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EMERGE Guide Introduction to EMERGE ...........................................

EMERGE Guide Introduction to EMERGE ............................................................................................................... 1 Part 1: Estimating P-wave Velocity from Seismic Attributes....................................................... 2 Starting EMERGE....................................................................................................................... 4 Performing Single-Attribute Analysis....................................................................................... 23 Performing Multi-Attribute Analysis........................................................................................ 29 Applying Attributes to the 3D Volume..................................................................................... 38 Saving the Project ..................................................................................................................... 49 Part 2: Estimating Porosity from Seismic Attributes.................................................................. 50 Training Neural Networks ........................................................................................................ 68 Applying the Trained Neural Network to the 3D Volume........................................................ 84 Part 3: Using EMERGE to Predict Logs from Other Logs......................................................... 88 Saving the Project ................................................................................................................... 110 EMERGE 1 GUIDE TO EMERGE Introduction to EMERGE EMERGE is a program whose purpose is to merge well log and seismic data. The general objective is to predict a well log property using attributes of the seismic data. That property may be any measured log type such as velocity or porosity, or it may even be a derived lithologic attribute, such as volume of shale. The seismic attributes may be calculated internally, or they may be provided as external attributes. The analysis proceeds in several stages: (1) Examine the log and seismic data at well locations to determine which set of attributes is appropriate. (2) Derive a relationship using multi-linear regression or Neural Networks. (3) Apply the derived relationship to a 3D SEGY volume to create a volume of the desired log property. This guide section takes you through the complete EMERGE analysis for three separate examples: Part 1: Predicting sonic logs from seismic attributes using multi-linear regression Part 2: Predicting porosity logs from seismic attributes using Neural Networks Part 3: Predicting sonic logs from other logs Each example is independent and may be performed without doing the others. Each example uses logs which have already been loaded into a GEOVIEW database. If you are unfamiliar with the use of GEOVIEW, please refer to the Guide to GEOVIEW and eLOG section of this documentation manual. January, 2006 2 EMERGE Part 1: Estimating P-wave Velocity from Seismic Attributes We are now ready to do the first EMERGE example. In this example, we will estimate P-wave or sonic log velocity from seismic attributes. The data set consists of the following: • A SEGY file, seismic.sgy, which is a 3D post-stack data set. • A SEGY file, inversion.sgy, which is the 3D result of performing inversion on the input seismic data. • 12 wells that tie the two SEGY files. Each of these wells contains a sonic log and a check-shot file. The objective of this analysis is to predict new sonic logs for the entire 3D survey, using the seismic data and the inversion result. The first step is to start the GEOVIEW program. GEOVIEW is the application manager that acts as a launch pad for other Hampson-Russell programs. On a Unix workstation, do this by going to a command window and typing: geoview <RETURN> On a PC, initialize GEOVIEW by clicking the Start button and selecting the Geoview option on the Programs>HRS applications window. When you first launch GEOVIEW, the first window that you see is the Opened Database List, which displays your recently used databases. For this example, a database has already been created for you. To load this database, click Open: January, 2006 EMERGE 3 For detailed information on entering logs into GEOVIEW, see the Guide to GEOVIEW and eLOG documentation manual. GEOVIEW lets you open up an existing database, access logs and transfer them to and from EMERGE. The database selection window looks like this: A database is identified by the extension wdb. Select the database guide.wdb as shown above and click OK. The GEOVIEW Well Explorer window now shows the twelve wells within this database: January, 2006 4 EMERGE Starting EMERGE Now that the database has been opened in GEOVIEW, we are ready to start the EMERGE program. To do this, click the EMERGE button on the GEOVIEW main window. The following window will appear: Click OK to Start a New Project. The File Selection window now appears. Fill it in as shown below and click OK (note that we are calling the new project guide): January, 2006 EMERGE 5 The main EMERGE window now appears: Before starting the EMERGE project, it is a good time to look at the online help feature in EMERGE. If you click the Help button at the top of the main EMERGE window, you will see this pull-down menu: January, 2006 6 EMERGE Click Hampson-Russell Assistant, and a new window will appear, showing you the complete documentation for all Hampson-Russell programs: The left column of the Help window shows the Index. Each item corresponds to a topic within the manual. Select one of these topics with the mouse (EMERGE Main Window, for example) to display that section: Note that the entire documentation manual, as well as the current Guide and Theory are available in this manner. January, 2006 EMERGE 7 Let us now review the EMERGE process. We wish to use the seismic data to “predict” new sonic logs at every location in the 3D seismic volume. To do this, we will collect some sample data around the well locations and find a relationship between the seismic data at those locations and the measured logs. This step is called “training”. After the training is completed, we will assume that the derived relationship is valid for the entire 3D volume, and apply that relationship to the 3D data set. To start the training process, we will need to read the sonic logs from GEOVIEW into the EMERGE main window. To do this, select Wells>Read From Database. The following window appears: Notice that this window has a series of pages, which can be viewed by using the Next >> and << Back buttons. You will not be able to click OK until the required pages have been filled in. The first page is the Wells page, which allows us to select which wells to include in the EMERGE analysis. As you can see above, the left column contains all the wells in the guide database. By default, all of the wells are also listed in the right column, meaning that we will use all of them in the training. January, 2006 8 EMERGE Now click the Next >> button at the bottom of the window. The second page will now appear: This page is used to tell EMERGE which of the logs in the database is the one that we are trying to predict, i.e., which one is the “Target”. For this guide example, we wish to predict the P-wave (sonic) log, as shown above. Also, we are specifying that, although the log is measured in depth, the analysis (Processing Domain) will be done in Time. This is because the seismic data is measured in time. We need to specify the sample rate correctly (Processing Sample Rate), so that EMERGE can do the depth-to-time conversion properly. Note that the check-shot corrected sonic log will be used for this conversion. When you have filled in the page as shown above, click the Next >> button. January, 2006 EMERGE 9 The third page then appears: The Tops page allows you to specify the analysis window for training in terms of the tops that have already been entered into the GEOVIEW database. In this project, we have entered four tops: viking, mann, ch_top, and miss. As shown above, select the viking as the start of the analysis window and the miss as the end of the analysis window. Note that the analysis window can be changed later if desired. At this point, the OK button is enabled, indicating that EMERGE has enough data from the GEOVIEW database to proceed. The Next >> button would still be active if the option Predicting Logs From Other Logs had been selected on the first page of this window. January, 2006 10 EMERGE Now that the entire window has been filled in, click OK. One more confirmation window appears: The reason this window appears is that for each of the selected wells, there are actually two P- wave logs. One is the original log and the second is the check shot corrected log. By default, the most recently created log will be used. This is the check shot corrected log, which is shown in the table. If you wished to use the other log, clicking on the word P-wave CheckShotCorrected for any of the wells will produce a pull-down menu that allows you to select the desired log. For our case, accept the defaults by clicking OK on this window. January, 2006 EMERGE 11 The main EMERGE window now looks like this: The EMERGE window now shows the target log for each of the wells. The red horizontal lines indicate the analysis window selected in the previous window. We will examine how to change that later. By moving the horizontal scroll bar, you can see all the remaining wells. Now we wish to read in the seismic data near the well locations. As mentioned at the beginning of the guide, the seismic data actually consists of two SEGY files, seismic.sgy and inversion.sgy. uploads/Geographie/ emerge-guide.pdf