Lab 1: Examine Seismic Data

The objective of this lab session it to look at the seismic header which contains the basic information of the seismic survey and tabulation of parameter used to acquire the data. The format the we receive is usually in SEG-Y. 




          1.  Examining the data set 

ü Load data into matlab; SeismicData_B.mat
ü It will view two main information; a) the original data is stored in variable D & b) the header value is stored in variable H

ü Result : 




2. Header Information 

ü Call for header
ü Extract geometrical information such as the source coordinate (sx and sy) and receiver coordinate (gx and gy), the source elevation (gz) and others


ü Result :


                                      Figure 1: The number of traces per shot


Figure 2: The source elevation profile for each 
Figure 3: The stacking chart plot of the seismic data




1            3. Displaying seismic data

                 Two ways of displaying seismic sections
·         Seismic shot gather
·         CMP gather

Common use displays are
·         Wiggle display
·         The variable area display
·         The variable density display


Extracting shot gather number 12-15; which is displayed using variable area display scheme and variable density display scheme in wiggle, grey and colors display respectively
Figure 4: Variable area/wiggle display 

Figure 5: Grayscaled variable density display

Figure 6: Colored variable density display 

Figure 7: Wiggle on top of colored variable display

However, if we display shot gather num 16, the trace num 1 amplitude increases as time increases. For this, we need to edit by muting this trace since it will affect the subsequence processing steps.


Comments

Post a Comment

Popular posts from this blog

Lab 5: Sorting, Velocity Analysis, Stacking

Image
After performing various seismic data processing steps such as data quality control, frequency filtering and deconvolution on the east Texas real seismic data, the objective of today's lab session is to display the true image of the subsurface which required compressing the seismic data to infer a first approximation for such image. This includes :  1. Sorting the shot gathered data into common mid-point gathers (CMP) 2. Picking appropiate stacking velocities and applying accordingly normal move-out corrections (NMO).  3. Stacking all the CMPs such as average each CMP to form stacked CMP and then concatenate all stacked CMP traces together.  1. Common Midpoint Sorting  Figure 1: CMP Sorting  Seismic data acquisition with multifold coverage is done in shot-receiver ( s, g ) coordinates.  Figure 1  depicts the geometry of a CMP gather and raypaths associated with a flat reflector. Note that CDP gather is equivalent to a CMP gather only when reflectors are hor
Read more

Lab 6: Static Corrections

Image
Seismic reflection data in different traces are not always lying on a hyperbole for a horizontal reflector. Reflected data have certain displacement due to the different length of ray paths. Static displacements can be caused by topographic conditions (difference in elevation), weathered/unconsolidated layer; slow velocity, different borehole/gun and cable depth, tidal wave as well as water layer effect.  Figure 1: Topographic and weathered layer effect of seismic survey Thus, static corrections are applied to seismic data in order to compensate for various effects on the data such as those related to near surface, variations in elevations, weathering, and reference to a datum. By applying static corrections, we aim to determine the reflection time assuming the existence of a flat surface plane with no weathering layer.  These corrections include: 1. Elevation static correction, which accounts for variable elevations of the sources and receivers. 2. Residual static co
Read more

INTRODUCTION

Image
I am Nur Khalisa Binti Abdul Hamid (20381). Welcome to my blog Mr. Halim! Hope you like it! For our lab assignment, as a student who is taking Geophysics as a major, we are expected to go through every lab module and understand the concept of processing the seismic data from the very beginning until the migration process. The software that we use is called the MATLAB which lately, has been an increasingly popular tool in earth sciences. It has been used for finite element modeling, processing of seismic data, analyzing satellite imagery, and for the generation of digital elevation models from satellite data. The objective of this lab is to explore the functions of MATLAB, familiarize with seismic coding language, as well as to u nderstand how to use basic MATLAB functions and plotting commands on data vector which relates to the subject we are taking ; Seismic Data Processing.  Common procedures to streamline seismic data processing include: 1. Working wi
Read more