Drilling technical difficulties and countermeasures of SY1 well in north China

SY1 well is a shale gas survey well, and the deviation between geological prediction and actual drilling is large due to the lack of adjacent well data. In the drilling process, there will be a variety of complex situations, such as stickiness, collapse, leakage, low drilling speed and so on. A design task of the well was successfully completed by adopting various targeted measures, such as optimizing drill bit, adjusting drilling fluid system, optimized coring technique and anti-slant straightening technique. The results show that the drilling of calcareous mudstone in the interval of 1 488～2 045 m and siliceous cementitious sandstone in the interval of 2 045～2 238 m should focus on the bit aggression. The performance control of drilling fluid should focus on inhibition and collapse prevention. Pendulum assembly had a good anti oblique effect, the vast majority of the hole deviation should be controlled within 1°. The optimized Chuan7-4 dual-barrel coring tool can achieve a core harvest rate of more than 95%.