# Dykstra-Parsons coefficient of permeability variation

Dykstra-Parsons coefficient of permeability variation is a common descriptor of reservoir heterogeneity. It measures reservoir uniformity by the dispersion or scatter of permeability values. A homogeneous reservoir has a permeability variation that approaches zero, while an extremely heterogeneous reservoir would have a permeability variation approaching one.s

Given the permeability distribution of a layered reservoir the heterogeneity can be expressed using the Dykstra-Parsons coefficient.

Layer # | Layer Thickness (ft) |
Permeability of the layer (md) |
---|---|---|

1 | 3 | 365 |

2 | 3 | 275 |

3 | 3 | 165 |

4 | 3 | 121 |

5 | 3 | 73 |

6 | 3 | 37 |

7 | 3 | 19 |

8 | 3 | 9.3 |

9 | 3 | 3.5 |

10 | 3 | 1.9 |

The coefficient is expressed as follow:V=(k50-k84.1)/k50V: coefficient of Permeability Variation k50: Permeability mean k84.1: Permeability mean plus a standard deviation

Using this spreadsheet is you can get the results in a automated way.

Just introduce the permeability and thickness pairs, sort and calculate.

Then a log-normal (probability) chart show the points and a best fit line.

The results can be readed in a box at the left of the chart.