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whitson+ - PNR DCA Certification

1. Introduction

Complete the steps outlined below to become a PNR DCA certified whitson+ user. It includes performing workflow for two wells —one oil and one gas— with actual production data from the SPE Data Repository . Those certified have the software skills necessary to complete most PNR DCA projects in tight unconventionals.

Need help?

Send an e-mail to support@whitson.com.

1.1. Before Starting

Make sure you have watched these three videos in the Getting Started part of the manual (click here).

  • Login (1 min)
  • Overview of important basics (3 min 30 sec)
  • Zoom Plots (3 min)

1.2. Create a Project

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  1. Go to the Projects module in the navigation panel.
  2. Click ADD PROJECT up to the right.
  3. Name the project "Your Name - whitson Certificate - PNR DCA".
  4. Click SAVE.
  5. All steps are shown in the .gif above.

1.3. Upload the Well Data

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  1. Click MASS UPLOAD up to the right.
  2. In the pop-up window, select EXAMPLES
  3. Search for PNR DCA Certificate Wells and click UPLOAD
  4. All the data will be uploaded into the project. You can then close the Mass Upload pop-up window.
  5. All steps are shown in the GIF above.

2. Oil Well : SPE-DATA-REPOSITORY-DATASET-1-WELL-5-SWIFT

2.1. PVT

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  1. Click on the well named "SPE-DATA-REPOSITORY-DATASET-1-WELL-5-SWIFT"
  2. Go to the PVT module in the navigation panel.
  3. Open the Reservoir Fluid Composition Input Card
  4. Click SAVE.

2.2. Bottomhole Pressure Calculations

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  1. Go to the Bottomhole Pressure module in the navigation panel.
  2. Click the CALCULATE BOTTOMHOLE PRESSURES button.
    • This will run the calculation for four different BHP correlations at the same time.
  3. Select Woldesemayat and Ghajar as the "Bottomhole pressure to be used in calculations".
    • The dropdown menu can be found right of the CALCULATE BOTTOMHOLE PRESSURES button.
    • The selected BHP is used everywhere in the software where BHPs are required (FMB, PNR DCA, RTA, Numerical Model, Nodal Analysis).
  4. To isolate the Woldesemayat and Ghajar calculation in the plot, double-click the legend.
  5. All steps are shown in the .gif above.

2.3. Analytical RTA

2.3.1. Identifying Flow Regime

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  1. Go to the Analytical RTA module in the navigation panel.
  2. In the Pressure Normalized Rate plot (bottom left), add the unit slope as shown in the GIF.
  3. Use the Lasso tool to highlight the Boundary Dominated Flow (BDF) region.
  4. From the plot, BDF starts at around 2,000 material balance days (~1,000 real days).
  5. Use the Rate-Time plot (top right) to confirm the real-time start of BDF.

2.3.2. Identifying Arp's Rate Exponent, b

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  1. In the Analytical RTA module, go to the FRACTIONAL tab.
  2. In the Rate Normalized Pressure plot (top right) open the Fit Options menu and select Spray Gun Fit. Apply the fit to the data after ~2,000 material balance days. The slope from this fit gives the delta value, which corresponds to Arps’ rate exponent (b).
  3. Copy the Arps b value—you’ll use this rate exponent in the PNR DCA module.

2.4. PNR DCA

2.4.1. Manually Fitting the Segment

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  1. Go to the PNR DCA module.
  2. Paste the b value from the Fractional RTA into the rate exponent field.
  3. Click the arrow icon next to End Day to set it to the last historical production day.
  4. Set the Start Day to 1,000 days.
  5. Shift the decline curve to match the historical oil rate as shown below.

Shifting or adjusting the segment

There are three options to shift or adjust the segments points without changing the rate exponent.

  • Shift entire decline
  • Shift segment points along the decline curve
  • Adjust shape of decline curve

2.4.2. Adjusting Forecast Parameter

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  1. You can view the limiting decline start point by clicking the Show limiting decline start point option as shown in gif above.
  2. Set Max Well Life as 100 years.
  3. Increase the Limiting Secant Effective Decline Rate, \(d_{sec}\) to 10%/yr

2.4.3. Saving a PNR DCA Case

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  1. Click the CREATE CASE option and then select the Create Case For Oil to save the case.
  2. Save the case as PNR DCA Case
  3. All the steps are shown in the gif above.

