Unconventional Petroleum Geology

Caineng Zou

• Publisher: Elsevier
• Year: 2012
• eBook ISBN: 9780123977861
• Topic: Physical Sciences
• Subtopic: Geology & Earth Sciences

Unconventional Petroleum Geology is the first book of its kind to collectively identify, catalog, and assess the exploration and recovery potential of the Earth's unconventional hydrocarbons. Advances in hydrocarbon technology and petroleum development systems have recently made the exploration of unconventional hydrocarbons—such as shale gas, tight sandstone oil and gas, heavy oil, tar sand, and coalbed methane—the hottest trend in the petroleum industry.Detailed case studies act as real-world application templates, making the book's concepts immediately practical and useful by exploration geologists. The logical and intuitive three-part approach of systematically identifying an unconventional hydrocarbon, cataloguing its accumulation features, and assessing its exploration and recovery potential can be immediately implemented in the field—anywhere in the world.- Provides a detailed assessment of the exploration and recovery potential of the full range of unconventional hydrocarbons- More than 300 illustrations—many in full color—capture the detailed intricacies and associated technological advances in unconventional hydrocarbon exploration- More than 20 case studies and examples from around the world conclude each chapter and aid in the application of key exploration and recovery techniques

Chapter 1

Introduction

Chapter Outline

Section 1. History of Petroleum Geology

1. Enlightenment Stage (Before the 1860S)

2. Formative Stage (1860S–1920S)

3. Development Stage (1920S–Present)

(1) Development of Petroleum Geology Theory in Foreign Countries

A. Trap Theory (1920s–1950s)

B. Oil Generation Theory and Primary Migration (1960s–1980s)

C. Dynamic Accumulation and Unconventional Petroleum Geology Stage (1990–Present)

(2) History of Petroleum Geology Theory in China

A. Continental Oil Generation and Source Control Theory

B. Hydrocarbon-Rich Depressions with Terrestrial Origin and Multiple Oil and Gas Accumulation Areas

C. Natural Gas Theory

D. Foreland Thrust Petroleum Geology Theory

E. Lithostratigraphic Reservoirs

F. Unconventional Petroleum Accumulations

Section 2. Current Situation and Trend of Global Petroleum Exploration

1. Current Situation

2. Distribution of Giant to Supergiant Oil and Gas Fields

(1) Conventional Giant to Supergiant Oil and Gas Fields

A. Passive Continental Margin

B. Large Foreland Thrust Zones

C. Large Cratonic Paleouplifts

(2) Unconventional Giant to Supergiant Oil and Gas Fields

A. Foreslope of Foreland Basin

B. Center of Depression Basins

C. Cratonic Syncline Areas

D. Tundra and Deep Marine

3. Distribution of Remaining Global Hydrocarbon Resources

4. Recent Trend of Global Conventional Oil and Gas Discoveries

(1) Steady Growth of Oil Reserves and Production, and Rapid Increase in Gas Reserves and Production

(2) Targets for Conventional Giant and Unconventional Oil and Gas Exploration

(3) Global Oil and Gas Exploration Increasingly Difficult

Section 3. Differences Between Conventional and Unconventional Petroleum Accumulations

1. Conventional Petroleum Geology

2. Unconventional Petroleum Geology

(1) Type

(2) Studied Content

(3) Methods and Technologies

(4) Exploration Potential

Section 4. Position and Significance of Unconventional Petroleum Geology

1. Study History of Unconventional Petroleum Geology

2. Strategy Position of Unconventional Petroleum Resources

3. Strategic Breakthroughs and Significance of Unconventional Petroleum

(1) Tight-Sandstone Gas Exploration

(2) Tight-Oil Exploration

(3) Coalbed Methane Exploration

(4) Shale Gas Exploration

References

The global oil and gas industry is approximately 300 years old, and during this time the exploration targets have shifted focus from structural petroleum deposits to lithostratigraphic petroleum deposits to unconventional petroleum accumulations. Oil and gas deposits occur in isolated, clustered, or continuous accumulations. The first significant exploration shift was to move from isolated structural deposits to clustered lithostratigraphic deposits and to determine how to discover and define lithostratigraphic traps. The second shift was to transfer focus from lithostratigraphic deposits to unconventional petroleum accumulations. The key concepts here were to define favorable reservoirs by going beyond the conventional thinking of lower physical property limits and lithostratigraphic or structural traps. According to the statistics of the U.S. Geological Survey (USGS) and the U.S. Department of Energy (DOE), the global resources of unconventional oil are 4495 × 10⁸ t, which is close to that of conventional oil. The production of unconventional oil in 2008 was more than 6000 × 10⁴ t, which is nearly two times that produced in 2001. The global resources of unconventional gas are 3921 × 10¹² m³, which is eight times that of conventional gas, and its production has accounted for 18% of total natural gas production. As future exploration targets, unconventional petroleum resources are becoming increasingly important in the global energy structure. In this chapter, the history of petroleum geology is first reviewed, and then the characteristics, status, and significance of unconventional petroleum resources are discussed.

Section 1. History of Petroleum Geology

The history of petroleum geology is closely related to the history of the petroleum industry, which gradually went from a theory of seepages in the 1850s to anticlinal theory in the 1880s to trap theory in the 1920s to hydrocarbon generation from kerogen thermal pyrolysis and terrestrial hydrocarbon generation theory in the 1950s. In the 1990s, the overriding theory of oil and gas transferred from static element analysis (i.e., source rocks, reservoirs, caprocks, trap, migration, and preservation) to static and dynamic element analysis (i.e., petroleum system, dynamic accumulation system) and continuous petroleum accumulation.

