The Pennsylvania State University The Graduate School ... Numerous individuals that have helped...

download The Pennsylvania State University The Graduate School ... Numerous individuals that have helped shape

of 109

  • date post

    14-Jul-2020
  • Category

    Documents

  • view

    1
  • download

    0

Embed Size (px)

Transcript of The Pennsylvania State University The Graduate School ... Numerous individuals that have helped...

  • The Pennsylvania State University

    The Graduate School

    College of Earth and Mineral Sciences

    GEOPRESSURE AND FLOW FOCUSING ON THE

    SLOPE OF THE GULF OF MEXICO, GC 65

    A Thesis in

    Geosciences

    by

    Jacek Andrzej Lupa

    Copyright 2002 Jacek Andrzej Lupa

    Submitted in Partial Fulfillment of the Requirements

    for the Degree of

    Master of Science

    May 2002

  • r the

    c on

    _

    I grant The Pennsylvania State University the non-exclusive right to use this work fo

    University’s own purposes and to make single copies of the work available to the publi

    a not-for-profit basis if copies are not otherwise available.

    _______________________

    Jacek Lupa

  • _

    _

    _

    _

    We approve the thesis of Jacek Andrzej Lupa.

    Date of Signature

    _________________________________________ ___________________

    Peter B. Flemings

    Associate Professor of Geosciences

    Thesis Advisor

    _________________________________________ ___________________

    Derek Elsworth

    Professor of Energy and Geo-Environmental Engineering

    _________________________________________ ___________________

    Rudy L. Slingerland

    Professor of Geology

    _________________________________________ ___________________

    Peter Deines

    Professor of Geochemistry

    Associate Head for Graduate Programs and Research

  • e-

    floor

    har-

    de.

    ssure

    ckage

    sand

    trolling

    res-

    rofrac-

    f the

    n ana-

    thin

    Abstract

    At Green Canyon 65, on the slope of the Gulf of Mexico, rapid deposition of low perm

    ability Pleistocene sediments has resulted in overpressures originating near the sea

    and increasing at near lithostatic gradients with depth. In the Bullwinkle mini-basin, c

    acterization of sand and shale overpressures, usingin situ data and wireline prediction,

    suggest sand and salt geometry play a role in overpressure distribution and magnitu

    Three 2- and 3-D steady-state flow models are developed to account for the overpre

    and flow phenomena that occur around the J-Sands, a bowl shaped turbidite sand pa

    located at 3350 m depth. The models illustrate the effect of sand and salt geometry on

    overpressure, and suggest that an impermeable salt layer beneath the J Sand is con

    overpressure in both the sand and the Bullwinkle basin.

    The flow focusing model is then applied to a trap integrity case study in GC 64. As p

    sure converges on the least principal stress, processes such as shear failure or hyd

    ture may generate fracture permeability. This enhanced permeability facilitates the

    expulsion of hydrocarbons from a reservoir. In the J Boxer sand, pressure at the top o

    hydrocarbon column is within 2.5 MPa of the maximum principal stress (Sv). Seismic evi-

    dence suggests that gas is being expelled from the top of the sand. I describe with a

    lytical flow model how flow focusing has elevated pressure at the top of structure to wi

    1 MPa of the minimum principal stress (Shmin). I then discuss the implication of flow

    focusing for prospect evaluation and for estimating trap integrity before drilling.

