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This is the inverse of velocity and is what is displayed on a sonic log, usually in units of μs/ft or μs

...generated where there is a contrast in impedance (which is the product of velocity and density). ==Velocity data sources==

...er such as glacial till). It also fails when there are extreme [[lateral]] velocity variations in the subsurface (subsalt, subthrust, etc.). When it works, thi # Calculate depth conversion velocity at locations where both well and seismic time picks exist.

...away from the vertical. If anisotropy is present (and it usually is), then velocity depends on the direction the wave is traveling. It is not uncommon to see a

==Seismic velocity== ...dicate an undercompacted (overpressured) interval. Unusually fast interval velocity, conversely, may indicate overcompaction (underpressure).

| Classic || Mapping a surface of interest (from data) using [[Average velocity|average velocities]] ...a (with time axis) converted to a depth cube using a ''V'' ( ''X, Y, Z'' ) velocity model

...fig12-8.png|300px|thumb|{{figure number|1}}Sonic log converted to time and velocity. From Liner;<ref name=Liner1999>Liner, C., 1999, Elements of 3-D Seismology ...a [[Basic open hole tools#Sonic|sonic]] log has been converted to time and velocity. Note that the time axis on the seismic section and the converted sonic log

# Identify online wells with velocity control. ...oints. Whatever the method, it should also be used in the depth conversion velocity map (next section). The wells-only depth structure map is a useful baseline

...about the lithology and the fluid content of the formation. Stoneley wave velocity and amplitude have been shown to be useful in the detection of fractures an ...hat is slower than both the formation shear wave velocity and the acoustic velocity of the borehole fluid.

* [http://wiki.seg.org/wiki/Dictionary:Interval_velocity Interval velocity] * Velocity and density contrasts of individual interfaces

...teral differences in velocity on conversion of time and depth. If a single velocity function of 8300 ft/sec were used, errors of +6 ft at A and -440 ft at B wo mapping-with-two-dimensional-seismic-data_fig5.png|{{figure number|5}}Velocity map with velocities marked at grid intersections.

...where high-velocity (high-resistivity, low-conductivity) rocks overlie low-velocity (low-resistivity, high-conductivity) sediments.

==Calculating depth conversion velocity==

...rth reflections as a function of time to the geologist's view of the earth velocity as a function of depth. This is not as easy as it may seem. The reason for ...ide, we introduce geological constraints taken from a sonic log or seismic velocity information and produce a forward model. We then combine the information fr

...daries of these units need to be mapped in depth. Thus, the concept of the velocity checkshot survey has been developed to establish time-depth calibration fun ...s measured.<ref name=pt07r1>Anstey, N. A., and R. L. Geyer, 1987, Borehole velocity measurements and the synthetic seismogram: Boston, MA, IHRDC, 355 p.</ref>

...ey conducted over a subsurface medium that is homogeneous (constant P-wave velocity) with the exception of an isolated boulder at some depth. Also shown are th ...for a subsurface consisting of a single dipping reflector. For a constant-velocity subsurface, the many weak diffractions from very closely spaced points alon

...ocity and a 15-Hz wavelet. Resolution decreases rapidly with depth because velocity increases and frequency decreases. ...contributing to limit the horizontal resolution include uncertainty in the velocity and the mathematical completeness of the migration algorithm. One of the mo

...ks were reversed (that is, travel is from a high velocity rock to a slower velocity rock), the coefficient of reflection is said to be ''negative'' and is disp ...raphic sequences. A display of a variation in amplitude, phase, frequency, velocity, or any other trace-related attribute can be represented by different color

...presented by a color-coded map in which a color is assigned to the seismic velocity at each point. This map, or plot, is referred to as a ''tomogram''. Other d ...2.png|Figure 2]]. These traveltime data are then used to infer the seismic velocity field between the wellbores. If attenuation measurements can be made on the

: <math>\text{IA} = \text{Density} \times \text{Velocity}</math> ...sure and pore pressure. The relationship between gas saturation and P wave velocity drops drastically resulting in the formation of anomalies such as DHI, AVO,

...seismic, plus [[Seismic array|arrays]], [[offset]], [[dip]], and [[lateral velocity]] variation. The next layer, 3-D seismic, includes all of 2-D plus [[azimut ...smic analysis is, in effect, an edge detection technique. The bigger the [[velocity]] and/or [[density]] contrast between the rocks, the stronger the edge.