3. Gas well : SPE-DATA-REPOSITORY-DATASET-1-WELL-12-LORIKEET

3.1. PVT

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  1. Go to the Wells module in the navigation module
  2. Click on the well named "SPE-DATA-REPOSITORY-DATASET-1-WELL-12-LORIKEET"
  3. Go to the PVT module in the navigation panel.
  4. Open the Reservoir Fluid Composition Input Card
  5. Click SAVE.

3.2. Bottomhole Pressure Calculations

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  1. Go to the Bottomhole Pressure module in the navigation panel.
  2. Click the CALCULATE BOTTOMHOLE PRESSURES button.
  3. Select Gray as the "Bottomhole pressure to be used in calculations".
  4. To isolate the Gray calculation in the plot, double-click the legend.
  5. All steps are shown in the GIF above.

3.3. Analytical RTA

3.3.1. Identifying the Time to the End of Characteristic Flow

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  1. Go to the Analytical RTA module in the navigation panel.
  2. In the Pressure Normalized Rate plot (bottom left), add the unit slope as shown in the GIF.
  3. Use the Lasso tool to highlight the Boundary Dominated Flow (BDF) region.
  4. From the Rate Time plot (top right), BDF starts at around ~2000 real time.

3.4. PNR DCA

3.4.1. Autofit

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  1. Click Edit Autofit Setting to open the dialog box. Review the ranges for Peak Production Rate Ratio, Initial Nominal Decline Rate, Rate Exponent (b), and Noise Reduction. Leave the default values unchanged.
  2. Click AUTOFIT to run the fit.
  3. Click the CREATE CASE option and then select the Create Case For Gas to save the case.
  4. Enter a case name, e.g., AUTOFIT PNR DCA. The case will be created and can be seen under the SAVED Case section at the bottom.

3.4.2. Fit Using Fractional RTA

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  1. Click the icon next to the Rate Exponent (b) field to open the Fractional RTA plot.
  2. In the Fractional RTA window, set the Segment Start Day to 2000 days (this corresponds to the time to end of characteristic flow found using the Analytical RTA module).
  3. Fit the slope line to the data after 2000 days to determine the rate exponent (around 1.2).
  4. Click SAVE
  5. You can view the Rate vs Time plot by disabling the Rate vs Cum plot — disable the RATE VS CUM option at the top right of the plot.
  6. Save this fit by clicking the CREATE CASE option, then select Create Case for Gas to save the case.
  7. Enter the case name FRTA PNR DCA. The newly created case will appear in the Saved section at the bottom.
  8. All the steps are shown in the GIF above.

3.4.3. Exporting the segments to the DCA

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  1. Click the Export Segment Parameters icon (denoted by double arrows).
  2. Select Use Parameters in DCA Module option.
  3. Keep the default name PNR DCA or edit it as desired.
  4. Click SAVE. You will be directed to the DCA Module.

Exporting PNR DCA Segments to the DCA Module

When exporting PNR DCA segments to the DCA module, the PNR flow rate decline trend converges to the actual rate decline trend when bottomhole pressure is relatively stable. This is because PNR flow rates are scaled by \((p_i − p_{wf,min})\), and when BHP is constant, the PNR fit align more closely with the DCA fit.

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Source: Xie, Xueying (2025)

3.4.4. Comparing DCA and PNR DCA EURs

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  1. In the DCA Module, check the box for PNR DCA saved case in the SAVED Case section at the bottom to view the PNR DCA fit.
  2. Enable the Rate vs Time plot by disabling the RATE VS CUM option in the top right of the plot. Turn on the RATE VS CUM plot again.
  3. Note the EUR value (~2700 MMscf) for the current DCA Module fit.
  4. Change the Current Case from Main to PNR DCA using the dropdown under CURRENT CASE.
  5. Observe the change in the EUR value.
  6. All the steps are shown in the GIF above.

3.5. Want to Learn More?

Schedule a PNR DCA session with one of our engineers. Contact support@whitson.com.

4. Done?

When you are done with your PNR DCA please:

  1. Send an e-mail to certification@whitson.com
  2. Make the subject: "whitson+ PNR DCA certificate: [YOUR NAME HERE]".
  3. Include the link to your project.
  4. Report the following from your DCA and PNR DCA Module for the gas well.
    1. EUR from the DCA module
    2. EUR from the Autofit PNR DCA case
    3. EUR from the FRTA PNR DCA case
  5. If you have any notes, comments, or observations related to the well, feel free to share them with us. Also feedback on the user friendliness of the software is always appreciated.

After that we'll provide some feedback on your evaluation and issue your whitson+ certificate if all looks good.

5. Want to Learn More?

Read more about the PNR DCA here: 1. →→ Pressure Normalized Rate (PNR) DCA ←←