Participants will gain an understanding of how to effectively design, guide, and quality control depthimaging projects in a variety of geologic settings and be able to. The timetodepth conversion strategy involves the following steps. The measured time is known as the two way time twt. Interpret a set of time horizons from an image volume derived from time migration. Timetodepth conversion and seismic velocity estimation using time. Depth conversion is an important step of the seismic reflection method, which converts the acoustic wave travel time to actual depth, based on the acoustic velocity of subsurface medium sediments, rocks, water depth conversion integrates several sources of information about the subsurface velocity to derive a threedimensional velocity model. Reliable information about the coronavirus covid19 is available from the world health organization current situation, international travel.
Publication date 2014 isbn 9781523101412 electronic bk. Seismic data is acquired in time the time taken for the sound to travel from the source to reflectors and to return to receivers. Panorama technologies chapter 6 prestacktimeanddepth migration prestackmigrationalgorithmsarerelativelysimplevariantsofthepoststack methodologies. There are many methods to convert seismic times to depths, too many to cover in one article. A good approach to depth conversion, especially in a complex geological environment, is first to perform a depth migration with a velocity model optimized for structural imaging, second to render the resulting laterally positioned depth image to time using the provelocities, and finally to convert the depthmigrated seismic data now in the. If such procedures are to be applied after a depth imaging project has been conducted, it is necessary to convert the data to the time domain from the depth domain. Depth conversion is an important step of the seismic reflection method, which converts the acoustic wave travel time to actual depth, based on the acoustic velocity of subsurface medium sediments, rocks, water.
In this paper, an analogous wave approach is introduced. Pdf the objective was to build an efficient algorithm 1 to estimate seismic velocity from timemigration velocity, and 2 to convert timemigrated. Oclcs webjunction has pulled together information and resources to assist library staff as they consider how to handle coronavirus. Geostatistical techniques were used for seismic timedepth conversion over labod field offshore western niger delta basin with the aid of surface seismic and borehole data. Pdf timetodepth conversion and seismic velocity estimation. Smallpdf pdf converter operates fully in the cloud. Each of these options requires converting the time migration velocity to a velocity model in depth. The combinations tools, driven from the wizard module, allow you to assess the stability of these methods with varying number of wells using a leave pout crossvalidation scheme. Seismic velocity estimation and timetodepth conversion of time. Principles of seismic velocities and timetodepth conversion. An upper depth surface corresponding to the upper time surface is determined, either from well data or by timedepth conversion of the upper time surface. A well depth and a seismic horizon time to the same event can be used to define a socalled pseudovelocity and these are often used in depth conversion.
A robust approach to timetodepth conversion and interval velocity estimation from time migration in the presence of lateral velocity variations a published in geophysical prospecting, 63, no. Image ray in left the depthdomain can be traced with a source at location x 0 with slowness vector normal to the earth surface. Such information can aid increasing confidence in your selected depth. Timetodepth conversion and seismic velocity estimation using timemigration velocitya apublished in geophysics, 73, no. Seismic velocity estimation and timetodepth conversion. Numerous and frequentlyupdated resource results are available from this search. The time to depth conversion strategy involves the following steps. Approximating a seismic horizon timedepth conversion using a twovelocity layer approach in seisworks frequently in industry you will want to display a horizon map in depth ft instead of the landmark seisworks default, which is twoway time twt. The basic issue in seismic reflection interpretation is the conversion of the measured two way time into depth. Seismic velocity estimation and time to depth conversion of timemigrated images article pdf available in seg technical program expanded abstracts 251 january 2006 with 274 reads. Hence, as you zoom in closer, it will interpolate the converted data at ever increasing levels of detail.
Seismic interpretation and depth conversion of the. Distinguish between commonly used migration algorithms. The need for a velocity model for time to depth conversion is well understood in the geoscientific community. Prestack depth migration is now commonplace, and there is always the need to calibrate the depth volumes with well control. Time to depth conversion geological structures are picked from seismic profiles in the time domain. Timetodepth conversion geological structures are picked from seismic profiles in the time domain. Gamma ray and resistivity logs in four exploratory wells were utilized to delineate formation lithologies facies and formation fluid content. Quantifying the uncertainty attached to the conversion is also.
Pdf converter convert files to and from pdfs free online. Pdf time to depth conversion using v0k methods and. This depth converter and conversion scale can be used to convert any measurement of depth from one unit of depth to another. Geo expro a simple guide to seismic depth conversion ii. Timetodepth conversion crewes research report volume 7 1995 301 timetodepth conversion using image waves waikin chan abstract image rays have been used for timetodepth conversion of seismic horizons.
