Directional drilling technology for large borehole in shallow strata with small well space in Shengli shallow sea oilfield;

Through the drilling of thicker conglomerate in large borehole,the new requirement for the manufacture of drilling tools has been put forward.

This paper analyzes the main factors to decrease drilling rate in large boreholes ( ≥311mm), such as large bit size, large shatter area, single bit types and insufficient mechanical and hydraulic power.

Development of big borehole circlip lead seal packer with sand control.;

The use of drilling fluid technology in annulus space of large hole;