Landmark培训多媒体之三.ppt

1、StratWorks Chapter 8: Creating Structure and Isochore Maps,Presenter Title Landmark Graphics Corporation,Part No. 625579 Rev. J,8-1,Chapter 8:Creating Structure and Isochore Maps,StratWorks uses the mapping algorithms of Z-MAP Plus to produce reliable, high-quality structure, thickness, and producti

2、on maps. You had a preview of mapping in Chapter 5, when you generated quick maps of the existing interpretation. In this chapter, you cover mapping in greater depth.,8-1,Overview,This chapter describes the basic mapping functions available in StratWorks. Through examples and exercises, you learn ho

3、w to create structure maps based on picks, profiles, and existing pointsets (from earlier maps or from imported data) map unit-related data such as gross thickness, average porosity, porosity*thickness (FH), and production history display maps using contour lines and/or colorfill overlay maps to fac

4、ilitate comparisons adjust grid parameters to make contours “honor” the data perform mathematical operations on grids,8-2,Training Workflow,8-3,Mapping: Basic Functions and Use,StratWorks generates maps by first building a grid over the area of interest and calculating values for each node (intersec

5、tion) on the grid. Contours are generated from the gridded surface. In StratWorks, you can make eight types of structure maps. Structure mapping uses the least squares algorithm from Point Gridding Plus (Z-MAP Plus). Surface maps can be made from well picks, and/or interpreted surface segments (prof

6、iles), and/or saved pointsets (which you created when you made a previous map or you imported fromZ-MAP Plus) Pointsets and grids are saved in the database under the output name you assign them. Contours are not saved; they are regenerated each time you display the map.,8-3,Mapping: Basic Functions

7、and Use (continued),Isochore mapping uses either the least squares, isochore, or bounding grid algorithms. You can perform a variety of mathematical operations (+, -, *, /, , blank ) on a single grid or between two grids. The result is a new output grid, which you can then contour. Pointsets, grids,

8、 and faults can be imported from Z-MAP Plus master files (MFDs) or exported to them. You can delete pointsets, grids (including 3D fault models) and zone attributes. The Print option lets you generate presentation-quality hardcopy plots of the maps you create in StratWorks.,8-5,Gridding,Gridding is

9、basically a process of changing irregularly spaced data (such as well picks, profiles, and seismic data) to regularly spaced data (grid node values). The advantage is that regularly spaced data lends itself to mathematical computations. Contours and surface profiles can be constructed easily and qui

10、ckly. And, you can easily add, subtract, multiply, or divide a grid by a constant or by another grid, as youll see later in this chapter.,8-6,Gridding,Using picks and other specified source data, the program builds a pointset of x,y,z data points. It then builds a matrix of grid nodes. For each grid

11、 node, the program gathers all the data points that fall within a specified radius of the node and weights them based on the distance from the node. Using a gridding algorithm, a plane is fitted through the weighted data points. The value of the plane at the x,y location of a grid node is assigned t

12、o that node.,8-7,Grid X and Y Increment,The grid increment is the distance, in map units, between the nodes of the grid. The smaller the grid increment the more surface detail introduced by the data will be retained in the grid. A good rule is that the grid increment should be half the distance betw

13、een the closest wells to be honored.,8-8,Grid Reach,The grid reach is the distance (radius) from each node that the program will search for data points to be used in computing the z-value for that node. The default grid reach is one-half the diagonal of the grid. Unless the data is highly faulted, t

14、here is usually no need to change the grid reach from the default.,8-9,Grid Algorithms,For Structure mapping, StratWorks defaults to the Least Squares griddingalgorithm used by Z-MAP Plus. For Isochore mapping, StratWorks provides two other gridding algorithmsto choose from: the Isochore and Bounded

15、 griddingalgorithms. Both of these are specialized versionsof the Least Squares method.,8-9,Least Squares Gridding,Least Squares is the default algorithm for modeling subsurface structure and is capable of emulating many traits of the hand contoured map. Least Squares finds the equation of a plane t

16、hat minimizes the sum of squared, weighted errors between the plane and the data points.,Once the planes equation is calculated as a function of x and y, the x,y location of the node is plugged into the equation, and a z-value for the node is obtained.,8-10,Isochore Gridding,Isochore gridding is ide

17、ntical to least squares gridding, except that “0” data values in the input data set are adjusted to negative numbers prior to grid node initialization. This algorithm is used in overcoming a zero-line problem at the edge of positive thickness values.,You set a Compression Factor to control the posit

18、ioning of the “0” contour line. The default is “2”, which will place the “0” contour line half way between the “0” and positive data points.,Isochore,Least Squares,8-12,Bounded Gridding,The Bounded algorithm is identical to Isochore gridding, except that it works at two ends of a range that you defi

19、ne, rather than just at zero, to define an accurate transition between endpoint values. Upper and Lower Boundary - these two parameters allow you to set the range that the algorithm uses (e.g. 0 - 1, 0 - 100).,8-13,Customized Structure Maps,In Chapter 5 you used MapView to generate quick structure a

20、nd isochore maps to check your existing interpretation before making your own picks in Correlation. At that time, you were introduced to the steps required to select data for your surface of interest, and available output options (pointsets, grids, contours). In this chapter, youll adjust gridding a

21、nd contour parameters to create customized structure maps.,8-14,Setting Grid and Contour Parameters,You can set grid increments, grid reach, contour range, and contour interval manually, or you can let the application calculate appropriate values for your dataset. A grid or contour value of -999999

22、tells the program to calculate a default value for the plot parameter. Defaults for grid increments are based on the input data range and number of points. If you choose to include faults, all active fault polygons associated with the selected surface are used as line-of -sight barriers in gridding

23、and contouring.,The Grid AOI parameter determines whether the grid is extrapolated a little past the data (From Data Set), or all the way to the MapView borders (From Map AOI),8-16,Setting Display Parameters,Most of the Display Parameter settings are self explanatory. You can accept the default disp

24、lay parameters or change them to suit your tastes. Overlaying Contours and Choosing Colors are discussed on the next two overheads.,8-18 if not, output the grid. Blank A if A C - Output null if the grid is less than the constant; if not, output the grid.,8-59,Performing Grid Operations,Grid-to-Grid

25、Operations With two grids, you can: Add - Add the two grids at each node. Subtract - Subtract one grid from the other at each node. Multiply - Multiply one grid by the other. Divide - Divide one grid by the other. Output Maximum - Output the value of the greater grid. Output Minimum - Output the value of the smaller grid. Blank A if A B - Output the first grid if it is less than the second; if not, output n