounts of the shale boom were based on perceptions of the past, rather than facts. This chapter's reading of the gold rush history is that it was orderly, and that the government was involved in the governance of miners in California. States have also been responsive to new challenges presented by the shale boom, which calls into question the notion of laissez-faire regulatory stances by the states. On balance, states that allowed fracking balance economic opportunities with regulation of the socially costly aspects of shale gas production. It is also important to keep in mind that there are many external effects that are not internalized, including the fact that no amount of fracking is “sustainable.”Less
This chapter offers several points that frame the analysis of governance, planning, and economic impacts associated with fracking in the rest of the book. It shows that some of the accounts of the shale boom were based on perceptions of the past, rather than facts. This chapter's reading of the gold rush history is that it was orderly, and that the government was involved in the governance of miners in California. States have also been responsive to new challenges presented by the shale boom, which calls into question the notion of laissez-faire regulatory stances by the states. On balance, states that allowed fracking balance economic opportunities with regulation of the socially costly aspects of shale gas production. It is also important to keep in mind that there are many external effects that are not internalized, including the fact that no amount of fracking is “sustainable.”
William M. Alley and Rosemarie Alley
- Published in print:
- 2017
- Published Online:
- September 2017
- ISBN:
- 9780300220384
- eISBN:
- 9780300227550
- Item type:
- chapter
- Publisher:
- Yale University Press
- DOI:
- 10.12987/yale/9780300220384.003.0014
- Subject:
- Environmental Science, Nature
Few environmental issues have received more media attention than fracking (hydraulic fracturing) for oil and gas development in shales and other unconventional resources. This chapter provides an ...
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Few environmental issues have received more media attention than fracking (hydraulic fracturing) for oil and gas development in shales and other unconventional resources. This chapter provides an objective overview of the potential impacts on groundwater and the need for better groundwater monitoring to resolve some of the uncertainties.Less
Few environmental issues have received more media attention than fracking (hydraulic fracturing) for oil and gas development in shales and other unconventional resources. This chapter provides an objective overview of the potential impacts on groundwater and the need for better groundwater monitoring to resolve some of the uncertainties.
Adelyn Hall and Carla Chifos
- Published in print:
- 2022
- Published Online:
- May 2022
- ISBN:
- 9781501760983
- eISBN:
- 9781501761003
- Item type:
- chapter
- Publisher:
- Cornell University Press
- DOI:
- 10.7591/cornell/9781501760983.003.0006
- Subject:
- Sociology, Urban and Rural Studies
This chapter reflects on the resource curse and the boom-bust consequences familiar in the rural United States. It presents a case study of Bradford County in Pennsylvania's northern tier, which lies ...
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This chapter reflects on the resource curse and the boom-bust consequences familiar in the rural United States. It presents a case study of Bradford County in Pennsylvania's northern tier, which lies above part of the Marcellus Shale. As largely agricultural Bradford County transforms rapidly with natural gas extraction, boomtown models are compared, with the Bradford County current shale gas boom following along lines of previous energy boomtowns. The new energy development in Bradford County and its communities follows models developed over decades by researchers and planners studying boom and bust trends and development. But in contrast to more typical scenarios, Bradford County responded with new focuses on human capital investments, new partnerships with higher education institutions, and other capacity-building initiatives for local officials and community stakeholders to shift the power balance to community development rather than reactive responses.Less
This chapter reflects on the resource curse and the boom-bust consequences familiar in the rural United States. It presents a case study of Bradford County in Pennsylvania's northern tier, which lies above part of the Marcellus Shale. As largely agricultural Bradford County transforms rapidly with natural gas extraction, boomtown models are compared, with the Bradford County current shale gas boom following along lines of previous energy boomtowns. The new energy development in Bradford County and its communities follows models developed over decades by researchers and planners studying boom and bust trends and development. But in contrast to more typical scenarios, Bradford County responded with new focuses on human capital investments, new partnerships with higher education institutions, and other capacity-building initiatives for local officials and community stakeholders to shift the power balance to community development rather than reactive responses.
Sabina E. Deitrick and Ilia Murtazashvili (eds)
- Published in print:
- 2022
- Published Online:
- May 2022
- ISBN:
- 9781501760983
- eISBN:
- 9781501761003
- Item type:
- book
- Publisher:
- Cornell University Press
- DOI:
- 10.7591/cornell/9781501760983.001.0001
- Subject:
- Sociology, Urban and Rural Studies
This book traces the response of local communities to the shale gas revolution. Rather than cast communities as powerless to respond to oil and gas companies and their landmen, it shows that ...
