| 摘要 |
The present invention relates to a method of forming fractures and placing proppants therein, which comprises creating a foam having a down-well Mitchell quality of form about 0.53 to 0.99 and passing that foam down the well in admixture with a particulate proppant in an amount of up to four pounds of proppant per gallon of foam, then decreasing the gas volume in said foam, whereby the proppant carrying medium being passed down the well changes from a foam to a liquid. The proppant concentration is decreased as the change occurs from foam to liquid so that the proppant material will not deposit out prematurely in the well. Once liquid flow has been established, the proppant to fluid ratio is gradually increased and the fracture of the formation is continued with liquid and proppant. The liquid is capable of carrying an amount of proppant greater than that which could be carried by the foam, namely an amount up to twelve pounds per U.S. gallon.
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