Although the general geological model, based on well data. The book is written for the interpretation geophysicist working in exploration and development, for the seismic processor seeking a wider perspective on the quality. Basic principles of the seismic method tu delft ocw. Good morning everyone, im trying to build a velocity. In the earth, seismic waves can propagate as longitudinal p or as shear s waves. Original content in datapages find the book in the aapg store. Here we will go through a time to depth conversion of a 2d seismic survey in the sichuan basin using a velocity model provided in depth. The topics it covers include basic structural interpretation and mapmaking. 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. To remove structural errors inherent in time migration, it is necessary.
Approximating a seismic horizon timedepth conversion. The process of transforming seismic data from a scale of time the domain in which they are acquired to a scale of depth to provide a picture of the structure of the subsurface independent of velocity. Currently construction of the underground research facility, onkalo, is going on at the olkiluoto site. Prerequisites knowledgeexperienceeducation required. Reflection seismic data measure the traveltime of a seismic pulse from its. 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. In this paper, we develop a new method for time to depth conversion of time migrated images. Time, depth kirchoff, wave, beam steer, widemulti azimuth.
A robust approach to timetodepth conversion and interval. Depth conversion is a way to remove the structural ambiguity inherent in time and verify structure. Time to depth conversion and uncertainty characterization for. Topics covered in this book include basic structural interpretation and mapmaking. In the oil and gas business, seismic time to depth conversion problems are best solved, in many cases, by looking for velocity versus depth relationships on a.
The two horizons in the inline seismic section occurred at the levels of 2120ms. The timetodepth conversion strategy involves the following steps. Seismic data creating an integrated structure map aapg wiki. Velocity first steps in seismic interpretation geoscienceworld. Velocity analysis and depth conversion in the offshore. Good morning everyone, im trying to build a velocity model using some seismic profiles in twtt. Seismic depth conversion some articles on depth con v ersion using kriging has been published this is an attempt to commen t on these approac. The authors have found that geologists and geophysicists tend to approach the depth conversion process. Seismic velocity estimation and time to depth conversion of. It honors all wellcontrol depth points by definition and uses the seismic events to interpolate between these points.
Pdf seismic velocity estimation and time to depth conversion of. The structural interpretation of the seismic data is presented in figures 4 and 5. The event depth z measured from seismic datum is known from well control, and the vertical reflection time t is known from the previous item. How to convert depht in doubletime depthtwt, to depths in distance in seismic profiles. Vertical depth conversion of 2d and 3d time migrated data. Seismic 2d reflection processing and interpretation of shallow refraction data abstract posiva oy takes care of the final disposal of spent nuclear fuel in finland. Unless explicitly stated otherwise, average velocity in interpretation usage always refers to the interval velocity between the seismic datum and a time or depth value or surface. Stanford libraries official online search tool for books, media, journals, databases, government documents and more. Figure 3 illustration showing effect of lateral differences in velocity on conversion of time and depth. Alchalabi and a great selection of similar new, used and collectible books available now at. Two aspects of the geophysical interpretation, depth conversion and seismic sandshale characterization, are discussed in this paper. When seismic is processed through isotropic velocity modeling and migration, more. Feb 15, 2017 in this video you will learn the different methods for depth 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. Quantitative seismic interpretation stanford rock physics. Understand depth conversion methodologies and perform quality control for validity of methods used this course is designed for, but not limited to, geologists, geophysicists, and managers to understand general concept and recent advances in 3d seismic depth interpretation, time to depth conversion, and 3d velocity modeling. Good well ties and reliable depth conversion are also required. The emerson seismic interpretation suite is an integrated, modern interpretation and visualization system designed to carry out all seismic interpretation tasks, including. The problem of conversion from time migration velocity to an interval velocity in depth in the presence of lateral velocity variations can be reduced to solving a system of partial di erential equations. Construction and interpretation of structural map using. Seg books, 1998 imaging systems in geophysics 202 pages. The final product zx, y is called an integrated structure map. A good seismic image is not enough for an exploration or field development interpretation. Principles of seismic velocities and timetodepth conversion in searchworks catalog.
