Seismic Driven Pore Pressure Prediction

Transcription

1 Seismic Driven Pore Pressure Prediction Joanne Wang 2016, PARADIGM. ALL RIGHTS RESERVED.

2 Today s Topics PPP technology overview Suit-for-purpose seismic velocity analysis A workflow example PPP in 1D and 3D

3 Why Pore Pressure Prediction? Indian Ocean South America - 98 Southern California

4 Why Pore Pressure Prediction? Drilling Annual Cost ~ $40-60 Billion Steel:29% Mud: 24% Rig Time: 29% Trouble: 18% Cost Related to Abnormal Pressure ($6 8 Billion) Blow-Out Lost Well Kick Stuck Pipe Unneeded Casing String or Liners $500,000/day for a Deepwater Well A Kick ~ $1,500,000

5 Why Pore Pressure Prediction? Risk & Cost Reduction Well Bore Stability Optimal Casing Seat Selection Mud Program Design

6 Terminology & Definitions VES P Over Pressure Pressure Depth

7 Pore Pressure Prediction Technology Regional Lithostratigraphy Hydrodynamics Structure Lithology (Seal, Drainage, Sand/Clay) Compaction History Clay Mineralogy Geothermal Gradient Maturity of Organic Matter Measured Pressure at Wellbore Lithology at Wellbore Well Logs at Wellbore Seismic Survey (2D, 3D, 4D, multicomponent) Modeling Transformation Pressure Field

8 Pore Pressure Prediction Methods Rock Properties (Velocity/Impedances/Vp/Vs) Change with: Depth Lithology Porosity Pore Fluid Pressure

9 Empirical Relationships Empirical Rock Property Relationship Some of the Examples Eaton s Formula VES = ( OBP HP) v v measured normal exp Bower s Formula v m = vml + A ves B Dutta s Formula ves = c exp( ε A( T ) / B( t))

10 Terzaghi s Principle OBP = PP + VES OBP = Overburden Pressure PP = Pore Pressure VES = Vertical Effective Stress OBP Matrix Type Shape Pores Porosity Fluid Type VES PP

11 Pressure in Sand Centroid Concept low pressure Overburden Pressure Hydrostatic Pressure Shale Pore Pressure Sand Pore Pressure Pressure Fluid contact high pressure Depth Sands provide a mechanism for vertical and lateral transfer of pressures Shale pressure and sand pressure follow different gradients The centroid is the depth at which sand and shale pore pressures are in equilibrium

12 Sand Pressure Estimation Workflow Sand Spatial Distribution Single Fuild Sand Pressure Centroid Point (Zcp, Pcp) Sand Pressure Estimation P sand = Pcp ( Z Zcp) G fl Fluid Contact (Zfl) 5/26/2016

13 PPP Workflow Example (Eaton Method) Input Data Preparation { OBP High Res Velocity Analysis (FastVel) Interval Velocity Creation (CVI) Generation NCTL Analysis Poisson s Ratio Estimation PP = OBP - VES VES = ( OBP HP) υ HES = VES 1 υ v v measured normal exp Pressure Transformation & Calibration { Pore Pressure Fracture Pressure FP = PP + HES

14 Velocity Analysis Techniques Suit for Purpose Velocity Analysis High Lateral and Vertical Resolution Automatic Velocity Refinement AVO Based Semblance Based Manual Velocity Refinement Semblance Based Tomographic Velocity Update

15 AVO Based Residual Velocity Analysis 15

16 Residual Moveout & Updated Velocity 16

17 Interval Velocity Standard Dix (1955) inversion formula may produce an unstable and non-geologically plausible interval velocities V 0, k = V 2 2, k t k t k V t 2 2, k 1 k 1 t k 1 Small or moderate uncertainties of the input RMS velocity lead to highly amplified uncertainties of the resulting piecewise-constant interval velocities Constrained Velocity Inversion (CVI) F = B Data Misfit + C Trend Misfit + D Damper min

