Patent US3766985A successfully refreshed from Google Patents.
US3766985A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Production of oil from well cased in permafrost
Assignee: University of Kansas
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Filing: 1971-12-01
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Granted: 1973-10-23
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Expires: 1991-12-01
Abstract
Abstract Thawing of permafrost surrounding a surface casing of a wellbore is minimized during production of hot oil by injecting liquid refrigerant in an annulus between the surface casing and the production casing, allowing heat from the hot oil to vaporize the refrigerant as it descends in said annulus, and removing the resulting vaporized refrigerant at the well-head, thereby maintaining the surface casing at a temperature of 32* F. or lower.
Inventors
- 👤 G Willhite
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 07:31
CPC Classifications
E; E21; E21B; E21B36/00; E21B36/003; Y; Y10; Y10S; Y10S166/00; Y10S166/901
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
22 words
The method according to claim 1, wherein said production string is encircled by insulation medium, such as foamed polyurethane or gelled oil.
Claim 2
Dependent Claim
14 words
The method according to claim 1, wherein said liquefied refrigerant is propane or ammonia.
Claim 3
Dependent Claim
36 words
The method according to claim 1, wherein said injected liquefied refrigerant is injected at a rate sufficient to ensure substantially complete coverage of said inner wall of said surface casing with said falling film of refrigerant.
Claim 4
Dependent Claim
37 words
The method according to claim 4, wherein said production string comprises a production casing which can have one or more production tubings disposed therein, and wherein said annulus is between said surface casing and said production casing.
Claim 5
Dependent Claim
38 words
The method according to claim 1, wherein said production string comprises a production tubing, the outer surface of which is bonded to a layer of foamed polyurethane insulation extending over the upper portion of all of said permafrost.
Claim 6
Dependent Claim
81 words
Apparatus for producing fluids from reservoirs penetrated by a wellbore surrounded at its upper end by permafrost, which comprises surface casing and production string depending within said surface casing with an annulus therebetween, means to inject liquefied refrigerant in said annulus, means to direct said injected liquefied refrigerant to the inner wall of said surface casing to cause said injected refrigerant to descend thereon as a falling film, and means for withdrawing vaporized refrigerant from the upper end of said annulus.
Claim 7
Dependent Claim
20 words
Apparatus according to claim 7, further comprising insulation means, such as polyurethane foam or gelled oil, encircling said production string.
Claim 8
Dependent Claim
34 words
Apparatus according to claim 7, wherein said production string comprises a production casing which can have one or more production tubings disposed therein, said annulus being between said surface casing and said production casing.
Claim 9
Dependent Claim
55 words
Apparatus according to claim 7, further comprising a perforated sleeve depending within said annulus and dividing the same into an outer annular region and an inner annular region, said means for injecting communicating with the upper end of said outer annular region, and said means for withdrawing vaporized refrigerant communicating with said inner annular region.
Claim 10
Dependent Claim
26 words
Apparatus according to claim 7, further comprising perforated tubing depending within said annulus, said means for injecting communicating with the upper end of said perforated tubing.
Claim 11
Dependent Claim
71 words
ApparatuS according to claim 7, further comprising two concentric insulating placement casings encircling said production string with an outer annular region between the said placement casings and an inner annular region between said production string and the innermost of said placement casings, said annular regions being filled with insulation fluid, said annulus in which said liquid refrigerant is injected being between said surface casing and the outermost of said placement casings.
Claim 12
Dependent Claim
29 words
Apparatus according to claim 7, further comprising means for compressing and liquefying said withdrawn vaporized refrigerant and means for recycling the resulting reliquefied refrigerant to said means for injecting.
Claim 13
Dependent Claim
40 words
Apparatus according to claim 7 wherein said production string comprises a production tubing having a layer of foamed polyurethane insulation bonded to the outer surface of said production tubing and extending over the upper portion or all of said permafrost.
Claim 14
Independent Claim
205 words
A method of minimizing the thawing of permafrost surrounding a wellbore in which are disposed a surface casing adjacent said permafrost and production string disposed within said surface casing with an annulus between said casing and said production string, wherein said annulus is divided into an inner annular region and an outer annular region by means of a perforated sleeve depending within said annulus, which method comprises, during production, injecting liquefied refrigerant into the upper end of said outer annular region, filling the same, passing said liquefied refrigerant from said outer annular region into said inner annular region through perforations in said perforated sleeve whereby a portion of said liquid refrigerant vaporizes as it passes through said perforations and a portion of it passes downwardly in said inner annular region as a falling film on the inner wall of said perforated sleeve while retaining free gas space in said inner annular region, heat emanating from said production string vaporizing said falling film as it descends within said inner annular region, the resulting vaporized refrigerant ascending in said inner annular region and being removed from the upper end thereof without commingling the same with production fluid and without accumulating liquid refrigerant within said inner annular region.
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) | 1976-10-22 | 1977-04-23 | 1977-10-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-10-22 | 1981-04-23 | 1981-10-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-10-22 | 1985-04-23 | 1985-10-23 | $7700.00 | Window Closed / Lapsed |