Chapter
1.2 Developmental and evolutionary mechanism of palaeo-karst
1.2.1 Karst dynamic mechanism
1.2.2 Formation condition and controlling factors
1.2.2.1 Relationship between carbonate rock properties and karstification
1.2.2.2 Relationship between carbonatite structure and fracture-vug system
1.2.2.3 Relationship between geological structure and karstification
1.2.2.4 Effect of topographic and geomorphic conditions on karstification
1.2.2.5 Relationship between underground hydrodynamic circulation and karst development
1.2.3 Developmental and evolutionary mechanisms of paleo-karst in the Tahe region
1.2.3.1 Geological background
1.2.3.2 Formation conditions and controlling factors
1.2.3.3 Geochemical characteristics
1.2.3.4 Evolution features
1.3 Development pattern of carbonate fracture-vug system
1.3.1 Single-pipe underground stream system
1.3.2 Pipe network underground stream system
1.3.3 Tectonic corridor underground stream system
1.3.4 Hall-like cave system
1.3.5 Solution cave system
1.3.6 Shaft-like cave system
1.3.8 Solution fracture system
1.4 Plane distribution features of fracture-vug systems in the Tahe Oilfield
1.4.1 Combined identification of the genesis of paleokarst geomorphology
1.4.2 Paleokarst geomorphology types and distribution features
1.4.3 Storage properties of paleokarst geomorphic units
1.5 Vertical distribution of fracture-vug systems in the Tahe Oilfield
1.5.1 Vertical zonation type in the Tahe Oilfield
1.5.2 Vertical distribution features of the fracture-vug system
1.6 Forming mechanism and development characteristics of fracture system
1.6.2 Development characteristics
1.7 Filling materials and characteristics
1.7.4 Filling characteristics
2 Geophysical characterization of fracture-vug carbonate reservoirs
2.1 Seismic forward modeling
2.1.1.1 How to make physical models
Geologic features of physical models
Model materials and model making
2.1.1.2 Physical modeling experiments
2.1.2 Numerical simulation
2.1.2.1 Random medium description
2.1.2.2 Variable-grid finite difference using elastic wave equation
2.1.2.3 Variable-grid numerical simulation using acoustic wave equation (VS&T)
2.1.2.4 Staggered-grid high-order finite difference using elastic wave equation with variable grid and time-step (VGTS)
2.2 Seismic responses of fracture-vug carbonate units
2.2.1 Seismic responses of isolated caverns
2.2.1.1 Theoretical analysis of scattered seismic waves in a single cavern
2.2.1.2 Seismic responses of single caves with varied sizes
Single-cave physical modeling experiment
2.2.1.3 Seismic responses of single caves with varied geometries
2.2.1.4 Seismic responses of single caves with different filling materials
2.2.2 Seismic responses of a complicated cave system
2.2.2.1 Seismic responses of random caves
2.2.2.2 Seismic responses of cave group
2.2.2.3 Numerical simulation of an actual geologic model
2.2.3 Seismic responses of fractures
2.2.3.1 P-wave azimuthal anisotropy in a vertically fractured medium
Analysis of experimental results
2.2.3.2 P-wave azimuthal anisotropy in a fractured medium with varied fracture dips
2.2.3.3 P-wave responses for varied fracture densities
2.2.4 Physical simulation of a 3D fracture-vug model
2.3.1 Offset plane-wave finite-difference prestack time migration
2.3.1.1 3D offset plane-wave decomposition
Slant stacking within a limited range
Azimuth-independent 3D slant stacking
2.3.1.2 3D offset plane-wave migration
2.3.2 Time-shift depth migration and velocity analysis in angle domain
2.3.2.1 Imaging conditions for velocity analysis
2.3.2.3 Velocity analysis workflow
2.3.3 How to improve resolution of diffraction imaging
