lecture - 01 feb 13 2015 friday.unlocked

Department of Earth & Environmental Sciences,

Bahria University, Karachi Campus

www.bahria.edu.pk By: M. Hammad [email protected]

3D SEISMIC INTERPRETATION (GEO3D SEISMIC INTERPRETATION (GEO--518)518)

M. S (Geophysics)M. S (Geophysics)

By InstructorBy Instructor

M. Hammad ManzoorM. Hammad Manzoor

February 13, 2015 (Friday)February 13, 2015 (Friday) Lecture # 1Lecture # 1Lecture # 1Lecture # 1



1. Introduction

2. Importance and Applications

3. Practical Points in Seismic Interpretation

4. Quality Control of Surveying & Processing


4. Quality Control of Surveying & Processing

5. Reflection Identification

6. Following a Reflection

7. Miss Tie

8. Digitization and Map Construction

9. Two Way Time Maps

10. Depth Contoured Maps

11. Isopach Maps

12. 3D Seismic Interpretation Techniques

13. Horizon & Seismic Trace Attributes



Plate Plate TectonicsTectonics Three Phases (Convergent, Divergent & Strike Slip)Three Phases (Convergent, Divergent & Strike Slip) Different phases of Different phases of bainbain formationformation Thin Skinned & Thick SkinnedThin Skinned & Thick Skinned Different types of accumulation featureDifferent types of accumulation feature Structural & Structural & StratigraphicStratigraphic


Structural & Structural & StratigraphicStratigraphic Different types of faults in compressional, Different types of faults in compressional, extensional extensional

and and transform faultstransform faults Acoustic ImpedanceAcoustic Impedance Reflection CoefficientReflection Coefficient



PlatePlate TectonicsTectonics

Plate tectonics is the theory that Earth's outershell is divided into several plates that glide over themantle, the rocky inner layer above the core.The plates act like a hard and rigid shell compared toEarth's mantle.


Earth's mantle.

Where plates meet, their relative motiondetermines the type of boundary

I. ConvergentII. DivergentIII. Transform



Plate Tectonics (cont..)


Video clip about the theory



Convergent boundaries

Convergent boundaries (Destructive) (or active) occur where two plates slide toward each



Convergent boundaries (Destructive) (or activemargins) occur where two plates slide toward eachother to form either a subduction zone ora continental collision.



Divergent boundaries

Divergent boundaries (Constructive) occur wheretwo plates slide apart from each other. At zones of



two plates slide apart from each other. At zones ofocean-to-ocean rifting, divergent boundaries formby seafloor spreading, allowing for the formationof new ocean basin.



Transform boundaries

Transform boundaries (Conservative) occurwhere two lithospheric plates slide, or perhaps



where two lithospheric plates slide, or perhapsmore accurately, grind past each otheralong transform faults, where plates are neithercreated nor destroyed.



DifferentDifferent phasesphases ofof basinbasin formationformation

Sedimentary basins are regions where considerablethicknesses of sediments have accumulated.

THE WILSON CYCLE


Describes the evolution of tectonic plates and plateinteractions through geological time. Simplified as theopening and closing of ocean basins atI. Oceanic spreading centersII. Subduction zones



Different phases of basin formationDifferent phases of basin formation




Thrust tectonics is concerned with the structuresformed, and the tectonic processes associatedwith, the shortening and thickening of thecrust or lithosphere. In areas of thrust tectonicstwo main styles are recognized


two main styles are recognized

I. thin-skinned deformationII. thick-skinned deformation



I. Thin-skinned deformation

Shortening that only involves thesedimentary cover. This style is typical ofmany fold and thrust belts developed inthe foreland of a collisional zone. This is


the foreland of a collisional zone. This isparticularly the case where a goodbasal decollement exists such as salt or azone of high pore fluid pressure.



II. Thick-skinned deformation

Shortening that involves basementrocks rather than just the overlying cover.This type of geometry is typically found inthe hinterland of a collisional zone. This


the hinterland of a collisional zone. Thisstyle may also occur in the foreland whereno effective decollement surface is presentor where pre-existing extensional riftstructures may be inverted.



Hydrocarbon traps form where permeable reservoir rocks(carbonates, sandstones) are covered by rocks with low permeability (caprocks) that are capable of preventing the hydrocarbons from further upwardmigration.

Traps are usually classified according to the mechanism that produces

DifferentDifferent typestypes ofof accumulationaccumulation featurefeature


Traps are usually classified according to the mechanism that producesthe hydrocarbon accumulation. The two main groups of traps

I. Structural trapsII. Stratigraphic traps

Many traps result from both of these factors (strati-structural orcombination traps).



DifferentDifferent typestypes ofof accumulationaccumulation featurefeature (cont(cont....))