Geophysicalinvestigation of the subsurface structure at mapi, niger delta area was carried out by the construction and interpretation of structural maps using seismic reflection times. Timetodepth conversion and seismic velocity estimation using timemigration velocitya. Nevertheless, as part of the common strategy for time to depth conversion, interval velocities are derived from dix conversion of rms velocities. Mcquillin and a great selection of related books, art and collectibles available now at. 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. The main thrust is for the use of these velocities for time todepth conversion.
Figure 5 is a comparison of the first depth map from well control only and the seismic plus well integrated depth map figure 4 is a zoom of the central area in the maps in figure 5. How to convert depht in doubletime depthtwt, to depths. Seismic data mapping with twodimensional data aapg wiki. In addition to providing excellent structural images, the dense sampling of a 3d survey makes it possible to map reservoir quality and the distribution of oil and gas. Interpret a set of time horizons from an image volume derived from time migration. Geo expro a simple guide to seismic depth conversion i. Seismic interpretation better tools, better understanding, in less time. Approximating a seismic horizon time depth 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. Particular reference is given to prestack depth migration. Extensive details of depth conversion procedures are established, together with velocity models, each to suit the various depth conversion situations arising in practice. Distribution of the 541 seismic lines black and 19 wells white circles used in this study. By joanne wang one of the major challenges in seismic interpretation is seismictowell tie in the depth domain. How to convert depht in doubletime depthtwt, to depths in. Jul 19, 2016 by joanne wang one of the major challenges in seismic interpretation is seismic towell tie in the depth domain.
Geostatistics provides consistent methods for integrating well and seismic data to obtain a depth map from seismic time interpretation. A seismic velocity model is necessary to map depth and thickness of subsurface layers interpreted from seismic reflection images. Time to depth conversion and seismic velocity estimation using time migration velocitya apublished in geophysics, 73, no. Based on the well to seismic ties two horizons were identified in the seismic sections. A velocity model is required in the form of a voxet. Depth conversion concerns the seismic interpreter because seismic measurements are made in time, but the wells based on a seismic interpretation are drilled in depth. Twowaytimetodepth conversion strategy for seismic intepretations, involves. For free space, the onedimensional wave equation is derived. Principles of seismic velocities and timetodepth conversion principles of seismic velocities and timetodepth conversion. Seismic data is acquired in time the time taken for the sound to travel from the source to reflectors and to return to receivers. Approximating a seismic horizon timedepth conversion using a.
Despite the obvious drawback of this top down strategy, i. Seismic velocity estimation and timetodepth conversion. Hence, we use the dix velocity instead of timemigration velocity as a more convenient input. Timetodepth conversion is performed iteratively layer after layer. Accurate depth conversion assures that the sagd well pairs can be appropriately placed close to the base of the reservoir allowing for an optimal drainage of the reservoir. 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. Understand depth conversion methodologies and perform quality control for validity of methods used monday august 25, 2014 wook lee kuala lumpur, malaysia this course is designed for, but not limited to, geologists, geophysicists, and managers to understand general concept and recent advances in 3d seismic depth interpretation, timetodepth. In year 2001 olkiluoto was selected for the site of final disposal. Depth conversion integrates several sources of information about the subsurface velocity to derive a threedimensional velocity model. Our method is based on the image ray theory but establishes a new raytheoretic connection between timemigration velocities and interval seismic velocities.
In this paper, we formulate the problem as a nonlinear leastsquares optimization for seismic interval velocity and seek its solution iteratively. Alchalabi and a great selection of similar new, used and collectible books available now at great prices. Geost a tistics f or seismic depth conversion petter abrahamsen nor wegian computing center abstra ct dieren t kriging metho ds used for seismic depth con v ersion found. The importance of timetodepth conversion would be evident in the. Structural interpretation of seismic data from an xy field. A good approach to depth conversion, especially in a complex. The data allow a consistent interpretation on one seismic data set in depth that.
Quantitative seismic interpretation demonstrates how rock physics can be applied to predict reservoir parameters, such as lithologies and pore fluids, from seismically derived attributes. Seismic velocity estimation and time to depth conversion. The depth conversion can now be carried out as part of the data processing, but this depth imaging is only done in special circumstances. In this paper, we develop a new method for timetodepth conversion of timemigrated images. The authors have found that geologists and geophysicists tend to approach the depth conversion process quite differently. The interpreter identifies the time horizons that are associated with depositional sequence boundaries and geologically and lithologically significant layer boundaries within some of the depositional units. Principles of seismic velocities and timetodepth conversion. Data source for interpretation includes 2d and 3d seismic interpretation, and both pstm and psdm. The emerson seismic interpretation suite is an integrated, modern interpretation and visualization system designed to carry out all seismic interpretation tasks, including structural, stratigraphic, and volume interpretation. Data consist of picked zerooffset travel times of primary reflections, which can be obtained from interpretation of unmigrated stacked sections. In this video you will learn the different methods for depth conversion. Basic principles of the seismic method in this chapter we introduce the basic notion of seismic waves. Depth conversion domain conversion of seismic time interpretations and data.