2.3.3.1 Diffracted waves on CSP gathers
2.3.3.2 Mapping noise suppression
2.3.3.3 Theoretical modeling
2.3.3.4 Field data testing
2.4 Reservoir description and fluid detection
2.4.1 Reservoir prediction
Reflection configuration analysis
Strong amplitude clustering
2.4.1.2 Fracture prediction
2.4.2 Prestack azimuthal anisotropy-based fracture detection
2.4.2.1 Fracture prediction based on residual P-wave NMO for TTI media
Residual NMO for TTI media
Fracture detection based on residual P-wave NMO for TTI media
2.4.2.2 Fracture prediction based on P-wave AVO for TTI media
Model-based AVO inversion
2.4.3 Comprehensive description of fracture-vug units
2.4.3.1 Logging and seismic responses
2.4.3.2 Nonlinear reconstruction of log curves
2.4.3.3 Well-controlled frequency-divided inversion
2.4.3.4 Multiattribute optimization and fusion
2.4.3.5 Palaeogeomorphology-controlled sculpting
Palaeogeomorphologic study
Palaeogeomorphology-controlled sculpting
2.4.3.6 Petrophysical properties inversion
2.4.4.1 Sensitivity analysis
2.4.4.2 Prestack fluid detection
Prestack elastic impedance inversion
2.4.4.3 Fluid probabilistic analysis based on AVO inversion
2.5 Comprehensive application of geophysical technology
2.5.1 Data quality and acquisition
2.5.1.1 High-density seismic acquisition
2.5.1.2 High-density data processing
2.5.1.3 Discussions of 15-m cave identification
2.5.2 Fracture-vug units prediction
2.5.2.1 Fracture-vug units prediction
Poststack seismic attributes
Prestack azimuthal anisotropy-based fracture detection
2.5.2.2 Comprehensive description of fracture-vug reservoir
Apparent volume estimation
Fluid detection based on prestack elastic inversion
Fluid probability analysis
3 3D geological modeling of a fracture-vug carbonate reservoir
3.1 Identification of fracture-vug reservoir
Fracture development level and morphology
Dynamic indicator of fractures
3.1.2 Single-well identification of fracture-vug reservoirs
3.1.2.1 Cavernous reservoirs
3.1.2.3 Large-scale fracture reservoirs
3.1.2.4 Microscale fracture reservoir
3.1.3 Cross-well identification of fracture-vug reservoirs
3.1.3.1 Identification of fracture-vug reservoir by seismic reflection feature
3.1.3.2 Identification of fracture-vug reservoir by wave impedance inversion
3.1.3.3 Identification of fracture-vug reservoir by seismic attribute volume
3.1.4 Distribution law of a fracture-vug reservoir
3.2 Characterization of fracture-vug unit
3.2.1 Division of a fracture-vug unit
3.2.2 Karst facies pattern
3.2.3 Characterization of a typical fracture-vug unit
3.3 3D modeling of a fracture-vug reservoir
3.3.1 Designing a 3D model grid
3.3.2 Building a 3D caverns model
3.3.3 Build a 3D vug model
3.3.4 Build a large-scale fracture model
3.3.5 Build a microscale discrete fracture network model
3.3.6 Fusion of discrete distribution models of fracture-vug carbonate reservoirs
3.4 Attribute parameter modeling of a fracture-vug carbonate reservoir
3.4.1 Attribute parameters
3.4.1.1 Attribute parameters for caverns
3.4.1.2 Attribute parameters for vugs
3.4.1.3 Attribute parameters for fractures
3.4.2 Attribute parameter modeling method
3.5 Verification and application
3.5.1 Verification by drilled well
3.5.2 Verification by production data
3.5.3 Verification by performance data
3.5.4 Application of geologic model
4 Fluid flow law in fracture-vug carbonate reservoir
4.1 Design of physical modeling experiment for fracture-vug media
4.1.1 Fundamental principles and similarity criteria
4.1.1.1 Fundamental principles
4.1.1.2 Similarity criteria
4.1.2 Physical modeling experiment design
4.1.2.1 Selecting experiment materials
