Environmental Aspects of Oil and Gas Production

 
 
Wiley-Scrivener (Verlag)
  • erschienen am 15. Juni 2017
  • |
  • 416 Seiten
 
E-Book | ePUB mit Adobe-DRM | Systemvoraussetzungen
978-1-119-11739-1 (ISBN)
 
Oil and gas still power the bulk of our world, from automobiles and the power plants that supply electricity to our homes and businesses, to jet fuel, plastics, and many other products that enrich our lives. With the relatively recent development of hydraulic fracturing ("fracking"), multilateral, directional, and underbalanced drilling, and enhanced oil recovery, oil and gas production is more important and efficient than ever before. Along with these advancements, as with any new engineering process or technology, come challenges, many of them environmental.
More than just a text that outlines the environmental challenges of oil and gas production that have always been there, such as gas migration and corrosion, this groundbreaking new volume takes on the most up-to-date processes and technologies involved in this field. Filled with dozens of case studies and examples, the authors, two of the most well-known and respected petroleum engineers in the world, have outlined all of the major environmental aspects of oil and gas production and how to navigate them, achieving a more efficient, effective, and profitable operation. This groundbreaking volume is a must-have for any petroleum engineer working in the field, and for students and faculty in petroleum engineering departments worldwide.
1. Auflage
  • Englisch
  • New York
  • |
  • USA
John Wiley & Sons
  • 31,00 MB
978-1-119-11739-1 (9781119117391)
weitere Ausgaben werden ermittelt
John O. Robertson, PhD, is the owner of Earth Engineering, Inc. and an adjunct professor at ITT Tech in National City, CA. He has over 50 years of experience in petroleum and environmental engineering and geology and is the author of over 12 textbooks and 75 articles.
George V. Chilingar, PhD, is an Emeritus Professor of Engineering at the University of Southern California in Los Angeles, CA. He is one of the most well-known petroleum geologists in the world and the founder of several prestigious journals in the oil and gas industry. He has published over 70 books and 500 articles and has received over 100 awards over his career.
  • Cover
  • Title Page
  • Copyright Page
  • Dedication
  • Contents
  • Acknowledgments
  • 1 Environmental Concerns
  • 1.1 Introduction
  • 1.2 Evaluation Approach
  • 1.3 Gas Migration
  • 1.3.1 Paths of Migration for Gas
  • 1.3.2 Monitoring of Migrating Gases
  • 1.3.3 Identification of Biological vs. Thermogenic Gases
  • 1.4 Underground Gas Storage Facilities
  • 1.5 Subsidence
  • 1.6 Emissions of Carbon Dioxide and Methane
  • 1.7 Hydraulic Fracturing
  • 1.7.1 Orientation of the Fracture
  • 1.8 Oil Shale
  • 1.9 Corrosion
  • 1.10 Scaling
  • 1.11 Conclusion
  • References and Bibliography
  • 2 Migration of Hydrocarbon Gases
