Performance of Re-Fracturing in Multiple Thin Layers of Low Permeability Oilfields

For the low permeability formation of Daqing oilfield, we have to stimulate the multiple thin layers in one stage during a separated layer fracturing job because there are many of layers in one well. Based on the logging data analysis, the hard fracturing layers identified method has been built for the multiple thin layers re-fracturing in low permeability layers in Daqing. According to the calculating result of the broken pressure difference within multiple layers, we can recognize the layer which is not been stimulated in the first time multiple layers limited entry fracturing job. We can optimize the fracturing parameters design in the re-fracturing treatment. Based on the research of interference disciplinarian between fractures, we can get the boundary of the least interval without the interference. So we can analysis which layer is not been stimulated enough because of fractures interference in the first time fracturing. Researching the relationship of perforation holes erosion with fracturing treatment parameters can help us to estimate the first time fracturing and optimize the re-fracturing treatment parameters designing. By using above method, we have got a satisfactory re-fracturing result in 27 wells. After fracturing, the oil production is increased 6.8t/d and the water ratio is decreased 4.2%. The oil production is even higher 1.2t/d than the first time fracturing. That shows the new layers have been stimulated.