Shale reservoir characterization is also the focus of 3d seismic interpretation. Then, reflection times are picked by combining seed detection and linebased interpretation strategies interpretation of 3d seismic data. Seismic data interpretation and evaluation for hydrocarbon. Seismic map present the shape and form of geological formation top or bottom. Use of well data for seismic inversion and modeling. Timedomain seismic processing has been a popular and e ective tool in areas with mild lateral velocity variations yilmaz, 2001. Hence, we use the dix velocity instead of timemigration velocity as a more convenient input. 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. Construction and interpretation of structural map using.
Depth conversion is a way to remove the structural ambiguity inherent in time and verify structure. Harilal, dgm gp geopic, ongc, dehradun 27th march 2012 rajahmundry. Seismic interpretation better tools, better understanding, in less time. Alchalabi and a great selection of similar new, used and collectible books available now at great prices. Here we will go through a time to depth conversion of a 2d seismic survey in the sichuan basin using a. We have introduced a novel nonlinear inversion formulation for timetodepth velocity. A velocity model is required in the form of a voxet. Timetodepth conversion and seismic velocity estimation. This book is published in under open access creative commons license ccby ncnd. Although the two way time twt is known measured, still there are two unknown parameters. The measured time is known as the two way time twt. Currently construction of the underground research facility, onkalo, is going on at the olkiluoto site.
Advanced seismic interpretation is a course designed for graduate students. Introduction to seismic interpretation linkedin slideshare. This publication is the definitive, and now classic, text on the subject of interpretation of 3d seismic data. Depth conversion and seismic lithology inversion of a. 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.
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. 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. Velocity modeling petrel workflow polynomial equations. Time migration produces images in the time coordinate as opposed to the usual depth coordinate. 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. 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. Pdf first steps in seismic interpretation khaled magdy. Seismic pwave velocity may be measured directly by recording a conventional seismic energy source such as a dynamite charge, a vibrator, or an air gun with a. Travel time curves analysis of seismic refraction data is primarily based on interpretation of critical refraction travel times. Basics of seismic interpretation the lesson uses the basics seismic reflection principles, and allows the student to apply them to interpret a geologic framework, conduct a data analysis, prospect for hydrocarbons, and then assess whether the basin should be bid on and provide an economic analysis. Seismic interpretation an overview sciencedirect topics. 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. By joanne wang one of the major challenges in seismic interpretation is seismictowell tie in the depth domain.
Traveltime in media with linear velocitydepth functions. In year 2001 olkiluoto was selected for the site of final disposal. The depth conversion can now be carried out as part of the data processing, but this depth imaging is only done in special circumstances. Mathematics of multidimensional seismic imaging, migration, and inversion. Seismic lines must be laid out in order to facilitate the interpretation of the tx. Timetodepth conversion and seismic velocity estimation using time. 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 using timemigration velocitya apublished in geophysics, 73, no. While modern multichannel data have increased the quantity and quality of interpretable data, proper interpretation still requires that the interpreter draw upon his or her geological understanding to pick the most likely interpretation from the many. Thickness can be determined by seismic stratigraphic interpretation and conversion from time data to depth. Pdf seismic time to depth conversion is an important part of seismic interpretation work flow. Time to depth conversion and uncertainty characterization. Function 2nd order polynomial function this is the basic timedepth conversion methodology.
When seismic is processed through isotropic velocity modeling and migration, more. The time coordinate, along with timemigration velocities, is determined. 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. Each of these options requires converting the time migration velocity to a velocity model in depth. Principles of seismic velocities and timetodepth conversion. A seismic velocity model is necessary to map depth and thickness of subsurface layers interpreted from seismic reflection images. 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. 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. In the case of a laterally homogeneous medium, the conversion from time to depth is provided by the classic dix method dix, 1955. Simply defined, seismic interpretation is the science and art of inferring the geology at some depth from the processed seismic record.
A robust approach to timetodepth conversion and interval velocity. Pdf summary we address the problem of time to depth conversion of. The book focuses mainly on land and offshore geophysical data acquired at. Seismic velocity estimation and timetodepth conversion. In contrast, continental crust has a greater range in both number and thicknesses of layers. Analysis of seismic timedepth conversion using geostatistically. Interpretation of any data, especially seismic data in petroleum exploration. Introduction gocad offers conversion of horizons and seismic in the time domain to the depth domain and vice versa. Depth conversion domain conversion of seismic time interpretations and data is a basic skill set for interpreters. Geo expro a simple guide to seismic depth conversion i. Seismic data is acquired in time the time taken for the sound to travel from the source to reflectors and to return to receivers.
Usually we analyze p wave refraction data, but s wave data occasionally recorded. Seismic 2d reflection processing and interpretation of. Conceived in 1979 and first published in 1986, the book helps geoscientists extract more information from their seismic data and improve the quality of their interpretations. Seismic data interpretation using digital image processing. Pdf seismic time to depth conversion and uncertainty analysis. 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.
It makes use of the twt and depth information from checkshot, calculates velocities at wach checkpoint depth and uses this. Hence, we use the dix velocity instead of time migration velocity as a more convenient input. W7 well logs and synthetic seismograms, seismic well calibration 10. Seismic interpretation and depth conversion of the. Pdf seismic velocity estimation and time to depth conversion of. Basics of seismic interpretation incorporated research. The class provides hands on experience in the structural and stratigraphic interpretation of seismic reflection data. Time to depth conversion in the presence of structure. In this video you will learn the different methods for depth conversion. Integrated geophysical models principles of seismic. Thickness, fracture permeability, brittleness, organic richness, pore pressure, and more can be determined from seismic data chopra et al.
A petroleum geologists guide to seismic reflection. The primary objective of geophysical seismic interpretation is to prepare contour seismic maps showing the two way time to a reflector as picked on the seismic. A robust approach to timetodepth conversion and interval. Approximating a seismic horizon timedepth conversion. To perform the depth conversion, the velocity of the medium situated above the. Seismic velocity distributions indicate that oceanic crust can broadly be divided into three layers, which are, in order of increasing depth, the following. In large part, this book is a compilation of notes from seismic inter pretation. Seismic velocity estimation and time to depth conversion of. After careful picking in the time domain, the depth conversion of the bounding surfaces is optimized, then the intra reservoir horizons are scaled between the boundaries.
Real 2d seismic section interpretation single lines emphasizing funny looking things, wrench fault, ramp anticline, extensional fault blocks, carbonate buildup, passive margin shelf, etc. The basic issue in seismic reflection interpretation is the conversion of the measured two way time into depth. The book is written for the interpretation geophysicist working in exploration and development, for the seismic processor seeking a wider perspective on the quality of output and on the provision of the data to help the frontline geoscientist, for the geologist using geophysical methods as a. Principles of seismic velocities and timetodepth conversion 9789073834873 by m. This book is published in under open access creative commons license. To convert from time s to depth ft you must know the velocity of the material. The combination of the interval velocity maps from step c with the depth horizons from step d constitutes the initial model derived from timetodepth conversion. Also, you can visit our facebook page and group at. Depth conversion interpretation of threedimensional. With the data acquired, showing the seismic reflection times was converted from a time data to a depth data using time to depth conversion chat. However, there is no single methodology that is optimal for all cases since the available seismic and geologic control varies in quantity and quality within each project. Timetodepth conversion and seismic velocity estimation using timemigration velocitya. Depth conversionsimple average velocity convert depth to depth below seismic reference datum, and convert twt to a oneway time. Principles of 3d seismic interpretation and applications.
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