Introduction to RE through Petrel This is a quick exercise going through the creation of a very simplified ECLIPSE model in Petrel RE, consisting of a cubic grid with a producer well in the center. A constant pressure boundary condition is set on the borders by the implementation of an aquifer, and its influence is analyzed through three ECLIPSE simulations. Throughout all steps it is expected that a parallel to real field cases are made, in order to teach Reservoir Engineering through a practical workflow.
1. Setting unit system in our new project We will start from a new project in Petrel. Take a few minutes to familiarize yourself with the interface in case you need to. We will now set the unit projects to metric. To do so, click on Project on the menu bar and then Project Settings. Now click on the tab Units and coordinates. Make sure the Unit system is set to Metric. Schlumberger Public
2. Creating the simple grid Our grid will be created from the Make simple grid process, which can be found under Utilities in the Process pane. Double-click it and, on the first tab, Input data, fill in the following parameters: Top: -1524 Bottom: -1578
With that, we just specified the top and bottom limits of our grid. Now click the next pane, Geometry and fill in the following values: XMax: 330 YMax: 330 Xinc: 30 Yinc: 30
This will provide our areal limits (going from 0 to 330 meters on both X and Y), and divide it into 11x11 grid blocks (or 12x12 nodes). Hit Ok and a new model with a grid inside named 3D Grid will be stored in the Models pane.
a. Create boundary surfaces On the Models pane, expand New model and 3D grid. Rightclick Skeleton and select Convert to surface. These will be stored in a folder under the Input pane.
b. Creating the horizons In the Processes pane, under Structural modeling, double-click the process Make horizons to open its dialog window. Click the Append item in table button
twice to add two lines which will create the
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3. Creating the vertical subdivision In order to make the vertical subdivision (layering), we need to go through three steps:
horizons. Highlight the surface Top under the Input pane by clicking its name once, and then drop it in the Make Horizons process by clicking the blue arrow icon in line 1 under the Input #1 column. Do the same with the Base surface for line 2. Hit Ok after your process window looks like the following:
c. Layering With the horizons defined, we can now do layering by activating the Layering process under Structural modeling in the Processes pane. Change the number of layers to 6 and keep all the other settings default. Hit Ok when done.
4. Creating petrophysical properties We will populate our model with simple petrophysical properties: porosity of 20%, areal permeabilities of 200 mD and vertical permeability corresponding to 10% of areal permeability.
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This will add new items, horizons, to the Models pane.
We will create them via the Calculator. To open it, navigate to the Models pane and, under 3D Grid, right-click Properties and choose Calculator. Choose Porosity under Attach new to template, and type the following equation in the empty field next to the blue arrow icon:
PORO = 0.2 Hit Enter when you are done. Now change the template to Permeability and enter the equation: PERM = 200
PERMZ = 0.1*PERM And after hitting Enter, notice how all the properties are stored under Properties inside 3D grid (Models pane). With that, our ‘static model’ is complete, and we can now work on the other inputs.
5. Creating the well We will now create our centered, vertical well. Click on Insert, which can be found in the menu bar, and select New well folder.
New well folders are stored in the Input pane. Click on Insert again, but now choose New well. Create a well with the following parameters:
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Hit Enter once again when done. Finally, change the template to Permeability Z and type in the equation:
Name: Producer Well symbol: (3) Oil Well head X: 165 Well head Y: 165 Specify vertical trace: checked Top MD: 0 Bottom MD: 1700 The well will be stored under our well folder in the Input pane. Next, we can work on our fluid model and saturation functions. We will not add completions to the well. This means that, by default, Petrel will consider that it is completed (perforated) in all layers.
6. Creating a fluid model Schlumberger Public
We create the fluid model by accessing the Make fluid model process, which can be found under Simulation in the Processes pane. First we click the Use defaults button and select Heavy oil + gas.
Next, we will supply a series of initial conditions. To do so, we switch to the Initial conditions tab and fill in the following data:
Name: No GOC Pressure (bar): 207 Datum depth (m): -1493 Gas-oil contact (m): -1493 Oil-gas PC (bar): 0 Water contact (m): -1554 Water-oil Pc (bar): 0
7. Creating rock physics functions Activate the dialog for Make rock physics functions under Simulation in the Processes pane. Click the button for Use defaults and choose Sand. Hit Apply.