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This book traces the response of local communities to the shale gas revolution. Rather than cast communities as powerless to respond to oil and gas companies and their landmen, it shows that communities have adapted their local rules and regulations to meet the novel challenges accompanying unconventional gas extraction through fracking. The multidisciplinary perspectives of the book's chapters tie together insights from planners, legal scholars, political scientists, and economists. What emerges is a more nuanced perspective of shale gas development and its impacts on municipalities and residents. Unlike many political debates that cast fracking in black-and-white terms, this book embraces the complexity of local responses to fracking. States adapted legal institutions to meet the new challenges posed by this energy extraction process while under-resourced municipal officials and local planning offices found creative ways to alleviate pressure on local infrastructure and reduce harmful effects of fracking on the environment. The book tells a story of community resilience with the rise and decline of shale gas production.Less
This book traces the response of local communities to the shale gas revolution. Rather than cast communities as powerless to respond to oil and gas companies and their landmen, it shows that communities have adapted their local rules and regulations to meet the novel challenges accompanying unconventional gas extraction through fracking. The multidisciplinary perspectives of the book's chapters tie together insights from planners, legal scholars, political scientists, and economists. What emerges is a more nuanced perspective of shale gas development and its impacts on municipalities and residents. Unlike many political debates that cast fracking in black-and-white terms, this book embraces the complexity of local responses to fracking. States adapted legal institutions to meet the new challenges posed by this energy extraction process while under-resourced municipal officials and local planning offices found creative ways to alleviate pressure on local infrastructure and reduce harmful effects of fracking on the environment. The book tells a story of community resilience with the rise and decline of shale gas production.
Sabina E. Deitrick and Ilia Murtazashvili
- Published in print:
- 2022
- Published Online:
- May 2022
- ISBN:
- 9781501760983
- eISBN:
- 9781501761003
- Item type:
- chapter
- Publisher:
- Cornell University Press
- DOI:
- 10.7591/cornell/9781501760983.003.0015
- Subject:
- Sociology, Urban and Rural Studies
This concluding chapter pulls together the conclusions of the case studies discussed throughout this book. The shale boom has created many studies on environmental and health impacts, but far less on ...
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This concluding chapter pulls together the conclusions of the case studies discussed throughout this book. The shale boom has created many studies on environmental and health impacts, but far less on what happens in local communities in practical terms of governance, planning, and economic impacts. Stepping outside the usual range of outcomes considered in economic studies of boom and bust dynamics—typically employment and earnings—heightens the challenge of understanding a resource boom. Such a broader approach is essential to understand the governance, planning, and economic impacts of hydraulic fracturing. Furthermore, these cases demonstrate the role and importance of local and state officials, civic leaders, and resident stakeholders in challenging—and often untested—conditions. This chapter offers recommendations and the role of continuing research on understanding the practice and impacts of shale gas production in local and state planning and governance.Less
This concluding chapter pulls together the conclusions of the case studies discussed throughout this book. The shale boom has created many studies on environmental and health impacts, but far less on what happens in local communities in practical terms of governance, planning, and economic impacts. Stepping outside the usual range of outcomes considered in economic studies of boom and bust dynamics—typically employment and earnings—heightens the challenge of understanding a resource boom. Such a broader approach is essential to understand the governance, planning, and economic impacts of hydraulic fracturing. Furthermore, these cases demonstrate the role and importance of local and state officials, civic leaders, and resident stakeholders in challenging—and often untested—conditions. This chapter offers recommendations and the role of continuing research on understanding the practice and impacts of shale gas production in local and state planning and governance.
Michael Bradshaw, Joseph Dutton, and Gavin Bridge
- Published in print:
- 2015
- Published Online:
- September 2015
- ISBN:
- 9780198719526
- eISBN:
- 9780191788628
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198719526.003.0016
- Subject:
- Economics and Finance, Development, Growth, and Environmental
The global gas industry is currently experiencing considerable turbulence. A number of factors are shaking the fundamentals of international trade in gas: the shale gas revolution in North America; ...
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The global gas industry is currently experiencing considerable turbulence. A number of factors are shaking the fundamentals of international trade in gas: the shale gas revolution in North America; the Fukushima disaster in Japan; and ongoing concerns in Europe about dependence on Russian gas imports. This chapter examines how these events are changing trade in liquefied natural gas and challenging price formation and trading arrangements. The conclusions suggest that the direction of travel is towards greater reliance on gas-to-gas competition for price formation and an increased role for hub-based trading and spot market transactions. These changes are seen as necessary if gas is to compete against coal and realize its role as a bridge to a low-carbon future.Less
The global gas industry is currently experiencing considerable turbulence. A number of factors are shaking the fundamentals of international trade in gas: the shale gas revolution in North America; the Fukushima disaster in Japan; and ongoing concerns in Europe about dependence on Russian gas imports. This chapter examines how these events are changing trade in liquefied natural gas and challenging price formation and trading arrangements. The conclusions suggest that the direction of travel is towards greater reliance on gas-to-gas competition for price formation and an increased role for hub-based trading and spot market transactions. These changes are seen as necessary if gas is to compete against coal and realize its role as a bridge to a low-carbon future.
