Active deformation over multiple earthquake cycles in the southern Junggar fold and-thrust belt, NW China and fractured reservoir characterization using 3D geomechanical restorations The Harvard community has made this article openly available. Please share how this access benefits you. Your story matters Citation Stockmeyer, Joseph M. 2016. Active deformation over multiple earthquake cycles in the southern Junggar fold and-thrust belt, NW China and fractured reservoir characterization using 3D geomechanical restorations. Doctoral dissertation, Harvard University, Graduate School of Arts & Sciences. Citable link http://nrs.harvard.edu/urn-3:HUL.InstRepos:33493253 Terms of Use This article was downloaded from Harvard University’s DASH repository, and is made available under the terms and conditions applicable to Other Posted Material, as set forth at http:// nrs.harvard.edu/urn-3:HUL.InstRepos:dash.current.terms-of- use#LAA Active deformation over multiple earthquake cycles in the southern Junggar fold-and-thrust belt, NW China and fractured reservoir characterization using 3D geomechanical restorations A dissertation presented by Joseph M. Stockmeyer to The Department of Earth and Planetary Sciences in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the subject of Earth and Planetary Sciences Harvard University Cambridge, Massachusetts April 2016 © 2016 – Joseph M. Stockmeyer All Rights Reserved. Advisor: Professor John H. Shaw Joseph M. Stockmeyer Active deformation over multiple earthquake cycles in the southern Junggar fold-and-thrust belt, NW China and fractured reservoir characterization using 3D geomechanical restorations Abstract This dissertation investigates natural deformation processes over multiple earthquake cycles in the seismically active, southern Junggar basin, NW China and additionally explores the capabilities of 3D geomechanical restoration as an effective tool for fractured reservoir characterization. Chapter 1 presents a detailed 3D fault model of the active Southern Junggar Thrust (SJT) – constrained by seismic reflection data – in the southern Junggar basin. This work demonstrates the significance of mid-crustal detachments as a physical mechanism to accommodate destructive, multi-segment earthquakes in active thrust sheets. Moreover, it highlights the efficacy of surface folds to delineate fault geometries at depth in the absence of subsurface data constraints. Chapter 2 describes active thrust sheet deformation across the Tugulu anticline, which sits in the hanging wall of the SJT, from Late Quaternary to present. Holocene terrace deformation records of surface faulting and folding yield consistent fault slip rates. We develop a quantitative method for extracting fault slip rates from terrace fold geometries using a mechanical modeling approach, yielding a 250 kyr history of SJT slip. This study provides new insights into natural fold growth associated with fault slip. Moreover, it addresses several shortcomings of traditional seismic hazards assessment methodologies. Chapter 3 characterizes the styles, timing, and sequence of deformation across southern Junggar. Southern Junggar underwent extension followed by tectonic inversion and shortening, forming a series of imbricate structural wedges. A kinematic model for the evolution of shear fault-bend fold wedges is presented. We discuss the implications of structural style, fold growth and thrusting sequence on the ~175 Myr evolution of this fold-and-thrust belt and its petroleum system. Chapter 4 investigates the impact of natural fold strains on fractured reservoir properties in the Permian Basin, West Texas. This study details the ability of 3D geomechanical iii restorations to accurately model natural strain distributions associated with fold growth. Modeled strains from geomechanical restorations are integrated with proxies for natural deformation and production data to describe how tectonic strain impacted observed gas production, water cuts and reservoir temperatures. When used in conjunction with additional datasets, geomechanical restoration shows promise for predictive abilities in characterizing conventional and unconventional fractured reservoir properties. iv Active deformation over multiple earthquake cycles in the southern Junggar fold and-thrust belt, NW China and fractured reservoir characterization using 3D geomechanical restorations INTRODUCTION ........................................................................................................................................ 1 CHAPTER 1: SEISMIC HAZARDS OF MULTI-SEGMENT THRUST FAULT RUPTURES: INSIGHTS FROM THE 1906 MW 7.4-8.2 MANAS, CHINA EARTHQUAKE ................................................................................... 7 INTRODUCTION ............................................................................................................................................ 7 GEOLOGIC AND SEISMOTECTONIC SETTING OF THE SOUTHERN JUNGGAR BASIN ........................................ 8 THREE-DIMENSIONAL FAULT MODEL OF THE SOUTHERN JUNGGAR THRUST ............................................ 10 SEISMIC HAZARDS OF MULTI-SEGMENT THRUST FAULTS ......................................................................... 17 CONCLUSION ............................................................................................................................................. 19 CHAPTER 2: ACTIVE THRUST SHEET DEFORMATION OVER MULTIPLE RUPTURE CYCLES: A QUANTITATIVE BASIS FOR RELATING TERRACE FOLDING TO FAULT SLIP RATES ...................................................................... 20 INTRODUCTION .......................................................................................................................................... 20 STYLES OF ACTIVE THRUST SHEET DEFORMATION ................................................................................... 23 SOUTHERN JUNGGAR BASIN ...................................................................................................................... 26 SUBSURFACE DEFORMATION ..................................................................................................................... 31 SURFACE DEFORMATION ........................................................................................................................... 35 INTEGRATED RECORDS OF ACTIVE THRUST SHEET DEFORMATION ........................................................... 41 A MECHANICAL MODEL OF DEFORMATION IN THRUST SHEETS ................................................................ 47 250 KYR RECORD OF ACTIVE THRUST SHEET DEFORMATION .................................................................. 54 CONCLUSIONS ........................................................................................................................................... 56 CHAPTER 3: STRUCTURAL INVERSION, IMBRICATE WEDGING, AND OUT-OF-SEQUENCE THRUSTING IN THE SOUTHERN JUNGGAR FOLD-AND-THRUST BELT, NORTHERN TIAN SHAN, CHINA .................................. 57 INTRODUCTION .......................................................................................................................................... 57 TECTONIC SETTING ................................................................................................................................... 60 REGIONAL STRUCTURAL CHARACTERIZATION .......................................................................................... 63 STRUCTURAL STYLES IN THE SOUTHERN JUNGGAR FOLD-AND-THRUST BELT.......................................... 68 IMPLICATIONS FOR RESERVOIR GEOMETRY AND HYDROCARBON CHARGE ................................................. 91 CONCLUSIONS ........................................................................................................................................... 94 CHAPTER 4: GEOMECHANICAL RESTORATION AS A TOOL FOR FRACTURED RESERVOIR CHARACTERIZATION: APPLICATION TO THE PERMIAN BASIN, WEST TEXAS .......................................... 96 INTRODUCTION .......................................................................................................................................... 96 GEOMECHANICAL RESTORATION ............................................................................................................ 100 GEOLOGIC SETTING OF OATES SW FIELD ............................................................................................... 103 THREE-DIMENSIONAL GEOMECHANICAL RESTORATIONS ....................................................................... 109 STRAIN-SEMBLANCE ANALYSIS .............................................................................................................. 115 RESERVOIR CHARACTERIZATION USING GEOMECHANICAL RESTORATIONS ............................................ 120 CONCLUSIONS ......................................................................................................................................... 132 APPENDICES ........................................................................................................................................... 134 APPENDIX A: CHAPTER 1 SUPPLEMENTAL FIGURES ................................................................................ 134 APPENDIX B: EVALUATING ALTERNATIVE SJT KINEMATIC MODELS ..................................................... 137 APPENDIX C: EXTRACTING TERRACE PROFILES FOR STRUCTURAL ANALYSIS ........................................ 139 APPENDIX D: SJT FAULT SLIP AND SLIP RATE UNCERTAINTIES