ISTANBUL ISTANBUL UNIVERSITYUNIVERSITY

ASSOCIATE PROF.DR. HÜSEYİN ASSOCIATE PROF.DR. HÜSEYİN TURTUR

Basic seismic Basic seismic interpretationinterpretation

RECORDING SEISMIC DATARECORDING SEISMIC DATA

Compressional (P) and Shear (S) wavesCompressional (P) and Shear (S) waves

P wave: the fastest P wave: the fastest kind of seismic kind of seismic wave. The P wave wave. The P wave can move through can move through solid rock and solid rock and fluidsfluids

S wave: slower S wave: slower than a P wave and than a P wave and can only move can only move through solid rockthrough solid rock

Re

flect

ed

Refle

cted

M

ode

Conv

erte

d

Mod

e Co

nver

ted

S-w

ave

(SV)

S-w

ave

(SV)

SurfaceSurface/ / seafloorseafloor

ReflectorReflector

P-wave P-wave SourceSource 3C/4C 3C/4C

ReceiverReceiverCMPCMP CCPCCP

Reflec

ted

Reflec

ted

P-wav

e

P-wav

e

Incident P-waves

Incident P-waves

Transmitted P and Transmitted P and SV wavesSV waves

Basic reflection theoryBasic reflection theory Refected and Transmitted wavesRefected and Transmitted waves Reflection coefficientReflection coefficient

the velocity increases across the the velocity increases across the interface the reflection coefficient interface the reflection coefficient will be will be positive (peak)positive (peak)

RC's are negativeRC's are negative when moving when moving from a high velocity to a low from a high velocity to a low velocity velocity (trough)(trough)

PhasePhase: Refers to the SHAPE of a : Refers to the SHAPE of a waveletwavelet

PolarityPolarity: Only has positive and : Only has positive and negative conditionsnegative conditions

Bright Spot Dim spot and Flat SpotBright Spot Dim spot and Flat Spot Bright spotBright spot is preresented is preresented

with high ampliture with high ampliture indicacate low velocity gas indicacate low velocity gas sand. Sometime bright spot sand. Sometime bright spot may exist because of some may exist because of some lithologic variationlithologic variation

Dim spotDim spot have nearly the have nearly the same velocity between two same velocity between two layers. layers.

Flat spot is a reflection from Flat spot is a reflection from the flat upper surface of a the flat upper surface of a liquid, that is a liquid, that is a contact contact between a liquid and a gas. between a liquid and a gas. Only recognizable when theOnly recognizable when the other reflections around it other reflections around it are not flatare not flat

VelocityVelocity

Some factors effect to velocity:Some factors effect to velocity:

Compaction (depend on depth)Compaction (depend on depth)

Lithology Lithology (limestone>sandstone)(limestone>sandstone)

PorosityPorosity

Pore fluid type (H2O>Oil>Gas)Pore fluid type (H2O>Oil>Gas)

Geologic ageGeologic age

WorkflowWorkflow

2D Seismic data acquisition

Seismic data processing

Seismis data interpretation

3D seismic data acquisition

Time to depth conversion

Geology

Location to Drill

Seismic data interpretationSeismic data interpretation

Interpretation workflow (3D)Interpretation workflow (3D)

Display basemap and seis2Dv/3Dv

Interpret faults

Interpret horizons,create fault contacts

Create fault boundaries

Grid andContour map

IESX

CPS-3

Time to depthconversion

Depth mapVolumetriccalculation

Location To drill

Display BasemapDisplay Basemap

3D Survey

2D line

3Dinline) Crossline: 500-770, Increment: 20

2DCDP increment: 50

Display Seis2DV/3DVDisplay Seis2DV/3DV

Display style:Display style:

VI: variable intensity VI: variable intensity wiggle tracewiggle trace

VA VI

IN-LINE AND CROSS-LINEIN-LINE AND CROSS-LINESource PointsSource Points

4C Receivers4C Receivers In-line GeophoneIn-line Geophone

Cross-line GeophoneCross-line Geophone

NN

Method to pick the FaultsMethod to pick the Faults

Inline 570: parallel to Fault strike Crossline 570: perpendicular to Fault strike

Interpret FaultsInterpret Faults

Fault location

Interpret HorizonsInterpret HorizonsHorizon_1 Horizon_2

Create fault boundariesCreate fault boundaries

Fault_2

Fault_1

Fault_3

Horizon_1

Horizon_2

Grid and Contour Horizon_1Grid and Contour Horizon_1

Time map with Fault boundaries Time map with no Fault boundaries

Time: 680-770 (ms)Gridding>structural Gridding

Grid and Contour Horizon_2Grid and Contour Horizon_2

Time map with Fault boundaries Time map no fault boundaries

Time: 940-1110 (ms)

Time to Depth ConversionTime to Depth Conversiontime to depth conversion

y = -1E-14x5 + 1E-10x4 - 4E-07x3 +

0.001x2 + 2.3851x + 0.4211

0

2000

4000

6000

8000

10000

12000

14000

16000

0 1000 2000 3000 4000

Time

Dep

th

Series1

Series2

Series3

Series4

Series5

Series6

Series7

Series8

Series9

Series10

Series11

Series12

Series13

Series14

Series15

Series16

Series17

Series18

Series19

Series20

Series21

Series22

Series23

Series24

Series25

Series26

Series27

Series28

Poly. (Series28)

Create Depth MapCreate Depth Map

Horizon_1: 1959-2265 (ft) Horizon_2: 2900-3536 (ft)

Interval: 25 (ft)Interval: 20 (ft)

Location to drillLocation to drill

model seismic

drill