Methods for compositional analysis of downhole fluids using data from NMR and other tools

Patent metadata

Field	Value
Publication number	US-9703003-B2
Application number	US-201314109354-A
Country	US
Kind code	B2
Filing date	Dec 17, 2013
Priority date	Dec 17, 2013
Publication date	Jul 11, 2017
Grant date	Jul 11, 2017

Abstract

Apparatus and methods of analyzing a composition of a hydrocarbon-containing fluid including using a nuclear magnetic resonance (NMR) tool to conduct a NMR relaxation measurement, a diffusion measurement, or both on the hydrocarbon-containing fluid to obtain NMR data, using a non-NMR tool to conduct an additional measurement of a reference fluid to obtain non-NMR data wherein the additional measurement comprises gas chromatography, optical observation, or both, and using the NMR data and the non-NMR data in an inversion process to determine an indication of the composition of the hydrocarbon-containing fluid. In some embodiments, the indication is determined over 4 chain length nodes.

First claim

What is claimed is:

1. A method of analyzing a composition of a hydrocarbon phase of a hydrocarbon-containing fluid containing a plurality of hydrocarbons of different chain lengths, comprising:
using a nuclear magnetic resonance (NMR) tool to conduct a NMR relaxation measurement, a diffusion measurement, or both on the hydrocarbon-containing fluid to obtain NMR data;
using a non-NMR tool to conduct an additional measurement of a reference fluid containing hydrocarbons to obtain non-NMR data wherein the additional measurement comprises gas chromatography, optical spectroscopy, or both; and
using the NMR data and the non-NMR data in an inversion process to determine an indication of the composition of the hydrocarbon phase of the hydrocarbon-containing fluid.

2. The method of claim 1 , wherein the indication is determined over a plurality of chain length nodes.

3. The method of claim 2 , wherein the plurality of nodes comprises 4 nodes.

4. The method of claim 2 , wherein the nodes are C 1 , C 2 , C 45 , and C 60 .

5. The method of claim 2 , wherein the using the NMR data and the non-NMR data in an inversion process includes (i) assuming an estimated mean chain length M current for the hydrocarbon phase of a hydrocarbon-containing fluid, (ii) using the temperature and pressure of the hydrocarbon-containing fluid together with the M current to compute T 2 relaxation times at the plurality of chain length nodes, (iii) estimating component proton fractions P j by solving a linear system, (iv) replacing proton fraction estimates of a plurality of the smallest chain values with corresponding estimates obtained from the additional measurement and renormalizing the component proton fractions other than the replaced proton fraction estimates so that the sum of all proton fractions is 100%; (v) updating the mean chain length estimate using the modified set of proton fractions, and (vi) repeating (ii) - (vi) until the mean chain length estimate converges.

6. The method of claim 5 , wherein the using the NMR data and the non-NMR data in an inversion process further includes (vii) optimizing the selection of T 2 relaxation times at the plurality of nodes by minimizing error in fitting the proton fraction estimates from the additional measurement to obtain adjusted T 2 relaxation times, and (viii) estimating mixture component proton fractions utilizing the adjusted T 2 relaxation times.

7. The method of claim 5 , wherein, the replacing proton fraction estimates of a plurality of the smallest chain values comprises replacing the first five estimate values for proton fractions p j , and the renormalizing is for p j for j =6, . . . 60.

8. The method of claim 7 , wherein the plurality of chain length nodes comprises four nodes.

9. The method of claim 8 , wherein the four nodes are C 1 , C 2 , C 45 , and C 60 .

10. The method of claim 9 , wherein the linear system is given by

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Assignees

• Schlumberger Technology Corp

Inventors

• Bennett Nicholas N
• Zeng Yi
• Venkataramanan Lalitha
• Freed Denise E
• Hürlimann Martin D

Classifications

• G01V3/32 Primary

  operating with electron or nuclear magnetic resonance · CPC title

• E21B49/082

  Wire-line fluid samplers (E21B49/083 takes precedence) · CPC title