  • 2.1 Introduction
  • 2.2 Geochemical Exploration for Petroleum
  • 2.3 Primary and Secondary Migration of Hydrocarbons
  • 2.3.1 Primary Gas Migration
  • 2.3.2 Secondary Gas Migration
  • 2.3.3 Gas Entrapment
  • 2.4 Origin of Migrating Hydrocarbon Gases
  • 2.4.1 Biogenic vs. Thermogenic Gas
  • 2.4.1.1 Sources of Migrating Gases
  • 2.4.1.2 Biogenic Methane
  • 2.4.1.3 Thermogenic Methane Gas
  • 2.4.2 Isotopic Values of Gases
  • 2.4.3 Nonhydrocarbon Gases
  • 2.4.4 Mixing of Gases
  • 2.4.5 Surface Gas Sampling
  • 2.4.6 Summary
  • 2.5 Driving Force of Gas Movement
  • 2.5.1 Density of a Hydrocarbon Gas under Pressure
  • 2.5.2 Sample Problem (Courtesy of Gulf Publishing Company)
  • 2.5.3 Other Methods of Computing Natural Gas Compressibility
  • 2.5.4 Density of Water
  • 2.5.5 Petrophysical Parameters Affecting Gas Migration
  • 2.5.6 Porosity, Void Ratio, and Density
  • 2.5.7 Permeability
  • 2.5.8 Free and Dissolved Gas in Fluid
  • 2.5.9 Quantity of Dissolved Gas in Water
  • 2.6 Types of Gas Migration
  • 2.6.1 Molecular Diffusion Mechanism
  • 2.6.2 Discontinuous-Phase Migration of Gas
  • 2.6.3 Minimum Height of Gas Column Necessary to Initiate Upward Gas Movement
  • 2.6.4 Buoyant Flow
  • 2.6.5 Sample Problem (Courtesy of Gulf Publishing Company)
  • 2.6.6 Gas Columns
  • 2.6.7 Sample Problem 2.2 (Courtesy of Gulf Publishing Company)
  • 2.6.8 Continuous-Phase Gas Migration
  • 2.7 Paths of Gas Migration Associated with Oilwells
  • 2.7.1 Natural Paths of Gas Migration
  • 2.7.2 Man-Made Paths of Gas Migration (boreholes)
  • 2.7.2.1 Producing Wells
  • 2.7.2.2 Abandoned Wells
  • 2.7.2.3 Repressured Wells
  • 2.7.3 Creation of Induced Fractures during Drilling
  • 2.8 Wells Leaking Due to Cementing Failure
  • 2.8.1 Breakdown of Cement
  • 2.8.2 Cement Isolation Breakdown (Shrinkage-Circumferential Fractures)
  • 2.8.3 Improper Placement of Cement
  • 2.9 Environmental Hazards of Gas Migration
  • 2.9.1 Explosive Nature of Gas
  • 2.9.2 Toxicity of Hydrocarbon Gas
  • 2.10 Migration of Gas from Petroleum Wellbores
  • 2.10.1 Effect of Seismic Activity
  • 2.11 Case Histories of Gas Migration Problems
  • 2.11.1 Inglewood Oilfield, CA
  • 2.11.2 Los Angeles City Oilfield, CA
  • 2.11.2.1 Belmont High School Construction
  • 2.11.3 Montebello Oilfield, CA
  • 2.11.3.1 Montebello Underground Gas Storage
  • 2.11.4 Playa Del Rey Oilfield, CA
  • 2.11.4.1 Playa del Rey underground Gas Storage
  • 2.11.5 Salt Lake Oilfield, CA
  • 2.11.5.1 Ross Dress for Less Department Store Explosion/Fire, Los Angeles, CA
  • 2.11.5.2 Gilmore Bank
  • 2.11.5.3 South Salt Lake Oilfield Gas Seeps from Gas Injection Project
  • 2.11.5.4 Wilshire and Curson Gas Seep, Los Angeles, CA, 1999
  • 2.11.6 Santa Fe Springs Oilfield, CA
  • 2.11.7 El Segundo Oilfield, CA
  • 2.11.8 Honor Rancho and Tapia Oilfields, CA
  • 2.11.9 Sylmar, CA - Tunnel Explosion
  • 2.11.10 Hutchinson, KS - Explosion and Fires
