Type Curve Analysis

As per Decline Curve Analysis Using Type Curves by M.F. Fetkovich in SPE 4629.

Click here for a sheet of Log-log 5x4 paper for the anaylsis.

Click here for link to Arp Type Curves_PDF_-_Created by web program.

Click here for link to web program to create Arp Type Curves.

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Click here for link to Type curve match of Arp's hyperbolic decline (example)._PDF

In reservoir evaluation we can use type curve analysis to predict the future oil production of an oil well. Simply speaking we plot the rate vs time on a piece of tracing paper and overlay it on known curves on another sheet of paper. We can use the known curve to predict the amount of oil a well will produce. The basic steps used in type curve matching of declining rate-time data are as follows.
1. Plot the actual rate vs.time data in any convenient units on log-log tracing paper of the same size cycle as the type curve to be used. (For convenience all type curves should be plotted on the same log-log scale so that various solutions can be tried.)
2. The tracing paper data curve is placed over a type curve, the coordinate axes of the two curves being kept parallel and shifted to a position that represents the best fit of the data to a type curve.
3. Draw a line on the tracing paper through and extending beyond the rate-time data overlain along the uniquely matched type curves. Future rates then simply are read from the time scale on the tracing paper.

Arp's Hyperbolic Decline Example

Use the following method if you wish to determine qi and Di for the decline curve equation: q(t)/qi = 1 / [1 + b*Di*t]exp1/b
Click here for link to Type curve match of Arp's hyperbolic decline (example)._PDF

1. First we select a match point 100 months, 1000 BOPM which corresponds to 12, .033
2. Then we calculate qi as follows:
qDd= 0.033 = q(t)/qi = 1,000 BOPM/qi
qi = 1,000 BOPM/0.033 = 30,303 BOPM
3. Then we calculate Di as follows:
tDd = 12.0 = Di*t = Di*100 months
Di = 12.0/100 months = 0.12 months -1

How to Use Arp's Hyperbolic Decline Curve

Once you have defined the hyperbolic decline curve you can use it in more advanced analysis as per Predicting production performance using a simplified model by Khaled Abdel Fattah in World Oil.

Sample Project - Production Decline and Evaluation with Excel Spreadsheet

Link here to a complete PDF sample project.

Link here to sample Excel spreadsheet for the project..

Sample Project - Fetkovich Type Curves for Gas Well

Link here to sample Excel spreadsheet for Type Curves for Gas Well.

Link here to sample PDF document for Type Curves for Gas Well

Link here to Fetkovich Paper on Decline Curves.