海上稠油热采环空注氮隔热增产机理研究  

Study on Heat Insulation and Stimulation Mechanism of Nitrogen Injection in Annulus for Offshore Heavy Oil Thermal Recovery

作　　者：孙玉豹[1] 张伟 姬辉[1] 王秋霞 邹剑 张卫行[1] 林珊珊[1] Sun Yubao;Zhang Wei;Ji Hui;Wang Qiuxia;Zou Jian;Zhang Weihang;Lin Shanshan(COSL,Tianjin 300450;CNOOC Tianjin Company,Tianjin 300450)

机构地区：[1]中海油田服务股份有限公司,天津300450 [2]中海石油(中国)有限公司天津分公司,天津300450

出　　处：《中外能源》2019年第10期35-39,共5页Sino-Global Energy

摘　　要：为了提高热采效果,降低热采管柱失效风险,海上热采常采用环空注氮的工艺。本文对氮气的隔热效果和增产机理机型了研究。利用软件对不同隔热条件下的井筒沿程温度损失和套管温度进行了计算,计算结果表明采用隔热油管配套环空充氮工艺相比不采取隔热措施或环空不充氮,井筒沿程热损失最小,套管温度更低,可进一步降低套管受热伸长抬升井口及多轮次吞吐后套管及水泥环受热损坏的风险。通过室内实验对氮气进入地层的增产机理进行了研究,对现场油样的黏度试验表明,加入氮气后原油黏度降低了约10%~30%。利用数值模拟分析了氮气注入地层后的压力情况,结果表明,氮气能增加地层压力。氮气进入地层后能在地层上部形成隔热层,减少油层内热量向上覆岩层的散失,减小油层内的热量损失,提高热利用率。该工艺现场应用情况表明,环空注氮气隔热工艺能有效减小井筒热损失、防止井口抬升,避免套管及水泥环遭受高温破坏,还能提高产量,取得较好的热采效果。In order to improve the effect of thermal recovery and reduce the deformation risk of thermal recovery string,the process of nitrogen injection in the annulus is often applied to the offshore thermal recovery.In this paper,the heat insulation effect and stimulation mechanism of the nitrogen are studied.The software is used to calculate the temperature loss along the wellbore and the casing temperature under different heat insulation conditions.The nitrogen injection technology by insulated tubing matched with annulus is applied.Its results compared with that by injection string with no insulation measures or annulus with no nitrogen injection show that the heat loss along the wellbore is minimal and the casing temperature is lower,which can further reduce the risk of wellhead rise resulted from casing elongation after heating and the damage of the casing and cement ring after multiple cycles of huff and puff.The stimulation mechanism of nitrogen injection into the formation is studied by laboratory experiments.The viscosity test of the field oil sample shows that the viscosity of the crude oil decreases by about 10%-30%after the nitrogen injection.Numerical simulation shows that nitrogen can increase the formation pressure.In addition,after the nitrogen is injected into the formations,it can form a heat insulation layer on the upper part of the formations,which reduces the heat loss of the oil reservoirs to the overlying strata and among the oil reservoirs and improves the heat utilization efficiency.The field application shows that the technology of nitrogen injection in annulus for heat insulation can effectively reduce the heat loss of the wellbore,prevent the wellhead from rising,avoid the damage of the casing and cement ring at high temperature and improve thermal recovery performance by oil production increase.

关 键 词：环空隔热 热损失 注氮隔热 氮气增产 

分 类 号：TE3[石油与天然气工程—油气田开发工程]