| 摘要 |
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 </= h < 10, m >/= 500,000; -for 10 </= h < 15, m >/= 750,000; -for 15 </= h < 20, m >/= 1,000,000; -for 20 </= h < 25, m >/= 2,000,000; and -for h >/= 25, m >/= 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. |
