Seismic Driven Pore Pressure PredictionJoanne Wang 2016, PARADIGM. ALL RIGHTS RESERVED.

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

Why Pore Pressure Prediction?Indian OceanSouth America - 98Southern California

Why Pore Pressure Prediction? Drilling Annual Cost 40-60 Billion Steel:29%Mud:Rig Time:Trouble:24%29%18%Cost Related to Abnormal Pressure ( 6 – 8 Billion) Blow-OutLost Well“Kick”Stuck PipeUnneeded Casing String or Liners 500,000/day for a Deepwater Well A “Kick” 1,500,000

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

Terminology & DefinitionsVESPressure POver PressureDepth

Pore Pressure Prediction TechnologyRegional LithostratigraphyMeasured Pressure at WellboreHydrodynamicsLithology at WellboreStructureLithology (Seal, Drainage, Sand/Clay)Well Logs at WellboreCompaction HistoryClay MineralogySeismic Survey (2D, 3D, 4D, multicomponent)Geothermal GradientMaturity of Organic MatterTransformationModelingPressure Field

Pore Pressure Prediction MethodsRock Properties (Velocity/Impedances/Vp/Vs) Change with:DepthLithologyPorosityPore FluidPressure

Empirical RelationshipsEmpirical Rock Property Relationship – Some of the Examples Eaton’s Formula v vVES (OBP HP ) measurednormal exp Bower’s Formulavm vml A ves BDutta’s Formulaves c exp( εA(T ) / B (t ))

Terzaghi’s PrincipleOBP PP VESOBPOBP Overburden PressurePP Pore PressureVES Vertical Effective StressPPMatrix Type ShapePores Porosity Fluid TypeVES

Pressure in SandPressureCentroid ConceptOverburden PressureHydrostatic PressureShale Pore PressureSand Pore Pressurelow pressureFluid contactDepthhigh pressure 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 inequilibrium

Sand Pressure Estimation WorkflowSand SpatialDistributionCentroid Point(Zcp, Pcp)Fluid Contact (Zfl)5/26/2016Single Fuild Sand PressureSand PressureEstimationPsand Pcp ( Z Zcp ) Gfl

PPP Workflow Example (Eaton Method)Input DataPreparationPressureTransformation &Calibration{{High Res VelocityAnalysis (FastVel)Interval VelocityCreation (CVI)PP OBP - VESv VES (OBP HP ) vmeasuredOBP GenerationnormalNCTL AnalysisPoisson’s RatioEstimationPore PressureFracture Pressure υ HES VES 1 υ FP PP HESexp

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

AVO Based Residual Velocity Analysis15

Residual Moveout & Updated Velocity16

Interval Velocity Standard Dix (1955) inversion formula may produce an unstable andnon-geologically plausible interval velocitiesV0,k V22,k t k V22,k 1 t k 1t k t k 1 Small or moderate uncertainties of the input RMS velocity lead tohighly amplified uncertainties of the resulting piecewise-constantinterval velocities Constrained Velocity Inversion (CVI)F B C D Data MisfitTrend MisfitDamper min

Updating Interval Velocity with CVI18

Macuspana Basin The Macuspana Basin––––East:West:South:North:Yucatan PlaformReforma/ComalacalcoChiapas FoldbeltGulf of Mexico The Studied Area

Overpressure2990m, 12.7ppgNormal Pressure1330mWell 23280m, 8.3ppgWell 15/26/2016

OverpressureNormalPressure1330mWell 2Well 15/26/2016

Velocity Control Locations20 inlines x 20 xlines5 inlines x 5 xlines600m x 600m150m x 150mOriginalUpdated

Velocity Volume Before and AfterOriginalUpdated

Velocity AnalysisInterval Velocity at Depth 3000 metersSparse5/26/2016Dense

Velocity AnalysisWell 1BeforeWell 2AfterBeforeAfter

Pressure TransformationPressure CalculatorInterval Velocity Volumev PP OBP (OBP HP) vmeasurednormalVmeasured:Seismic or Log Derived Interval VelocityVnormal:Normal Compaction Trend LineHP:Hydrostatic PressureOBP:Overburden PressurePP:Pore Pressure5/26/2016exp Pore Pressure Volume

Pressure CalibrationWell 2: Pore PressureWell 2Well 1Well 2Well 25/26/2016Well 991458458526490464356046248Error1.3%4.2%3.7%Well 1: Pore Pressure

OverpressureNormalPressure1330mWell 2Well 15/26/2016


Velocity Calibration – A GOM ProjectWell 1Well 2Well 3130561252 ft14312

Pore PressurePP - SonicPP - Seismic

Seismic Velocity High resolution velocity analysis –gather flatness AVO based residual moveout picking FastVel Automatic Semblance based - Geostack Manual picking Auto picking CVI – Constrained dix Calibration to well velocity What if the seismic velocity doesn’tmatch sonic velocity?AutomaticResidual Velocity PickingCRP Gathers &Migration Velocity Time and DepthOffset and AngleInterval VelocityCreation w/CVICalibration to Velocityfrom WellsyesAgree?noWhy? Anisotropy?Correction?32

PPP Workflow Example (Eaton Method)Input Data PreparationPressureTransformation &Calibration{{High Res VelocityAnalysis (FastVel)Interval VelocityCreation (CVI)PP OBP - VESv VES (OBP HP ) vmeasuredOBP GenerationnormalNCTL AnalysisPoisson’s RatioEstimationPore PressureFracture Pressure υ HES VES 1 υ FP PP HESexp

Live DemoVelocity QC- Seismic and seismic velocity QC1D PPP- Develop 1D model and optimize parameters at wellbores3D PPP- Create 3D input volumes- Transform seismic velocity to pressures- Visualize, calibrate and interpret pressures

Uncertainty Evaluation – an Example Source of UncertaintyVelocityDensityPoisson’s ratioTrend LineTrend Line Volume Depth and structure dependent Methodologyincreases Pressure calibration and re-estimationshould be conducted after a new well isdrilled

Pore Pressures at Wellbores

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

Pore Pressure GUI in P1638

Paradigm PPP Technologies PPP Software Licensing GeoLog PPP – 1D/Log based PPP QSI PPP High resolution velocity analysisConstrained interval velocity creationTime to depth conversionPressure volume generationPressure volume visualization and interpretation PPP Services Worldwide Onshore Offshore39