Petrel TIPS&TRICKS from SCM

Transcription

1 Petrel TIPS&TRICKS from SCM Knowledge Worth Sharing Well Path Design Part II This TIPS&TRICKS is the second of a three part series intended to aid the geoscientist working in Petrel and tasked with providing proposed well paths to a well engineering department for further analysis as part of an exploration or development project. Well planning in Petrel can be done interactively or automatically. The interactive method creates a proposed well path based on target points digitized by the interpreter one well at a time. Design points can be edited either graphically or through the well trace spreadsheet. This article focuses on the automatic method which utilizes an optimized well path design program accessed through the Create wells tab found in the Settings dialog window of the Well path design process. The program will automatically generate proposed well paths based on a set of optimization criteria variables. Input variables include 3D model properties, target points, boundary polygons and drilling cost models. All forms of well planning in Petrel can only be done in the depth domain. THIS DOCUMENT IS VALID FOR VERSIONS AND THE ONLY DIFFERENCE IS THE ADDITION OF THE MOVE WELL METHOD IN THE WELL PATH DESIGN PROCESS IN

2 Optimized Well Path Design The optimized well path design program is accessed in the Create wells tab of the Well path design dialog window. This program automatically generates well path designs based on discrete 3D model properties or predefined target points. Well path designs created in this manner may not always be practical and often need to be edited. There are three methods to choose from, Create best fit well, Move well, and Well optimizer. Wells created using these methods are automatically placed in a folder in the Input tab named Optimized wells. 2

3 Create Best Fit The Create best fit well method requires a discrete property from a 3D model as input. There are numerous ways to create this discrete model property. For the purpose of this example, we used a combination of the Property Calculator and Geometrical modeling to create a discrete property based on a porosity property cutoff value. 3

4 To automatically generate well paths using the Best fit well method: 1. Double click on Well path design under Well engineering in the Processes tab to open the dialog window. 2. Go to the Create well(s) tab. 3. Activate the Create new radio button and type a name. The program will generate a new subfolder with this name in the Optimized wells folder in the Input tab. 4. Select Create best fit well as the method. 5. Go to the Models tab and make the desired discrete property active. Use the blue arrow icon to enter the property in the Settings region of the dialog window. 6. You can optionally apply a filter using the 3D model property filter. The filter can be applied to the discrete property as a whole or each individual unique property code. The following parameters can be assigned to the discrete property as a whole or, in the case of a discrete property such as a facies property with many integer property codes with in it, each unique property code. By default they all use the same parameters. To change this, click on the unique property or facies and uncheck the Use defaults option. 7. Additional required parameters include: a. Well name wells will be created using this as a prefix and numbered sequentially. b. Min length the minimum length of an individual well path through the property to constitute a well. The default is 100 project units. This is usually too small for practical purposes and needs to be adjusted to avoid too many undesired wells. c. Max length the maximum length of well paths generated. The default is project units. This is usually too large for practical purposes and needs to be adjusted. d. Well heads a point file used to locate the initial design point or surface location of individual proposed wells. e. Existing well enter a well that the proposed wells will sidetrack from. If this is selected, the well heads point file is not used and grayed out. 4

5 8. Optional parameters include: a. Allow laterals The Kick off depth is the measured depth from the first auto generated target in the designated discrete property. The Min length and Max length are as described above. b. Shift well in moves the well path in the X, Y direction or normal to the tangent of the well path. c. Limiting surfaces confine the proposed well path between 2 surfaces. d. Collision detection keeps the proposed well paths a safe distance from existing wells. 9. Click on Make run to automatically generate proposed well paths. The program will create only one well path for each body through the thickest portion and along its longest axis to maximize exposure to the well path. 5

6 The results from using the parameters used in the previous figure on an example dataset are shown below. As you can see, if the discrete properties are elongated, the targets will be placed along the major axis while honoring the DLS parameters set in the Dogleg severity tab of the dialog window. Several problems can be quickly identified with this first pass run. First, a single surface location is not practical to reach all objectives. Some targets are too far away and others result in paths that are too severely circular. The next iteration will require additional surface locations input to the program. The auto generated well proposals are color coded and numbered according to the template of the discrete property they intersect. 6

7 After a few minor adjustments and adding additional surface locations, the results appear more practical. 7

8 Each proposed well path should be scrutinized closely for practicality. There are often cases where the program produces unexpected results. Finer adjustments must be made. In some cases the only choice may be to edit the well trace spreadsheet. 8

