008 Resolucion Sismica f2

RESOLUCION SISMICA

RESOLUCION RESOLUCIONSISMICA SISMICA Resolución Sísmica Vertical

has two common definitions. The first of these relates to determination of the position of a reflector in time or space. Resolution by this definition is inversely related to pulse width or sharpness of the wavelet and, potentially, directly related to bandwidth of the frequency spectrum. The second definition of resolution relates to determination of the spacing of close features such as thin beds. This type of resolution is determined by the Rayleigh criterion which inversely relates resolution to wavelength…” “Resolution

Ralph W. Knapp

RESOLUCION RESOLUCIONSISMICA SISMICA Resolución Sísmica Vertical

RESOLUCION SISMICA Resolución Sísmica Vertical

RESPUESTA RESOLUCION RESOLUCION SISMICA SISMICA SISMICA Resolución Sísmica Vertical



Typical Limits of Visibility and Separability for a range of geologic situations Very Young

Age of rocks

Shallow

Medium

Deep

1600

2000

3500

5000

6000

70

50

35

25

20

λ

23

40

100

200

300

λ/4

6

10

25

50

75

Predominant Frequency (Hz)

LIMIT OF VISIBILITY

Old

Very Deep

Formation Velocity (m/s)

LIMIT OF SEPARABILITY

Medium

Very Shallow

Depth of target

Wavelength (m)

Young

Very Old

Poor S/N

e.g. Water sand poor data

~ λ/8

3

5

13

25

38

Moderate S/N

e.g. Water or oil sand fairly good data

~ λ/12

2

3

8

17

25

High S/N

e.g. Gas sand good data

~ λ/20

1

2

5

10

15

Outstanding S/N

e.g. Gas sand excellent data

~ λ/30

<1

1

3

7

10



100 mts


Teoricamente, Una capa puede ser distinguida cuando tiene un espesor de ¼ wavelength.

Widess (1973), Una capa puede ser distinguida cuando tiene un espesor de 1/8 wavelength.


Como calcular??? Espectro de Amplitud

EE=Vi / 4fd donde Vi:Velocidad Intervalica fd: frecuencia dominante

fd = fmin

fmax

fmax - fmin 2


Como calcular???


Como calcular???


Como calcular???


Como calcular???

RESPUESTA SISMICA RESOLUCION SISMICA Resolución Sísmica Horizontal

SE REFIERE A QUE TAN CERCA DOS PUNTOS EN EL SUBSUELO SE PUEDEN SEPARAR HORIZONTALMENTE.

•

Depende del tamaño de la zona de fresnel. La zona de Fresnel depende de la profundidad, velocidad y la frecuencia. •


Segun Sheriff en 1991.

Radio de Fresnel

La Primera zona de Fresnel es: Esta area del reflector a partir del cual la energia reflejada alcanza el detector (Geófono) dentro de la mitad del ciclo. The area wh ere the waves interfere with each other constru ctively is our area of concern,

r



V T 0 2

f

called the “First Fresnel Zone.”

This definition involves wave theory not ray theory.

To: TWT f: frecuencia dominante V: vel


NOMOGRAMA PARA DETERMINAR EL RADIO DE LA ZONA DE FRESNEL

008 Resolucion Sismica f2

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