Diverting re-fracturing technology and field test in low permeability horizontal wells of Daqing oilfield

For two kinds of horizontal wells,one is the well with small angle between fractures and wellbore,the other is the well with the poor cement quality that cannot be separated mechanically;the diverting re-fracturing technology was studied.Moreover,two diverting re-fracturing modes,one is the diverting re-fracturing within fractures and the other is the multi-stage diverting re-fracturing within the scope of the whole wellbore were created.Depending on the evaluation experiments,the physical model of the diverter was established and two diverting agents related with the above different modes were selected.Meanwhile,based on the field implementation there are two construction control methods,namely squeezing injection test and lifting displacement test were formed.The two types of re-fracturing downhole string,the double-packer isolation re-fracturing one and the single-packer isolation re-fracturing one were formed.By far,nine horizontal wells diverting re-fracturing field test were completed.The results showed that the productivity of low permeability horizontal wells had a good effect on increased production after the re-fracturing,which effectively extends the production period of the above two types wells.