  • 2.11.11 Huntsman Gas Storage, NE
  • 2.11.12 Mont Belvieu Gas Storage Field, TX
  • 2.11.13 Leroy Gas Storage Facility, WY
  • 2.12 Conclusions
  • References and Bibliography
  • 3 Subsidence as a Result of Gas/Oil/Water Production
  • 3.1 Introduction
  • 3.2 Theoretical Compaction Models
  • 3.3 Theoretical Modeling of Compaction
  • 3.3.1 Terzaghi's Compaction Model
  • 3.3.2 Athy's Compaction Model
  • 3.3.3 Hedberg's Compaction Model
  • 3.3.4 Weller's Compaction Model
  • 3.3.5 Teodorovich and Chernov's Compaction Model
  • 3.3.6 Beall's Compaction Model
  • 3.3.7 Katz and Ibrahim Compaction Model
  • 3.4 Subsidence Over Oilfields
  • 3.4.1 Rate of Subsidence
  • 3.4.2 Effect of Earthquakes on Subsidence
  • 3.4.3 Stress and Strain Distribution in Subsiding Areas
  • 3.4.4 Calculation of Subsidence in Oilfields
  • 3.4.5 Permeability Seals for Confined Aquifers
  • 3.4.6 Fissures Caused by Subsidence
  • 3.5 Case Studies of Subsidence over Hydrocarbon Reservoirs
  • 3.5.1 Los Angeles Basin, CA, Oilfields, Inglewood Oilfield, CA
  • 3.5.1.1 Baldwin Hills Dam Failure
  • 3.5.1.2 Proposed Housing Development
  • 3.5.2 Los Angeles City Oilfield, CA
  • 3.5.2.1 Belmont High School Construction
  • 3.5.3 Playa Del Rey Oilfield, CA
  • 3.5.3.1 Playa Del Rey Marina Subsidence
  • 3.5.4 Torrance Oilfield, CA
  • 3.5.5 Redondo Beach Marina Area, CA
  • 3.5.6 Salt Lake Oilfield, CA
  • 3.5.7 Santa Fe Springs Oilfield, CA
  • 3.5.8 Wilmington Oilfield, Long Beach, CA
  • 3.5.9 North Stavropol Oilfield, Russia
  • 3.5.10 Subsidence over Venezuelan Oilfields
  • 3.5.10.1 Subsidence in the Bolivar Coastal Oilfields of Venezuela
  • 3.5.10.2 Subsidence of Facilities
  • 3.5.11 Po-Veneto Plain, Italy
  • 3.5.11.1 Po Delta
  • 3.5.12 Subsidence Over the North Sea Ekofisk Oilfield
  • 3.5.12.1 Production
  • 3.5.12.2 Ekofisk Field Description
  • 3.5.12.3 Enhanced Oil Recovery Projects
  • 3.5.13 Platform Sinking
  • 3.6 Concluding Remarks
  • References and Bibliography
  • 4 Effect of Emission of CO2 and CH4 into the Atmosphere
  • 4.1 Introduction
  • 4.2 Historic Geologic Evidence
  • 4.2.1 Historic Record of Earth's Global Temperature
  • 4.2.2 Effect of Atmospheric Carbon Content on Global Temperature
  • 4.2.3 Sources of CO2
  • 4.3 Adiabatic Theory
  • 4.3.1 Modeling the Planet Earth
  • 4.3.2 Modeling the Planet Venus
  • 4.3.3 Anthropogenic Carbon Effect on the Earth's Global Temperature
  • 4.3.4 Methane Gas Emissions
  • 4.3.5 Monitoring of Methane Gas Emissions
  • References
  • 5 Fracking
  • 5.1 Introduction
  • 5.2 Studies Supporting Hydraulic Fracturing
  • 5.3 Studies Opposing Hydraulic Fracturing
  • 5.4 The Fracking Debate
  • 5.5 Production
  • 5.5.1 Conventional Reservoirs
  • 5.5.2 Unconventional Reservoirs
  • 5.6 Fractures: Their Orientation and Length
  • 5.6.1 Fracture Orientation
  • 5.6.2 Fracture Length/Height
  • 5.7 Casing and Cementing
  • 5.8 Blowouts
  • 5.8.1 Surface Blowouts
  • 5.8.2 Subsurface Blowouts
  • 5.9 Horizontal Drilling
  • 5.10 Fracturing and the Groundwater Contamination
  • 5.11 Pre-Drill Assessment
  • 5.12 Basis of Design
  • 5.13 Well Construction
  • 5.13.1 Drilling
  • 5.13.2 Completion
  • 5.13.3 Well Operations
  • 5.13.4 Well Plug and Abandonment P&A
  • 5.14 Summary
  • 5.15 Failure and Contamination Reduction
  • 5.15.1 Conduct Environmental Sampling Before and During Operations
  • 5.15.2 Disclose the Chemicals Used in Fracking Operations
  • 5.15.3 Ensure that Wellbore Casings are Properly Designed and Constructed
  • 5.15.4 Eliminate Venting and Work toward Green Completions
  • 5.15.5 Prevent Flowback Spillage/Leaks
  • 5.15.6 Dispose/Recycle Flowback Properly
  • 5.15.7 Minimize Noise and Dust
  • 5.15.8 Protect Workers and Drivers
  • 5.15.9 Communicate and Engage
  • 5.15.10 Record and Document
  • 5.16 Frack Fluids
  • 5.17 Common Fracturing Additives
  • 5.18 Typical Percentages of Commonly Used Additives
  • 5.19 Chemicals Used in Fracking
  • 5.20 Proppants
  • 5.20.1 Silica Sand
  • 5.20.2 Resin-Coated Proppant
  • 5.20.3 Manufactured Ceramics Proppants
  • 5.20.4 Other Types of Proppants
  • 5.21 Slickwater
  • 5.22 Direction of Flow of Frack Fluids
  • 5.23 Subsurface Contamination of Groundwater
  • 5.23.1 Water Analysis
  • 5.23.2 Possible Sources of Methane in Water Wells
  • 5.24 Spills
  • 5.24.1 Documentation
  • 5.25 Other Surface Impacts
  • 5.26 Land Use Permits
  • 5.27 Water Usage and Management
  • 5.27.1 Flowback Water
  • 5.27.2 Produced Water
  • 5.27.3 Flowback and Produced Water Management
  • 5.28 Earthquakes
  • 5.29 Induced Seismic Event
  • 5.30 Wastewater Disposal Wells
  • 5.31 Site Remediation
  • 5.31.1 Regulatory Oversight
  • 5.31.2 Federal Level Oversight
  • 5.31.3 State Level Oversight
  • 5.31.4 Municipal Level Oversight
  • 5.32 Examples of Legislation and Regulations
  • 5.33 Frack Fluid Makeup Reporting
  • 5.33.1 FracFocus
  • 5.34 Atmospheric Emissions
  • 5.35 Air Emissions Controls
  • 5.35.1 Common Sources of Air Emissions
  • 5.35.2 Fugitive Air Emissions
  • 5.36 Silica Dust
  • 5.36.1 Stationary Sources
  • 5.37 The Clean Air Act
  • 5.38 Regulated Pollutants
  • 5.38.1 NAAQS Criteria Pollutants
  • 5.39 Attainment versus Non-attainment
  • 5.40 Types of Federal Regulations
  • 5.41 MACT/NESHAP
  • 5.42 NSPS Regulations: 40 CFR Part 60
  • 5.42.1 NSPS Subpart OOOO
  • 5.42.2 Facilities/Activities Affected by NSPS OOOO
  • 5.43 Construction and Operating New Source Review Permits
  • 5.44 Title V Permits
  • 5.45 Chemicals and Products on Locations
  • 5.46 Material Safety Data Sheets (MSDS)
  • 5.47 Contents of an MSDS
  • 5.48 Conclusion
  • State Agency Web Addresses
  • References
  • Bibliography
  • 6 Corrosion
  • 6.1 Introduction
  • 6.2 Definitions
  • 6.2.1 Corrosion
  • 6.2.2 Electrochemistry
  • 6.2.3 Electric Potential
  • 6.2.4 Electric Current
  • 6.2.5 Resistance
  • 6.2.6 Electric Charge
