Method of determining planar events from borehole or core images
First Claim
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1. A method for detecting planar events from an image using a Hough transform technique comprising the steps of:
- a. Storing a borehole image into a computer based system;
said computer based system performing the following tasks;
b. Invite a human user to specify an upper and a bottom reference curve that border the pattern corresponding to a series of essentially co-planar events to delimit a subset of the 3D Hough accumulator array corresponding to the whole borehole image, said reference curves being used to define a range of reference planar event parameters and a depth interval;
c. Computing the accumulator matrix for said subset;
d. Computing a 1D average trace representing the extrema of the subset of the Hough transform accumulator for each depth;
e. Searching in the 1D average trace the extrema beyond a given threshold;
f. For each extremum in the 1D average trace, getting the horizontal coordinates of the point of the 3D Hough accumulator corresponding to this extremum at depth Zi, said horizontal coordinates representing one planar event to detect; and
g. Detecting the planar events from the image from all the planar events detected from step (f);
h. Storing the detected planar events from the image in the computer based system for retrieval by the human user.
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Abstract
The present invention relates to a user-guided dip picking method from electrical borehole images using Hough Transform. It includes defining a top and bottom reference curve, applying the Hough Transform to the borehole image limited by the top and bottom reference dips so that the Hough Transform space is restrained in the neighborhood of the reference dips. A 1D average trace representing the extrema of the 3D Hough parameter space for each depth is then computed and the extrema exceeding a given threshold are search in this 1D trace. The position in the 3D Hough space of an extremum represents a dip event.
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Citations
20 Claims
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1. A method for detecting planar events from an image using a Hough transform technique comprising the steps of:
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a. Storing a borehole image into a computer based system;
said computer based system performing the following tasks;b. Invite a human user to specify an upper and a bottom reference curve that border the pattern corresponding to a series of essentially co-planar events to delimit a subset of the 3D Hough accumulator array corresponding to the whole borehole image, said reference curves being used to define a range of reference planar event parameters and a depth interval; c. Computing the accumulator matrix for said subset; d. Computing a 1D average trace representing the extrema of the subset of the Hough transform accumulator for each depth; e. Searching in the 1D average trace the extrema beyond a given threshold; f. For each extremum in the 1D average trace, getting the horizontal coordinates of the point of the 3D Hough accumulator corresponding to this extremum at depth Zi, said horizontal coordinates representing one planar event to detect; and g. Detecting the planar events from the image from all the planar events detected from step (f); h. Storing the detected planar events from the image in the computer based system for retrieval by the human user. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11)
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2. A method for detecting multiple set of planar events from an image using a Hough transform technique comprising the steps of:
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a. Storing a borehole image into a computer based system;
said computer based system performing the following tasks;b. Invite a human user to specify at least three reference curves to border the multiple pattern corresponding to the multiple set of a series of essentially co-planar events; c. Sorting the reference curves along depth; d. For each consecutive pair of reference curves, said reference curves being used to define a range of reference planar event parameters and a depth interval;
i. Computing the accumulator matrix for the subset of the 3D Hough accumulator delimited by said reference curves;
ii. Computing a 1D average trace representing the extrema of the subset of the Hough transform accumulator for each depth;
iii. Searching in the 1D average trace the extrema beyond a given threshold;
iv. For each extremum in the 1D average trace, getting the horizontal coordinates of the point of the 3D Hough accumulator corresponding to this extremum at depth Zi, said horizontal coordinates representing one planar event to detect;
v. Detecting the planar events from the image from all the planar events detected from step (iv);
vi. Storing the detected planar events from the image in the computer based system for retrieval by the human user. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification