This paper recommends the application of acidic fracturing technology for horizontal wells in Yubei region basing on its fractured reservoir’s characteristics, and the numerical simulation method is used to optimize the parameters of acidic fracturing. According to the results of optimization, the proper acid system is selected, and the construction parameters of acidic fracturing are optimized. According to the results of numerical simulation, we recommend the fracture half-length to be 120m, the fracture conductivity to be 30D.cm, and the fracture number to be 5. According to the properties of reservoir in Yubei region and the optimization results of fracture half-length and fracture conductivity, the alternative injection of crosslinked acid and ordinary gelled acid is recommend. The injection rate of crosslinked acid is 5m3/min, with volume 300m3. The injection rate of ordinary gelled acid is 6m3/min, with volume 300m3.

During the development of the oilfield, the water cut of the water controlled field is an aggregative indicator which is affected by various factors. It can reflect the restriction of liquid flowing rules from the oil layer and crude oil physical property, and the effect of serious technical measures during the exploitation. Water cut increasing rate is closely related with water cut. The level of water-cut increasing rate of various well network was evaluated during oil producing with extra-high water cut in Xingnan development area, compared the differences among various well networks, and analyzed the geology causes and development causes.

In this paper, the indexes have been determined for identifying ineffective injection-production circulation and corresponding mathematical model was constructed with fuzzy theory. Application examples show that this method is simple, fast and accurate. For high and extra-high water cut oilfields, because of the long-term erosion of injected water, there are some high penetrative channels between the injection and production wells, resulting in most injected water along the channel to cause the invalid injection and production, for which it is hard to increase water flooding swept volume, causing flooding and high water cut well and reducing oil production. To improve the effectiveness of water injection to achieve stable yields, it is important to take the measures of ineffective injection-production wells profile control, plugging and so on for fast and accurate identifying ineffective injection-production wells. To that end, this paper applied fuzzy theory to establishing the mathematical model for identifying ineffective injection-production wells.

Based on the analysis of the formation of the residual oil in the area , combined with the fine geological and multidisciplinary research results, summed up the main types of remaining oil, combined with dynamic and static data, used some measures such as cyclic flooding, fracturing, profile control , to tap the potential of remaining oil, and achieved good results.