  • 6.2.7 Electrical Energy
  • 6.2.8 Electric Power
  • 6.2.9 Corrosion Agents
  • 6.3 Electrochemical Corrosion
  • 6.3.1 Components of Electrochemical Corrosion
  • 6.3.1.1 Electromotive Force Series
  • 6.3.1.2 Actual Electrode Potentials
  • 6.4 Galvanic Series
  • 6.4.1 Cathode/anode Area Ratio
  • 6.4.2 Polarization
  • 6.4.3 Corrosion of Iron
  • 6.4.4 Gaseous Corrodents
  • 6.4.4.1 Oxygen
  • 6.4.4.2 Hydrogen Sulfide
  • 6.4.4.3 Carbon Dioxide
  • 6.4.5 Alkalinity of Environment
  • 6.4.6 The influence of pH on the Rate of Corrosion
  • 6.4.7 Sulfate-Reducing Bacteria
  • 6.4.8 Corrosion in Gas-Condensate Wells
  • 6.5 Types of Corrosion
  • 6.5.1 Sweet Corrosion
  • 6.5.2 Sour Corrosion
  • 6.6 Classes of Corrosion
  • 6.6.1 Uniform Attack
  • 6.6.2 Crevice Corrosion
  • 6.6.3 Pitting Corrosion
  • 6.6.4 Intergranular Corrosion
  • 6.6.5 Galvanic or Two-metal Corrosion
  • 6.6.6 Selective Leaching
  • 6.6.7 Cavitation Corrosion
  • 6.6.8 Erosion-corrosion
  • 6.6.9 Corrosion Due to Variation in Fluid Flow
  • 6.6.10 Stress Corrosion
  • 6.7 Stress-Induced Corrosion
  • 6.7.1 Cracking in Drilling and Producing Environments
  • 6.7.1.1 Hydrogen Embrittlement (Sulfide Cracking)
  • 6.7.1.2 Corrosion Fatigue
  • 6.8 Microbial Corrosion
  • 6.8.1 Microbes Associated with Oilfield Corrosion
  • 6.8.2 Microbial Interaction with Produced Oil
  • 6.8.3 Microorganisms in Corrosion
  • 6.8.3.1 Prokaryotes
  • 6.8.3.2 Eukaryotes
  • 6.8.4 Different Mechanisms of Microbial Corrosion
  • 6.8.5 Corrosion Inhibition by Bacteria
  • 6.8.6 Microbial Corrosion Control
  • 6.9 Corrosion Related to Oilfield Production
  • 6.9.1 Corrosion of Pipelines and Casing
  • 6.9.2 Casing Corrosion Inspection Tools
  • 6.9.3 Electromagnetic Corrosion Detection
  • 6.9.4 Methods of Corrosion Measurement
  • 6.9.5 Acoustic Tool
  • 6.9.6 Potential Profile Curves
  • 6.9.7 Protection of Casing and Pipelines
  • 6.9.8 Casing Leaks
  • 6.9.9 Cathodic Protection
  • 6.9.10 Structure Potential Measurement
  • 6.9.11 Soil Resistivity Measurements
  • 6.9.12 Interaction between an Old and a New Pipeline
  • 6.9.13 Corrosion of Offshore Structures
  • 6.9.14 Galvanic vs. Imposed Direct Electrical Current
  • 6.10 Economics and Preventitive Methods
  • 6.11 Corrosion Rate Measurement Units
  • References and Bibliography
  • 7 Scaling
  • 7.1 Introduction
  • 7.2 Sources of Scale
  • 7.3 Formation of Scale
  • 7.4 Hardness and Alkalinity
  • 7.5 Common Oilfield Scale Scenarios
  • 7.5.1 Formation of a Scale
  • 7.5.2 Calcium Carbonate Scale Formation
  • 7.5.3 Sulfate Scale Formation
  • 7.6 Prediction of Scale Formation
  • 7.6.1 Prediction of CaSO4 Deposition
  • 7.6.2 Prediction of CaCO3 Deposition
  • 7.7 Solubility of Calcite, Dolomite, Magnesite and Their Mixtures
  • 7.8 Scale Removal
  • 7.9 Scale Inhibition
  • 7.10 Conclusions
  • References and Bibliography
  • Appendix A
  • About the Authors
  • Author Index
  • Subject Index
  • EULA

