Understanding Seals Outline

CHAPTER OUTLINE

CHAPTER 1 – EXECUTIVE SUMMARY

• 1.1 INTRODUCTION
• 1.2 EMPIRCAL APPROACH TO SEALS ANALYSIS
• 1.3 C&C RESERVOIRS SEALS CLASSIFICATION
• 1.4 ATTRIBUTES OF SIMPLE TOP SEALS
• 1.4.1 Capillary measurements are insufficient for subsurface seal analysis
• 1.4.2 Lithology, not thickness, is more significant in top seals
• 1.4.3 Seal failure mechanisms
• 1.5 UPDID LATERAL FAULT SEALS
• 1.5.1 Juxtaposition versus fault membrane seals
• 1.5.2 Underfilling is common in reservoirs with updip faults
• 1.6 LATERAL STRATIGRAPHIC SEALS
• 1.6.1 Most common sealing mechanisms: clastic and carbonate facies changes
• 1.6.2 Sealing by truncation and onlap depends mostly on capacity of top seal
• 1.6.3 Most reservoirs with stratigraphic seals are filled-to-spill or overfilled
• 1.7 COMBINATION SEALS
• 1.7.1 Most common sealing combination: Simple Top-Lateral Fault
• 1.7.2 The majority of reservoirs with fault-dominated seals are underfilled
• 1.8 MISCELLANEOUS-UNCONVENTIONAL SEALS
• 1.8.1 Tar seals and tar-mats
• 1.8.2 Relationship between tilt of HWC and reservoir dip is critical for hydrodynamic sealing
• 1.9 INTRA-RESERVOIR BARRIERS AND BAFFLES
• 1.9.1 Faults are the most significant lateral barriers and compartment boundaries
• 1.9.2 Vertical barrier thickness does not control vertical intra-reservoir communication
• 1.10 SEAL RISKING
• 1.10.1 Seal risking workflow

CHAPTER 2 – OVERVIEW OF CURRENT KNOWLEDGE ON SEALS

• 2.1 INTRODUCTION
• 2.2 WHY STUDY SEALS?
• 2.3 SEALS CLASSIFICATIONS
• 2.3.1 Classifications by Sealing-Leakage Mechanisms
• 2.3.2 Classifications by Sealing Properties and Processes
• 2.3.3 Classifications by Geometrical Configuration
• 2.4 SEAL POTENTIAL
• 2.4.1 Seal Capacity
• 2.4.1.1 Capillary phenomena of seals
• 2.4.1.2 Seal capacity of various lithologies
• 2.4.2 Seal Geometry
• 2.4.3 Seal Integrity
• 2.5 SEAL FAILURE AND LEAKAGE
• 2.5.1 Tools for Geomechanical Analysis of Seals
• 2.5.2 Tectonic Breaching of Seals
• 2.5.3 Seal Failure by Hydrofracturing
• 2.6 FAULT SEALS
• 2.6.1 Juxtaposition
• 2.6.2 Shale or Clay Smears
• 2.6.3 Cataclasis and Diagenesis
• 2.6.4 Integrated Fault Seal Analysis

CHAPTER 3 – METHODS AND SUMMARY STATISTICS

• 3.1 C&C RESERVOIRS METHODS OF EMPIRICAL SEAL ANALYSIS
• 3.1.1 General seal parameters from the C&C Reservoirs DIGITAL ANALOGS Knowledge System (DAKS)
• Estimating vertical closure and hydrocarbon column height
• Evaluating the degree of trap fill
• 3.1.2 Evaluating top seal capacity and geometry
• Calculating the buoyancy pressure
• Top seal lithology
• Determining top seal thickness
• Describing top seal depositional system
• 3.1.3 Evaluating top-seal integrity
• 3.1.4 Evaluating fault and stratigraphic seals
• 3.2 C&C RESERVOIRS SEALS CLASSIFICATION
• 3.3 SUMMARY STATISTICS
• 3.3.1 Statistics by seal type and reservoir size
• 3.3.2 Filled and underfilled reservoirs
• 3.3.3 Top seal age and lithology
• 3.3.4 Top seal depositional system and thickness

CHAPTER 4 – SIMPLE TOP SEALS

• 4.1 CHAPTER SUMMARY
• 4.2 INTRODUCTION AND SUMMARY STATISTICS
• 4.2.1 Convex Top Seals
• 4.2.2 Irregular Top Seals
• 4.3 TOP SEAL CAPACITY AND GEOMETRY
• 4.3.1 Top Seal Lithology
• 4.3.2 Top Seal Thickness
• 4.3.3 Top Seal Depositional Systems
• 4.4 TOP SEAL INTEGRITY
• 4.4.1 Seal Failure Through Capillary Leakage
• 4.4.2 Seal Failure by Tectonic Breaching
• 4.4.3 Seal Failure by Overpressure or Hydraulic Fracturing
• 4.5 CHARACTERISTICS OF THE BEST TOP SEALS
• 4.5.1 Anhydrite Top Seal, Gachsaran Field, Iran
• 4.5.2 Shale Top Seals, Smorbukk Sor (South) Field, Norway
• 4.5.3 Interlayered shale-limestone top seal, Greater Burgan Field, Kuwait

