高研磨性硬地层钻井提速技术

川东北陆相自流井组和须家河组地层岩性致密、研磨性强,机械钻速低、钻头消耗量大,是制约该区域钻井提速的关键层段。为实现提速,各种新型井下工具得到了试验应用,但效果参差不齐。通过计算分层段岩石可钻性,推荐自流井组至须家河组采用孕镶金刚石钻头提高破岩效率;为降低硬地层和软硬交互层段钻头失效导致的钻速低问题,开展了三开井段典型钻具组合扭转和纵向振动理论分析,提出东岳庙段以浅地层采用扭力冲击器配合PDC钻头降低黏滑,珍珠冲段含砾岩层段需使用减震工具或改变钻具组合降低纵振,砂泥岩互层段需推广使用双向减震器或水力加压器降低纵振;采用高速螺杆+孕镶金刚石钻头的复合钻进,提高自流井组至须家河组大井眼定向速度。5口井现场实施后,机械钻速成倍增加、钻头新度提高30%,须家河组?311.2 mm井眼定向速度提高1.32倍。

Technology for increasing drilling speed in high abrasive hard formation

The formation in Ziliujin Group and Xujiahe Group in northeast of Sichuan has compact and highly abrasive rock, can lead to low mechanical drilling speed and high consumption of drill bit, so that it is the key formation which restrict the increase of drilling speed in this area. In order to increase the drilling speed, various new-type downhole tools have been applied, but the effect varies from one to another. Through calculation of rock drillabillity in rock stratum separation section, it is recommended to adopt the impregnated diamond drill bit in the areas from Ziliujin Group to Xujiahe Group, so as to improve the rock-breaking efficiency. In order to reduce the low drilling speed problem caused by failure of drill bit in hard formation and soft-hard alternating formation, the theoretical analysis on torsion and longitudinal vibration of typical drilling tool combination in Three Section has been carried out, so as to advise that, the torsional impacter should be used to help the PDC drill bit to reduce sliding effect in the formation above Dongyuemiao Section, the shock absorbing tool should be used or the drilling tool combination should be changed to reduce the longitudinal vibration in conglomerate-bearing formation in Zhenzhuchong Section, and the double-acting shock absorber or hydraulic thruster should be used to reduce the longitudinal vibration in sand slime formation. The combined drilling technology based on high-speed screw + impregnated diamond drill bit should be used to increase the orientation speed of large wellbore in areas from Ziliujin Group to Xujiahe Group. After the implementation of such technologies in 5 wells, the mechanical drilling speed has been doubled, the new degree of drill bit has been improved by 30%, and the orientation speed of ?311.2 mm wellbore in Xujiahe Group has been increased by 1.32 times.