4.1.2.2 Building experiment models
4.1.2.3 Physical modeling experiment system
4.2 Single-phase flow law in a fracture-vug medium
4.2.1 Single-phase flow experiments
4.2.1.1 On unfilled vug models
4.2.1.2 On fractured models
4.2.1.3 On fracture-vug models
4.2.2 Single-phase flow pattern and conversion conditions
4.2.2.1 Discrimination of flow pattern
4.2.2.2 Features of flow pattern conversion
4.3 Two-phase flow law in fracture-vug medium
4.3.1 Two-phase flow patterns
4.3.2 Oil–water two-phase flow experiment
4.3.2.1 On unfilled vug models
4.3.2.2 On fractured models
4.3.2.3 On fracture-vug models
4.3.3 Oil–water two-phase flow features
4.3.3.1 Relative permeability curves based on fractured models
4.3.3.2 Relative permeability curves based on fracture-vug models
4.4 Fluid flow law among different systems in fracture-vug media
4.4.1 Flow law between fracture and matrix
4.4.1.1 Experimental design and methodology
Physical property parameters of lab cores
Experimental method and workflow
4.4.1.2 Experimental results and analyses
4.4.1.3 Mathematical model and calculation
4.4.1.4 Crossflow law at pseudosteady state
4.4.2 Flow law between matrix and vug
4.4.2.1 Flow law between matrix and vug
4.4.2.2 Flow law between filler and vug
4.4.3 Flow law in different fracture-vug combinations
4.4.3.1 Flow law in single-vug–near-vug fracture (high dip) medium
4.4.3.2 Flow law in double-vug medium
4.4.3.3 Flow law in multifracture and multivug medium
4.5 Applications and numerical experimental study
4.5.1.1 Production characteristics in isolated vug reservoirs
4.5.1.2 Production characteristics in a near-vug fracture reservoir
4.5.1.3 Production characteristics in vug-fracture-vug reservoir
4.5.2 Numerical experimental study
4.5.2.1 One-phase flow regime in fracture-vug medium
4.5.2.2 Two-phase flow regime in fracture-vug medium
5 Numerical simulation of a fracture-vug carbonate reservoir
5.1.1 Mathematical model for an equivalent multimedium reservoir
5.1.1.1 Equivalent multiple medium
5.1.1.2 Multimedium representative elementary volume
5.1.1.3 Equation of mass conservation of equivalent multimedium reservor
5.1.1.4 Pipe flow, fracture flow, and high-speed Darcy flow
5.1.1.5 Multiphase vug (cave) flow
5.1.1.6 Fluid flow interface in caverns
5.1.2 Coupling mathematical reservoir model
5.1.2.1 Continuity equation
5.1.2.2 Momentum equation
5.1.2.3 Equation of state
5.1.2.4 Equation of indicator function
5.1.2.5 Mathematical model
5.1.2.6 Boundary conditions
5.2 Numerical solution to fracture-vug reservoir model
5.2.1 Numerical solution based on equivalent multimedium model
5.2.1.1 Numerical simulation of Darcy flow
5.2.1.2 Numerical simulation of high-speed non-Darcy flow
5.2.1.3 Numerical simulation of cavern flow
5.2.1.4 Full-implicit algorithm
5.2.1.5 Solution of linear equations
5.2.2 Numerical solution based on the coupling model
5.2.2.1 Finite volume discretion in solution domain
5.2.2.2 Discretion of transfer equation
5.2.2.3 Discretion of momentum equation
5.2.2.4 Coupling solution of pressure–velocity equations
5.2.2.5 Solution to linear equations
5.3 Validation of numerical simulation method
5.3.1 Validation of equivalent multimedium numerical simulation
5.3.1.1 Numerical simulation
5.3.1.2 Simulation of high-speed non-Darcy flow
5.3.1.3 Physical experiment on a plate fracture-vug model
5.3.1.4 Comparison of KarstSim with similar software based on single-medium model
5.3.1.5 Comparison of KarstSim with similar software based on dual-medium model
5.3.2 Validation of coupling numerical modeling method
5.3.2.1 Physical experiment modeling of fluid flow in filled vugs