...d the [[African Plate|Nubian Plate]]. Its discovery is very recent, so the velocity of the plate isn't well known or understood.<ref name=Saria>Saria, E., 2014 ...iors.<ref name=Nocquet&Calais>Nocquet, J.-M., and E. Calais, 2003, Crustal velocity field of western Europe from permanent GPS array solutions, 1996-2001: Geop

Velocity data from the sonic log (and the [[density log]], if available) are used to * ''υ'' = rock velocity

...wever, the Vs does not affected much and therefore will produce low Vp/Vs. Velocity ratio is mathematically defined as follow: <p><math>V_p/V_s = \frac{V_p}{V_ ...upper layer, whereas AI2, Vp2, and Rho2 are the acoustic impedance, P-wave velocity, and density of the lower layer. On [[:File:GeoWikiWriteOff2021-Muamamr-Fig

| AV || Annular velocity || ft/min | JNV || Jet nozzle velocity || ft/sec

...arity]], [[phase]], [[Seismic frequency|frequency]], or [[Seismic velocity|velocity]]. [[Horizon attribute]]s were first used in the mid-1980s for interpreting

# [[Injection]] or production of fluids at rates exceeding the critical velocity beyond which mobilization of rock fines by mechanical (drag) forces is init ...e conducted at rates below the critical velocity. Conversely, the critical velocity will vary depending on whether fluids are chemically compatible with the ro

* Injection or production of fluids at rates exceeding the critical velocity beyond which mobilization of rock fines by mechanical (drag) forces is init ...e conducted at rates below the critical velocity. Conversely, the critical velocity will vary depending on whether fluids are chemically compatible with the ro

...ons will be the difference of acoustic impedance (product of density and P velocity) over the sum. ...ludes the first P wave velocity, the second node density and the last wave velocity.

...number|5}}Condensate saturation versus radial distance from wellbore, with velocity stripping zone.<ref name=Daungkaewandgringarten_2004 /> ...e in gas mobility is observed at higher velocities, and thus is termed the velocity stripping effect, which can increase the productivity of a well. This can f

...spersive nature of the volcanics and because of the decrease in [[acoustic velocity]] at the base of the volcanics.

...dual statics are all techniques used to estimate and apply the appropriate velocity and time corrections ([[:file:basic-seismic-processing_fig5-part1.jpg|Figur ===f–k or apparent velocity filter===

| Sonic || 2 ft || Typically 6 in. || Measure compressional velocity and estimate porosity || Sensitive to compressibility ...timate porosity || Cannot measure shear velocity when shear velocity > mud velocity

...lity, etc.) which are more geology-like and rock physics (elasticity, wave velocity, etc.) which are more geophysics-like. Every properties are related each ot ...alculate clay volume, permeability calculation, porosity calculation, wave velocity calculation, etc.

...rface. The actual depth to this surface is a function of the thickness and velocity of overlying rock layers. The second is the shape of the reflection, which ...ages is made, including ''p'' wave seismic, shear wave seismic, well data, velocity surveys, and VSP. The data are scanned for quality and suitability. At this

...ght is tight. [[Porosity]] is represented in the model by a lower interval velocity and lower density than the surrounding rock (see [[Porosity]]). ...The porosity is identified by the dim spot on traces 6 through 11 and the velocity pulldown of the underlying event. The results from this modeling indicate t

...eases with depth. If the shales have not been able to compact, the seismic velocity will be less. ...rface by the common depth point method of seismic acquisition. If interval velocity increases normally with depth and then decreases, it is possible that a zon

production-logging_fig3.png|{{figure number|3}}Tracer velocity shot technique and injection profile. ...surface recordings are shown to the right of the well sketch. The highest velocity and flow rate are recorded above the perforations, while zero flow is detec

...ts near the wellbore. Fluid flow within the pores may also reach turbulent velocity, thus generating additional pressure drop and reducing the productivity of ...an also accumulate in the wellbore if the gas is not flowing at sufficient velocity to lift the water from the well. Accumulation of this static fluid column c

* Special seismic processing and velocity analysis (e.g., prestack migration; amplitude vs. [[offset]])

| Platform's velocity & heading

...ng requires the following: (1) a depth-[[velocity]] model, (2) density and velocity trend curves, (3) [[porosity]] ranges, (4) fluid content variation, (5) Poi ...as the starting point for the inversion process, the final [[compressional velocity]], [[density]], and [http://en.wikipedia.org/wiki/Poisson%27s_ratio Poisson

**Velocity information ...a correction time is added or subtracted to each profile and a correction velocity is applied to the profile. During interpretation, corrections dealing with

* [[Velocity]] This is on the [[Seismic attributes]] page

...e range of 6500–8500 ft/s (1981.2–2590.8 m/s) with very little increase in velocity with depth; (2) low density, estimated to be in the range of 2.1–2.3 g/cm * Shales have a much slower velocity than salt. Salt will be underlain by seismic pull-up versus no pull-up bene

...ace, uphole survey is conducted to find the thickness and velocity of low- velocity layer; which will be followed by seismic refraction. ...d obtain imagery of the subsurface. The process include noise attenuation, velocity analysis, deconvolution, migration, stacking, and so on. Once the data have

