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The dual-packer multistage fracturing system is the dominant horizontal well fracturing technique in the Daqing oil field, which adopts the dual packers to stimulate the targeted formations one by one. For several intervals, treatment can be done in one trip; reverse sand flushing and pulling the tubing upward fulfills the multiple stage fracturing operations. However, long time fluid discharge is needed before pulling the tubing upward in order to reduce the overflow of the tubing, which leads to the high-operation cost and the low job efficiency [1]. Tubing plug is often used to seal the oil pipe for pulling the tubing upward without fluid discharge. But the operation of running tubing plug is complicated and increases costs. Especially in horizontal well, it is difficult to run plug to working depth and set it. A new pressure control valve is developed and can achieve switching by controlling the pressure difference between tubing and casing, which offers a hydraulic control method to seal the oil pipe and makes the anti-blowout operation simple. Field runs have confirmed that this new pressure control valve is viable option to reduce the overflow of the tubing and improve operation efficiency in the dual-packer multistage fracturing operation.

Recently the major methods of extracting road from remote sensing image are manually. It becomes a hotpot to realize automatic information extraction of road according to the feature of high-resolution image and the characteristics of road. In this paper, an improved approach for road extraction based on Watershed segmentation is proposed according to theories of object-oriented and mathematical morphology. The image is first processed by improved Watershed segmentation to acquire feature-units after preprocessing. Then object-oriented method is used to analyze road feature-units in order to optimize the road extraction results. Finally, after binary image processing, the incomplete results can be removed and corrected by using mathematical morphological transformation. At last this paper gives the result and analysis of the experiment sample.