Geomechanical Controls on Fracture Development in Chalk and Marl in the Danish North Sea: Understanding and Predicting Fracture Systems (Petroleum Engineering)

Acknowledgements
Contents
Introduction
	1 The Danish Offshore Technology Centre (DOTC)
	2 The Chalk of the Danish North Sea
	3 Chalk Research at DHRTC/DOTC
	4 Structure of This Book
	References
Establishing a High Resolution 3D Fracture Dataset in Chalk: Possibilities and Obstacles Working with Outcrop Data
	1 Introduction
	2 Study Site
	3 Geological Setting
	4 Workflow
	5 Digital Outcrop Models
		5.1 DOM Data Acquisition
		5.2 DOM Processing
		5.3 Combination and Fracture Mapping of DOMs
	6 Ground Penetrating Radar
		6.1 GPR Data Acquisition
		6.2 GPR Data Processing
	7 Shallow Seismic
		7.1 Data Acquisition
		7.2 Data Processing
	8 Data Combination and Observations—Geological Implications
		8.1 Faults
		8.2 Folds
	9 Analogue Considerations
	10 Discussion
	11 Summary and Conclusions
	References
Improved Visualization of Structural Deformation on the Kraka Structure (Danish Central Graben) with Color-Processed Seismic Data
	1 Introduction
	2 Geological Setting
	3 Data and Methods
		3.1 Seismic Data and Attributes
		3.2 Borehole Data
	4 Results
		4.1 Comparison of Ant-Tracked Chaos, Variance and eXchroma Colour-Processed Data
		4.2 Overview of the eXchroma Ant-Tracked Data Cubes
		4.3 Breakdown by Stratigraphic Units
		4.4 Comparison of the Lineations with Seismic Amplitude and Borehole Data
	5 Discussion
		5.1 Data Resolution and Quality
		5.2 Discrepancies of Scale
		5.3 Interpreting the Features on the Ant-Tracked Seismic Data
	6 Conclusions
	References
Calibration and Applications of a Rate-Dependent Geomechanical Model for Danian and Maastrichtian Reservoir Chalk (Danish North Sea)
	1 Introduction
	2 Methodology
		2.1 Laboratory Study
		2.2 Geomechanical Model
	3 Experimental Studies
		3.1 Tensile Strength (Pt)
		3.2 Shear
		3.3 Plastic
		3.4 Water Weakening Effect
	4 Geomechanical Modelling
		4.1 The Shape of the Yield Surface
		4.2 The Yield Function
		4.3 Back-Analysis of Triaxial Tests
		4.4 In Situ Compaction Measurements
		4.5 Field Application
	5 Discussion and Final Remarks
		5.1 Properties of Danian and Maastrichtian Chalk
		5.2 Compaction Simulation of Chalk Reservoir
	References
Variations in the Porosity of the Chalk Group in the North Sea Basin Due to Subsidence Related Deformation
	1 Introduction
	2 The Numerical Model and Parameters Herein
	3 Geological Boundary Conditions for the Modelling
		3.1 The Kraka Structure
	4 Model Geometry
	5 The Model Setups
		5.1 Model 1
		5.2 Model 2
		5.3 Model 3
		5.4 Model 4
	6 Results of the Modeling
		6.1 Model 1 (Fig. 3a)
		6.2 Model 2 (Fig. 4b)
		6.3 Model 3 (Fig. 4c)
		6.4 Model 4 (Fig. 4d)
	7 Discussion and Conclusion
		7.1 Does the Subsidence Model Mimic Reality?
		7.2 Stratigraphic Model Used
		7.3 Porosity Distribution
		7.4 Impact onto the Understanding of Porosity in Chalk Fields Above Salt Structures
	8 Conclusions
	References
Strain Evolution in the Strata Overlying the Kraka Salt Pillow, Inferred from Stratigraphic Reconstruction
	1 Introduction
	2 Flexural Strain
	3 Method
		3.1 Seismic Stratigraphy
		3.2 Decompaction and Backstripping
		3.3 Strain Modeling
	4 Results
		4.1 Top Chalk
		4.2 Top Tor
		4.3 Top Hod
		4.4 Base Chalk
	5 Discussion and Conclusion
		5.1 Interpretation of the Observed Patterns
		5.2 Comparison with Forward Modelling
		5.3 Applications of This Technique
		5.4 Further Development of the Model
	References
Using Geomechanical Models to Simulate the Growth of the Fracture Network in the Ekofisk Formation of the Kraka Structure, Danish Central Graben
	1 Introduction
	2 Method
	3 Input Parameters for the Fracture Models
		3.1 Layer Thickness
		3.2 Elastic Properties
		3.3 Initial Horizontal Stress, Stress and Strain Relaxation
		3.4 Initial Fracture Population
		3.5 Horizontal Strain
	4 Sensitivity Models
		4.1 Initial Fracture Distribution Coefficient
		4.2 Thickness of the Brittle Layer
		4.3 Horizontal Strain
		4.4 Presence of Oblique Strike-Slip Fractures
		4.5 Initial Horizontal Stress, Strain Relaxation and Fluid Overpressure
		4.6 Subcritical Fracture Propagation Index
	5 Full Field Models
	6 Conclusions
	References
Geomechanical Modelling the Evolution of a Connected Natural Fracture Network to Explain Fluid Flow Variations Across a Fractured Chalk-Marl Reservoir
	1 Introduction
	2 Geological Setting
		2.1 Structural Setting
		2.2 Valdemar Field
		2.3 Reservoir Zonation
	3 Fracture Characterization
	4 Fracture Prediction
	5 Results
		5.1 Lower Tuxen
		5.2 Middle-Upper Tuxen
		5.3 Upper Tuxen
		5.4 Upper Sola
		5.5 Models with Fluid Overpressure
	6 Discussion
	7 Conclusions
	References
Numerical Study on the Influence of Induced Hydraulic Fractures on Oil Production in a Line Drive
	1 Introduction
		1.1 The Oil Recovery Process
		1.2 Modelling Assumptions
	2 Field Equations
		2.1 Constitutive Equations
		2.2 Balance Laws
	3 Numerical Method
		3.1 Discretization of the Field Equations
	4 The Model
		4.1 Material Data
		4.2 Boundary Conditions
	5 The Sweep Zone
		5.1 Particle Tracing Algorithm
		5.2 Water Front and Sweep Zone
		5.3 Fluid Phase Model
		5.4 Time-Stepping and Discretization of Domain
	6 Results and Discussion
		6.1 Varying the Fracture Height
		6.2 Effects of Gravity
		6.3 Effects of the Two-Phase Model
	7 Conclusion
	References
Conclusions