...n a rock directly affects its properties by lowering density slowing sonic velocity increasing radioactivity raising resistivity and raising hydrogen and carbo

...zed for age, [[Total organic carbon (TOC)|organic richness]], and acoustic velocity can advance the understanding of basin history, the [[source rock]] [[Litho

...tic. In high velocity, water washes oil completely from matrix, but in low velocity where capillary pressure become significant, oil stuck in the porous. So fr ...y Abgrall dan Iffly, 1973, shows that gas saturation can be very high when velocity decrease very slowly. Gas phase in porous without move from porous until mo

...whether karstification can develop or not and simulation factors determine velocity and completeness of the karstification proces.s The velocity of reaction so true as bigger in low temperature, because concentration of

** velocity surveys

...ces are collected as common-cell gathers (bins). These gathers are used in velocity analysis, and common-cell stacks are generated. Typical cell sizes are 25 b

...l waveform acoustics have enabled some vendors to successfully measure the velocity of compressional and/or shear waves in formations behind casing, under appr

...difficult to recognize beneath complex structure and because of a lack of velocity contrast with the dense dolomites that overlie the basement in many areas.

| Checkshot and vertical seismic profile log || Measures velocity data at specific borehole depths || Used to calibrate the seismic response ...ophysicist as they give velocity information for calibrating seismic data. Velocity data allow the geophysicist to convert the time taken for a seismic wave to

...ect [[Methods of detecting exoplanets|observation methods]] such as radial velocity and [[coronagraph]]s can give envelope estimates of exoplanet parameters su ...a et al. (2007)<ref name=Valencia_etal /> concluded the increase in mantle velocity (driving force) is large compared to the gravitationally-forced increase of

* Interval velocity http://wiki.seg.org/wiki/Dictionary:Interval_velocity

...lbore, causing high pressure drops near the wellbore because of high fluid velocity (see [[Fluid flow fundamentals]]).

...rveys. All previous maps will be updated with the new seismic data and the velocity control available from the newly drilled wells. Based on the revised depth ...S. A. (2019). Machine learning technique for the prediction of shear wave velocity using petrophysical logs. Journal of Petroleum Science and Engineering, 174

* Cs=wave velocity shear (m/sec)³ .

...d N. K. Boyd III, 2001, Delineation of Jonah field using seismic and sonic velocity interpretations, ''in'' D. S. Anderson, J. W. Robinson, J. E. Estes-Jackson ...The gas chimney has subsequently been identified through the use of sonic velocity data.<ref name=Surdametal_2001 />

...elocities of India's convergence with Asia. The [[lateral]] variability in velocity between the central and marginal regions of the orogen sugest strain is par

...west frequency boosted by the maximum amount is calculated by dividing the velocity of sound in water (1500 m/sec) by four times the depth of the detector or t

...tential]], [[Basic open hole tools#Resistivity|resistivity]], density, and velocity logs calibrated by well-cutting descriptions and formation microscanner dis

...eters. These can vary widely depending on factors such as sediment, stream velocity, availability of oxygen and others.

...on the continental shelf below base level and above areas where the water velocity is no longer supporting the particles weight. This zone is called depositio

...] and [[Checkshots_and_vertical_seismic_profiles#Vertical_seismic_profiles|velocity profiles]]

...of the cross section, the sonic log is a critical tool to demonstrate the velocity structure, and consistency of conversion of time to depth.

...ions]] and [[Subsurface maps]]). The first well in a field provides depth, velocity, [[dipmeter]], and hydrocarbon distribution information that can improve th

...at a separated interval while the transmitter travels upward at a constant velocity. Following this technique, a complete cross-well tomography is generated.<r

...rizons that need to be tied to the well control using an accurate interval velocity model. The geologist may also deal with periodic or cumulative production d

...evelop beneath the [[lateral]] boundaries of the expanding effluent, where velocity gradients are generally steepest. Development of subaqueous levees tends to ...tributary-mouth channel. Shoaling is a direct consequence of a decrease in velocity and a reduction in carrying power of a stream as it leaves the confines of

...d N. K. Boyd III, 2001, Delineation of Jonah field using seismic and sonic velocity interpretations, ''in'' D. S. Anderson, J. W. Robinson, J. E. Estes-Jackson

...nt can also transported by traction or saltation by wind with unusual high velocity. This transport process will produce 3 kinds of deposits : dust (silt) depo

...seismic observations since the rock is not exposed on the surface. Seismic velocity, ranging from 6.5 – 7.6 km s-1, represents that rocks are more felsic tha

...on volumetric sweep, directional flow, flow barrier distribution and fluid velocity

...lts in an increase of the channel's cross-sectional area, thereby reducing velocity and causing deposition on the point-bar side of the channel.