The gas reservoirs of Hongtai Gas Field are characterized by low porosity,super-Low permeability and severe heterogeneity with multilayer in vertical.If the strings for two-layer separate fracturing are taken to complete five-layer fracturing,there will be some problems,such as killing well many times,long-term construction,serious reservoir damage and the little production increasing,so a pilot testing of the string for five-layer separate layer fracturing was conducted,that is,ball-off was used to open sand blower for sand fracturing by three Y241 and a Y221,then releasing packer step by step,releasing string stage-by-stage and running the production string were carried after the end of spurting.The pilot testing of the string for five-layer separate layer fracturing was conducted successfully in Hongtai 25-2 well,which increased the gas productivity obviously.

The utility model discloses a five-layer layered compression fracture technology pipe column capable of mechanical isolating and progressive unpacking, which progressively unpacks, fishes by sections, and meets the requirement of layered compression fracture of five layered sections with one pipe column; the pipe column performs the layered compression fracture of five layered sections at one time, after the blowout is finished, the pipe column is directly uplifted, so as to progressively unpack the packer; by taking into consideration of the size of the unpacking additional force, directly lifting out the pipe column or sequentially lifting out the pipe column by sections is adopted, so that the pipe column is prevented from being jammed by the sand and the over-big unpacking force is prevented, as a result, the five-grade unpacking of the packer and the jamming difficulty of the compression fracture pipe column are solved, and the purposes of safety work, well workover time saving, and reservoir stratum damage reduction are achieved.