长庆气区储气库超低压储层水平井钻井液完井液技术

鄂尔多斯盆地长庆气区储气库选择在榆林气田的山西组山₂³储层实施，由于该气层经过长期开采和储层压裂改造，导致水平段目的层压力极低（压力系数0.4～0.6），成为诱发水平井段发生钻井液压差漏失的地质因素；且采用筛管完井方式又要求钻井液完井液必须具有非常好的暂堵效果。针对上述技术难题，以室内预防井漏、储层保护研究为技术支撑，研制出了具有抑制性强、润滑性高、总固相少等特点的无土相复合盐低伤害暂堵钻井液完井液体系。现场应用两口井，其中Y37-2H完钻井深5 044 m，水平段长1 819 m，创长庆气田水平段Φ215.9 mm井眼的施工记录，Φ139.7 mm筛管一次性下到预定位置，并获得无阻流量100×10⁴ m³/d 的高产气流。应用效果表明：该体系较好地保护了山₂³储层，钻完井施工作业安全顺利。

Drilling and completion fluid technology in the horizontal well drilling of the Changqing ultra-low-pressure gas storage reservoirs

The Changqing underground gas storage well is to be completed at the Shan23 reservoir in the Yulin Gas Field of the Changqing gas zone,Ordos Basin.Due to the long-time production and fracturing stimulation,the pressure at the pay zone of the horizontal well is extremely low with the pressure coefficient of only 0.4-0.6,which becomes a geological factor leading to lost circulation when the horizontal section is drilled.Apart from that,to meet the needs of the designed work of screen liner completion,the drilling and completion fluid should have very good plugging performance.In view of this,an experimental study is conducted to find ways to avoid lost circulation and provide reservoir protection in terms of drilling and completion fluid technology,thus,a low-damage and non-clay composite salt system is developed with high inhibition,high lubricity,low solids content,and temporary plugging capability.It has been applied in 2 wells,the well Y37-2H of which was drilled and completed with a total depth of 5044 m and a horizontal section length of 1819 m,thus,a new record of the length was set up for the φ215.9 mm horizontal well drilling in the Changqing Gas Field.As a result,the φ139.7 mm liner was smoothly run to the predetermined depth without any problem.And the potential flow rate was high up to 1 million m3 per day.This field application shows that this system can not only effectively protect the Shan23 reservoir but make a safe drilling and completion job possible.