US3657730A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for determining residual hydrocarbons present in a subterranean earth formation
Assignee: Shell USA Inc
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Filing: 1970-01-14
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Granted: 1972-04-18
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Expires: 1990-01-14
Abstract
Abstract A method for determining residual hydrocarbons present in a subterranean earth formation by quantitatively determining the amplitude of the proton free-precession signal that is due to the protons contained in the residual hydrocarbons that are present in an interval of the subterranean hydrocarbon-bearing earth formation. The mud cake is removed or made permeable along a section of a well borehole adjacent the interval to be tested. An aqueous solution is injected down the well borehole and into the interval to be tested until the injected fluid occupies substantially all of the space within the well borehole and the interval to be tested that was previously occupied by other aqueous liquids in a zone extending into the interval to be tested at least substantially as deeply as a nuclear magnetism measuring device is to be responsive to proton free-precession signals. The solution which is injected contains sufficient dissolved paramagnetic material to provide a water phase nuclear magnetism thermal relaxation time that is too short to be responded to by the nuclear magnetism measuring device. A nuclear magnetism measuring device is disposed within the well borehole adjacent the interval to be tested and measurements are made of the responses with time of the device to (a) noise in the absence of polarization and (b) proton free-precession signal plus noise. At least one function of the noise and at least one function of the signal plus noise are combined to determine the signal amplitude at the end of the polarization.
Inventors
- 👤 Joseph D Robinson
- 👤 Jay D Loren
- 👤 William T Higdon
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 15:49
CPC Classifications
G; G01; G01V; G01V3/00; G01V3/18; G01V3/32; Y; Y02; Y02A; Y02A90/00; Y02A90/30
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
224 words
A well logging method for determining residual hydrocarbons present in a subterranean earth formation by quantitatively determining the amplitude of the proton free-precession signal due to the protons contained in the hydrocarbons that are present in an interval of said subterranean hydrocarbon-bearing earth formaTion, said process comprising the steps of: removing the fluid impermeability of a mud cake formed on the wall of a well borehole adjacent said interval; pumping an aqueous solution through said well borehole and into said interval until substantially all of the space within said well borehole and said interval that was previously occupied by other aqueous liquid is occupied by said solution within a zone extending into said interval at least substantially as deeply as a nuclear magnetism measuring device is to be responsive to proton free-precession signals, said solution containing sufficient dissolved paramagnetic material to provide a water phase nuclear magnetism thermal relaxation time that is too short to be responded to by the nuclear magnetism measuring device; positioning a nuclear magnetism measuring device in said well borehole adjacent said interval; making a plurality of measurements of, respectively, noise in the absence of polarization and proton free-precession signal plus noise; and combining a function of the noise with a function of the signal plus noise in order to determine the signal amplitude at the end of said polarization.
Claim 2
Dependent Claim
224 words
A well logging method for determining residual hydrocarbons present in a subterranean earth formation by quantitatively determining the amplitude of the proton free-precession signal due to the protons contained in the hydrocarbons that are present in an interval of said subterranean hydrocarbon-bearing earth formaTion, said process comprising the steps of: removing the fluid impermeability of a mud cake formed on the wall of a well borehole adjacent said interval; pumping an aqueous solution through said well borehole and into said interval until substantially all of the space within said well borehole and said interval that was previously occupied by other aqueous liquid is occupied by said solution within a zone extending into said interval at least substantially as deeply as a nuclear magnetism measuring device is to be responsive to proton free-precession signals, said solution containing sufficient dissolved paramagnetic material to provide a water phase nuclear magnetism thermal relaxation time that is too short to be responded to by the nuclear magnetism measuring device; positioning a nuclear magnetism measuring device in said well borehole adjacent said interval; making a plurality of measurements of, respectively, noise in the absence of polarization and proton free-precession signal plus noise; and combining a function of the noise with a function of the signal plus noise in order to determine the signal amplitude at the end of said polarization.
Claim 3
Dependent Claim
33 words
The method of claim 1 including the step of filling said well borehole with fresh water prior to removing the fluid impermeability of the mud cake on the wall of said well borehole.
Claim 4
Dependent Claim
52 words
The method of claim 1 wherein the step of removing or making permeable said mud cake includes the step of swabbing said interval until formation water is produced from said interval of formation and any mud cake present on the wall of said well borehole adjacent said interval is substantially removed therefrom.
Claim 5
Dependent Claim
25 words
The method of claim 1 wherein the step of injecting an aqueous solution includes the step of injecting an aqueous solution of chelated paramagnetic material.
Claim 6
Dependent Claim
26 words
The method of claim 4 wherein the step of injecting an aqueous solution of chelated paramagnetic material includes the step of injecting a manganous versene solution.
Claim 7
Dependent Claim
61 words
The method of claim 5 including the step of following said injection of a manganous versene solution with an injection of a sufficient quantity of mud containing no magnetite into said interval to form a mud cake on the wall of said interval, said mud using as a make-up fluid the fluid from the previous step of injecting said aqueous solution.
Claim 8
Dependent Claim
42 words
The method of claim 6 including the step of following the formation of said magnetite-free mud cake on the wall of said interval with a disposition in the borehole of an aqueous liquid containing magnetite in suspension and manganous versene in solution.
Claim 9
Dependent Claim
41 words
The method of claim 1 wherein the step of injecting an aqueous solution into said interval includes the step of injecting enough of said aqueous solution to fill a zone extending approximately five feet into said interval from said well borehole.
Claim 10
Dependent Claim
30 words
The method of claim 1 wherein the step of making a plurality of measurements includes the step of making a plurality of measurements separated sufficiently in time to be independent.
Claim 11
Dependent Claim
49 words
The method of claim 1 including the step of utilizing the data obtained by combining a function of the noise with a function of the signal plus noise to determine the amount of oil per unit volume of earth formation that is present in said interval of earth formation.
Claim 12
Dependent Claim
40 words
The method of claim 1 wherein the step of removing the fluid impermeability of the mud cake formed on the wall of said well borehole includes the step of removing said mud cake from the wall of said well borehole.
Claim 13
Dependent Claim
36 words
The method of claim 1 wherein the step of removing the fluid impermeability of the mud cake formed on the wall of said well borehole includes the step of rendering said mud cake permeable to fluid.
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) | 1975-04-18 | 1975-10-18 | 1976-04-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-04-18 | 1979-10-18 | 1980-04-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-04-18 | 1983-10-18 | 1984-04-18 | $7700.00 | Window Closed / Lapsed |