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The production wells in tight glutenite reservoirs have great potential for refracturing, because most of fracturing fluid and proppant flow into the first-class layer with lower initiation pressure during initial stimulation with multi-layer simultaneous fracturing treatment. However, layer segmentation during refracturing can be a challenge, especially in vertical wells. Using only mechanical segmentation tools is of high risk and sometimes ineffective. This paper presents a new refracturing technology for vertical wells employing diverting agents. The segmentation tools are rarely needed in the new refracturing technology. The implementation procedures are as follows: First, reservoir characteristics, remaining oil distribution and water content are evaluated to identify the target layers of refracturing. Second, through the classification of predicted initiation pressure, number of temporary plugging and diverting fracturing are determined. The dosage of chemical diverting agents is designed. Finally, refracturing treatment are performed with an injection procedure of "fracturing fluid and proppants (dredging existing fractures) + granular plugging agents (blocking existing fracture entrances) + fracturing fluid and proppants (creating new fractures) + powdery plugging agents (blocking new fracture tips) + fracturing fluid and proppants (creating complex fracture networks)". The refracturing treatment was performed in Well B1401 located at Junggar Basin in China using the method presented in this paper. The fracturing construction curve of Well B1401 shows that obvious pressure increase was observed when the diverting agents was added, and the initiation pressure or propagation pressure of subsequent fracture was monitored higher than that of previous fracture. It is suggested that proper agents or combinations can effectively plug the opened fractures and generate high enough pressure in the fractures to initiate branch fractures. The production log data indicate that five new layers begin to produce oil after refracturing operation, and the daily oil production of Well B1401 remarkably increased from 1.5 t/d to 9.8 t/d in the field test, which verifies the validity of the tool-free refracturing of vertical wells employing diverting agents. This study provides a new refracturing technology for vertical wells in tight glutenite oil reservoir employing diverting agents is presented. The segmentation tools are rarely needed in the new refracturing technology. It has been applied to hundreds of low-yielding oil wells in tight glutenite reservoirs of Junggar Basin, China. The average annual oil production per well has increased by 950t. It also provides guidelines to the engineers with respect to refracturing design and commercial viability. In addition, this technology is not only suitable for vertical wells, but also for horizontal wells.

The Triassic Baikouquan Formation in the Junggar Basin has developed a large number of dense sandstore conglomerate reservoirs, which belong to ultra-low permeability and ultra-low permeability refractory reservoirs. In recent years, the productivity of single well is improved by selecting potential production wells for multi-stage steering fracturing. In order to realize the forced steering of fractures, it is very important to study the sealing pressure of temporary plugging agent. According to the actual needs of Baikouquan steering fracture, the net pressure model of steering fracture is established. The net pressure value in the seam is calculated according to the change of ground stress after steering, then calculated the minimum temporary plugging agent sealing pressure needed for a single fracture. Based on the net pressure model, the corresponding software is developed and applied to the field. The practical application effect is good, which provides economical and effective technical technical support for the continuous and stable production of low permeability oil field.

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