Patent US3727685A successfully refreshed from Google Patents.
US3727685A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for thermally cutting tubing
Assignee: Shell USA Inc
•
Filing: 1971-11-15
•
Granted: 1973-04-17
•
Expires: 1991-11-15
Abstract
Abstract A method for thermally cutting tubing, such as below an internal restriction in a tubing string located in a well bore, which comprises placing in the tubing at the desired location a mixture of finely granulated aluminum with an oxide of iron or other metal and igniting the mixture while applying a tensile load to the tubing string.
Inventors
- 👤 D Chestnut
- 👤 C Morris
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 15:01
CPC Classifications
E; E21; E21B; E21B29/00; E21B29/02
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
121 words
A method for thermally cutting tubing in well casing below an internal restriction in said tubing, said method comprising the steps of: determining the interval in which the tubing is restricted; plugging said tubing below said restriction by lowering suitable plugging means in said tubing a predetermined distance below said restriction; placing a predetermined volume of Thermit using suitable means below said restriction and on top of said plugging means; lowering starting Thermit and suitable ignition means into said tubing such that it is in contact with said thermit; igniting said starting Thermit with said ignition means; applying a tensile force to said tubing at a predetermined time interval after igniting said starting Thermit; and removing said tubing from said well.
Claim 2
Independent Claim
121 words
A method for thermally cutting tubing in well casing below an internal restriction in said tubing, said method comprising the steps of: determining the interval in which the tubing is restricted; plugging said tubing below said restriction by lowering suitable plugging means in said tubing a predetermined distance below said restriction; placing a predetermined volume of Thermit using suitable means below said restriction and on top of said plugging means; lowering starting Thermit and suitable ignition means into said tubing such that it is in contact with said thermit; igniting said starting Thermit with said ignition means; applying a tensile force to said tubing at a predetermined time interval after igniting said starting Thermit; and removing said tubing from said well.
Claim 3
Dependent Claim
24 words
The method of claim 1 wherein determining the interval in which the tubing is restricted is by free-pointing said tubing string using suitable means.
Claim 4
Dependent Claim
23 words
The method of claim 1 wherein the volume of Thermit is equal to the volume of 6 to 18 inches of tubing volume.
Claim 5
Dependent Claim
25 words
The method of claim 1 wherein plugging the tubing a predetermined distance below said restriction is above the first tubing collar occurring below the restriction.
Claim 6
Dependent Claim
28 words
The method of claim 1 wherein a tensile force of 5,000 to 30, 000 pounds over the weight of said tubing string is applied to said tubing string.
Claim 7
Dependent Claim
16 words
The method of claim 1 wherein the predetermined time interval ranges from 5 to 15 seconds.
References Cited (Backward Citations)
US2144208A
Cited
US2436036A
Cited
US2746550A
Cited
US2839143A
Cited
US3076507A
Cited
US3115184A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-04-16 | 1976-10-16 | 1977-04-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-04-16 | 1980-10-16 | 1981-04-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-04-16 | 1984-10-16 | 1985-04-17 | $7700.00 | Window Closed / Lapsed |