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whitson+ - Type Well Certification

1. Introduction

Complete the steps outlined below to become an DCA & Type Well certified whitson+ user. It includes performing auto-forecast and type well creation. Those certified have the software skills necessary to complete most type well evaluation 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).

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

1.2. Create a Project

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  1. Go to the Project module in the navigation panel.
  2. Click ADD PROJECT up to the right.
  3. Name the project "your name - whitson certificate".
  4. Click SAVE.
  5. All steps are shown in the .gif above.

1.4 Download Example Data

Download the example data here:

  1. →→ Well Completion List ←←
  2. →→ Well Production File ←←

1.5 Upload Production & Completion Parameters

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  1. In the Wells module, click MASS UPLOAD up to the right.
  2. Click ENERDEQ
  3. Drag and drop, or click and locate, the two files you downloaded in the previous step.
  4. All steps are shown in the .gif above.

2. Auto-Forecast

2.1 Create an Auto-Forecast

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  1. Click Auto-Forecast in the navigation panel.
  2. To the upper right, click ADD AUTO-FORECAST.
  3. Provide a name and select all the wells by clicking the check box at the top of the well list (left of Well Name).
  4. Click SAVE to the lower right.

You can store multiple auto-forecasts per project

This page gives you an overview of the created auto-forecasts, when they were created, who created them and what wells went into creating them.

2.2 Initialize Auto-Forecast

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Initialize the Auto-Forecast run using the ranges provided in the picture above.

What is the initial production ratio?

This is the ratio between the \(q_i\) that the DCA will use and the maximum production rate found in the production dataset for the well. As an example, if you have a given well where the maximum oil production in history is 1000 STB/d, having an initial production ratio between 0.8 and 1.2 means we are allowing the initial rate in DCA to be between 800 STB/d and 1200 STB/d. It is basically a generic way to specify the range for \(q_i\), for a large number of wells, and all the different phases (oil, gas and water) in one go.

2.3 Autofit All Wells

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  1. Click CONTINUE to the top right, or the second step in the stepper (2. Autofit).
  2. Click AUTOFIT ALL WELLS to the top left.
  3. The summary for each stream can be seen by clicking the tab OIL | GAS | WATER.

How does the default autofit work?

For each stream, the timestep associated with the peak rate, is found. Thereafter a regression fit of the

2.4 Sort Auto-Forecast Summary

\label{sort}

You can sort the rows by clicking the table headers.

Click the b-factor header. You are now sorting the table based on b-factor.

  • First click will sort it from minimun to maximum (ascending order).
  • Click it again and it will sort it from maximum to mininum (descending order).
  • Click it a last time and you'll get back to the unsorted list.

Why sort the results?

If you have a large number of wells, it can be helpful to quickly sort the wells by e.g. error and manually alter those large error fits only.

2.5 Manually Check Fits

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You can manually check and adjust each fit by clicking the row in the table.

  1. Click the row. A window showing the single-well DCA fit will appear.
  2. Navigate to the next well with the right arrow (→) and the previous well with the left arrow (←) on your keyboard.

What does the DCA b-factor represent?

DCA fits can be tied to physical parameters as long as the fit is done while the flowing bottomhole pressure is constant (or about constant). The b-factor represent recovery efficiency. A low b-factor indicates a low recovery efficiency. A high b-factor indicates a high recovery efficiency.

2.5 How adjust the DCA manually?

\label{save-cases}

  1. Values can be changed by typing.
  2. The fit can also be graphically edited.
  3. See .gif above (it's just for example purposes).

2.6 Save Cases

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  1. Click SAVE CASES to the top right.
  2. Name the DCA forecast base case.
  3. This will save the fit for each well, for each stream.

2.7 Roll-up

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  • To quality check that the overall fits are ok, a simple "roll-up" exercise can be performed on all the data.
  • That is done by adding up all the rates from all the wells producing at a given time step and plotting that over time in both rate and cumulative space.

  • Here you like to visually ensure that there are no strange discontinuities when the data goes from the historical data to the forecasted part of the data.

  • Click the third step in the stepper (3. Summary).

  • Click CREATE NEW CHARTS

2.8 Go back to the Auto-Forecast Overview?

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If you want to go back to the auto-forecast overview, either 1. click the Auto-Forecast tab in the navigation panel. 2. or click the Auto-Forecast menu in the top bar.

2.9 Want edit Auto-Forecast well selection?

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If you want to edit the well selection, either

  1. click the Edit Auto-Forecast tab in the Auto-Forecast Overview.
  2. or click the Edit Auto-Forecast menu in the top bar.

3. Type Well

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  • “Type Wells” are often referred to as “Type Curves”.
  • “Type Curves” refer to idealized production plots (based on equations and/or numerical simulation) to which actual production results are compared.
  • “Type Wells” are based on actual well production data and represent a typical production profile for a collection of wells for a specified duration.

