Abstract

The IOR is permanently issue for oil development. Zonal Water Injection Technology is a key technic about IOR. The zonal water injection technology faces several challenges for offshore oil field, such as numerous highly-deviated wells, complicated inter-layer contradiction, high cost, low operation efficiency, etc. High efficiency, low cost and low risk are crucial targets for offshore water-flooding. To achieve this target, CNPC developed a new offshore water injection technology featuring bridge concentric structure. It can realize multi-layer flow rate testing and adjusting efficiently and accurately with low cost and low risk. The system is composed of downhole bridge concentric regulator, downhole control instrument and surface control equipment. It can obtain multiple downhole critical parameters on line such as layer flow rate, tubing pressure, formation pressure and temperature. Also it can realize downhole flowrate dynamic adjustment automatically with no need to run and fish downhole valve. A steel cable with single core is employed for two-way data transmission. Concentric connection and adjustment between regulator and instrument is adopted to ensure successful connection for offshore deviated wells. The eccentric valve is designed as a innovation point with low leakage and low regulation torque. High-precision electromagnetic flow meter is employed to obtain layer flow rate directly to ensure test accuracy in deviated wells. Until recently, this technology has been applied in eleven wells including five in jidong offshore highly-deviated wells with maximum deviation 55 degree, maximum pressure 50MPa and maximum temperature 120 degree. The application successfully achieved the parameters of flow rate, tubing pressure, formation pressure and temperature. Besides it realized flow rate adjusting automatically. The whole process of water allocation and packer seal test were finished on line and the efficiency was significantly improved.

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