Methods of and apparatuses for identifying geological characteristics in boreholes
First Claim
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1. A method of processing geological information on a formation intersected by a borehole, the method comprising:
- obtaining data signals representative of the formation and generated by an image logging tool operated in the borehole to energize the formation, the data signals being processable to create an image of the formation including a plurality of pixels;
identifying sinusoidal geological characteristics in the data signals corresponding to a length of a borehole by;
employing a relatively computationally simple technique for analyzing the data signals corresponding to selected ones of said pixels to identify the presence of sinusoids among detected edge features; and
subsequently applying a relatively computationally complex technique for determining the parameters of the sinusoids identified using the relatively computationally simple technique, including disregarding the sinusoids extending over less than a predetermined proportion of a width of the image; and
determining, from the identified sinusoidal geological characteristics, planar geological features of the formation intersected by the borehole.
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Abstract
A method of detecting an edge of a geological characteristic in a borehole comprises, in respect of an image log of a length of a borehole, carrying out the steps of a gradient-based edge detection method, a phase congruence-based edge detection method or a combination of such methods as preliminary, pre-processing stages. Subsequent steps of the method may include operating a relatively computationally simple process to identify sinusoids among detected edge features; and a relatively computationally complex process for parameterizing the thus-identified sinusoids.
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Citations
13 Claims
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1. A method of processing geological information on a formation intersected by a borehole, the method comprising:
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obtaining data signals representative of the formation and generated by an image logging tool operated in the borehole to energize the formation, the data signals being processable to create an image of the formation including a plurality of pixels; identifying sinusoidal geological characteristics in the data signals corresponding to a length of a borehole by;
employing a relatively computationally simple technique for analyzing the data signals corresponding to selected ones of said pixels to identify the presence of sinusoids among detected edge features; and
subsequently applying a relatively computationally complex technique for determining the parameters of the sinusoids identified using the relatively computationally simple technique, including disregarding the sinusoids extending over less than a predetermined proportion of a width of the image; anddetermining, from the identified sinusoidal geological characteristics, planar geological features of the formation intersected by the borehole. - View Dependent Claims (2, 3, 4, 5)
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6. A method of processing geological information on a formation intersected by a borehole, the method comprising:
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obtaining data signals representative of the information and generated by an image logging tool operated in the borehole to energize the formation, the data signals being processable to create an image of the formation including a plurality of pixels; identifying sinusoidal geological characteristics in the data signals corresponding to a length of the borehole, by;
employing a relatively computationally simple technique for analyzing the data signals corresponding to selected ones of said pixels to identify the presence of sinusoids among detected edge features; and
subsequently applying a relatively computationally complex technique for determining the parameters of the sinusoids identified using the relatively computationally simple technique, the method including searching for counterpart edge features in respective locations spaced approximately π
radians apart in the image; anddetermining, from the identified sinusoidal geological characteristics, planar geological features of the formation intersected by the borehole.
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7. A method of processing geological information on a formation intersected by a borehole, the method comprising:
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obtaining data signals representative of the formation and generated by an image logging tool operated in the borehole to energize the formation, the data signals being processable to create an image of the formation including a plurality of pixels; identifying sinusoidal geological characteristics in the data signals corresponding to a length of the borehole by;
employing a relatively computationally simple technique for analyzing the data signals corresponding to selected ones of said pixels to identify the presence of sinusoids among detected edge features; and
subsequently applying a relatively computationally complex technique for determining the parameters of the sinusoids identified using the relatively computationally simple technique, the method including;a. processing the data signals for the image on the basis of a sequential line-by-line approach in which each line in the data signals for the image is vertically spaced from at least one neighbor; b. at each line analyzing a window of the pixels above and below the line; c. for each pixel position p1 in the window, assessing whether the pixel contains part of an edge feature; d. if the result of Step c is positive, determining the slope of the edge feature at the location p1; e. identifying a further pixel position p2 shifted horizontally by W/2, where W is a width of the image, and reflected vertically about the line; f. determining the slope of any edge feature at or near position p2; and g. if the value of the slope at p2 is equal in magnitude and opposite in sign to that determined at position p1, incrementing an accumulator relating to the line;
performing a threshold analysis on the value of the accumulator; and
using the result of the threshold analysis to determine whether a sinusoid is present at the position of the line; anddetermining, from the identified sinusoidal geological characteristics, planar geological features of the formation intersected by the borehole.
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8. A method of processing geological information on a formation intersected by a borehole, the method comprising:
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obtaining data signals representative of the formation and generated by an image logging tool operated in the borehole to energize the formation, the data signals being processable to create an image of the formation including a plurality of pixels; identifying sinusoidal geological characteristics in the data signals corresponding to a length of the borehole by;
employing a relatively computationally simple technique for analyzing the data signals corresponding to selected ones of said pixels to identify the presence of sinusoids among detected edge features; and
subsequently applying a relatively computationally complex technique for determining the parameters of the sinusoids identified using the relatively computationally simple technique, the method including parameterizing one or more of the identified sinusoids through practicing of the steps of;a. creating a two-dimensional accumulator space representing a range of values of A and φ
, being respectively the amplitude and phase angle of the sinusoid;b. analyzing each line of the data signals for the image that has been identified as containing a sinusoid; c. for each line, analyzing a window of the pixels above and below the line and for each pixel position x, y within the window that contains an identified part of an edge feature, determining the local slope of the edge; d. for each said local slope, determining estimates of A and φ
;e. incrementing the element of the accumulator that corresponds to the resulting, estimated values of A and φ
so as to derive an accumulated count of different values of A and φ
;f. repeating steps a. to e above in respect of the whole window and determining the maximum value in the accumulator space and, if it exceeds a threshold, g. selecting the values of A and φ
corresponding to the accumulator element values that exceed the threshold as values of A and φ
whereby to generate data and/or one or more signals representative of a parameterized sinusoid; anddetermining, from the identified sinusoidal geological characteristics, planar geological features of the formation intersected by the borehole. - View Dependent Claims (9, 10, 11, 12, 13)
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Specification