Chapter 1
Environmental Concerns


1.1 Introduction


This book is a systematic evaluation of surface and subsurface environmental hazards that can occur due to the production of hydrocarbons and how these problems can be avoided. The importance of such a study is dramatized by recent examples that have occurred within the Los Angeles Basin, CA:

  1. In the early 1960s, a portion of the Montebello Oilfield developed in the 1920s was converted to the Montebello Gas Storage Project, under the City of Montebello (a city within Los Angeles County). A minimal amount of work was done on the older wells to prepare the wells for repressurization. In the early 1980s, significant gas seepages were discovered alongside and under homes from several prior abandoned wells. Homes were torn down to allow a drilling rig to reabandon the leaking wellbores which were endangering the community with migrating gas. These home sites were then converted to mini-parks so that future casing leaks could be resealed if necessary. These problems led to the abandonment of the gas storage project in 2000.
  2. On December 14, 1963, water burst through the foundation of the earthen dam of the Baldwin Hills Reservoir, CA, a hilltop water storage facility which had been weakened by differential subsidence. This facility was located in a square-mile of metropolitan Los Angeles, CA, consisting of a large number of homes, of which 277 were damaged by moving water and inundated with mud and debris, or destroyed. Hamilton and Meehan (1971) noted that differential subsidence was a result of fluid withdrawal from the Inglewood Oilfield and the subsequent reinjection of water into the producing formation (for secondary oil recovery and waste water disposal). This resulted in the differential subsidence that was responsible for the ultimate demise of the earthen dam (see Chapter 3).
  3. On March 24, 1985, migrating subsurface gas filled the Ross Dress for Less department store in the Fairfax area of Los Angeles. There was an explosion followed by a fire, due to a spark in the basement of the store. Over 23 people were injured and an entire shopping center was destroyed. The area around this center had to be closed down as migrating gas continued to flow into the area, burning for several days through cracks in sidewalks and around the foundations. This site was located directly over a producing oilfield containing many abandoned and improperly completed wells (see Chapter 2).
  4. On October 23, 2015, massive volumes of escaping methane gas from a well (SS-25) in the Aliso Canyon Underground Storage facility reservoir flowed out and spread over the surrounding community of Porter Ranch, Los Angeles County, CA (Curwen, 2016). Engineers suspected that the escaping gas was coming from a hole in the 7-in casing about 500 ft below the surface. Therolf et al. (2016) reported the concerns of California Regulators to delay plans to capture and burn the leaking gas that had sickened and displaced thousands of Porter Ranch residents. The Aliso Oilfield was developed in the late 1930s and a portion of this oilfield was converted to a gas storage reservoir. The oilfield had previous fires from leaking wellbores that were put out by Paul "Red" Adair in 1968 and 1975 (Curwen, 2016). The escaping gas flowed into the nearby community for over 3 months, endangering the residents with health, fire and possible explosion hazards. At the time of writing of this book, the well has not been repaired.

Unfortunately, many oilfields located in urban settings similar to that of the Los Angeles Basin, CA, have been managed by catastrophe rather than through preventative management.

The objective of this book is to identify the environmental problems associated with the handling of hydrocarbons and suggest procedures and standards for safer operation of oilfields in urban environments.

This book is intended to help evaluate hydrocarbon production operations by looking at specific environmental problems, such as migrating gas and subsidence. The writers recommend a systems analysis approach that is supported by a monitoring program. Today there are many wells over 50 years of age and some over 100 years. The capability of these older wells to isolate and contain hydrocarbons decreases with time as the cement sheath deteriorates and the well casing corrodes. Chapter 3 describes the breakdown process of the cement in the wellbore with respect to time, resulting in the decrease of the ability for cement to isolate the reservoir fluids. Chapter 6 reviews the corrosion that can result in gas leaking holes in the casing. Thus, increased pressure by water injection, at a later date in the life of an oilfield, can create an environmental hazard in areas that contain wells with weakened cement and corroded steel casing, or inadequately abandoned coreholes and oilwells.

The intent of the writers is also to identify and establish procedures and standards for safer drilling and production of oilfields within the urban community. A necessary adjunct to these procedures is the establishment of a monitoring program that permits detection of environmental problems before occurrence of serious property damage or personal injury. This includes the following:

  1. Monitoring of wells for surface seepage of gas.
  2. Monitoring for surface subsidence.
  3. Recognition of the oilfield geologic characteristics, including fault planes and potential areas and zones for gas migration to the surface.
  4. Establishing procedures for the systematic evaluation of the integrity of both producing and abandoned oilwells and coreholes.
  5. Monitoring of distribution pipelines and frequent testing for corrosion leaks.

1.2 Evaluation Approach


This evaluation approach requires development of a functional model for each oilfield operation. This approach should identify the basic hydrocarbon drive mechanism that is responsible for the movement of hydrocarbons in the reservoir. Particular attention should be given to faults and the caprock of the reservoirs.

Emphasis should be placed on the individual well production history, i.e., gas/oil ratio, water production and pressure history. Frequent surface soil gas tests should be made for all wells 50 years of age and older.