I. Structural trapsare those that are formed by structural deformation

(folding and (or) faulting, or both) of rocks. Types of traps area. Anticlinal (fold) and dome traps

Simple fold traps(anticlinal) Salt domes


Salt domes Growth domes

b. Fault traps Normal faults Strike-slip faults Thrust faults Growth faults



II. Stratigraphic Trapsthat are related to depositional or diagenetic

features in the sedimentary sequence (stratigraphic traps). Two main groups

I. Primary stratigraphic traps: result from variations in facies that

Different types of accumulation feature (cont..)Different types of accumulation feature (cont..)


I. Primary stratigraphic traps: result from variations in facies that developed during sedimentation. These include features such as lenses, pinch-outs, and appropriate facies changes.

II. Secondary stratigraphic traps: result from variations that developed after sedimentation, mainly because of diagenesis.



DifferentDifferent typestypes ofof faultsfaults inin compressionalcompressional,,extensionalextensional andand transformtransform faultsfaults

Compressional RegimeReverse faults/Dip-slip: Reverse or thrust faults, are a result oftectonic forces that compress or shrink the crust.

Thrust fault: Thrust faults are a special class of "reverse faulting" thattypically have low dip angles


typically have low dip anglesBlind thrust faults: If the fault plane terminates before it reaches theEarth's surfaceDuplex structures: Duplexes occur where there are two decollementlevels close to each other within a sedimentary sequenceAccretionary wedge: The accretionary wedge, at the front of theoverriding plate,



DifferentDifferent typestypes ofof faultsfaults inin compressionalcompressional,,extensionalextensional andand transformtransform faultsfaults

Extensinal FaultsNormal faulting occurs, in which the overlying (hanging-wall)block moves down with respect to the lower (foot wall) block.

Listric normal faults: concave upward faults whose dip decreases with


Listric normal faults: concave upward faults whose dip decreases withincreasing depth.Detachment fault: a low-angle fault that marks a major boundarybetween unfaulted rocks.Synthetic faults: small scale faults parallel to the major fault with thesame sense of shear.Antithetic faults: small scale faults with comparable dips but in theopposite dip direction from the main faults.



Graben: a down dropped block bounded on both sides by conjugate normalfaults that dip toward the down-dropped block on both sides.Half-graben: a down-dropped tilted block bounded on only one side by amajor normal fault.Horst: an uplifted block bounded by two conjugate normal faults that dipaway from the uplifted block on both sides.

DifferentDifferent typestypes ofof faultsfaults inin compressionalcompressional,, extensionalextensional andandtransformtransform faultsfaults


away from the uplifted block on both sides.Horst-and-graben structure: alternating uplifted and down-dropped faultblocks.Extensional Duplex: a stack of horses that are progressively cut from thefootwall block and transferred to the hanging wall block.Ring faults: a system of concentric normal faults into which surficial rockscollapse when a cavity forms at depth.



Strike-slip tectonics: zones of lateral displacement withinthe crust or lithosphere.

Dextral faults :Those with right-lateral motion

DifferentDifferent typestypes ofof faultsfaults inin compressionalcompressional,, extensionalextensional andandtransformtransform faultsfaults


Dextral faults :Those with right-lateral motionSinistral faults: Strike-slip faults with left-lateral motionRiedel shear structuresFlower structuresStrike slip duplexes



Acoustic impedance:

The product of density and seismic velocity, whichvaries among different rock layers, commonlysymbolized by Z. The difference in acoustic impedancebetween rock layers affects the reflection coefficient.


between rock layers affects the reflection coefficient.Z=Pv

Amplitude anomalies in seismic data can be associatedwith hydrocarbon accumulations and controlled by theAcoustic impedance.



Reflection CoefficientReflection Coefficient

The ratio of amplitude of the reflected wave to theincident wave, or how much energy is reflected. If the


incident wave, or how much energy is reflected. If thewave has normal incidence, then its reflectioncoefficient.



Remote sensing: Remote sensing is the acquisition ofinformation about an object or phenomenon without makingphysical contact with the object and thus in contrast to on siteobservation.

Overview of Geophysical MethodsOverview of Geophysical Methods


Magnetics Survey: Local variations, or anomalies, in the Earthsmagnetic field are the result of disturbances caused mostly byvariations in concentrations of ferromagnetic material in thevicinity of the magnetometers



Gravity: Gravity surveying measures variations in the Earthsgravitational field caused by differences in the density of sub-surface rocks.

Magneto Tellurics: An electromagnetic surveying method

OverviewOverview ofof GeophysicalGeophysical MethodsMethods


Magneto Tellurics: An electromagnetic surveying methodused to map subsurface resistivity variations by measuringnaturally occurring electric and magnetic fields on the seabedor the Earths surface. MT measurements can investigatedepths from about 300m down to hundreds of kilometers,though investigations in the range of 500m to 10,000m aretypical.



Overview of Geophysical MethodsOverview of Geophysical Methods

Seismic Refraction: Method is based on the property of seismic waves to refract (or be bent) when they travel from one medium to another of different density


travel from one medium to another of different density or elasticity.

Seismic Reflection: uses the principles of seismologyto estimate the properties of the Earth's subsurfacefrom reflected seismic waves.



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lecture - 01 feb 13 2015 friday.unlocked

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