5.3.2.2 Two-phase numerical simulation in large caves (caverns)
5.3.2.3 Injection-recovery simulation in a cave-fracture-vug model
5.3.3 Numerical modeling on S48 fracture-vug unit
5.3.3.1 General description of S48
5.3.3.2 Production history fitting in S48
5.3.3.3 Functions of the numerical simulation software
6 Development technology for fracture-cavern carbonate reservoirs
6.1 Performance analysis techniques for fracture-cavern reservoirs
6.1.1 Variation characteristics and prediction model for individual well production
6.1.1.1 Variation characteristics of individual well production
6.1.1.2 Prediction model for individual well production
6.1.2 Evaluation of natural energy in fracture-cavern reservoir
6.1.2.1 Comprehensive evaluation index of natural energy – Dpr
6.1.2.2 Evaluation index of elastic energy – elastic productivity
6.1.2.3 Evaluation index for edge and bottom water energy – Npr
6.1.3 Numerical well testing model and interpretations for fracture-cavern reservoirs
6.1.3.1 Numerical well testing based on triple-porosity medium
6.1.3.2 Coupled flow well testing model and analytical method
6.1.3.3 Interpretation of testing data from fracture-cavern carbonate reservoirs of the Tahe Oil Field
6.2 Waterflooding development technology for fracture-cavern oil reservoirs
6.2.1 Waterflooding development mechanisms for fracture-cavern oil reservoirs
6.2.1.1 Recovery mechanisms of production wells in a cavern zone
6.2.1.2 Recovery mechanisms for production wells in fractured zone
6.2.1.3 Factors influencing development effectiveness and development countermeasures
6.2.2 Waterflooding development technology
6.2.2.1 Spatially structured well grid
6.2.2.2 Water injection timing
6.2.2.3 Water injection mode
6.2.2.4 Optimization of injection/production parameters
6.2.3 Evaluation of waterflooding effectiveness
6.2.3.1 Technical evaluation index system
6.2.3.2 Overall evaluation methods for fracture-cavern units
6.2.4 Analysis of field waterflooding development results
6.3 Nitrogen injection EOR technology for fracture-cavern reservoirs
6.3.1 Formation mechanism and distribution pattern of residual oil in fracture-cavern reservoirs
6.3.2 EOR technology by nitrogen injection for single wells
6.3.2.1 EOR mechanism of gas injection in single wells
6.3.2.2 Factors controlling the effectiveness of N2 injection in single wells
6.3.2.3 Well selection principles for gas injection in single well
6.3.2.4 Optimization of gas injection parameters for single well
6.3.3 Gas injection EOR technology for fracture-cavern units
6.3.4 Analysis of gas injection effectiveness
6.3.4.1 Effectiveness of typical single well gas injection
6.3.4.2 Effectiveness of typical well-cluster gas injection
6.4 Horizontal well sidetracking and reservoir stimulation technologies for fracture-cavern oil reservoirs
6.4.1 Small-radius horizontal well sidetracking technology for fracture-cavern oil reservoirs
6.4.1.1 Drilling string optimization technology for small-radius ultradeep sidetracked horizontal wells
6.4.1.2 Trajectory optimization technology for short-radius ultradeep sidetracked horizontal wells
6.4.2 Reservoir stimulation technology for fracture-cavern oil reservoirs
6.4.2.1 Prefrac effect prediction technology
6.4.2.2 Optimization and improvement of acid fracturing fluid
6.4.2.3 Fracture height control technology
6.4.2.4 Optimization and support of combined acid fracturing technology
6.4.3 Application results of sidetracking and acid fracturing
Development Theories and Methods of Fracture-Vug Carbonate Reservoirs
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