Multiple-stage coal seam fracing method
US4665990A · kind A · utility
Inventor
Key dates
| Filing date | Oct 17, 1985 |
| Grant date | May 19, 1987 |
| Priority date | — |
| Expiry date | Oct 17, 2005 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B43/27
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
An improved method of multiple-stage hydraulic fracturing of coal seams to improve the rate and total recovery of gas therefrom. In one aspect, the improvement comprises completing the well with 7-inch or larger casing and 31/2 inch or larger tubing. In another aspect, the stagewise fracturing is continued until the following quantity of 60-140 mesh proppants has been deposited in the formation: ______________________________________ for 5 .ltoreq. h < 10, m .gtoreq. 500,000; for 10 .ltoreq. h < 15, m .gtoreq. 750,000; for 15 .ltoreq. h < 20, m .gtoreq. 1,000,000; for 20 .ltoreq. h < 25, m .gtoreq. 2,000,000; and for h .gtoreq. 25, m .gtoreq. 3,000,000; ______________________________________ wherein h is the vertical thickness of the coal seam in feet and m is the minimum quantity of the fine proppants in pounds deposited therein. In another aspect, a coal seam fractured by the multiple-stage method is refractured after producing or shutting in the well for a period of time to permit closure of the fractures on the proppant placed therein in the earlier multiple-stage fracturing of the coal seam.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.