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1. (WO2018106585) CHROMATOGRAMME SYNTHÉTIQUE À PARTIR DE PROPRIÉTÉS PHYSIQUES
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CLAIMS

What is claimed is:

1. A method (30, 40) for estimating a chemical composition of hydrocarbons of interest, the method (30, 40) characterized by:

performing a measurement for each physical property of a plurality of physical properties of the hydrocarbons of interest using a sensor (9) to provide a value for each different physical property being measured; and

estimating, by a processor, the chemical composition of the hydrocarbons of interest by using a correlation prediction function for each chemical component in the chemical composition in terms of the different physical properties being measured.

2. The method (30, 40) according to claim 1, further comprising generating the prediction function by:

obtaining a plurality of measurements of values of different physical properties of samples of hydrocarbons at reservoir temperatures and pressures, each sample having a known chemical composition, to serve as a training set;

generating a plurality of composite independent variables comprising two or more variables corresponding to the physical properties of the samples being measured; and

performing a regression on the training set for dependent variables representing the chemical composition of the hydrocarbons in terms of the composite independent variables so as to develop the correlation prediction function that uses measured values of the different physical properties as input to predict the chemical composition of a sample being evaluated downhole.

3. The method (30, 40) according to claim 2, wherein the chemical composition comprises a relative concentration for each of two or more carbon molecules.

4. The method (30, 40) according to claim 3, wherein the two or more carbon molecules comprises methane (CI), ethane (C2), propane (C3), butane (C4), pentane (C5), hexane (C6), and heptane and higher (C7+).

5. The method (30, 40) according to claim 3, wherein the prediction function comprises a prediction function for each of the two or more carbon molecules.

6. The method (30, 40) according to claim 1, wherein the composite independent variables comprise terms of a multinomial expansion of variables representing the plurality of physical properties being measured.

7. The method (30, 40) according to claim 6, wherein at least one variable in the multinomial expansion is a reciprocal of a physical property being measured.

8. The method (30, 40) according to claim 2, wherein the regression comprises a step forward multiple linear regression with substitution.

9. The method (30, 40) according to claim 1, wherein the plurality of physical properties comprises at least two selections from a group consisting of density, viscosity, sound speed, pressure, and temperature.

10. The method (30, 40) according to claim 1, wherein the estimating is performed in real time upon receiving the measurements for each physical property in the plurality of physical properties of the hydrocarbons of interest.

11. The method (30, 40) according to claim 1, further comprising performing a hydrocarbon production action using the estimated chemical composition of the hydrocarbons of interest.

12. The method (30, 40) according to claim 11, wherein the hydrocarbon production action comprises hydraulic fracturing an earth formation (4) containing the hydrocarbons in a selected range of depths.

13. The method (30, 40) according to claim 1, further comprising conveying a carrier (5) through a borehole (2) penetrating the earth (3), wherein the sensor (9) is disposed on the carrier (5) and the measurement for each physical property is performed downhole.

14. An apparatus for estimating a chemical composition of hydrocarbons of interest, the apparatus characterized by:

a sensor (9) configured to perform a measurement for each physical property in a plurality of physical properties of the hydrocarbons of interest to provide a value for each different physical property being measured; and

a processor configured to estimate the chemical composition of the hydrocarbons of interest by using a correlation prediction function for each chemical component in the chemical composition in terms of the different physical properties being measured.

15. The apparatus according to claim 14, further comprising a carrier (5) configured to be conveyed through a borehole (2) penetrating the earth (3), wherein the sensor (9) is disposed on the carrier (5) and is configured to perform the measurement for each physical property downhole.