US4822422A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Ca(OH)2 -treated ceramic microsphere
Assignee: Associated Universities, Inc.
•
Filing: 1987-10-09
•
Granted: 1989-04-18
•
Expires: 2007-10-09
Abstract
Abstract Geothermal wells with lost circulation problems are treated with a lightweight, high temperature (i.e. 350° C.) cement slurry which incorporates pressure resistant hollow microspheres into the slurry wherein the spheres have been pretreated with an alkali compound such as Ca(OH) 2 for up to 20 hours and at 100°-300° C. Preferably, the alkali solution is a saturated aqueous solution and the treatment is for 10 hours.
Inventors
- 👤 Toshifumi Sugama
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 18:38
CPC Classifications
C; C09; C09K; C09K8/00; C09K8/42; C09K8/46; C09K8/467; C09K8/473; C04; C04B; C04B20/00; C04B20/02; C09K8/487; C04B2103/00; C04B2103/46
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
58 words
A lightweight cement slurry composed of: ______________________________________
Weight percent
______________________________________
Class H Cement (C) 30
Silica flour (S) 10
Water 35
Pressure resistant sillimanite-
25
based microspheres treated before
inclusion in the slurry by washing
and exposing to a solution of an
alkali earth metal hydroxide at an
elevated temperature for a period
up to twenty hours
______________________________________
Claim 2
Dependent Claim
58 words
A lightweight cement slurry composed of: ______________________________________
Weight percent
______________________________________
Class H Cement (C) 30
Silica flour (S) 10
Water 35
Pressure resistant sillimanite-
25
based microspheres treated before
inclusion in the slurry by washing
and exposing to a solution of an
alkali earth metal hydroxide at an
elevated temperature for a period
up to twenty hours
______________________________________
References Cited (Backward Citations)
US4504320A
Cited
US4689084A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-04-17 | 1992-10-17 | 1993-04-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-04-17 | 1996-10-17 | 1997-04-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-04-17 | 2000-10-17 | 2001-04-18 | $7700.00 | Window Closed / Lapsed |