Velpak velit depth conversion with hidef velocities. Pdf a case study of a new timedepth conversion workflow. Each time slice from the time migrated section is used to propagate as an. Seismic velocity trend guided modelling method for time to. Seismic based structural models are in time domain whereas the geological models need to be in depth domain. We then convert the time migration velocity model to the depth domain by means of the time to depth conversion strategy based on imagewavefront propagation valente, 20. The residuals are the difference between the depth predicted by the velocity model using the seismic time at the well marker and the actual depth observed in the well. A small mean residual difference indicating an unbiased depth conversion and a low standard deviation meaning the method explains the depth quite well are indications of a. However, timetodepth conversion is certainly as important in obtaining the end product. Jones abstract many data processing and interpretation procedures are performed on time domain data. How it works timedepth conversion dug insight 4 user.
A simple linear regression model has to be constructed to translate the seismic data picked in the time domain external drift to a smooth trend model in the depth domain. In the case of a laterally homogeneous medium, the conversion. Actual future conditions including economic conditions, energy demand, and energy supply could differ materially due to changes in technology, the 1 development of new supply sources, political events, demographic changes, and other factors discussed herein and in item 1a of exxonmobils latest. A timetodepth velocity conversion can be done by rst applying the dix inversion tccs8. Geo expro a simple guide to seismic depth conversion i. The timedepth conversion is exact to the limit of your screen resolution. Hence, we use the dix velocity instead of timemigration velocity as a more convenient input. This is a case study and gives the practical approach for velocity modeling which can be further utilized for time to depth conversion. Timetodepth conversion and seismic velocity estimation using timemigration velocity.
In the recent past, most effort has been directed towards improving the quality of the seismic time definition of the subsurface. Although the two way time twt is known measured, still there are two unknown parameters. However, it does not explain how a depth velocity model can be converted to the timemigration velocity. Velocity model and timedepth conversion for the northwestern. Time to depth conversion using v0k methods and accoustic impedance seismic inversion for layer z14 in 123 field, cibulakan atas formation, nort west java basin indonesian version. In order to create a reservoir model or compute volumetrics, these time interpretations need to be converted to depth and calibrated to well markers. Purchase of an open document does not constitute license for republication in any form, nor does it allow web posting without prior written permission. Many depth conversion methods are reliant on well velocities, either in the form of sonic, check shot or apparent interval velocities. Conversion felix obere this presentation includes forwardlooking statements. Us7525874b2 method for converting seismic data from the. The classic calculation relating depth z to vo and time is.
The tool will instantly upload and transform the file into a pdf. Depth conversion integrates several sources of information about the subsurface velocity to derive a three dimensional velocity model. The workflow is versatile enough to convert directly time in depth or to compute intermediate enhanced velocity models when required. A presentation prepared for new afpc staff introduction. A robust approach to timetodepth conversion and interval. Domain conversion can be performed backward and forward between time and depth for any object, including surfaces, horizons, faults and multiz interpretations, points, well data logs and tops, 2d and 3d seismic data, and pillar and stairstepped 3d grids. The application of ked in timetodepth conversion is quite common geophysics 2001 among others. Compress, edit or modify the output file, if necessary. Timetodepth conversion is usually accomplished by converting zerooffset traveltimes, interpreted from a stacked section, to depth using a known velocity field. Timetodepth conversion and seismic velocity estimation. Depth conversion methods can be separated into two broad. Thus, simply put, velocity models transform time domain seismic data s x,y,t to depth domain geological model gx,y,z.
To convert from time s to depth ft you must know the velocity of the material. Categorize the various timetodepth conversion methodologies. This has important outcomes both from a modeling point of view and from a. Fast timetodepth conversion and interval velocity estimation in the. This has important outcomes both from a modeling point of view and from a practical prospective. The main thrust is for the use of these velocities for time todepth conversion. In contrast, if you export the volume, it must be actually resampled onto the requested export sample interval. Approximating a seismic horizon timedepth conversion.
Time to depth conversion of geological surfaces is critical for structural model building. Extensive details of depth conversion procedures are established, together with velocity models, each to suit the various depth conversion situations arising in practice. Hence, we use the dix velocity instead of time migration velocity as a more convenient input. The basic qcs and methods used for depth conversion will also be applied to validating the ties between the formation tops and the surfaces used for calibration. Time to depth conversion and uncertainty characterization. In the case of a laterally homogeneous medium, the conversion from time to depth is provided by the classic dix method dix, 1955.