元坝地区陆相地层钻井提速配套技术

ROP enhancing technologies for ultra-deep wells in the continental strata in the Yuanba Gas Field , Sichuan Basin

四川盆地元坝气田天然气资源丰富,是中国石化的重点勘探开发区块,但钻速慢、钻井周期长是该区深井—超深井所面临的共同难题,该区域陆相侏罗系沙溪庙组—三叠系须家河组地层岩石致密、硬度高、可钻性差,此井段钻井周期约200d,占全井钻井周期的45%,严重制约了钻井提速提效。为此,开展了扭力冲击器配合PDC钻头、涡轮配合孕镶金刚石钻头、气体钻井等新技术应用试验,在试验效果的技术经济分析基础上,提出了延长气体钻井应用井段和深度的方案;对于不宜开展气体钻井的钻井液井段,如侏罗系自流井组中上部以浅地层或钻井液密度较低的地层推荐采用扭力冲击器提速,自流井组中下部—须家河组地层推荐应用涡轮钻具提速的方案。YB27-1H等11口井第三次开钻的314.1mm井段平均进尺1 885.29m,钻井周期缩短到166.18d,较前期平均值缩短34d。采用上述配套技术后,无论是钻井周期、日进尺均优于前期施工井,陆相地层提速提效取得了显著效果。

As one of the most important exploration ＆ development target zones of Sinopec, the Yuanba Gas Field is promising for its great potential of natural gas resources in the deep continental formations in the Sichuan Basin. However, the low drilling speed and long drilling cycle are the common challenges of ultra-deep wells in this field. The continental Shaximiao and Xujiahe reservoir rocks are made up of tight and hard quartz sandstones with poor drillability, where the average drilling cycle of wells is approximately 200 days, accounting for 45% of the total drilling cycle. Hence, the ROP enhancement is severely restricted there. In view of this, through technical research and the introduction of advanced technologies, pilot tests were conducted, such as gas drilling, drilling with the torsional impact generator and PDC bit, drilling with the turbine and impregnated diamond bit, and so forth. Based on the technical and economic analysis of the test effects, an innovative drilling performance plan was put forward for extending the well in- tervals and increasing the depth of gas drilling l as for such intervals that could not undergo gas drilling, it is recommended that the torsional impact generator be adopted to improve the drilling speed in shallow formations in the upper and middle parts of the Ziliu- jing Fm or the formation with relatively low density drilling fluid and that turbine drilling tools be used for raising the drilling speed in the middle and lower parts of the Ziliujing and Xujiahe Fms. Under the guidance of the ROP enhancement plan, 11 wells, inclu- ding Well YB27-1H, were drilled, and the statistical analysis showed that the average footage of .Q＇314. l mm interval in the third spud-in is 1,885.29 m, the drilling cycle is shortened to 166.18 days, which is 34 days shorter than the earlier average record. The effect of the plan is excellent in shortening the drilling cycle and improving the daily footage compared with the earlier drilling record, proving its capability to meet the challenges in this study area.