System and method to determine volumetric fraction of unconventional reservoir liquid

Patent metadata

Field	Value
Publication number	US-9448322-B2
Application number	US-201313866459-A
Country	US
Kind code	B2
Filing date	Apr 19, 2013
Priority date	Apr 20, 2012
Publication date	Sep 20, 2016
Grant date	Sep 20, 2016

Abstract

A system determines a volumetric fraction of oil in a formation penetrated by a borehole, the formation comprising an unconventional reservoir. The system includes a carrier configured to be conveyed through the borehole and a geochemical tool disposed at the carrier and configured to determine a mineral makeup of the formation and excess carbon not apportioned to any mineral of the mineral makeup, the excess carbon being associated with kerogen and oil in the formation. An NMR tool disposed at the carrier determines porosity of fluid in the formation, the fluid excluding the kerogen in the formation. A density tool disposed at the carrier determines bulk density of the formation, and a processor determines the volumetric fraction of oil in the formation based on the excess carbon, the porosity of the fluid in the formation, and the bulk density of formation.

First claim

The invention claimed is:

1. A system to determine a volumetric fraction of oil in a formation penetrated by a borehole, the formation comprising an unconventional reservoir, the system comprising:
a carrier configured to be conveyed through the borehole;
a geochemical tool disposed at the carrier and configured to determine a mineral makeup of the formation and excess carbon not apportioned to any mineral of the mineral makeup, the excess carbon being associated with kerogen and oil in the formation;
an NMR tool disposed at the carrier and configured to determine porosity of fluid in the formation, the fluid excluding the kerogen in the formation;
a density tool disposed at the carrier and configured to determine bulk density of the formation; and
a processor configured to determine the volumetric fraction of oil in the formation based on the excess carbon, the porosity of the fluid in the formation, and the bulk density of formation.

2. The system according to claim 1 , further comprising a spectroscopy tool disposed at the carrier and, in conjunction with the geochemical tool, configured to determine an inorganic grain density of the formation.

3. The system according to claim 1 , wherein the processor determines volumetric fraction of oil V oil as:
V oil =W oil /ρ oil ,

where W oil is a weight fraction of oil in the formation, and
ρ oil is a known density of oil.

4. The system according to claim 3 , wherein the processor determines oil saturation of the formation as:
S oil =V oil /φ NMR ,

where φ NMR is the porosity of the fluid determined by the NMR tool.

5. The system according to claim 3 , wherein the processor determines the weight fraction of oil W oil as:
W oil =W C _ oil *C oil ,
where C oil is a known weight portion of carbon in pure oil, and
W C _ oil is a weight fraction of carbon residing in the oil relative to carbon in the formation.

6. The system according to claim 5 , wherein the processor determines the weight fraction of carbon residing in the oil relative to the carbon in the formation as:
W C _ oil =W ExcessCarbon −W C _ Kerogen ,
where W C _ Kerogen is a weight fraction of carbon in the kerogen relative to the carbon in the formation, and
W ExcessCarbon is the excess carbon determined using the geochemical tool.

7. The system according to claim 6 , wherein the weight fraction of the carbon in the kerogen relative to the carbon in the formation is determined as:
W C _ Kerogen =W kerogen *C k ,
where C k =weight portion of carbon in pure kerogen, and

W
kerogen

=

V
kerogen

*

(

1
-

ϕ
NMR

)

*

ρ
kerogen

ρ
b

,

where V kerogen is a volumetric portion of the kerogen in the solid portion of the formation,
φ NMR is the porosity of the fluid determined by the NMR tool, and
ρ b is the bulk density determined by the density tool.

8. The system according to claim 7 , wherein the processor determines the volumetric portion of the kerogen in the solid portion of the formation from the following:
ρ solid =ρ minerals *(1 −V kerogen )+ρ kerogen *V kerogen ,

where ρ solid is density of a solid portion of the formation,
ρ minerals is the inorganic grain density determined from the geochemical tool and the spectroscopy tool, and
ρ kerogen =the kerogen density.

9. The system according to claim 8 , wherein the processor determines the density of the solid portion of the formation from:
ρ b =ρ solid *(1−φ NMR )+ρ fluid *φ NMR ,

where
ρ fluid =density of the fluid in the formation.

10. A method of determining a volumetric fraction of oil in a formation penetrated by a borehole, the formation comprising an unconventional reservoir, the method comprising:
obtaining measurements from downhole tools, the measurements indicating excess carbon, the excess carbon being associated with kerogen and oil in the formation, bulk density, and porosity of the fluid in the formation;
determining inorganic grain density of the formation based on a determined mineral makeup of the formation;
determining the kerogen component of the excess carbon; and
determining the volumetric fraction of oil in the formation based on the excess carbon and the kerogen component of the excess carbon.

11. The method according to claim 10 , further comprising determining oil saturation of the formation based on the volumetric fraction of the oil and the porosity of the fluid in the formation.

12. The method according to claim 10 , wherein the determining the kerogen component of the excess carbon includes determining a weight fraction of carbon in the kerogen as:
W C _ Kerogen =W kerogen *C k ,
where C k =weight portion of carbon in pure kerogen, and

W
kerogen

=

V
kerogen

*

(

1
-

ϕ
NMR

)

*

ρ
kerogen

ρ
b

,

where V kerogen is a volumetric portion of the kerogen in the solid portion of the formation,
φ NMR is the porosity of the fluid in the formation, and
ρ b is the bulk density.

13. The method according to claim 12 , wherein the determining the kerogen component of the excess carbon further includes determining the volumetric portion of the kerogen in the solid portion of the formation as:
ρ solid =ρ minerals *(1 −V kerogen )+ρ kerogen *V kerogen ,

where ρ solid is density of a solid portion of the formation,
ρ minerals is the inorganic grain density, and
ρ kerogen =the kerogen density.

14. The method according to claim 13 , wherein the determining the volumetric portion of the kerogen in the solid portion of the formation includes determining the density of the solid portion of the formation as:
ρ b =ρ solid *(1−φ NMR )+ρ fluid *φ NMR ,

where
ρ fluid =density of the fluid in the formation.

15. The

Assignees

• Quinn Terrence H
• Ashby Michael P
• Bratovich Matt W
• Chen Jinhong
• Frost Elton
• Sommer Duane A
• Warrington Daniel S
• Zhang Jilin
• Baker Hughes Inc

Inventors

• Quinn Terrence H
• Ashby Michael P
• Bratovich Matt W
• Chen Jinhong
• Frost Elton
• Sommer Duane A
• Warrington Daniel S
• Zhang Jilin

Classifications

• G01V9/00

  Prospecting or detecting by methods not provided for in groups G01V1/00 - G01V8/00 · CPC title

• G01V3/32

  operating with electron or nuclear magnetic resonance · CPC title

• G01V3/14

  operating with electron or nuclear magnetic resonance · CPC title

• G01V3/38 Primary

  Processing data, e.g. for analysis, for interpretation, for correction · CPC title