海上油田多元热流体吞吐隔热工艺

Application of multiple-thermal-fluid cycle stimulation insulation technology in offshore oilfield

海上稠油油藏埋深多在1000 m以上,采用普通光油管注汽,井筒热损失大、热能利用率低,同时,套管及水泥环经受高温作用易变形损坏。为此,根据不同环空隔热工艺技术及海上油田热采作业特点,优选隔热油管+环空注氮作为海上油田热采隔热工艺。利用室内实验及理论计算:确定采用高真空预应力、内连接、P110钢级隔热油管,综合考虑管柱承压、隔热效果及安全等因素:环空注氮压力小于20 MPa、纯度大于97%。现场应用情况表明,隔热油管+环空注氮隔热措施现场操作方便,能够满足现阶段海上稠油热采工艺及安全控制要求。

The heavy oil reservoir depth of offshore oilfield is more than 1000 m. If the common tubing is taken for steam injecting, the wellbore heat loss is higher and the heat energy utilization is lower. The casing and the cement sheath are more easily damaged because of high temperature. On the basis of the characteristics of insulation technology and multi-thermalfluid cyclic stimulation, the optimization of insulated tubing and the annulus nitrogen-injecting are used for the insulated technology of offshore oilfield thermal-recovery. The insulated tubing with high vacuum pressure,inside connection and P 110 steel grade has been adopted by using the results of laboratory test and the theoretical calculation. Based on the pressure-bearing heat insulation effect and security of string, the pressure of annulus nitrogen-injecting must be lower than 20 MPa and the nitrogen purity must be higher than 97%. The site application results show that the insulation technology is easy to operate and can meet the requirements of heavy oil thermal-recovery and security control at this stage of offshore oilfield.