US4191883A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for determining residual oil concentration of a formation using thermal neutron decay measurements
Assignee: ConocoPhillips Co
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Filing: 1978-06-01
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Granted: 1980-03-04
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Expires: 1998-06-01
Abstract
Abstract An improvement in the method of determining oil saturation in a subterranean formation, penetrated by a well-bore, is disclosed. In the method of determining oil concentration by measuring thermal neutron decay with a low salinity aqueous liquid in said well-bore and said formation, and measuring thermal neutron decay with a high salinity aqueous liquid in said well-bore and said formation, the improvement comprises adding to said low salinity liquid in the well-bore, only, a material which adjusts the thermal neutron capture cross section of the well-bore so that it is approximately the same as the thermal neutron capture cross section of the well-bore when it contains the high salinity liquid.
Inventors
- 👤 James C. Albright
- 👤 Preston L. Gant
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 15:49
CPC Classifications
G; G01; G01V; G01V5/00; G01V5/04; G01V5/08; G01V5/10
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
159 words
In the method of determining oil saturation in a subterranean formation penetrated by a well-bore wherein the method comprises: (a) measuring the thermal neutron decay of a liquid, said liquid having either low or high salinity, in said well-bore and said formation to obtain a first value Σ A (b) measuring the thermal neutron decay of a liquid, said liquid having a salinity value opposite of that used in step (a) in said well-bore and said formation to obtain a second value Σ B and (c) determining from Σ A and Σ B the oil saturation in said reservoir, the improvement comprising adding to said low salinity liquid a sufficient amount of a material which adjusts the thermal neutron capture cross section of that part of said low salinity material which remains in the borehole so that the thermal neutron capture cross section is approximately the same as the thermal neutron capture cross section of the high salinity liquid.
Claim 2
Dependent Claim
159 words
In the method of determining oil saturation in a subterranean formation penetrated by a well-bore wherein the method comprises: (a) measuring the thermal neutron decay of a liquid, said liquid having either low or high salinity, in said well-bore and said formation to obtain a first value Σ A (b) measuring the thermal neutron decay of a liquid, said liquid having a salinity value opposite of that used in step (a) in said well-bore and said formation to obtain a second value Σ B and (c) determining from Σ A and Σ B the oil saturation in said reservoir, the improvement comprising adding to said low salinity liquid a sufficient amount of a material which adjusts the thermal neutron capture cross section of that part of said low salinity material which remains in the borehole so that the thermal neutron capture cross section is approximately the same as the thermal neutron capture cross section of the high salinity liquid.
Claim 3
Dependent Claim
30 words
The method of claim 1 wherein the thermal neutron additive material is selected from the group consisting of boron, cadmium, gadolinium, dysprosium, samarium, europium, chlorine and compounds containing these elements.
Claim 4
Dependent Claim
73 words
The method of claim 2 wherein the amount of material which is added is determined by using the equation ##EQU3## wherein X is the volume fraction of the material, Σ WH is the thermal neutron capture cross section of the high salinity liquid, Σ WL is the thermal neutron capture cross section of the low salinity liquid in the well-bore, and Σ M is the thermal neutron cross section of the additive material.
Claim 5
Dependent Claim
24 words
The method of claim 3 wherein the term high salinity liquid refers to a liquid containing at least 100,000 parts per million sodium chloride.
Claim 6
Dependent Claim
24 words
The method of claim 4 wherein the term low salinity liquid refers to material containing not more than 50,000 parts per million sodium chloride.
Claim 7
Dependent Claim
13 words
The method of claim 5 wherein the material which is added is boron.
Claim 8
Dependent Claim
17 words
The method of claim 6 wherein the boron is added in the form of borated polyethylene beads.
Claim 9
Dependent Claim
14 words
The method of claim 5 wherein the material is cadmium or a cadmium-containing compound.
Claim 10
Dependent Claim
14 words
The method of claim 5 wherein the material is gadolinium or a gadolinium-containing compound.
Claim 11
Dependent Claim
14 words
The method of claim 5 wherein the material is dysprosium or a dysprosium-containing compound.
Claim 12
Dependent Claim
14 words
The method of claim 5 wherein the material is samarium or a samarium-containing compound.
Claim 13
Dependent Claim
14 words
The method of claim 5 wherein the material is europium or an europium-containing compound.
Claim 14
Dependent Claim
14 words
The method of claim 5 wherein the material is chlorine or a chlorine-containing compound.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-03-04 | 1983-09-03 | 1984-03-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-03-04 | 1987-09-03 | 1988-03-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-03-04 | 1991-09-03 | 1992-03-04 | $7700.00 | Window Closed / Lapsed |