What is a "typical" well?

The arithmetic average of a group of wells are commonly applied to estimate a type well. That said, experts (e.g. David Fulford) would argue that a geometric mean better approximates the median. Production rates and EURs are generally distributed lognormal, accordingly averaging the logs of the associated values make a lot of intuitive sense. We have option for both in whitson+.

3.1 Create a Type Well

\label{add-type-well}

  1. Click Type Well in the navigation panel (just under Auto-Forecast).
  2. To the upper right, click ADD TYPE WELL.
  3. Provide a name and select all the wells by clicking the check box at the top of the well list (left of Well Name).
  4. Click SAVE to the lower right.

You can store multiple type wells per project

This page gives you an overview of the created type wells, when they were created, who created them and what wells went into creating them.

3.2 Select Wells

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Click the check-box next to search wells.

3.3 Normalization

Normalization restructures data to improve comparability.

3.3.1 Start Time Alignment

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In this example, we'll set the start at peak rate. See .gif above.

Time Alignment

Time Align on First Production
* Strength: on larger well sets, communicates the production profile considering time to peak.
* Weakness: may not accurately reflect production decline behavior.

Time Align on Peak Rate Date
* Strength: more accurately reflects production behavior.
* Weakness: excludes ramp up time which might have a small impact on EUR but is important to first year revenue projection.

3.3.2 Condensing Time

\label{5-x-axis}

In this example, we'll just keep the default Normalized Time. That said, ensure you read and understand the different options mentioned below.

There are 4 different x-axis time options available

  1. Normalized Time: aligns time to first production.
  2. Normalized Flowing Time (by total production): considers only time steps with active oil, gas, or water production, excluding periods with no production (all rates must be 0).
  3. Normalized Flowing Time (by stream): considers only time steps when the rate of the chosen stream (oil, gas, or water) is non-zero, excluding periods with zero flow in the selected stream.
  4. Cumulative Production: plots the cumulative production on the x-axis.

3.3.3 Dimensional Normalization

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Dimensional normalization puts wells into a meaningful comparative context.

It's common to normalize to lateral length, which we'll also do in this example.

Non-linear Normalization

It's also possible to perform non-linear normalization in the software, but we'll not cover that in this example. Contact support@whitson.com if you'd like to know more.

3.4 Averaging Method

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There are to options for calculating the average:

  1. The geometric mean represents the central tendency of a set of values using the product of all values, with the nth root taken (where n is the number of values).
  2. The arithmetic mean is the average of a set of values, calculated by summing up all values and dividing by the total count.

Geometric Mean

“The geometric mean better approximates the median. Medians are more predictive for the outcome of a small number of samples (in this case, drilled wells), as well as being much more robust to outliers. Since production rates and EURs are generally distributed lognormal, an average of the logs of values makes a lot of intuitive sense.“
- David Fulford

3.5 Overview of Plot Options

Watch the video above to get an overview of the different plot options.

3.6 Forecast the Average vs. Average the Forecasts

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You can either Forecast the Average or Average the Forecast. In this example we'll append the forecasts.

3.6.1 What's the Difference?

Forecast the Average

  • Apply a decline to the truncated type well to obtain a full life profile of EUR
  • Time effective, but does not provide distribution of EURs

Average the Forecasts

  • Time consuming without auto forecast option
  • Useful for statistical evaluation and P10/P90 quantification of EUR

3.6.2 Append a DCA Forecast

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Append the forecast as shown in the .gif above (this is the saved forecast from Auto-Forecast).

3.7 Probit Plot

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  • Represent the statistical distribution of something (e.g. EUR, IP60, physical parameter) at a point in time.

  • The shape can help to determine if the results trend towards a lognormal distribution.

  • A “probit best fit” regression can yield statistical insights including a measure of uncertainty (e.g. P10/P90 ratio)

3.8 Fit Type Well

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  1. Click DCA.
  2. Run AUTOFIT.
  3. SAVE with an appropriate name.
  4. Go back to SETTINGS.
  5. Check the saved case and the Type Well DCA fit of the Type Well will be plotted.

3.9 Want to learn more?

Schedule a Type Well session with one of our engineers. Contact support@whitson.com.

4. Done?

When you are done with your Type Well please:

  1. Send an e-mail to certification@whitson.com
  2. Make the subject: "whitson+ Type Well certificate: [YOUR NAME HERE]".
  3. Include the link to your project.
  4. 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.

Want to learn more?

Read more about the following here:

  1. →→ Decline Curve Analysis (DCA) ←←
  2. →→ Auto-Forecast ←←
  3. →→ Type Well Generation ←←