seismic acquisition geometry

Gathered by : maryam seyed mahmoudi

Dear master: dr.Ali misaghi

1

2

index•Index• Introduction• Geometry in seismic• Expolaration seiemology• Geometry difinition• Geomertry seismic recorder 2D survey 3D survey• Geometry in marin survey• GPS system• Maps of the Survey Layout• Parameters of the Survey layout• Geometry in processing• database

3

Introduction4

Geometry  

from the Ancient Greek:( γεωμετρία; geo- "earth",  metron

 "measurement )" is a branch of 

mathematics

 concerned with questions of

shape size

relative position of figures

and the properties of space.

5

in seismic

6

Configuration and parameters

of the seismic acquisition

geometry, location of receiving and shooting

lines within the area under

study play the

crucial role for exploration of

hydrocarbondeposits and new

territories for oil & gas prospects

7

Geometry definition is fundamental to the success of every seismic processing project

8

Geometrics seismic recorder at the 3C-3D seismic micro-survey

9

Schematic diagram of 3C-3D seismic micro-survey showing the double serpentine spread of geophones.

10

A raw data shot, sorted by offset, is plotted in Figure

 Red pin flags outline the survey area containing the blue geophones.

11

It for each source record in the survey. We meticulously verify the actual x, y, z locations—particularly source and receiver locations

12

•A seismic survey is acquired, either

•on or offshore, either 2D or 3D.

13

2D Surveys

•A 2D survey consists of a grid of coarsely spaced seismic lines

14

3D surveys•A 3D survey consists of a grid of closely spaced parallel lines, forming a data cube

15

3D surveys - viewing optionsin the direction of acquisition, perpendicular to the seismic lines,at constant time slices through the survey,any random track through the survey

16

geometry in Marin surveyPositional control is generally provided by a global positioning system )GPS( where the GPS sensor is mounted on the vessel towing the magnetometer, with a constant offset equal to the distance from the GPS sensor to the geophone array.  

17

Land and Marine differencespractical applications of field techniques, field equipment, and geographic control can vary greatly between surface and marine surveys.

18

It’s important to choose an technique in geometry

• is a space-based satellite navigation system

19

The computational burden for geophysicists increased markedly.By providing high-precision GPS orbits in a well-definedterrestrial reference frame

20

 It is maintained by the United States government and is freely accessible to anyone with a GPS receiver.

21

GPSeismic is a suite of software applications that are geared towards

the seismic survey industry and work hand in hand with the Trimble

Access Land Seismicapplication

22

Survey Layout scheme (survey planning package)

23

Survey Layout on Land Map (survey planning package)

24

Survey Layout on Structure Map backgroud (survey planning package)

25

Map of the Survey Overlay Fold Object (survey planning package)

26

•Parameters of the Survey Layout:

•- geophone layout 4200 m•- type - static•- interval between geophone groups 20 m

•- interval between shots 40 m•- record sampling rate 2 ms•- record length 4 s•- frequency bandwidth 8-80 Hz

27

The majority of data processing was performed using the

ProMAX software system.

28

The processing approach was to follow a conventional 3D seismic processing flow adapted to the unique geometry of this survey

29

Geometery in omni software

30

31

CMP = Common Mid Point the midpoint is the position half way between the source and receiver.

32

database•When merging seismic data with coordinate data• you are actually setting up a database)of sorts(

• contains:

• all of the survey information•; such as shot point definitions, source and receiver coordinates, and elevations.

33

This ‘database’

is accessed for a variety of uses including refraction

statics calculations, CDP binning, creating CDP gathers, and populating SEG-Y trace

headers

34