US3874451A
Expired / Lapsed
US
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Determination of oil saturation in a reservoir
Assignee: Marathon Oil Co
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Filing: 1974-04-12
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Granted: 1975-04-01
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Expires: 1994-04-12
Abstract
Abstract Oil saturation in a reservoir is determined by injecting into the reservoir a displacing fluid that will displace oil and water toward an observation well forming a ''''stable'''' oil-water bank, and measuring the arrival time of the stable oil-water bank at the well--a substantial difference in the rate of bottom-hole pressure change is realized once the bank arrives at the observation well. From these data, the oil saturation is determined by the formula:
Inventors
- 👤 Stanley C Jones
- 👤 Robert W Parson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 20:42
CPC Classifications
E; E21; E21B; E21B49/00; E21B43/00; E21B43/16
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
204 words
A process of determining in situ the average oil saturation in an oil-bearing reservoir in fluid communication with at least one observation well removed from the injected well, and wherein the oil saturation in the reservoir is not equal to the oil saturation in the below defined oil-water bank and/or the mobility of the fluids flowing ahead of the oil-water bank is not equal to the mobility of the fluids within the oil-water bank, the process comprising injecting into the reservoir sufficient volume of a displacing fluid to substantially displace the formation fluids toward the observation well and to obtain a stable oil-water bank at the observation well, determining the time of arrival of the oil-water bank at the observation well, and thereafter determining the average oil saturation by the following formula: Soi fob (1 - Vi) + foi Vi wherein Soi is the average oil saturation between the injectioN well and the observation well, fob is the fractional flow of oil in the oil-water bank, Vi is the pore volume of displacing fluid injected into the injection well to obtain arrival of the oilwater bank at the observation well, and fob is the fractional flow of oil before arrival of the oil-water bank.
Claim 2
Dependent Claim
204 words
A process of determining in situ the average oil saturation in an oil-bearing reservoir in fluid communication with at least one observation well removed from the injected well, and wherein the oil saturation in the reservoir is not equal to the oil saturation in the below defined oil-water bank and/or the mobility of the fluids flowing ahead of the oil-water bank is not equal to the mobility of the fluids within the oil-water bank, the process comprising injecting into the reservoir sufficient volume of a displacing fluid to substantially displace the formation fluids toward the observation well and to obtain a stable oil-water bank at the observation well, determining the time of arrival of the oil-water bank at the observation well, and thereafter determining the average oil saturation by the following formula: Soi fob (1 - Vi) + foi Vi wherein Soi is the average oil saturation between the injectioN well and the observation well, fob is the fractional flow of oil in the oil-water bank, Vi is the pore volume of displacing fluid injected into the injection well to obtain arrival of the oilwater bank at the observation well, and fob is the fractional flow of oil before arrival of the oil-water bank.
Claim 3
Dependent Claim
18 words
The process of claim 1 wherein at least a majority of the displacing fluid is a micellar dispersion.
Claim 4
Dependent Claim
12 words
The process of claim 1 wherein the reservoir is under primary production.
Claim 5
Dependent Claim
17 words
The process of claim 1 wherein the reservoir is at or substantially close to residual oil saturation.
Claim 6
Dependent Claim
22 words
The process of claim 1 wherein two or more observation wells on different azimuths are in fluid communication with the injection well.
Claim 7
Dependent Claim
26 words
The process of claim 1 wherein two or more observation wells at different distances on the same azimuth are in fluid communication with the injection well.
Claim 8
Dependent Claim
25 words
The process of claim 1 wherein the observation well has pressure measuring capabilities from which the arrival time of the oil-water bank can be determined.
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) | 1978-03-31 | 1978-09-30 | 1979-04-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-03-31 | 1982-09-30 | 1983-04-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-03-31 | 1986-09-30 | 1987-04-01 | $7700.00 | Window Closed / Lapsed |