Then, reflection times are picked by combining seed detection and linebased interpretation strategies interpretation of 3d seismic data. Depth conversion accurate depth conversion assures that the sagd well pairs can be appropriately placed close to the base of the reservoir allowing for an optimal drainage of the reservoir. Also, you can visit our facebook page and group at. To acquire skills in interpretation of 3d seismic data to enhance theoretical knowledge of seismic structural interpretation, stratigraphic interpretation, reservoir identification and evaluation, and horizon and formation attributes. Exploration in the uk southern north sea rotliegend transition zone by. Calculate depth conversion velocity at locations where both well and seismic time picks exist. Seismic data creating an integrated structure map aapg. Categorize the various time to depth conversion methodologies. The wave phenomena occurring at a boundary between two layers are discussed, such as snells.
Advanced seismic interpretation is a course designed for graduate students. Velocity analysis and depth conversion in the offshore northern perth basin figure 1. Depth conversion, ideally, is an iterative process that begins with proper seismic processing, seismic velocity analysis and study of well data to refine the conversion. Seismic 2d reflection processing and interpretation of. The problem of conversion from timemigration velocity to an interval velocity in depth in the presence of lateral velocity variations can be reduced to solving a system of partial di erential equations. In reference to step c of the procedure outlined above, interval velocities may be estimated by methods other than dix conversion table 91. Our method is based on the image ray theory but establishes a new raytheoretic connection between time migration velocities and interval seismic velocities. Participants should be familiar with the seismic method and have several years of interpretation experience. The seismic datum is normally above the surface or grid of interest and the td chart has a zerozero entry for time and depth.
The wells used as control do not need velocity or density logs but must penetrate the event of interest. This book introduces geophysicists and geologists to the technique of interpreting 3d seismic data. Introduction gocad offers conversion of horizons and seismic in the time domain to the depth domain and vice versa. Timetodepth conversion and seismic velocity estimation using timemigration velocitya apublished in geophysics, 73, no. Seismic attribute scaling features converts seismic and attributes data between time and depth option to scales in same domain can use maps, fm.
Timetodepth conversion and seismic velocity estimation. Acoustic logs, checkshot surveys and vertical seismic profiles can aid depth conversion efforts and improve correlation of well logs and drilling data with surface seismic data. The main thrust is for the use of these velocities for timetodepth conversion. Note that depth migration is a seismic imaging technique that improves reflector positioning. 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. This would be a great textbook for an introduction to seismic interpretation course that focuses on the geology side, or a great reference manual for geoscientists or perhaps even engineers who are working with seismic data probably in the petroleum industry, but also in academia, or the environmental industry. W7 well logs and synthetic seismograms, seismic well calibration 10. Principles of seismic velocities and timetodepth conversion 9789073834873 by m. Timetodepth conversion and seismic velocity estimation using time. Depth conversion is the process by which interpreted seismic horizons and time domain seismic itself are converted from the travel time domain to the depth domain.
Understand depth conversion methodologies and perform quality control for validity of methods used this course is designed for, but not limited to, geologists, geophysicists, and managers to understand general concept and recent advances in 3d seismic depth interpretation, timetodepth conversion, and 3d velocity modeling. Depth conversion and seismic lithology inversion of a. Aug 21, 2003 3d seismic data have become the key tool used in the petroleum industry to understand the subsurface. Time to depth conversion and uncertainty characterization. Conversion felix obere this presentation includes forwardlooking statements. To convert from time s to depth ft you must know the velocity of the material. Seismic velocity estimation and timetodepth conversion of. One can regard this connection as a natural extension of the classical dix formula dix, 1955 to. The authors provide an integrated methodology and practical tools for quantitative interpretation, uncertainty assessment, and characterization of subsurface.
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