How to create a synthetic seismogram?
The steps necessary to create a synthetic seismogram manually are described below:
- Edit the sonic and density logs for bad intervals.
- Calculate vertical reflection times.
- Calculate reflection coefficients, Ro .
- Combine the last two items to create a reflection coefficient time series.
What is synthetic seismogram and how it is created?
A synthetic seismogram is the result of forward modelling the seismic response of an input earth model, which is defined in terms of 1D, 2D or 3D variations in physical properties. Synthetic seismograms are generated using specialized geophysical software.
What is synthetic seismogram in geophysics?
1. n. [Geophysics] A more narrow definition used by seismic interpreters is that a synthetic seismogram, commonly called a synthetic, is a direct one-dimensional model of acoustic energy traveling through the layers of the Earth.
What does sonic log measure?
The sonic or acoustic log measures the travel time of an elastic wave through the formation. This information can also be used to derive the velocity of elastic waves through the formation. Its main use is to provide information to support and calibrate seismic data and to derive the porosity of a formation.
What does acoustic impedance depend on?
Acoustic impedance (Z) is a physical property of tissue. It describes how much resistance an ultrasound beam encounters as it passes through a tissue. Acoustic impedance depends on: the density of the tissue (d, in kg/m3)
What is PEF log?
1. n. [Formation Evaluation] A log of photoelectric absorption properties. The log measures the photoelectric absorption factor, Pe, which is defined as (Z/10) 3.6 where Z is the average atomic number of the formation.
How does a sonic log work?
A sonic log is an acoustic log that emits sound waves which start at the source, travel through the formation, and return back to the receiver. The travel time from the source to the receiver is called slowness and as a result sonic logs are sometimes referred to as sonic slowness logs.
What is the effect of acoustic impedance?
The effect of acoustic impedance in medical ultrasound becomes noticeable at interfaces between different tissue types. The ability of an ultrasound wave to transfer from one tissue type to another depends on the difference in impedance of the two tissues. If the difference is large, then the sound is reflected.
What is the formula for acoustic impedance?
The acoustic impedance is defined as Z = ρv, ρ is the density of a medium through which the sound travels and v is the speed of sound through that medium.
Why double detector is used in density log?
To overcome the problems of mudcake and hole irregularities, the new compensated formation density logging device employs two detectors spaced at different intervals from the source. The detector at the shorter spacing is particularly sensitive to the density of material immediately adjacent to the face of the pad.
What does PEF measure?
Peak flow measurement is a quick test to measure air flowing out of the lungs. The measurement is also called the peak expiratory flow rate (PEFR) or the peak expiratory flow (PEF). Peak flow measurement is mostly done by people who have asthma.
What is sonic log used for?
How is a synthetic seismogram used in science?
The synthetic seismogram (often called simply the “synthetic”) is the primary means of obtaining this correlation. Velocity data from the sonic log (and the density log, if available) are used to create a synthetic seismic trace.
What kind of data is needed for synthetic seismic trace?
As already stated, the primary well data required to generate a synthetic seismic trace are sonic log (inverse of the sonic log is the acoustic velocity) and density log. Check shots data from the well are also very important. Sonic logs are the principle source of well velocity data.
Why is the seismic datum too low in synthetic?
If a shift to a better synthetic results in a –50ft value corresponding to 0.0000 time, then the seismic datum is 50ft too low at that well. The shift in the T-D chart effectively moves it up. Most users want to ignore an error in the seismic datum in part because there is little that can be done about it.
How are sonic logs related to conventional seismic data?
Additionally, sonic logs are the result of a process similar to first-break picking on conventional seismic data, essentially the result of picking the time of the direct arrival on several receivers, and computing the time it takes energy to travel from the source to each of the receivers, spaced over several meters.
The synthetic seismogram (often called simply the “synthetic”) is the primary means of obtaining this correlation. Velocity data from the sonic log (and the density log, if available) are used to create a synthetic seismic trace.
How is a synthetic seismic trace generated in AAPG?
The synthetic wavelet is convolved with the reflection series for the entire well survey and generates a synthetic seismic trace. A potential pitfall in synthetic generation is using a wavelet of fixed frequency over the entire survey.
How is a wavelet chosen for a synthetic seismic trace?
A wavelet is chosen that has a frequency response and band width similar to that of the nearby seismic data. The synthetic wavelet is convolved with the reflection series for the entire well survey and generates a synthetic seismic trace. A potential pitfall in synthetic generation is using a wavelet of fixed frequency over the entire survey.
Additionally, sonic logs are the result of a process similar to first-break picking on conventional seismic data, essentially the result of picking the time of the direct arrival on several receivers, and computing the time it takes energy to travel from the source to each of the receivers, spaced over several meters.