Massimo Florio
- Published in print:
- 2013
- Published Online:
- September 2013
- ISBN:
- 9780199674855
- eISBN:
- 9780191758874
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199674855.003.0006
- Subject:
- Economics and Finance, Public and Welfare
Chapter 6 considers natural gas, a relative latecomer in the reform process, and an industry that poses interesting policy issues, particularly in terms of security of supply. Traditional and new ...
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Chapter 6 considers natural gas, a relative latecomer in the reform process, and an industry that poses interesting policy issues, particularly in terms of security of supply. Traditional and new technological aspects are reviewed, including the role of liquefied natural gas (LNG) and shale gas in changing the international trade pattern. After an examination of the different policies and market structures in selected EU Member States, the empirical analysis of data suggests that the reforms have had no impact on consumer prices, or sometimes impacted in the wrong direction. Possible reasons are discussed, including the role of long-term oil-indexed contracts.Less
Chapter 6 considers natural gas, a relative latecomer in the reform process, and an industry that poses interesting policy issues, particularly in terms of security of supply. Traditional and new technological aspects are reviewed, including the role of liquefied natural gas (LNG) and shale gas in changing the international trade pattern. After an examination of the different policies and market structures in selected EU Member States, the empirical analysis of data suggests that the reforms have had no impact on consumer prices, or sometimes impacted in the wrong direction. Possible reasons are discussed, including the role of long-term oil-indexed contracts.
Mohammed Abdelwahab Bekhechi
- Published in print:
- 2014
- Published Online:
- May 2014
- ISBN:
- 9780198703181
- eISBN:
- 9780191772474
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198703181.003.0011
- Subject:
- Law, Environmental and Energy Law, Public International Law
This chapter provides an overview of Algeria's legal and regulatory framework for the hydrocarbon industry; explains the specific rules applicable to unconventional hydrocarbon development; and ...
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This chapter provides an overview of Algeria's legal and regulatory framework for the hydrocarbon industry; explains the specific rules applicable to unconventional hydrocarbon development; and discusses the domestic legal challenges facing unconventional hydrocarbon development, focusing on environmental issues. Algeria has proceeded with decisions to authorize fracking for shale hydrocarbon development and to include, in the 2013 Amendment, general provisions to address the harmful impacts of fracking. While this legislation constitutes a positive first step, appropriate implementing regulations and effective enforcement are also required. Future developments should include the introduction of principles that govern public consultation and participation in decision-making processes related to hydrocarbon development; and transparency of the negotiation processes for and outcomes of investments in the hydrocarbon sector.Less
This chapter provides an overview of Algeria's legal and regulatory framework for the hydrocarbon industry; explains the specific rules applicable to unconventional hydrocarbon development; and discusses the domestic legal challenges facing unconventional hydrocarbon development, focusing on environmental issues. Algeria has proceeded with decisions to authorize fracking for shale hydrocarbon development and to include, in the 2013 Amendment, general provisions to address the harmful impacts of fracking. While this legislation constitutes a positive first step, appropriate implementing regulations and effective enforcement are also required. Future developments should include the introduction of principles that govern public consultation and participation in decision-making processes related to hydrocarbon development; and transparency of the negotiation processes for and outcomes of investments in the hydrocarbon sector.
Naomi Oreskes and Erik M. Conway
- Published in print:
- 2014
- Published Online:
- November 2015
- ISBN:
- 9780231169547
- eISBN:
- 9780231537957
- Item type:
- chapter
- Publisher:
- Columbia University Press
- DOI:
- 10.7312/columbia/9780231169547.003.0002
- Subject:
- Environmental Science, Environmental Studies
This chapter details the increase in fossil fuel production and consumption that led to climate change. In 2005, the U.S. Energy Policy Act exempted shale gas drilling from regulatory oversight under ...
