Petroleum Goodies

Monday, January 14, 2013

Petroleum Goodies: Gas Compressibility Factor

Posted: 13 Jan 2013 09:13 PM PST

Web Tool To Calculate Gas Compressibility Factor

We rewrite VBA Excel function to calculate gas compressibility factor (Z) using JavaScript and develop a web tool so Petroleum Goodies users can Z factor directly from our website.

This web tool calculates gas compressibility factor for natural gases based on equation of state from Dranchuk and Abou-Kassem. Required inputs: gas gravity (air=1), mole percent of CO₂ and H₂S, pressure and temperature.

This tool also includes intermediate calculation such as pseudocritical pressure and temperature.

References:

Dranchuk, P.M., and Abou-Kassem, J.H.: “Calculation of Z Factors For Natural Gases Using Equations of State,” J. Cdn. Pet. Tech. (July-Sept., 1975) 34-36.
“Theory and Practice of Testing Gas Wells”, 3rd. Edition (1975) Energy Resources Conservation Board 603 6th. Ave. S.W. Calgary, Alberta, Canada.

Link to Web Tool To Compute Gas Compressibility Factor.

This web tool is also available for download in Excel version.

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Cumulative Probability Chart

Thursday, December 27, 2012

Petroleum Goodies: Cumulative Probability Chart

Cumulative Probability Chart

Posted: 26 Dec 2012 05:55 PM PST

Cumulative Probability Plot

This tool helps you to create cumulative probability chart from your data. To do this, we sort your data in ascending order. Next, we calculate percentile rank from your data. The smallest number in your data has the smallest percentile. Then we plot your sorted data versus percentile rank.

You can do it easily in Excel. However, this useful web tool can help you to build cumulative probability chart up to 5 series, instantly, all in one chart! So you can compare your data side-by-side. This chart is also called percentile rank plot. We build this web tool using jquery and JavaScript plot. We have tested this web tool using Firefox, Chrome, Safari, Opera and IE.

Definition of percentile rank. A percentile rank is typically defined as the proportion of scores in a distribution that a specific score is greater than or equal to. For instance, if you received a score of 90 on a math test and this score was greater than or equal to the scores of 80% of the students taking the test, then your percentile rank would be 80. You would be in the 80th percentile.

How to use this tool?

Input your data (up to 5 series) in provided text area. You don’t need to sort your data.
Label your data by changing series name.
Hit Reset Scale to clear axis scales. If these input scales are empty, tool will use minimum and maximum numbers from your data.
You can rename axis labels.
Hit Update Plot.

In this tool we provided example showing initial production of 300 wells from 5 different operator. Total data in this example 1500 points. You can use this tool to analyze percentile rank of your own data.

Tips: No need to sort your data. Numbers with comma thousand separators are allowed. Tested up to 15,000 points (3,000 points for each series). Let us know if you are able to use this tool with more than 15,000 data points. Show data point when hovering the mouse over a data point on a chart.

Link to web tool: Cumulative Probability Plot Related Posts:

None Found

Saturday, November 17, 2012

Petroleum Goodies: Calculate Daily Step Rate from Production Volume

Calculate Daily Step Rate from Production Volume

Posted: 16 Nov 2012 09:00 PM PST

Imagine you have producing gas wells with small amount of liquid production oil or water. Your liquid productions are not producing continuously (intermittent). Your liquid productions are not tied in directly to sales line. Or your wells are located far away from central facilities. Consequently, liquid productions need to be hauled by truck every certain day or every week. As a result, your production data is not in daily rate but in volume collected from certain days.

As petroleum engineer, you want to have daily production data from this volume to do production analysis or put them into simulation for history matching. You can convert this volume into step daily rate by dividing the volume with number of elapsed days when you collect the liquid production. You can calculate daily rate manually in Excel sheet or use this Excel tool to get daily step rate. This Excel tool can calculate daily step rate from production volume automatically.

Production volume can be collected in different time intervals of day, not necessary every 5 days, every week, etc. For example, you collect your liquid production every 3 days for the first month of production, every week for the second month of production then every month for the rest of your well life. This Excel tool can calculate daily step rate from production volume from different time intervals of day.

How to use this tool?

Input date in column B and your production volume in column C. Please remember, this should be production volume NOT rate. Daily step rate will be calculated in this Excel tool.
Hit Calculate button to convert production volume to daily step rate.
Check total cumulative volume from production volume and step rate for QC purposes. These two numbers should match.

Using VBA macro? Yes Note: There is a file embedded within this post, please visit this post to download the file.

Disclaimer: This work falls under the GNU General Public License. Any usage of these Excel sheets is undertaken at users own risk. There is no warranty, that they will not cause damage to your computer system, network, software or other technology. This Excel tool has VBA macro that is currently not working on Microsoft Excel for Mac OS X due to unresolved issue.Related Posts: