Automated material balance system for hydrocarbon reservoirs using a genetic procedure
First Claim
1. A method of producing a material balance solution for well patterns in a hydrocarbon reservoir that automatically optimizes the fluid allocation factors for each well used in determining the solution, comprising the steps of:
- randomly generating a first generation of allocation factor strings, each string in the generation assigning allocation factors to each of the wells in the reservoir representing the fraction of fluid injected into or produced from a well into or out of a well pattern;
determining a fitness function value for each of the strings by evaluating a fitness function, wherein the fitness function comprises the sum of the differences between computed and measured field pressures for each pattern, and the sum of the differences between target allocation factors and the allocation factors specified within the string for each well;
producing a succeeding generation of allocation factor strings according to a genetic algorithm;
repeating the step of determining a fitness function value for each of the strings in the succeeding generation; and
identifying the string having fitness function value meeting a specified criteria, wherein the identified string includes optimized estimates of the allocation factors for the reservoir for use in determining the material balance solution.
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Abstract
A system for producing a material balance solution for well patterns in a hydrocarbon reservoir is described that automatically optimizes the fluid allocation factors for each well used in determining the solution. The system automatically optimizes estimates for the allocation factors to be used in the material balance solution by randomly generating a first generation of allocation factor strings, each string in the generation assigning allocation factors to each of the wells in the reservoir. A fitness function value is determined for each of the strings by evaluating a fitness function, wherein the fitness function comprises the sum of the differences between computed and measured field pressures for each pattern, and the sum of the differences between target allocation factors and the allocation factors specified within the string for each well. A succeeding generation of allocation factor strings is produced according to a genetic algorithm. The process of determining a fitness function value for each of the strings is then repeated for the succeeding generation. The string having a fitness function value meeting a specified criteria is identified, wherein the identified string represents the optimized estimates of the allocation factors for the reservoir for use in determining the material balance solution.
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Citations
21 Claims
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1. A method of producing a material balance solution for well patterns in a hydrocarbon reservoir that automatically optimizes the fluid allocation factors for each well used in determining the solution, comprising the steps of:
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randomly generating a first generation of allocation factor strings, each string in the generation assigning allocation factors to each of the wells in the reservoir representing the fraction of fluid injected into or produced from a well into or out of a well pattern; determining a fitness function value for each of the strings by evaluating a fitness function, wherein the fitness function comprises the sum of the differences between computed and measured field pressures for each pattern, and the sum of the differences between target allocation factors and the allocation factors specified within the string for each well; producing a succeeding generation of allocation factor strings according to a genetic algorithm; repeating the step of determining a fitness function value for each of the strings in the succeeding generation; and identifying the string having fitness function value meeting a specified criteria, wherein the identified string includes optimized estimates of the allocation factors for the reservoir for use in determining the material balance solution. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method of optimizing estimates of fluid allocation factors for well patterns in a hydrocarbon reservoir, the allocation factor for each well representing the fraction of fluid injected to or produced from a well into or out of a well pattern, and each well pattern representing a defined volume of the reservoir centered about a production well with fluid contributions from injection wells at the pattern boundaries, comprising the steps of:
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constructing a first generation of allocation factor strings, where each string represents the allocation factors for each well in the reservoir; for each string, performing a normalization procedure on the allocation factors in the string such that conservation of mass pertaining to the production and injection of fluids is achieved with respect to each well; for each string, performing material balance calculations using the normalized allocation factors and reservoir data to produce pressure values for each well pattern; determining a fitness function value for each of the strings by evaluating a fitness function; determining if any of the fitness function values for any of the strings meet a predetermined criteria; if the criteria is not met, then producing a succeeding generation of allocation factor strings according to a genetic algorithm and repeating the process of determining the fitness function values for each of the strings in the succeeding generation until the predetermined criteria is satisfied; such that when the criteria is satisfied, the satisfying string represents the optimal set of allocation factors for the reservoir. - View Dependent Claims (16)
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17. A computer program for producing a material balance solution for well patterns in a hydrocarbon reservoir that automatically optimizes the fluid allocation factors for each well used in determining the solution, the program stored on computer readable media, comprising:
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instructions for randomly generating a first generation of allocation factor strings, each string in the generation assigning allocation factors to each of the wells in the reservoir representing the fraction of fluid injected into or produced from a well into or out of a well pattern; instructions for determining a fitness function value for each of the strings by evaluating a fitness function, wherein the fitness function comprises the sum of the differences between computed and measured field pressures for each pattern, and the sum of the differences between target allocation factors and the allocation factors specified within the string for each well; instructions for producing a succeeding generation of allocation factor strings according to a genetic algorithm; instructions for repeating the of determining a fitness function value for each of the strings in the succeeding generation; and instructions for identifying the string having fitness function value meeting a specified criteria, wherein the identified string includes optimized estimates of the allocation factors for the reservoir for use in determining the material balance solution. - View Dependent Claims (18, 19)
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20. A system for producing a material balance solution for well patterns in a hydrocarbon reservoir that automatically optimizes the fluid allocation factors for each well used in determining the solution, comprising:
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means for randomly generating a first generation of allocation factor strings, each string in the generation assigning allocation factors to each of the wells in the reservoir representing the fraction of fluid injected into or produced from a well into or out of a well pattern; means for determining a fitness function value for each of the strings by evaluating a fitness function, wherein the fitness function comprises the sum of the differences between computed and measured field pressures for each pattern, and the sum of the differences between target allocation factors and the allocation factors specified within the string for each well; means for producing a succeeding generation of allocation factor strings according to a genetic algorithm; means for repeating the of determining a fitness function value for each of the strings in the succeeding generation; and means for identifying the string having fitness function value meeting a specified criteria, wherein the identified string includes optimized estimates of the allocation factors for the reservoir for use in determining the material balance solution.
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21. A method of producing a material balance solution for well patterns in a hydrocarbon reservoir that automatically optimizes the fluid allocation factors for each well used in determining the solution, the allocation factors representing the fraction of fluid injected to or produced from a well into or out of a well pattern, comprising the steps of:
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constructing a first generation of allocation factor strings, where each string represents a random estimate of the allocation factors for each well in the reservoir; for each string, performing material balance calculations using the allocation factors and reservoir data to produce pressure values for each well pattern; for each string, determining a fitness function value using a fitness function that has as inputs the produced pressure values for each well pattern and the allocation factors for each well; determining if the fitness function value for any of the strings meet a predetermined criteria indicative of accuracy of the estimated allocation factors; if the criteria is not met, then producing a succeeding generation of allocation factor strings according to a genetic procedure and repeating the determining of the fitness function value for each of the strings in the succeeding generation until the criteria is satisfied; such that when the criteria is satisfied, the satisfying string represents a nearly optimal estimate of allocation factors for the reservoir and a material balance solution is produced using the estimate of allocation factors.
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Specification