Introduction to Seismic Interpretation

EPT-LD

Introduction to (3D) Seismic Interpretation

C. Höcker, SIEP, EPT-S

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3D seismic an overview

EPT-LD

• an acoustic image of the subsurface • a volume made up by a series of ‘seismic lines’ • reflection time contains information on depth of subsurface interface • reflected energy contains information on properties

C. Höcker, SIEP, EPT-S

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Aspects of Seismic Interpretation EPT-LD

 Bridge between Geophysics and Geology (can we see a seismic section as a geological profile?)  Tries to overcome the ‘non-uniqueness problem’  Balance between ‘Science’ and ‘Art’  Young discipline with rapidly changing technology

C. Höcker, SIEP, EPT-S

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History of Seismic Exploration EPT-LD

  1900

theory of reflected and refracted waves

 1914-1918 (WW1) locating heavy guns by recording arrival times  1919

Mintrop: patent on the refraction method (salt dome discovery, Texas)

 1920’s

reflection method (Oklahoma)

 1953

magnetic tape: analog recording

 1956

patent on CDP method

 1975

first 3D surveys

 1980’s

development of seismic workstation software

C. Höcker, SIEP, EPT-S

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The Old Way EPT-LD

A refraction shot in West Texas. 2,000 pounds of dynamite shot by Humble Oil & Refining Company (now Exxon), 1930. C. Höcker, SIEP, EPT-S

(Geosource / Petty-Ray Geophysical)

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Salt dome exploration (Texas, 1930) EPT-LD

C. Höcker, SIEP, EPT-S

(Geosource / Petty-Ray Geophysical)

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The seismic reflection technique EPT-LD

Petroleum Handbook 1948 (Shell)

C. Höcker, SIEP, EPT-S

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Advantages of 3D over 2D Seismic EPT-LD

 Spatial continuity (less correlation problems)

 Correct positioning due to 3D migration (no ‘side-swipes’)

C. Höcker, SIEP, EPT-S

From A. Brown 8

2D vs. 3D Migration EPT-LD

Dipping events are not focussed with 2D migration but are with Events with out-of-plane dip 3D are not focused with 2D migration but are with 3D

C. Höcker, SIEP, EPT-S

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Maps from 2D and 3D Seismic Interpretation EPT-LD

closure shape updip of 15-B-4X

C. Höcker, SIEP, EPT-S

2D of faults in a subsurface description 3D • 3D likely increases the number • but it also likely will increase the geological feasibility of a fault pattern From A. Brown 10

Reacquisition and/or Reprocessing: Getting the target imaged for the first time

C. Höcker, SIEP, EPT-S

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Reacquisition and/or Reprocessing: Improving Resolution

1983

C. Höcker, SIEP, EPT-S

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1994

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Improvements in Migration and Noise-Suppression EPT-LD

1993

Time Migration

1998

Cluster PreSDM

1999/2000

1999/2000

Enhanced PreSDM

Post Migration Structurally Oriented Filtering

C. Höcker, SIEP, EPT-S

(Gerd Kleemeijer NAM TGS-S) 13

Influence of Workstation Technology on Interpretation EPT-LD

Started new era by:

 high accuracy of time picking  autotracking of seismic horizons  immediate extraction of amplitudes in grids, next to time grids  application to 3D seismic opens up new manipulations like:  creation of random lines  interpretation of timeslices  reservoir characterisation from continuous attributes

 Terminology: TIS = Trace Interpretation System

C. Höcker, SIEP, EPT-S

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3D data cube in visualisation environment EPT-LD

Detailed faults can be seen on the 3D cube. Hydrocarbons (gas) show as green. C. Höcker, SIEP, EPT-S

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The Interpreter at work EPT-LD

C. Höcker, SIEP, EPT-S

(Jaap van der Toorn, NAM TGS-S) 16

Virtual Reality EPT-LD

C. Höcker, SIEP, EPT-S

Schlumberger Inside Reality VR system

(Schlumberger web site)17

Seismic Interpretation – Positioning the Skill EPT-LD

 An inter-disciplinary skill  between geology, geophysics, petrophysics & reservoir engineering often ‘homeless’ between geology and geophysics skill pools  strong presence in E&A and early development – straddling prominent boundaries in Global Processes

 Boundary towards quantitative interpretation (QI) not well defined  Traditionally more involved in early modelling steps in the asset life cycle

C. Höcker, SIEP, EPT-S

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Skill Position of Seismic Interpretation EPT-LD

Bio-Stratigrapher: Markers and bio-facies from cores & cuttings

Geophysicist: seismic (Re-) Processing

depth conversion

sequence-stratigraphic interpretation

velocity model

stratigraphic / facies architecture model

Petrophysicist: physical properties from logs

Geologist: marker depths from logs facies from logs and cores, depositional history

Seismic Interpretation

quantitative interpretation property model

structural interpretation structural model Structural Geologist: faults & fracture prediction, tectonic history

Reservoir Engineer: volumetrics, simulations, development options, field development plan, well plans C. Höcker, SIEP, EPT-S

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Subsurface Modelling Stages as applied in the Oil&Gas Industry Velocity Modelling/ Seismic Processing Velocity Model

Structural Framework Modelling Struct.&Stratigr. Model

Reservoir Architecture Modelling Layer/Object Model

Seismic Processing  = impact of seismic data  Velocity Model Structural Framework Modelling   Framework of Structural & Large-Scale Stratigraphic Surfaces Reservoir Architecture Modelling   Detailed Layer/Object Model of Reservoir