CHAPTER 5 – UPDIP LATERAL FAULT SEALS

• 5.1 CHAPTER SUMMARY
• 5.2 INTRODUCTION AND SUMMARY STATISTICS
• 5.2.1 Characteristics of Traps with Updip Lateral Fault Seals
• 5.3 FAULT SEALING MECHANISMS
• 5.3.1 Fault Sealing by Juxtaposition
• 5.3.2 Fault Membrane Sealing
• 5.4 FAULT SEAL INTEGRITY
• 5.4.1 Capillary Leakage
• 5.4.2 Leakage by Tectonic Breaching and Hydraulic Fracturing
• 5.5 EXAMPLES OF SUCCESSFUL FAULT SEALS
• 5.5.1 Sandstone-Evaporite Juxtaposition, Badri Field, Gulf of Suez, Egypt
• 5.5.2 Sandstone-Shale Juxtaposition, Smørbukk Field, Norwegian North Sea
• 5.5.3 Sandstone-Chalk and Sandstone-Shale Juxtaposition, Rob Roy Field, Central North Sea, UK

CHAPTER 6 – LATERAL STRATIGRAPHIC SEALS

• 6.1 CHAPTER SUMMARY
• 6.2 INTRODUCTION AND SUMMARY STATISTICS
• 6.3 STRATIGRAPHIC SEALING MECHANISMS
• 6.3.1 Sealing by Clastic Facies Changes
• Facies change seals in continental depositional systems
• Facies change seals in coastal and shallow marine depositional systems
• Facies change seals in slope and deep-marine depositional systems
• 6.3.2 Sealing by Carbonate Facies Changes
• Facies change seals in low-energy carbonate shelves
• Facies change seals in high-energy carbonate shelves
• Facies change seals in organic buildup systems
• 6.3.3 Sealing by Truncation
• 6.3.4 Sealing by Onlap
• 6.3.5 Sealing of Clastics by Cementation
• 6.3.6 Sealing by Carbonate/Evaporite Cements
• 6.3.7 Sealing by Unaltered Carbonates
• 6.4 LATERAL STRATIGRAPHIC SEALS CLASSIFICATION
• 6.4.1 Updip-Only Stratigraphic Seals
• 6.4.2 Partially-Enclosing Stratigraphic Seals
• 6.4.3 Fully-Enclosing Stratigraphic Seals
• 6.5 BOTTOM SEALS
• 6.6 STRATIGRAPHIC SEAL INTEGRITY

CHAPTER 7: MISCELLANEOUS-UNCONVENTIONAL SEALS

• 7.1 CHAPTER SUMMARY
• 7.2 INTRODUCTION AND SUMMARY STATISTICS
• 7.3 TAR SEALS
• 7.3.1 Tar-mats
• 7.4 HYDRODYNAMIC SEALS
• 7.5 HYDROSTATIC-CAPILLARY SEALS
• 7.6 SEALING MECHANISMS FOR SHALLOW GAS HYDRATES
• 7.7 INTEGRITY OF MISCELLANEOUS SEALS

CHAPTER 8 – COMBINATION SEALS

• 8.1 CHAPTER SUMMARY
• 8.2 INTRODUCTION AND SUMMARY STATISTICS
• 8.3 TOP-DOMINATED COMBINATION SEALS
• 8.3.1 Simple Top-Lateral Fault
• 8.3.2 Simple Top-Lateral Stratigraphic
• 8.3.3 Simple Top-Lateral Fault-Lateral Stratigraphic
• 8.3.4 Simple Top-Updip Fault
• 8.3.5 Simple Top-Updip Fault-Lateral Fault
• 8.4 FAULT-DOMINATED COMBINATION SEALS
• 8.4.1 Updip Fault-Lateral Fault
• 8.4.2 Updip Fault-Lateral Stratigraphic
• 8.5 STRATIGRAPHIC-DOMINATED COMBINATION SEALS
• 8.5.1 Lateral Stratigraphic-Lateral Fault
• 8.5.2 Lateral Stratigraphic-Updip Fault-Lateral Fault
• 8.6 INTEGRITY OF COMBINATION SEALS

CHAPTER 9 – INTRA-RESERVOIR BARRIERS AND BAFFLES

• 9.1 CHAPTER SUMMARY
• 9.2 INTRODUCTION
• 9.3 LATERAL BARRIERS AND BAFFLES
• 9.3.1 Intra-reservoir faults and structural compartments
• 9.3.2. Examples of reservoirs with structural barriers
• 9.4 VERTICAL BARRIERS AND BAFFLES
  • 9.4.1 Stratigraphic barriers
  • Major flooding intervals and condensed sections
  • Minor flooding intervals, parasequence, and cycle boundaries
  • 9.4.2 Stratigraphic compartmentalization
  • Barriers and baffles in continental systems
  • Barriers and baffles in coastal and shallow marine systems
  • Barriers and baffles in carbonate systems
  • Barriers and baffles in deep-water systems
  • 9.4.3 Integrity of intra-reservoir stratigraphic and depositional barriers
  • 9.4.4 Examples of reservoirs with stratigraphic barriers
  • 9.4.5 Examples of reservoirs with depositional barriers or baffles

CHAPTER 10 – TRENDS IN SEAL PREDICTION

• 10.1 CHAPTER SUMMARY
• 10.2 EVALUATION OF DRY HOLE AND FAILED PROSPECT CASES
• 10.3 SEAL RISKING IN PRE-DRILL PROSPECT EVALUATION
• 10.3.1 Previous work
• 10.3.2 Seal risking workflow
• Risking of prospects with simple top seals
• Risking of prospects with updip lateral fault seals
• Risking of prospects with lateral stratigraphic seals
• Risking of prospects with miscellaneous-unconventional seals
• Risking of prospects with multiple sealing surfaces (combination seals)