1. Enlightenment Stage (Before the 1860S)

In the earliest stages of petroleum exploration, explorers did not understand oil and gas distribution and there were no published theories, so that direct observation of surface seepage was usually the basis for drilling wells. E. L. Drake (1859) found the first modern oil field in Pennsylvania on the basis of seepages, which was the beginning of the modern oil and gas industry. Also, a series of discoveries in China, including the Yanchang, Laojunmiao, Dushanzi, Shengdengshan, and Kelanayi oil fields, can be attributed to seepages. Since then, the modern petroleum industry has advanced 150 years.

The history of oil and gas exploration and development in China is very long. In Science and Civilisation in China, a book written by a famous English academic named Joseph Needham (1956–1971), the writer pointed out that drilling well technology used for oil and gas development originated in China and was exported to Western countries before the twelfth century. The first well with a depth of more than 1000 m was drilled in 1835, which was located at Da’anzhai of Zigong city in Sichuan Province. Also in 1850, the drilling depth of a single well reached 1100 m. In the United States, the first well was drilled in Pennsylvania; the depth was only 21.64 m in 1859 and 338.33 m in 1871. In Russia, the first well with depth of 60 m was drilled in 1848. The rotary drilling technology that emerged at the end of the nineteenth century was developed from percussion drilling technology in China (Joseph and Wang, 1956).

2. Formative Stage (1860S–1920S)

In 1848, William Logan found that oil seepages were associated with anticlines, and he introduced this concept into petroleum exploration. In 1861, T. Sterry Hunt proposed the anticlinal theory and discussed oil and gas accumulation conditions, including source rocks, anticlinal structures, fractures, and sealing conditions. This theory was largely ignored in the United States, but it was used in Europe until 1875 (Zhang et al., 1999; Jiang and Zha, 2006). In 1885, I. C. White gave a scientific introduction to anticlinal theory in his paper, “The Geology of Natural Gas in Science” (Zhang et al., 1999; Jiang and Zha, 2006). In 1888, this theory was successfully applied in well deployment. In North America (i.e., the United States and Mexico), petroleum exploration based on the anticlinal theory was becoming popular and spawned a series of successes in oil exploration (Zhang et al., 1999; Jiang and Zha, 2006). In 1917, the American Association of Petroleum Geologists (AAPG) was founded, and it began publishing the AAPG Bulletin, which was recognized as marking the birth of petroleum geology. The published books on petroleum geology during this period also include Oil Finding: An Introduction to the Geological Study of Petroleum by E. H. Cunningham (1920) and Geology of Petroleum by William H. Emmons (1921) (from Jiang and Zha, 2006; Liu, 2009).

At the beginning of the nineteenth century, explorers believed that oil and gas were distributed along a certain line or axis in Germany. They constructed this line or axis based on the known wells with oil production, and tried to find more oil along this axis. A series of oil fields were discovered using this method, as most of these fields were located in salt domes that were arranged in a line along a fault zone. However, further exploration in different areas caused this theory to break down, as areas with different geological conditions did not trap oil and gas in the same linear arrangement. Although this theory was not science-based, it caused petroleum geologists to find new and more realistic theories for oil and gas exploration, which lay the basis for the trap theory.

3. Development Stage (1920S–Present)

(1) Development of Petroleum Geology Theory in Foreign Countries

A Trap Theory (1920s–1950s)

With the development of petroleum exploration, other structures besides anticlines were discovered, including salt domes (Gulf of Mexico, 1901) and diapir structures (Romania, 1907). F. G. Clapp (1910, 1917, 1929) proposed the classification system for traps, which consisted of anticline, syncline, cove, unconformity, and fault. B. R. Lilley (1928) pointed out that the origins of oil fields and gas fields were different (Zhang et al., 1999; Jiang and Zha, 2006). McColoagh (1934) proposed the trap theory and its related critical factors, including reservoir, caprocks, and shelters (Jiang and Zha, 2006; Liu, 2009). Wilson divided oil and gas deposits into two types: (1) closed, and (2) open (Zou et al., 2009b). A. I. Levorsen (1956) constructed a better classification system for traps, and structural trap, stratigraphic trap, and combined trap were included in his classification. From 1920 to 1950, the most important academic achievement of petroleum geology was the trap theory, and from that time, people began to understand that reservoir, seal, and structures are critical to petroleum deposits. The anticline was the most common and simplest type of trap; other traps formed by lithology and stratigraphic changes were also favorable for petroleum accumulation, which enlarged the ...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Preface
• Chapter 1. Introduction
• Chapter 2. Unconventional Continuous Petroleum Accumulation
• Chapter 3. Tight-Sandstone Oil and Gas
• Chapter 4. Coalbed Methane
• Chapter 5. Shale Gas
• Chapter 6. Carbonate Fracture-Cavity Reservoir
• Chapter 7. Volcanic Reservoirs and Hydrocarbon Accumulations
• Chapter 8. Oil and Gas in Metamorphic Reservoirs
• Chapter 9. Heavy Oil and Bitumen
• Chapter 10. Natural Gas Hydrate
• Chapter 11. Outlook on Unconventional Petroleum Resources
• Index