冀东油田深层油藏注氮气井管柱及井口装置设计

冀东油田高5区块具有油藏压力高、注气井斜度大、管柱下入深等特点。根据该区块目前的注气井井身结构、地面设施状况和注气增效要求,设计了笼统注气的管柱结构方案。利用冲蚀模型优选油管尺寸,并按照不同工况条件开展高温高压动态腐蚀模拟实验,探究注氮气井的井筒腐蚀机理,确定各因素对腐蚀速率的影响。最后对管柱的剩余强度和服役寿命进行评价。结果表明,选用ϕ73 mm、13Cr油管作为笼统注气管柱能够应对注氮气产生的冲蚀、氧腐蚀等影响,并有着良好的服役寿命。配备地面安全阀等安全装置,可以大大降低高压注气井存在的安全风险。该设计方案能够满足冀东油田深层氮气驱的生产需要,具有广泛的应用前景。

Design of Nitrogen Injection Well String and Wellhead Device in Deep Reservoir of Jidong Oilfield

The Gao 5 Block of Jidong Oilfield has the characteristics of high reservoir pressure, large inclination of gas injection wells, and deep drilling of the pipe string. According to the current gas injection well structure, surface facilities and gas injection efficiency requirements, a commingled gas injection string structure scheme was designed. Self-programming of erosion model was used to optimize tubing size. The high temperature and high pressure dynamic corrosion simulation experiment was carried out under different working conditions to explore the wellbore corrosion mechanism of nitrogen injection wells and determine the influence of various factors on the corrosion rate. Finally, the remaining strength and service life of the pipe string were evaluated. The results showed that choosing ϕ73 mm and 13Cr tubing as the general gas injection string has a good service life under the influence of erosion and oxygen corrosion caused by nitrogen injection. Safety devices such as surface safety valves, can greatly reduce the safety risks of high-pressure gas injection wells. This design scheme can meet the production needs of deep nitrogen flooding in Jidong Oilfield and has a wide range of application prospects.