Research And Implementation Of Image Rendering And CGM Processing Of Seismic Interpretation System

Based on the project named " SEIWAVE seismic deposit layer prediction and well deploying system" which is developed by Daqing petrol Institute, the thesis practices work according to the design of 3D seismic interpretation system and the research of the CGM standards. The architecture of seismic interpretation system and the algorithm of image rendering have been studied deeply, which is combined with principle of generating seismic trace in CGM+. Exporting and viewing CGM based on this system and rendering seismic section are realized through above research.CGM(Computer Graphics Metafile) is announced by the United States Committee as a computer graphics file format standard in 1986,and becomes ISO standards which is ISO 8632.CGM is a industry standards of Petroleum Technology Association, and in the foreign countries ,CGM is considered as the most important exporting forms in the oil and gas exploration system. For the sake of our seismic interpretation software reaching the level of outstanding seismic interpretation software, it should be researched thoroughly.On the basis of the international standard ISO 8632, CGM format graphic elements, coding forms, and all versions are researched adequately. In order to realize outputting the CGM file, we focus on the principle of seismic trace in the CGM+. It is involved with the concept of seismic trace, trace coordinates, scaling factors, display mode and seismic data type and rendering process. Seismic trace can be considered as a simple curve. Trace coordinates part introduces the relation of baseline axis and amplitude axis, and Scale factors part explains the method of computation of the baseline factor, amplitude factor and trace factor. Display mode part describes any form of display mode detailed. Data type part gives six types of seismic data, explaining the relation of data type and display mode.After researching CGM, The thesis realizes the design and implementation of 3D seismic interpretation subsystem and CGM processing module. 3D seismic interpretation subsystems includes the following functions: File management, display control, section display, layer display, well display, fault display and help online. Subsystem mainly realizes the rendering of seismic section information, which is comprised of trace information, layer information, well information, fault information and oil information. CGM processing module includes: CGM Output module and CGM View module. CGM Output module includes: Reading seismic data part, Rendering trace part, Receiving parameter part, Rendering well and layer part and Configuring CGM part. The design of subsystem is by MVC pattern, encapsulating the seismic data class as Model, considering the input of user as the View, display mode control class as Controller. It separates the data model, data display and interaction to make the design more clear and improve the efficiency of parallel. Because other modules communicate via subsystem, majority need to read the parameters of subsystem. If there exits frequent communication between modules, It will increase the couple and cause the program chaos. It needs to set communicable interface as a bridge. Choosing the Facade pattern can implement the above request. Encapsulating the method and parameter as a class which can reduce the unnecessary communication between modules, and which make other modules not dependent on seismic interpretation subsystems. It will enhance the independence and portability of software.Based upon the study of image rendering, the seismic interpretation subsystem has realized the Variable Area fill and Background fill, which rich the patterns of seismic display. It will provide great convenience with the seismic interpreters that adds the rendering function of layer, well, fault and oil to the seismic interpretation subsystem that. The thesis has made detailed description and comparison of the variable performance optimization strategy of rendering. In the seismic interpretation process, image rendering primarily involves a large volume of seismic data , samples can be displayed in the right position via complex conversion of coordinates. If the time of rendering image to screen is longer than screen refurbishing time, it will appear phenomena of screen flicker. Double buffering technique can be used to solve this problem. First state a bitmap variable and set up a buffer in the memory region, then state a Graphic object which imports the buffer which can dispose the bitmap variable in the buffer. There is a disposed picture in the memory, then spread the pictures on the screen buffer which will implement double-buffering technique. From the Image Rendering Algorithm, The thesis analysis and compares the algorithm of rendering based on the current screen, changed zone rendering and whole rendering. Considering the seismic data and general operation of users, the algorithm of changed zone rendering is not suitable to this system. The algorithm of rendering based on the screen should be chosen as the algorithm of rendering. In the appropriate circumstances, calculates the time of image rendering based on different data, concludes that if data size is about more than 1G , the consuming time of rendering image is about 3 seconds.Using the toolkits of the Larson company, implements the exporting CGM based on the principle of creating seismic trace combining with 3D seismic interpretation subsystem. The default state of CGM file is the same as the state of section of 3D seismic interpretation subsystem, The user also can change the scope of trace and time. In this part, the principle of trace create is applied to 3D seismic interpretation subsystem, discusses how to implement conversion of VDC and the screen coordinates, determine the Scale factors (Scaling factor, Trstep factor, Basesc factor). Because the data size of seismic section usually is more than 1G. If we use the traditional operation of I/O, the efficiency is very low, then adopt the file stream technique to seek and read seismic data.This project is one of the main research project of Daqing petrol Institute. The research results are the implementation of seismic interpretation system and rendering seismic section based on Delphi 2006. It also provides the solution to realize the exporting and viewing the CGM based on this system. They are key technology to develop independently which is also an important meaning of research work of the thesis.