稠油热采不压井作业工艺管柱

Non-killing Operation Pipe String in Thermal Heavy Oil Production Wells

针对稠油井注汽后进行压井作业时压井液容易进入地层,吸收地层热量,降低开采效果的问题,进行了稠油热采不压井作业工艺管柱研究。研制的高温高压井下开关可在注汽时打开注汽通道;油井作业时关闭注汽通道。高温高压井下开关采用捅杆来控制,内部采用弹簧伸缩及轨道销钉在轨道管上滑动来实现机械式反复启闭,密封总成采用耐高温高压的组合式密封,外管通道外设计有防护罩,使注入蒸汽经过防护罩的缓冲再进入油、套环空,有效保护套管。在稠油热采井中采用该工艺管柱,可以在注汽后转抽时避免压井作业,减少作业过程中洗井、压井等工序对地层造成的冷伤害,最大限度地提高蒸汽热利用率,并保护油层和套管,提高稠油油藏蒸汽吞吐效果。

Thermal heavy oil production is at the stage of multi-cycle CSS period, which causes low formation pressure. If killing operation is carried out, kill fluid is easy to enter into formation and absorb formation heat, thus causes bad production effect. Aiming at this problem, non-kill- ing operation pipe string for thermal heavy oil production wells is studied. HPHT downhole switching valve is developed. The passageway of switching valve is opened as steam is injected or oil is produced and closed as operation is carried out. The repeated mechanical open/close of switching valve is controlled by spring expansion and compression and track pin＇s slipping along track pipe with a bar-like tool. The seal assembly is a combined thermostable and pressure-proof seal. There is a protective shield out of the passageway of switching valve, which lightening damage of steam on casing. With this pipe string used in thermal heavy oil production wells, killing operation can be omitted as switching to production after steam injection. Tripping operations can be eliminated, as well as cool damage of flushing and killing operation to formation during operation. Producing energy can be maintained and heat utilization ratio of steam can be increased, thus CSS effect of heavy oil can be improved.