18 Updating Interval Velocity with CVI 18

19 Macuspana Basin The Macuspana Basin East: Yucatan Plaform West: Reforma/Comalacalco South: Chiapas Foldbelt North: Gulf of Mexico The Studied Area

20 Overpressure 2990m, 12.7ppg Well_2 1330m Well_1 Normal Pressure 3280m, 8.3ppg 5/26/2016

21 Overpressure Well_2 1330m Normal Pressure Well_1 5/26/2016

22 Velocity Control Locations Original 20 inlines x 20 xlines 600m x 600m Updated 5 inlines x 5 xlines 150m x 150m

23 Velocity Volume Before and After Original Updated

24 Velocity Analysis Interval Velocity at Depth 3000 meters Sparse Dense 5/26/2016

25 Velocity Analysis Well_1 Well_2 Before After Before After

26 Pressure Transformation Interval Velocity Volume Pressure Calculator PP = OBP ( OBP HP) v v measured normal exp Pore Pressure Volume Vmeasured: Vnormal: HP: OBP: PP: Seismic or Log Derived Interval Velocity Normal Compaction Trend Line Hydrostatic Pressure Overburden Pressure Pore Pressure 5/26/2016

27 Pressure Calibration Well_2: Pore Pressure Well_1: Pore Pressure Well_2 Well_1 Depth Measured Predicted Error (Meters) (psi) (psi) Well_ % Well_ % Well_ % 5/26/2016

28 Overpressure Well_2 1330m Normal Pressure Well_1 5/26/2016

29 Co-Visualization 5/26/2016

30 Velocity Calibration A GOM Project Well 1 Well 2 Well ft 14312

31 Pore Pressure PP - Sonic PP - Seismic

32 Seismic Velocity High resolution velocity analysis gather flatness AVO based residual moveout picking - FastVel Automatic Semblance based - Geostack Time and Depth Offset and Angle CRP Gathers & Migration Velocity Automatic Residual Velocity Picking Interval Velocity Creation w/cvi Manual picking Auto picking CVI Constrained dix Calibration to Velocity from Wells Calibration to well velocity What if the seismic velocity doesn t match sonic velocity? yes Agree? no Why? Anisotropy? Correction? 32

33 PPP Workflow Example (Eaton Method) Input Data Preparation { OBP High Res Velocity Analysis (FastVel) Interval Velocity Creation (CVI) Generation NCTL Analysis Poisson s Ratio Estimation PP = OBP - VES VES = ( OBP HP) υ HES = VES 1 υ v v measured normal exp Pressure Transformation & Calibration { Pore Pressure Fracture Pressure FP = PP + HES

34 Live Demo Velocity QC 1D PPP 3D PPP - Seismic and seismic velocity QC - Develop 1D model and optimize parameters at wellbores - Create 3D input volumes - Transform seismic velocity to pressures - Visualize, calibrate and interpret pressures

35 Uncertainty Evaluation an Example Source of Uncertainty Velocity Density Poisson s ratio Trend Line Trend Line Volume Depth and structure dependent increases Pressure calibration and re-estimation should be conducted after a new well is drilled Methodology

36 Pore Pressures at Wellbores

37 Pore Pressure Prediction Deliverables High Resolution Velocity Volume Overburden Pressure Volume Vertical/Horizontal Effective Stress Pore Pressure Volume Fracture Pressure Volume Pressures at Existing and Proposed Wellbores

38 Pore Pressure GUI in P16 38

39 Paradigm PPP Technologies PPP Software Licensing GeoLog PPP 1D/Log based PPP QSI PPP High resolution velocity analysis Constrained interval velocity creation Time to depth conversion Pressure volume generation Pressure volume visualization and interpretation PPP Services Worldwide Onshore Offshore 39

40 Thank you! 2016, PARADIGM. ALL RIGHTS RESERVED.