US3784898A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for reducing borehole signals in nuclear magnetic logging
Assignee: Shell USA Inc
•
Filing: 1972-02-16
•
Granted: 1974-01-08
•
Expires: 1992-02-16
Abstract
Abstract In a nuclear magnetic logging system a method for reducing the proton free-precession signal emanating from the borehole fluids by replacing the borehole fluid with a fluid containing at least 0.10 lbs/bbl of fluid of magnetized magnetite. The magnetite is first mixed with a fluid to form a concentrated mixture or slurry and the slurry passed through a magnetic field to magnetize the magnetite. The concentrated slurry is then mixed with additional fluid to provide a fluid for use in displacing the borehole fluid.
Inventors
- 👤 H Darley
- 👤 J Robinson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-10 01:48
CPC Classifications
G; G01; G01V; G01V3/00; G01V3/18; G01V3/32
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
39 words
The method of claim 1 wherein the magnetizied magnetite is added to the borehole fluid by adding it to the fluid at the surface and then circulating the fluid containing magnetite through the borehole to replace the borehole fluid.
Claim 2
Dependent Claim
38 words
The method of claim 2 wherein the concentrated solution of magnetite is prepared by suspending at least 50 pounds of magnetite in a barrel of the compatible fluid and then passing the concentrated solution through a magnetic field.
Claim 3
Dependent Claim
12 words
The method of claim 3 wherein the compatible fluid is diesel oil.
Claim 4
Dependent Claim
14 words
The method of claim 3 wherein the compatible solution is a water-based drilling mud.
Claim 5
Dependent Claim
36 words
The method of claim 1 wherein the borehole fluid is drilling mud and the concentrated slurry is added to the drilling mud in the mud pits and then circulated through the borehole by the mud pump.
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) | 1977-01-07 | 1977-07-09 | 1978-01-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-01-07 | 1981-07-09 | 1982-01-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-01-07 | 1985-07-09 | 1986-01-08 | $7700.00 | Window Closed / Lapsed |