Research and Application of Drag Type Fine Control Multi-stage Fracturing Technology for Horizontal Wells

The large-scale volume fracturing is commonly believed as an effective way to recover oil from thin, low porosity and ultra-low permeability tight reservoirs. However, the proprietary single-stage & single-cluster drag type fine control fracturing technology is not suitable for the large scale fracturing application for the existence of such problems as serious wear & corrosion of the tools, tools broken accident, and the conventional mechanical Y211 bottom packer cannot meet the requirements of low setting force and high differential pressure. The dual-packer drag type tubing fracturing technology and the coiled tubing single-packer drag type casing fracturing technology are innovatively developed through the mechanical analysis, numerical simulation, and tool structure optimization design. The key tools such as K344-105 packer, large sand volume pressure-transmitting sand jet, series of tubing BOP, new Y211 bottom packer and hydraulic sand jet perforating gun with high performance are designed. Lab testing and field runs have confirmed that the dual-packer drag type fine control multi-stage fracturing technology rated up to differential pressure of 70 MPa at 120 ℃. Up to 18 stages of fracturing can be executed in one trip with the flowback circulation rate of below 8 m3/min and sand loading volume scale of 516 m3 during operation. The technology has been applied to 716 well times in the field application. The coiled tubing single-packer drag type casing fracturing technology rated up to differential pressure of 70 MPa at 150 ℃. Up to 94 stages of fracturing can be executed in one trip with the flowback circulation rate of over 8 m3/min, and the technology has been applied to 538 wells in the field application. The drag type fine control multi-stage fracturing technology for horizontal wells has become the domain fracturing technology in Daqing Oilfield.