    iii

  • Contents

    List of Figures vi

    List of Tables viii

    Acknowledgements ix

    Chapter 1: Introduction

    1.1. Background 1

    1.2. Overview 2

    Chapter 2: Flow Focusing in Turbidites on the slope of the GOM

    2.1. Introduction 9

    2.2. Structure and Geology of GC 65 & the J Sand Package 10

    2.2.1. Geology of the Bullwinkle Basin 10

    2.2.2. Geology of the J Sand Package 11

    2.3. Pressure Characterization 17

    2.3.1. Sand Pressure 17

    2.3.2. Shale Pressure Prediction 18

    2.3.3. Pressure in the J Sand Package 27

    2.4. Model 32

    2.5. Discussion 40

    2.6. Conclusions 44

    Chapter 3: Overpressure and Trap Integrity on the Slope of the GOM

    3.1. Introduction 54

    iv

  • 3.2. Flow Focusing 54

    3.3. Case study of the J Boxer Sand 57

    3.4. Discussion 65

    3.5. Conclusions 71

    Appendix A: Geometrical Sand Pressure Prediction Method

    A.1. Introduction 72

    A.2. Average Sand Depth 73

    A.3. Sand Overpressure Prediction 73

    A.4. Conclusions 78

    Appendix B: Derivation of the Cylindrical LaPlace Equation and Finite

    Difference Approximation

    B.1. Derivation of the Cylindrical LaPlace Equation 80

    B.2. Finite Difference Approximation 83

    Appendix C: Derivation of Radial Stream Function

    C.1. Stokes Stream Function 88

    C.2. Finite Difference Solution 89

    References 91

    v

  • 9

    List of Figures

    Figure 1.1. Multi-beam bathymetry of the Gulf of Mexico (GOM) 5

    Figure 1.2. Multi-beam bathymetry of the Bullwinkle basin 6

    Figure 1.3. Relative locations of the study areas 7

    Figure 2.1. Bathymetry of the Gulf of Mexico 12

    Figure 2.2. Cross section through the Bullwinkle basin 13

    Figure 2.3. Structure of top of salt 14

    Figure 2.4. Structure map of the J2 and J0 sands 15

    Figure 2.5. Depositional history of the Bullwinkle basin 16

    Figure 2.6. Measured pressure in the Bullwinkle basin 19

    Figure 2.7. Shallow velocity and porosity behavior of 109-1 well 20

    Figure 2.8. Porosity-effective stress regressions 23

    Figure 2.9. Comparison of pressure predictions at the 109-1 well 25

    Figure 2.10. Overpressure in the shallow subsurface 26

    Figure 2.11. Extrapolation of shale pressure to sand top 29

    Figure 2.12. Predicted shale overpressure above the J Sand 30

    Figure 2.13. Overpressure cross-section through Bullwinkle 31

    Figure 2.14. Model domain and parameters 33

    Figure 2.15. 2-D Model fluid flow and overpressure 35

    Figure 2.16. Cross sectional overpressure plots of model results 37

    Figure 2.17. Sand overpressure predicted by the steady state flow models 3

    vi

  • 2

    Figure 2.18. Sand overpressure estimated from J Sand geometry 43

    Figure 2.19. Summary of model results 46

    Figure 3.1. Pressure and flow around a 2-D dipping sand 56

    Figure 3.2. Bathymetric map of the Bullwinkle Region 58

    Figure 3.3. Seismic cross section through Bullwinkle Region 59

    Figure 3.4. Amplitude extraction of J Boxer Sand 61

    Figure 3.5. Sand and shale pressure around J Boxer sand in GC 64 6

    Figure 3.6. Pressure and stress state of major sands at Bullwinkle 64

    Figure 3.7. Seismic washout above the J Boxer sand 66

    Figure 3.8. Charge history of J Boxer sand 67

    Figure 3.9. Cross-section and pressure-depth plot of a protected trap 69

    Figure A.1. Depth distribution of the J2 and J Boxer sands 74

    Figure A.2. Estimated pressure in J Boxer sand 76

    Figure A.3. Estimated pressure in J Sand package 77

    Figure B.1. Illustration of radial flow domain 82

    Figure B.2. Description of finite difference approximation 85

    vii

  • List of Tables

    Table 2.1: Nomenclature 47

    Table 2.2: Time-Stratigraphic Correlation (Styzen, 1998) 48

    Table 2.3: RFT Measurements 49

    Table 2.3: RFT Measurements 49

    Table 2.4: Sand Characteristics 50

    Table 2.5: Sand Water Phase Pressure and Overpressure 51

    Table 2.6: Shale Porosity-Effective Stress Above RFT Measurements 52

    Table 2.7: Average Sand Depth and Overpressure 53

    Table A.1: Average Sand Depth and Overpressure 79

    Table B.1: Appendix Nomenclature 86

    viii

  • course

    m I

    sacri-

    d for

    duate

    lem-

    er-

    ng of

    on

    g

    come

    ave

    all

    py

    Acknowledgements

    Numerous individuals that have helped shape my graduate and academic career. Of

    those most directly responsible for my successes thus far have been my family who

    cannot thank enough for their support. I am forever indebted to my parents for their

    fices and their selflessness that gave me many incredible opportunities. My brother,

    Michal, I’d like to thank for his encouragement, his friendship and for helping define

    myself as a person. I’d like to thank Alyson Becker for her patience, understanding an

    making me happier than I could ever imagine by myself.

    From the onset, the people of the Basin Research Group made the transition into gra

    life a successful one. The support, advice and direction that my advisor, Dr. Peter F

    ings, provided were invaluable. His enthusiasm, drive and dedication cannot be und

    stated. Brandon Dugan’s (B Diddy) technical expertise, ideas and deep understandi

    fluid flow helped to shape and refine my thesis. Rachel Altemus and Heather Johns

    made my graduate career flow smoothly, solving all of my little dilemmas and makin

    sure I had all the resources I needed. Without these people, this thesis could not have

    to fruition.

    The richness, fullness and success of my graduate career at Penn State would not h

    been possible without all the people of the Deike Building. I’d especially like to thank

    the friends that I’ve made over the past several years for m