CLAIMS

1. A method for predicting hydrocarbon production from a subsurface reservoir by determining non-linear petrofacies, which comprises:

partitioning a cross-plot using a data frequency of data points in the cross-plot and a computer processor; and

repartitioning the cross-plot by one of refining one or more partitions in the cross- plot using a data frequency of data points in an investigation window in the cross-plot and modifying one or more partitions in the cross-plot using a sensitivity analysis of data points in a predefined region to grow and a predefined region to reduce.

2. The method of claim 1 , further comprising:

determining a data frequency minima and location within a Υ±ΔΥ range and a Χ±ΔΧ range of the cross-plot;

computing one or more partitions within the cross-plot using the data frequency minima and each respective location;

determining a data-frequency maxima and location within a Υ±ΔΥ range and a Χ±ΔΧ range of each region in the cross-plot formed by the one or more computed partitions;

locating a source term for each region in the cross-plot using the data frequency maxima and each respective location; and

partitioning the cross-plot using the source term for each respective region in the cross-plot.

3. The method of claim 1 , further comprising:

determining a data frequency of data points in each cell of an inscribed matrix in the cross-plot;

connecting each inscribed matrix cell with a data frequency that meets a petrofacies partition criteria to a contiguous inscribed matrix cell with a data frequency that meets the petrofacies partition criteria;

defining each petrofacies region and each petrofacies partition formed by the connected inscribed matrix cells using a unique name and index identifier; and

projecting each defined petrofacies region and each defined petrofacies partition from the inscribed matrix onto the cross-plot using each respective name and index identifier.

4. The method of claim 3, further comprising:

connecting isolated cells in the inscribed matrix with a petrofacies partition comprising the connected inscribed matrix cells by enforcing a connected cell condition value.

5. The method of claim 3, further comprising:

adding isolated cells in the inscribed matrix to cells forming a petrofacies region by enforcing a connected cell condition value.

6. The method of claim 2, wherein the investigation window is created in the cross-plot using a source term for a selected region in the cross-plot as a center and predetermined dimensions.

7. The method of claim 1 , further comprising refining each partition in the cross-plot that intersects the investigation window by reorienting each intersecting partition to be tangent to a side of the investigation window that the intersecting partition intersects.

8. The method of claim 1 , further comprising:

measuring a distance between each data point in the region to reduce and a common partition between the region to reduce and the region to grow; and

normalizing each distance.

9. The method of claim 8, further comprising assigning a predetermined threshold normalized distance to each normalized distance that does not meet the predetermined threshold normalized distance.

10. A non-transitory program carrier device tangibly carrying computer-executable instructions for predicting hydrocarbon production from a subsurface reservoir by determining non-linear petrofacies, the instructions being executable to implement:

partitioning a cross-plot using a data frequency of data points in the cross-plot; and

repartitioning the cross-plot by one of refining one or more partitions in the cross-plot using a data frequency of data points in an investigation window in the cross-plot and modifying one or more partitions in the cross-plot using a sensitivity analysis of data points in a predefined region to grow and a predefined region to reduce.

11 The program carrier device of claim 10, further comprising:

determining a data frequency minima and location within a Υ±ΔΥ range and a Χ±ΔΧ range of the cross-plot;

computing one or more partitions within the cross-plot using the data frequency minima and each respective location;

determining a data-frequency maxima and location within a Υ±ΔΥ range and a Χ±ΔΧ range of each region in the cross-plot formed by the one or more computed partitions;

locating a source term for each region in the cross-plot using the data frequency maxima and each respective location; and

partitioning the cross-plot using the source term for each respective region in the cross-plot.

12. The program carrier device of claim 10, further comprising:

determining a data frequency of data points in each cell of an inscribed matrix in the cross-plot;

connecting each inscribed matrix cell with a data frequency that meets a petrofacies partition criteria to a contiguous inscribed matrix cell with a data frequency that meets the petrofacies partition criteria;

defining each petrofacies region and each petrofacies partition formed by the connected inscribed matrix cells using a unique name and index identifier; and

projecting each defined petrofacies region and each defined petrofacies partition from the inscribed matrix onto the cross-plot using each respective name and index identifier.

13. The program carrier device of claim 12, further comprising:

connecting isolated cells in the inscribed matrix with a petrofacies partition comprising the connected inscribed matrix cells by enforcing a connected cell condition value.

14. The program carrier device of claim 12, further comprising:

adding isolated cells in the inscribed matrix to cells forming a petrofacies region by enforcing a connected cell condition value.

15. The program carrier device of claim 1 1 wherein the investigation window is created in the cross-plot using a source term for a selected region in the cross-plot as a center and predetermined dimensions.

16. The program carrier device of claim 10, further comprising refining each partition in the cross-plot that intersects the investigation window by reorienting each intersecting partition to be tangent to a side of the investigation window that the intersecting partition intersects.

17. The program carrier device of claim 10, further comprising:

measuring a distance between each data point in the region to reduce and a common partition between the region to reduce and the region to grow; and

normalizing each distance.

18. The program carrier of claim 17, further comprising assigning a predetermined threshold normalized distance to each normalized distance that does not meet the predetermined threshold normalized distance.

19. A non-transitory program carrier device tangibly carrying computer-executable instructions for predicting hydrocarbon production from a subsurface reservoir by determining non-linear petrofacies, the instructions being executable to implement:

partitioning a cross-plot using a data frequency of data points in the cross-plot;

repartitioning the cross-plot by modifying one or more partitions in the cross-plot using a sensitivity analysis of data points in a predefined region to grow and a predefined region to reduce;

measuring a distance between each data point in the region to reduce and a common partition between the region to reduce and the region to grow; and

normalizing each distance.

20. The program carrier of claim 19, further comprising assigning a predetermined tlireshold normalized distance to each normalized distance that does not meet the predetermined threshold normalized distance,