Study On Multi-stage Pressure-transmitted Packer Fracturing Technique String

The reserve located in the outer of Daqing oilfield distributes in the Fuyang reservoir,which is with low or even ultra-low permeability and natural capacity.To increase the production,it is prospective to raise the stimulation strength of wells.Multi-stage fracturing technique can decrease the fracturing time and workload and control the cost.Based on the comprehensive investigation of multi-stage fracturing technology in low-permeability reservoirs at home and abroad,two multi-stage pressure-transmitted packer fracturing schemes are proposed according to different well temperature and working pressure.The expansion-type pressure-transmitted packer is developed through the analysis of technical difficulties,optimization of the tool structure and design of temperature-resistant pressure-resistant rubber cylinder.The anchoring force of the anchor claw to the casing under different loads is measured by indoor pressure test.A new type of hydraulic anchor is developed.Compressed-type pressure-transmitted packer is developed by using SOLIDWORKS finite element software and laboratory test method.For a horizontal well,an example is given to analyze the mechanical behavior of three stages of fracturing process pipe string of multistage pressure-transmitted packer by using the steady torque model of oil and gas well string.All the tools were connected to verify the performance of multi-stage expansion-type pressure-transmitted packer.The experimental results show that the technical index of fracturing process pipe string of multistage pilot packer is 120 ? and 70 MPa,and the technical index of compression type pressure-transmitted packer is 150 ? and 70 MPa.Under diesel immersion conditions,after repeated bearing high pressure fatigue test,packers meet the needs of on-site fracturing.The steady-state tension-torque model of oil and gas wells can be used to analyze the lifting,lowering and rotating conditions during field application.The results show that the hook-load of the fracturing string is consistent with the theoretical The relative error is 13%.Through the string running-down-ability calculation,the fracturing string can be run down for the degree of the leg is less than 17.2deg/30 m in horizontal well.At present,the multi-stage pressure-transmitted packer fracturing process has been applied for more than 20,which shows that the construction process meets the requirements of large-scale fracturing construction,the rate is up to 6m3/min,the cumulative sand amount is up to 146m3,slippery water fracturing fluid is up to 2840m3 and gel fracturing fluid is up to 1260m3.The process can not only shorten the construction time,but also can improve the scale of the construction transformation,can be used as the main technology of oilfield development,promote the application.