Table of Contents
How do you find seismic velocity?
The rate at which a seismic wave travels through a medium, that is, distance divided by traveltime. Seismic velocity can be determined from vertical seismic profiles or from velocity analysis of seismic data.
What is effective velocity in geophysics?
The effective velocity is the algebraic sum of the actual fluid velocity and the velocity with which the flowmeter is moving, as determined by cable speed.
What is RMS velocity seismic?
The RMS velocity is that of a wave through sub-surface layers of different interval velocities along a specific ray path. From: Seismic Data Analysis Techniques in Hydrocarbon Exploration, 2014.
What does seismic velocity depend on?
Seismic velocities depend on the material properties such as composition, mineral phase and packing structure, temperature, and pressure of the media through which seismic waves pass. Seismic waves travel more quickly through denser materials and therefore generally travel more quickly with depth.
Why does seismic velocity increase with depth?
Seismic velocities tend to gradually increase with depth in the mantle due to the increasing pressure, and therefore density, with depth. However, seismic waves recorded at distances corresponding to depths of around 100 km to 250 km arrive later than expected indicating a zone of low seismic wave velocity.
Why do we do velocity analysis?
The process of calculating seismic velocity, typically by using common midpoint data, in order to better process seismic data. Successful stacking, time migration and depth migration all require proper velocity inputs.
What is RMS value of velocity?
The root-mean square (RMS) velocity is the value of the square root of the sum of the squares of the stacking velocity values divided by the number of values. The RMS velocity is that of a wave through sub-surface layers of different interval velocities along a specific ray path.
What is the most important factor in determining seismic velocity in rocks?
The most significant factor affecting seismic wave velocities is porosity. In the above table, we saw that seismic waves travel faster in solids than they do in fluids; with S-waves being unable to propagate through fluids. Thus as the porosity of a rock increases, both the P-wave and S-wave velocities will decrease.
What is Dix velocity?
Dix formula The equation by which the interval velocity (v int) can be calculated for a zone between two depths on a seismic section. For two reflectors with reflected-ray travel times t 1 and t 2, and root-mean-square velocities v rms1 and v rms2 respectively, then: v int = [(t 2v rms2 2 – t 1v rms1 2)/(t 2 – t 1)] ½.
How do you convert seismic time to depth?
To convert time reflections to a depth surface we need to know the velocity. The depth is then estimated from the simple geophysical relationship that depth = velocity x time.
What is the formula of root mean square velocity?
The root mean square velocity (RMS velocity) is a way to find a single velocity value for the particles. The average velocity of gas particles is found using the root mean square velocity formula: μrms = (3RT/M)½ μrms = root mean square velocity in m/sec. R = ideal gas constant = 8.3145 (kg·m2/sec2)/K·mol.
Which factors affect seismic velocity?
Composition, temperature, and pressure are all factors that can affect seismic velocity in the mantle. Laboratory elasticity data show that a decrease of 1% in the Mg/(Mg+Fe) ratio in olivine reduces the velocity by an amount equivalent to that caused by a temperature increase of 70 K.
How is seismic depth calculated?
What is RMS velocity of gas molecules?
The rms velocity is directly proportional to the square root of temperature and inversely proportional to the square root of molar mass. Thus quadrupling the temperature of a given gas doubles the rms velocity of the molecules.
How do you calculate RMS in chemistry?
v rms = v 2 – = 3 k B T m . The rms speed is not the average or the most likely speed of molecules, as we will see in Distribution of Molecular Speeds, but it provides an easily calculated estimate of the molecules’ speed that is related to their kinetic energy.