Ensembles of neural networks with different input sets
First Claim
1. A method of synthesizing a well log, the method comprising:
- receiving a set of input signals that represent measurements of downhole formation characteristics;
applying a first subset of the set of input signals to a first neural network to obtain one or more estimated logs;
applying a second subset of the set of input signals to a second neural network to obtain one or more estimated logs, wherein the first and second subsets are distinct in that one subset has at least one input signal not included by the other; and
combining corresponding ones of the one or more estimated logs from the first and second neural networks to output one or more synthetic logs to display to a user.
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Abstract
Methods of creating and using robust neural network ensembles are disclosed. Some embodiments take the form of computer-based methods that comprise receiving a set of available inputs; receiving training data; training at least one neural network for each of at least two different subsets of the set of available inputs; and providing at least two trained neural networks having different subsets of the available inputs as components of a neural network ensemble configured to transform the available inputs into at least one output. The neural network ensemble may be applied as a log synthesis method that comprises: receiving a set of downhole logs; applying a first subset of downhole logs to a first neural network to obtain an estimated log; applying a second, different subset of the downhole logs to a second neural network to obtain an estimated log; and combining the estimated logs to obtain a synthetic log.
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Citations
34 Claims
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1. A method of synthesizing a well log, the method comprising:
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receiving a set of input signals that represent measurements of downhole formation characteristics; applying a first subset of the set of input signals to a first neural network to obtain one or more estimated logs; applying a second subset of the set of input signals to a second neural network to obtain one or more estimated logs, wherein the first and second subsets are distinct in that one subset has at least one input signal not included by the other; and combining corresponding ones of the one or more estimated logs from the first and second neural networks to output one or more synthetic logs to display to a user. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A computer-based method that generates a trained neural network ensemble, the method comprising:
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receiving a set of available inputs; receiving training data comprising values for the available inputs and corresponding values for at least one output; training at least one neural network for each of at least two different subsets of the set of available inputs, wherein the at least two different subsets are distinct in that one subset has at least one input signal from a sensor type not included in the other subset; providing at least two trained neural networks having different subsets of the available inputs as components of a neural network ensemble that transforms said available inputs into said at least one output, wherein said components are selected at least in part based on a measure of negative correlation between the components; and plotting said at least one output from the neural network ensemble as a function of at least one of time, depth, and position. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
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29. An information storage medium that, when placed in operable relation to a computer, provides the computer with software that generates a trained neural network ensemble, the software comprising:
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a training process that generates a set of neural networks having diversity in inputs and in complexity, wherein diversity in inputs requires that at least one of the neural networks in the set operates on a different combination of input signals than another of the neural networks in the set; a selection process that identifies a combination of neural networks from the set having a desirable fitness measure, said fitness measure being based at least in part on a measure of negative correlation for each neural network in the combination; a transform process that applies the combination of neural networks in ensemble fashion to a set of inputs to synthesize at least one output; and a process to display said at least one output. - View Dependent Claims (30, 31, 32, 33, 34)
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Specification