Method for estimating faults in a three-dimensional seismic image block

1. A method, implemented by a computer comprising a human-machine interface, for estimating seismic faults in a three-dimensional seismic image block representing a real subsurface region, the method comprising:

generating the three-dimensional seismic image block representing the real subsurface region based on seismic data gathered from the real subsurface region;

generating directrices, wherein each directrix is within a respective first cross-section of the seismic image block and generated based on points graphically selected by a user on the respective first cross-section;

generating generatrices, wherein each generatrix is within a respective second cross-section of the seismic image block and generated based on points graphically selected by the user on the respective second cross-section;

obtaining relationships from the user, wherein each relationship is between a directrix and a generatrix;

estimating a seismic fault within the seismic image block as a surface including at least one directrix and at least one generatrix having a relationship therebetween in the obtained relationship; and

creating an updated seismic image block identifying the location of the seismic faults.

2. The method of claim 1 , further comprising:

building a graph having nodes and arcs, wherein the generated directrices and generatrices are each represented by a respective node of the graph and each arc of the graph represents a respective relationship obtained between a directrix and a generatrix; and

identifying a fault based on a connected set of nodes of the graph, wherein the fault is estimated, within the seismic image block, as a surface including each directrix and each generatrix represented by nodes of the connected set.

3. The method of claim 1 , further comprising:

defining a navigation line in a first cross-section based on a user input; and

selecting second cross-sections, for generating generatrices, as extending transversely to the navigation line.

4. The method of claim 1 , further comprising, in the process of generating directrices:

displaying points selected by the user using a first type of recognizable graphical parameters, and,

changing the first type of recognizable graphical parameters used to display selected points when the user switches from one seismic fault on a respective first cross-section to another seismic fault, or from a respective first cross-section to a respective second cross-section.

5. The method of claim 1 , further comprising, in the process of generating generatrices:

displaying points selected by the user using a first type of recognizable graphical parameters, and,

changing the first type of recognizable graphical parameters used to display selected points when the user switches from one seismic fault on a respective second cross-section to another seismic fault, or from a respective second cross-section to a respective first cross-section.

6. The method of claim 1 , further comprising:

displaying a point of intersection between a directrix and a respective second cross-section or between a generatrix and a respective first cross-section using a second type of recognizable graphical parameters.

7. The method of claim 1 , further comprising:

enabling the user to select a point of intersection between a directrix and a respective second cross-section or between a generatrix and a respective first cross-section in order to obtain a relationship between a directrix and a generatrix; and

displaying a selected point of intersection using a third type of recognizable graphical parameters.

8. The method of claim 7 , wherein the first, second and third recognizable graphical parameters are different from one another.

9. The method of claim 8 , wherein the first, second and third recognizable graphical parameters are chosen among a colour, a shape, a symbol, or a label.

10. The method of claim 1 , further comprising:

generating a generatrix based on points selected at an intersection between geological features belonging to two seismic faults in the seismic image block.

11. The method of claim 1 , further comprising:

generating a directrix based on points selected at an intersection between geological features belonging to two seismic faults in the seismic image block.

12. The method of claim 1 , wherein selecting points is done with one click on a first button and switching a selection of points from a respective first cross-section to a respective second cross-section or from a respective second cross-section to a respective first cross-section is done with a click on a second button.

13. The method of claim 1 , wherein a respective first cross-section is oriented along a seismic horizon, thus forming a horizontal section of the three-dimensional seismic image block.

14. A non-transitory computer-readable storage medium having stored thereon a computer program comprising instructions to carry out a method for estimating seismic faults based on seismic data gathered from a real subsurface region in a three-dimensional seismic image block representing the subsurface region, the method comprising:

generating directrices, wherein each directrix is within a respective first cross-section of the seismic image block and generated based on points graphically selected by a user on the respective first cross-section;

generating generatrices, wherein each generatrix is within a respective second cross-section of the seismic image block and generated based on points graphically selected by the user on the respective second cross-section;

obtaining relationships from the user, wherein each relationship is between a directrix and a generatrix;

estimating a fault within the seismic image block as a surface including at least one directrix and at least one generatrix having a relationship therebetween; and

creating an updated seismic image block identifying the location of the seismic faults.