Study and application of technologies for separate layer fracturing without pulling string in high pressure gas reservoir

Western Sichuan gas reservoirs are characterized by low permeability and high pressure with multilayers ranging from 10m to 100m between each layer. In order to improve the productivity of the gas producers and achieve good economic efficiency, fracturing strings are used directly as the string of production due to the fact that serious reservoir damage might occur and the postfracture response might be affected when killing well after sand fracturing. Therefore, separate fracturing technology was used with two layers separated by FCY211 or Y241 packers. Meanwhile, on the basis of the results of using the technology of two-layer separate fracturing, three-layer separate layer fracturing was developed with "packer and ball off " fracture technology. Field application results indicated that the separate layer fracturing can increase the gas productivity of individual well greatly and achieve obvious economic benefits, which provided a good example for separate layer fracturing and the gas production in similar multilayer gas reservoirs.