Reservoir Stress¶

Introduction¶

The input in-situ stress in Reservoir Formation Stress subpanel (Figure 1) assumes uniform stress distribution on defined horizontal planes. For example, the two horizontal normal stresses are \(\textrm{30 MPa}\) and \(\textrm{33 MPa}\) throughout the plane at Depth \(\textrm{-800 m}\) in Figure 1. However, Reservoir Stress panel inputs a more complex stress status of the reservoir for the simulation in the Reservoir Stress subpanel under Wellbore Perforation panel, which can specify shear stresses (e.g. \(S_{xy}\) ) and stresses of \(\textrm{z}\) (vertical) component on different points (East and North) at the same Depth, as shown in Figure 2.

Figure 1: The Layer Stress subpanel of the Reservoir Formation panel

Figure 2: The Reservoir Stress subpanel of the Wellbore Perforation panel

The input stress table here (Figure 2) will be the same as the one in Reservoir Formation Stress subpanel (Figure 1), if only Depth, Sxx and Syy (the horizontal plane position and two horizontal normal stresses) are considered.

Import the stress¶

Here is an example to import the stress from an external file. The details of importing a file can be found here, thus the example here is a relative brief one. We first click the Import button (blue box in Fig 3)on the Reservoir Stress subpanel,

Figure 3: The import button

and then click the New button on the pop-up window (blue box in Figure 4) to set up a new fod file, and then click the load button (green box in Figure 4) to load data from a tabular file, which is a csv file here.

Figure 4: Stress import-Step 1

After that, a user finds the csv file called “SampleReservoirStress” by clicking the Browse button (blue box in Figure 5) on the following Select Tabular File pop-up window, and then load it by clicking OK (green box in Figure 5). Because there is only one sheet in the imported file so that the Excel Sheet Name option is grey (inactivated).

Figure 5: Stress import-Step 2

Then a preview of the imported data is available as shown in Figure 6.

Figure 6: Stress import-Step 3

Then, the user goes to Import subpanel (red box in Figure 7), and click the Accept (blue box in Figure 7) to complete the import.

Figure 7: Stress import-Step 4

After clicking the Accept button in Figure 7, the user completes the stress data input, which is shown in the purple box in Figure 8.

Figure 8: Stress import-Step 5 (complete)

In the plotting of Figure 8, the golden parts in the blue box represents the plotting of one component of the imported Reservoir Stress. As a default, the plotted component is \(S_{xx}\).

The values of these data are the difference between the stresses defined in Reservoir Formation (see Figure 1 for example), instead of the absolute stress value (the stresses defined in Reservoir Formation are the absolute stresses). The stress Sxx and Syy here are defined in East and North directions (see Figure 9), respectively. Then the two stresses can be decomposed to the \(\sigma_\textrm{h,min}\) and \(\sigma_\textrm{h,max}\) directions to obtain two new horizontal \(\sigma_\textrm{h,min}\) and \(\sigma_\textrm{h,max}\).

Figure 9: The minimum horizontal stress azimuth