超临界CO_(2)分层注入井气嘴压力损失研究

Study on Pressure Loss of Gas Nozzle in Supercritical CO_(2) Stratified Injection Wells

CO_(2)驱分层注气工艺可以使CO_(2)均衡注入各层,有效减小CO_(2)气窜风险,合理配注各层流量是CO_(2)驱分层注气现场试验的关键。针对CO_(2)驱分层注气工艺,建立CO_(2)在超临界状态下通过气嘴的压力损失计算模型,确定CO_(2)流体在超临界状态下的气嘴压力损失图版。分析井筒温度和地层压力对CO_(2)驱压力损失的影响,便于现场对气嘴压力损失图版进行校正。同时设计了气嘴口径系列,确保在现场分层流量调配中选用合适口径气嘴。研究成果在某油田CO_(2)驱注气井的现场试验表明,选择合适气嘴后的实际注入流量与目标注入流量的误差约为1%,有效提高了CO_(2)驱分层流量调配精度,简化现场工艺流程和降低成本,为CO_(2)驱分层注气的气嘴选择和现场分层流量调配提供依据和指导。

The CO_(2) flooding layer by layer gas injection process can achieve balanced injection of CO_(2) into each layer and effectively reducing the risk of CO_(2) gas channeling.Reasonable allocation of flow rates in each layer is the key to on-site testing of CO_(2) flooding layer by layer gas injection.A pressure loss calculation model for CO_(2) is established through the gas nozzle under supercritical conditions in the CO_(2) drive stratified gas injection process,and the pressure loss diagram of CO_(2) fluid is determined through the gas nozzle under supercritical conditions.We analyze the impact of wellbore temperature and formation pressure on CO_(2) flooding pressure loss,facilitating on-site calibration of the gas nozzle pressure loss chart.At the same time,a series of nozzle diameters are designed to ensure the selection of appropriate caliber gas nozzles in on-site stratified flow allocation.The research results of the on-site test of CO_(2) flooding gas injection wells in a oilfield shows that the error between the actual injection flow rate and the target injection flow rate after selecting a suitable gas nozzle is about 1%.The method effectively improves the accuracy of CO_(2) flooding stratified flow rate allocation.The method proposed in this article effectively reduces the process flow and cost of on-site processes,providing a basis and guidance for the selection of gas nozzles for CO_(2) flooding stratified gas injection and on-site stratified flow rate adjustment.