Static Property Modelling



Property Model

Dynamic Reservoir Modelling

Static Property Modelling  3D Model of Properties Dynamic Reservoir Modelling  4D Model of Fluid Movements



Fluid Movement Model

Field Development Planning Development Plan

Facilities Planning Facility Design C. Höcker, SIEP, EPT-S

EPT-LD



Field Development Planning  HC Development Scenarios Facilities Planning  HC Evacuation Scenarios 20

Velocity Modelling and Seismic Processing EPT-LD

Pre-Stack Processing

Velocities from Seismic Data

Well Data Preproc/Interpr

Velocities from Well Data Stacking & Migration

Velocity Model Building

• Exploration / Appraisal / Production • 2D and 3D Seismic

Processing Geophysicist Seismic Interpreter Petrophysicist C. Höcker, SIEP, EPT-S

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Structural Framework Modelling EPT-LD

Filtering & Interpret. Proc.

Structural&Stratigraphic Segmentation

Well Data Preproc/Interpr

Tops & Faults from Well Data

Palinsp. Reconstruction Basin Modelling

Velocity Model • Exploration / Appraisal / Production • 2D and 3D Seismic Seismic Interpreter Quantitative Interpreter (GP) Petrophysicist Geologist C. Höcker, SIEP, EPT-S

Structural&Stratigraphic Model Building Depth Conversion Closure-Catchment Analysis Compartmentalisation Analysis Volumetric Analysis

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Stratigraphic / Reservoir Architecture Modelling EPT-LD

Interpretive Processing

Segmentation into Layers/Objects

Well Data Preproc/Interpr

Genetic/Property Units from Well Data Deposition Modelling

• Appraisal / Production • 3D Seismic

Layer/Object Model Building

Volumetric Analysis

Seismic Interpreter Petrophysicist Geologist C. Höcker, SIEP, EPT-S

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Static Property Modelling EPT-LD

Seismic Preprocessing

Seismic Modelling/ Seismic Inversion

Well Data Preproc/Interpr

Rock/Fluid Properties & Fractures from Well Data Reservoir Simulation

Property Model Building Compartmentalisation Analysis

• Appraisal / Production • 2D and 3D Seismic

Volumetric Analysis

Quantitative Interpreter (GP) Petrophysicist Geologist Reservoir Engineer C. Höcker, SIEP, EPT-S

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Dynamic Reservoir Modelling EPT-LD

Seismic Preprocessing

4D Seismic Analysis / Seismic Modelling

Well Data Preproc/Interpr

Fluid Properties / Pressure / Production from Well Data

Reservoir Simulation / History Matching • Production • 2D and 3D Seismic Quantitative Interpreter (GP) Geologist Reservoir Engineer Production Technologist C. Höcker, SIEP, EPT-S

Property Model Update Compartmentalisation Analysis Volumetric Analysis

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Amoco’s exploration balance, improvements mainly attributed to 3D seismic 1200

EPT-LD

$8.00

cost of finding

$7.00 1000 800

$5.00 $4.00

600

($/BOE)

(MMBOE)

$6.00

$3.00

400

$2.00

resources found 200

$1.00 $0.00

0 1991

1992

1993

1994

1995

1996 from Brown 1999

C. Höcker, SIEP, EPT-S

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Seismic Interpretation in Integrated Reservoir Modelling EPT-LD

 Who are the customers of seismic interpretation results?

 What do they want?  When do they want it?

 Software portfolio – recent movements

 Where does the seismic interpretation task end?

C. Höcker, SIEP, EPT-S

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Integrated Field Study Methodology (1) EPT-LD

Reservoir Structure

Integrated Field Model

Reservoir Architecture

 Global Process #5: IRM (3DATWTM) Production History

Optimised Field Development

C. Höcker, SIEP, EPT-S

Reservoir Properties

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Integrated Field Study Methodology (2) EPT-LD

Raw Data

Multiple Realisations Constructed Using Different Assumptions

Rock Model Property Model

Upscaled Simulation Model

Rule Sets

C. Höcker, SIEP, EPT-S

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Integrated Field Study Methodology (3) EPT-LD

Simple

STUDY COMMENCES

C. Höcker, SIEP, EPT-S

Complex

STUDY CONCLUDES

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Integrated Field Study Methodology (4) EPT-LD

STUDY COMMENCES

STUDY CONCLUDES

Detailed Full Field Model

Simple/ Conceptual Models

20 18 16 UR (MMm3)

Simple Full Field Model

Field Development Plan Economics Forecasting 14 12

Low Case Median Case High Case

10 8 6 4 2 0

No

Sm.Comp+Opt

W orkovers

W .Injection

H.well3

Lg.Comp+Opt

Optim. Void

Prod.&Inj.Constr

Data Analysis

DATA

C. Höcker, SIEP, EPT-S

Regional Seismic Logs Core SCAL PVT Well Data Production Data

Scenario

Model Complexity

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Iterative Cycles in Subsurface Interpretation EPT-LD

 Execution in iterative cycles:  parallel rather than sequential work in integrated teams  cycles of improving the model and assessing its behaviour in dynamic and economic modelling  additional cycles increase detail and confidence of single instances or generate new instances / scenarios  intermediate products should be complete at current level of maturity and detail  interruption or abandonment of work due to changed priorities does not cause waste

 Structure and organise your work such that intermediate products can be passed on to your customers or the activity be stopped at any time without the product being incomplete.

C. Höcker, SIEP, EPT-S

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