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

Patent metadata

Field	Value
Publication number	US-9733383-B2
Application number	US-201314109497-A
Country	US
Kind code	B2
Filing date	Dec 17, 2013
Priority date	Dec 17, 2013
Publication date	Aug 15, 2017
Grant date	Aug 15, 2017

Abstract

Methods and apparatuses are provided for analyzing a composition of a hydrocarbon-containing fluid. The methods include using a nuclear magnetic resonance (NMR) tool to conduct NMR measurements on the hydrocarbon-containing fluid to obtain NMR data. A non-NMR tool, such as an optical tool, is used to conduct additional measurements and to obtain non-NMR data on the fluid. The methods further include determining an indication of the composition of the fluid by using the NMR data and normalizing the indication of the composition of the fluid using the non-NMR data.

First claim

What is claimed is:

1. A method of analyzing a composition of a hydrocarbon-containing fluid, the method comprising:
(a) using a nuclear magnetic resonance (NMR) tool to conduct NMR measurements on the hydrocarbon-containing fluid to obtain NMR data;
(b) using at least one non-NMR tool to conduct additional measurements and to obtain non-NMR data on the fluid; and
(c) determining an indication of the composition of the fluid by using the NMR data; and
(d) normalizing the indication of the composition of the fluid using the non-NMR data.

2. A method according to claim 1 , wherein the indication of the composition comprises a chain length distribution.

3. A method according to claim 1 , wherein the NMR measurements comprise at least one of relaxation measurements and diffusion measurements.

4. A method according to claim 3 , wherein the NMR data comprise at least one of NMR magnetization decays, distributions of NMR relaxation times, and distributions of NMR diffusion coefficients.

5. A method according to claim 1 , wherein the non-NMR tool is an optical tool, the additional measurements are optical measurements, and the non-NMR data are optical data.

6. A method according to claim 5 , wherein the optical data comprise at least one of optical spectra and optical densities.

7. A method according to claim 5 , wherein the indication of the composition comprises a chain length distribution and the optical data is used to normalize the chain length distribution according to:

W
⁡

(

N
i

)

=

{

w
ci

for
⁢

⁢
i

≤
5

w
i

⁢

w

c
⁢

⁢

6
+

∑

j
≥
6

⁢

w
j

for
⁢

⁢
i

≥
6

.

where W(N i ) is the chain length distribution, i is an index of the number of carbon atoms in a particular component of the composition, w i is the weight fraction of molecules with chain length N i as determined by the NMR measurements, w c1 is a weight percentage for the carbon molecule with index i, and w c6+ is a weight percentage determined according to the optical data of components having a chain of at least six carbon molecules.

8. A method according to claim 5 , wherein the indication of the composition comprises a chain length distribution and the optical data is used to normalize the chain length distribution according to:

W
⁡

(

N
i

)

=

{

aw

c
⁢

⁢
1

+

(

1
-
a

)

⁢

w
1

for
⁢

⁢
i

≤
5

w
i

⁢

1
-

∑

i
=
1

5

⁢

W

Assignees

• Schlumberger Technology Corp

Inventors

• Freed Denise E
• Venkataramanan Lalitha

Classifications

• G01V11/00

  Prospecting or detecting by methods combining techniques covered by two or more of main groups G01V1/00 - G01V9/00 · CPC title

• G01N24/081

  Making measurements of geologic samples, e.g. measurements of moisture, pH, porosity, permeability, tortuosity or viscosity · CPC title

• E21B49/088

  combined with sampling · CPC title

• G01V3/32 Primary

  operating with electron or nuclear magnetic resonance · CPC title