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Hit Ok when done. Notice that we defined our GOC outside of the model boundaries and the WOC inside it. The fluid models are stored in a Fluids folder inside the Input pane. Try to visualize this data in a Function window.
Next, toggle the first dropdown menu (which should now read Saturation Function) and choose Rock Compaction Function. Click the Use defaults button again and pick Consolidated sandstone. Hit Ok when done. The new functions are stored in the Input pane under a Rock physics functions folder. You should inspect these in a Function window.
8. Creating the aquifer
Double-click the Make aquifer process found under Simulation in the Processes pane. First we need to create a polygon surrounding our entire model, so we click the button Start new set of polygons (deactivate old) which can be found on the right sidebar. Then, click outside of the model on three corners of the square, and finish by clicking the Close selected polygon(s) button . The created polygon is stored in the Input pane as Polygons 1, and can be renamed it by highlighting its name and pressing F2. Give it the name Aquifer boundary. Back to the Make aquifer dialog; change the Aquifer model to Constant pressure/head water. Now, select the Connections tab and drop in the Aquifer boundary polygon you just created.
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We will model an aquifer as a constant pressure at the side boundaries of our system.
Switch to the Properties tab and change the following parameters, leaving the others as default: Pressure: 200 Datum: -1551 Fluid model: Heavy oil + gas (drop it in using the blue arrow from the input pane) Hit Ok when done. The aquifer is stored under our grid in the Models pane.
Double-click the Make simulation strategy process under Simulation in the Processes pane. Click the Use defaults button and select Prediction depletion strategy. Name the new strategy ORAT. We will simulate one year in total. Switch the final date (2030-01-01) to 2011-01-01 by highlighting it and pressing F2. Select the Group rate production control (Field) rule, and under the Oil rate (sm3/d) field, insert a value of 50. Notice that since this group consists of only one well, this corresponds to a well control. Also note that the BHP limit is set to 1 bar under the Well pressure production control (Wells Folder) rule. Leave all the other settings default and press Apply.
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9. Creating development strategies Next, we create the flow controls for our single well. Two strategies should be created, both based on a constant oil rate control, however one will be limited by a BHP.
Now, for the BHP strategy, toggle the radio button on top back to Create new development strategy. Change the name to ORAT + BHP. Select the Well pressure production control rule and change the Bottom hole pressure (bar) limit to 138. Hit Ok. The development strategies should be stored in the Input pane under the Development strategies folder. Notice that we now have all the necessary information to create our simulation cases.
10.
Defining the simulation cases
Double click the Define simulation case process found under Simulation in the Processes pane. Give the case the name ORAT. Inspect the Grid tab but do not make any changes yet. Switch to the Functions tab. We will now drop in the relative permeability, fluid and rock compaction inputs we created earlier. First, select Sand from the input pane and drop it in via the blue arrow as the Rel perms item. Click the next item, Black oil fluid model, and drop in the initial condition No GOC from the input pane.
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At this point, save your project in case have not done so yet, by going to the File menu and choosing Save project.
Switch to the Strategies tab. Click the Append item in table button once and drop in the ORAT development strategy. Click Apply. Now Export and Run the case by clicking the appropriate buttons, Petrel will automatically load the results.
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Next, choose the final item, Rock compaction, and drop in the Consolidated sandstone function, also from the Input pane.
We will create a final case building from ORAT_BHP. Again, on the same Define simulation case dialog, toggle the upper radio button to Create new and give the case the name ORAT_BHP_AQUIFER. Switch to the Grid pane. Click the Append item in table button and, on the row inserted, choose Aquifer, which is the last item on the drop-down list. Drop in Aquifer from the Models pane via the blue arrow. Apply the changes and then Export and Run the case. After the case runs, close the dialog window.
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Before we check on the results, we will create two additional simulation cases. Still on the Define simulation case dialog, toggle the upper radio button to Create new and give it the name ORAT_BHP. Change to the Strategies tab and replace the ORAT strategy by ORAT + BHP. Apply the changes, then Export and Run the case.
11.
Visualizing the results
Open a new function window by selecting Window from the menu bar and clicking on New function window. Different results are stored in the Results pane, and cases organized in the Cases pane. Try activating the checkboxes to analyze different results such as Field Pressure and Field Oil Production Rate. As a final discussion, consider the effect of the aquifer as an energy provider to the system.
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