榆林南地下储气库注采井完井管柱的优化设计

地下储气库注采井与常规气田开发井运行工况存在着很大差异,要求具有采气和注气双重功能,能够实时监测井下动态,在长期(30~50a)频繁剧烈的注采气和压差变化下能够确保井筒的密封性和安全性。为此,针对鄂尔多斯盆地榆林南地下储气库注采井气量大、周期性强注强采的特点以及高安全性能、长使用寿命等的特殊要求,应用节点分析方法对天然气的流入、流出注采过程、不同尺寸油管注采能力等进行了分析,并结合冲蚀流量和临界携液流量等的计算结果,最终确定了Ⅰ类注采井(小于等于200×104 m3/d)采用139.7mm油管,Ⅱ类注采井(小于等于80×104 m3/d)采用114.3mm油管。通过管柱结构优化设计,注采井采用井下悬挂压力计测压完井管柱,从上至下完井工具包括"上流动短节+井下液控安全阀+下流动短节+循环滑套+永久式封隔器+磨铣延伸筒+堵塞坐落短节+带孔管+悬挂坐落短节"等。现场2个注采周期运行试验结果表明,完井管柱能够满足地下储气库生产运行要求,其设计方法可供同类储气库注采井完井设计时参考。

An optimal design of completion string of an injection and production well in the Yulinnan Underground Gas Storage

Unlike a conventional gas development well, an underground gas storage (UGS) well has a dual function of gas production and injection. In this case, any downhole condition change requires to be timely monitored, and the tightness and safety of the wellbore should be ensured under long term (30~ 50 years) frequent and intense gas production and injection with the fluctuation of differential pressure. In view of this, aimed at a large gas amount, periodic intensive injection and production, high safety performance, and long service life of an UGS well in the Yulinnan UGS, Ordos Basin, node analysis is applied to natural gas inflow and outflow dynamics and the capacity of different sized tubing. Combined with the calculation results of erosion flow and critical carrying liquid flow, the analysis results show thatΦ139.7 mm tubing is used in Class I wells (≤200×10⁴m³/d) whileΦ114.3 mm tubing used in Class II wells (≤80×10⁴m³/d). With an optimal design of string structure, a pressure gauge is hung downhole in the UGS well to measure the pressure of completion string. The completion tools from top to bottom include “upper flow coupling + downhole hydraulic control safety valve + lower flow coupling + sliding side door + permanent packer + mill out extension + R landing nipple+ perforated pup joint + RN landing nipple”. The test results of two injection cycles indicate that the completion string is capable of meeting the requirements for an UGS well and its design can be taken as a valuable reference.