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This chapter details the increase in fossil fuel production and consumption that led to climate change. In 2005, the U.S. Energy Policy Act exempted shale gas drilling from regulatory oversight under the Safe Drinking Water Act, leading to massive increases in shale gas production. Also, the melting of the Arctic sea ice opened seaways that permitted further exploitation of oil and gas reserves in the North Polar Region. As gas became cheap, its usage increased in transportation and home heating, and it became an additional energy source, satisfying expanding demand without replacing other forms of fossil fuel energy production. As new gas-generating power plants were built, infrastructures based on fossil fuels were set, and total global emissions continued to rise. By 2012, more than 365 billion tons of carbon had been released into the atmosphere from fossil fuel combustion and cement production. An additional 180 billion tons came from deforestation and other land use changes.Less
This chapter details the increase in fossil fuel production and consumption that led to climate change. In 2005, the U.S. Energy Policy Act exempted shale gas drilling from regulatory oversight under the Safe Drinking Water Act, leading to massive increases in shale gas production. Also, the melting of the Arctic sea ice opened seaways that permitted further exploitation of oil and gas reserves in the North Polar Region. As gas became cheap, its usage increased in transportation and home heating, and it became an additional energy source, satisfying expanding demand without replacing other forms of fossil fuel energy production. As new gas-generating power plants were built, infrastructures based on fossil fuels were set, and total global emissions continued to rise. By 2012, more than 365 billion tons of carbon had been released into the atmosphere from fossil fuel combustion and cement production. An additional 180 billion tons came from deforestation and other land use changes.
John H. Doveton
- Published in print:
- 2014
- Published Online:
- November 2020
- ISBN:
- 9780199978045
- eISBN:
- 9780197563359
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/oso/9780199978045.003.0009
- Subject:
- Earth Sciences and Geography, Geophysics: Earth Sciences
Formation lithologies that are composed of several minerals require multiple porosity logs to be run in combination in order to evaluate volumetric porosity. In the most simple solution model, the ...
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Formation lithologies that are composed of several minerals require multiple porosity logs to be run in combination in order to evaluate volumetric porosity. In the most simple solution model, the proportions of multiple components together with porosity can be estimated from a set of simultaneous equations for the measured log responses. These equations can be written in matrix algebra form as: . . . CV = L . . . where C is a matrix of the component petrophysical properties, V is a vector of the component unknown proportions, and L is a vector of the log responses of the evaluated zone. The equation set describes a linear model that links the log measurements with the component mineral properties. Although porosity represents the proportion of voids within the rock, the pore space is filled with a fluid whose physical properties make it a “mineral” component. If the minerals, their petrophysical properties, and their proportions are either known or hypothesized, then log responses can be computed. In this case, the procedure is one of forward-modeling and is useful in situations of highly complex formations, where geological models are used to generate alternative log-response scenarios that can be matched with actual logging measurements in a search for the best reconciliation between composition and logs. However, more commonly, the set of equations is solved as an “inverse problem,” in which the rock composition is deduced from the logging measurements. Probably the earliest application of the compositional analysis of a formation by the inverse procedure applied to logs was by petrophysicists working in Permian carbonates of West Texas, who were frustrated by complex mineralogy in their attempts to obtain reliable porosity estimates from logs, as described by Savre (1963). Up to that time, porosities had been commonly evaluated from neutron logs, but the values were excessively high in zones that contained gypsum, caused by the hydrogen within the water of crystallization. The substitution of the density log for the porosity estimation was compromised by the occurrence of anhydrite as well as gypsum.
Less
Formation lithologies that are composed of several minerals require multiple porosity logs to be run in combination in order to evaluate volumetric porosity. In the most simple solution model, the proportions of multiple components together with porosity can be estimated from a set of simultaneous equations for the measured log responses. These equations can be written in matrix algebra form as: . . . CV = L . . . where C is a matrix of the component petrophysical properties, V is a vector of the component unknown proportions, and L is a vector of the log responses of the evaluated zone. The equation set describes a linear model that links the log measurements with the component mineral properties. Although porosity represents the proportion of voids within the rock, the pore space is filled with a fluid whose physical properties make it a “mineral” component. If the minerals, their petrophysical properties, and their proportions are either known or hypothesized, then log responses can be computed. In this case, the procedure is one of forward-modeling and is useful in situations of highly complex formations, where geological models are used to generate alternative log-response scenarios that can be matched with actual logging measurements in a search for the best reconciliation between composition and logs. However, more commonly, the set of equations is solved as an “inverse problem,” in which the rock composition is deduced from the logging measurements. Probably the earliest application of the compositional analysis of a formation by the inverse procedure applied to logs was by petrophysicists working in Permian carbonates of West Texas, who were frustrated by complex mineralogy in their attempts to obtain reliable porosity estimates from logs, as described by Savre (1963). Up to that time, porosities had been commonly evaluated from neutron logs, but the values were excessively high in zones that contained gypsum, caused by the hydrogen within the water of crystallization. The substitution of the density log for the porosity estimation was compromised by the occurrence of anhydrite as well as gypsum.