In gravity drainage pools, oil moves downdip and gas moves updip. As the gas/oil ratio of updip wells increases, these wells are shut-in. Most of the production occurs at practically zero pressure in gravity drainage pools. Freed gas, which accumulates at the top of the structure and is no longer held in solution becomes available for migration. If there is a pathway for its migration toward the surface or if such an avenue is created, it will migrate to adjacent areas of lower pressure working its way to the surface. The freeing of solution gas substantially increases the volume of gas available for migration.

If this migrating gas encounters a fault (natural path) or a wellbore (man-made path), it can then move toward the surface. As also pointed out in Chapter 2, as the wells age the casing corrodes and the cement fractures enlarge. The reason that cement ages and develops fractures with time is hydration of the cement. The cement does not have the same capability to isolate the hydrocarbons that it did when first put in place. This is contrary to a mistaken belief by many, that the risk of gas seepage is reduced over time as the reservoir pressure declines through fluid production. There are many older wells, drilled and completed 50 to 100 years ago within urban settings that leak.

1.3 Gas Migration


The existence of oil and gas seeps in oil-producing regions of the world has been recognized for a long time. For example, Link (1952), then the Chief Geologist of Standard Oil Company (NJ), wrote a comprehensive article on the significance of oil and gas seeps in oil exploration. In this publication, he documented oil and gas seeps located throughout the world. Although the primary purpose of Link's paper was to identify the importance of surface oil and gas seeps in the exploration and location of oil and gas, it is of no less importance in identifying the hazards associated with the seepage or migration of hydrocarbons to the surface.

Various state agencies have published maps identifying seepage of oil and gas. For example, the Division of Oil and Gas of the State of California has published a detailed listing of seepages located throughout the state of California (Hodgson, 1987).

Many of these seeps are located in or near the immediate vicinity of producing or abandoned oilfields. As pressure drops, gas comes out of solution, allowing the freed gas to migrate toward the surface.

About 90% of all oil and gas seeps in the world are associated with faults, which provide natural pathways for migration of gas. Man-made pathways (wellbores) may be also present.

1.3.1 Paths of Migration for Gas


Fault planes and wellbores can serve as conduits for migration of gas from the oil/gas reservoirs to the surface (see Chapman, 1983; Doligez, 1987). Consensus of opinion, up to the mid-1960s, was that faults generally act as barriers to petroleum or water migration. Obviously faults acted as traps for oil/gas accumulations. The authors believe that, at best, faults are "leaky" barriers and that at a minimal differential pressure of 100-300 psi there is a flow of fluids across the fault planes. Thus, evaluation of fluid flow along (and across) fault planes is an important consideration, especially when monitoring for surface seepage.

The identification of...

Dateiformat: ePUB
Kopierschutz: Adobe-DRM (Digital Rights Management)

Systemvoraussetzungen:

Computer (Windows; MacOS X; Linux): Installieren Sie bereits vor dem Download die kostenlose Software Adobe Digital Editions (siehe E-Book Hilfe).

Tablet/Smartphone (Android; iOS): Installieren Sie bereits vor dem Download die kostenlose App Adobe Digital Editions (siehe E-Book Hilfe).

E-Book-Reader: Bookeen, Kobo, Pocketbook, Sony, Tolino u.v.a.m. (nicht Kindle)

Das Dateiformat ePUB ist sehr gut für Romane und Sachbücher geeignet - also für "fließenden" Text ohne komplexes Layout. Bei E-Readern oder Smartphones passt sich der Zeilen- und Seitenumbruch automatisch den kleinen Displays an. Mit Adobe-DRM wird hier ein "harter" Kopierschutz verwendet. Wenn die notwendigen Voraussetzungen nicht vorliegen, können Sie das E-Book leider nicht öffnen. Daher müssen Sie bereits vor dem Download Ihre Lese-Hardware vorbereiten.

Bitte beachten Sie bei der Verwendung der Lese-Software Adobe Digital Editions: wir empfehlen Ihnen unbedingt nach Installation der Lese-Software diese mit Ihrer persönlichen Adobe-ID zu autorisieren!

Weitere Informationen finden Sie in unserer E-Book Hilfe.


Download (sofort verfügbar)

199,99 €
inkl. 7% MwSt.
Download / Einzel-Lizenz
ePUB mit Adobe-DRM
siehe Systemvoraussetzungen
E-Book bestellen