9 Recommendations for using Create best fit well: 1. Surface locations should be chosen with the geometry and number of the discrete properties in mind. 2. If they are elliptical in shape, surface locations should be placed tangent to the major axis to avoid unpractical circular well paths. 3. More than one surface location should be used with widely spaced bodies. 4. Discrete properties should have good connectivity. 5. Sinuous channel bodies do not work well because well paths mimic sinuosity. 6. Run several iterations. 7. Inspect and verify well paths carefully. 8. Unexpected results do occur. Editing individual well paths or deleting some altogether is to be expected. 9. Minor adjustments to the Starting point MD parameter can solve some trajectory problems. 9

10 Well Optimizer The Well optimizer is designed primarily for offshore wells but can be used onshore with drilling pad locations used in place of platform locations. It requires a cost model which you are given the opportunity in the dialog to create. Inputs are a point set of targets, and optionally a platform main well and a boundary constraint. The results are placed in a named folder that you specify. The program will produce a number of realizations of different drilling patterns with the calculated cost based on the provided cost model for each realization added to the folder name. There is no lateral option available. To run the Well optimizer program and create new proposed platform/pad locations: 1. Create a point file of reservoir targets and an optional polygon file to constrain the proposed platform/pad location. This example uses a depth domain seismic attribute for identifying reservoir targets. 10

11 2. Double click on the Well path design process to open the dialog window. 3. Go to the Create well(s) tab, select the Well optimizer method. 4. Select Create new and type in a name for the new folder. 5. Click on the box next to Make report to create an output spreadsheet of the results. 6. Select the elevation of the first design point of the new wells created. You can use sea level, a surface, or a constant. This example is onshore, so we specify a constant elevation in the absence of a topographic grid. 7. Make the target point file active in the Input tab, and enter it into the Input targets column by clicking on the blue arrow above the column. 8. Skip the Platform column for now. 9. Make the platform constraint polygon active in the Input tab, and enter it into the Boundary column by clicking on the blue arrow above the column. 10. Click on the box next to Kick off MD to place a checkmark, and enter a value if desired. 11. Click on the box next to Allow new platforms to place a checkmark, and enter the number of slots allowed for each new platform the program creates. 11

12 12. Click on the Cost model tab to open it. 13. Click on the Create/edit button to open the Cost models dialog. Consult your drilling engineer for drilling cost parameter values. Click on OK to save and close the Cost models dialog window. 14. Click on Make run in the Well path design dialog window to run the program. 12

13 15. If you selected the Make report option, you will first get a display of the output sheet. The spreadsheet lists all of the parameters and results for each realization including the estimated drilling cost of each proposed platform and well. This report is lost once the output sheet is closed and cannot be retrieved. The only way to reproduce the report is to run the well planning program again. Notice in this example that the order of the report gets out of sequence at cell D25. To fix the sequence and make the spreadsheet more legible, you will need to copy the contents to Excel and adjust for easier reading. 13

14 16. A folder is created for each realization and each platform with the estimated drilling cost as part of the name. Realization 1 Realization 2 Realization 3 Realization 4 14

15 17. To use existing wells as platform locations select the desired wells in the Input tab and use the blue arrow above the Platforms column to enter them and enter the number of slots for each platform. 15

16 Move Well The Move well method does just that, it translates the existing well plan design points along a specified vector. This method is a new addition to the release. The action can be performed on a single well or all wells in a folder. When selecting a folder the well head is automatically fixed and will not move. 1. Double click on the Well path design process to open the dialog window. 2. Go to the Create well(s) tab, select the Move well method. 3. Select Create new and type in a name for the new folder. 4. Select either a single well or well folder in the input tab and use the blue arrow next to Well/Well folder to enter it. 5. Click on the box next to Fix well head to place a checkmark and activate the option. If you selected a well folder, this is automatically selected and grayed out. 6. Click on the box next to Shift well in to activate the option, and enter the value in project units to shift the design points in the X, Y, or Z direction. Be careful not to move the design points past the well head. The trajectory algorithm will breakdown and give bad results if you do, as shown in the figure below. 7. Click on Make run to run the program. 16

17 8. A new well is created from the translation and placed in a new folder. If you use different parameters for each well in a folder you will need to create a new move folder for each one. Anytime you use the Edit existing option in the dialog window it will overwrite the contents of that folder. The figures below show the result of moving all wells in a folder using the same parameters. One well (B1) worked fine, the other (B2) resulted in one design point being translated past the well head. The well path optimizer program in Petrel enables the interpreter to quickly generate multiple scenarios in well planning. The program uses a set of criteria parameters defined by the user to optimally locate well paths and surface locations. Proposed well plans often need to be exported for data exchange with partners and specialized engineering analysis. Part III of this series will address the data export workflow. 17