NUMERICAL SIMULATION OF SAFETY DRILLING CYCLE OF HORIZONTAL HOLE IN UNCONSOLIDATED SANDSTONE RESERVOIR

The instability of the horizontal hole in unconsolidated sand reservoir is the main topic which must be considered during the horizontal well drilling operation. Obtaining the steady-state creep constitutive equation by the laboratory experiments on unconsolidated sands sample from the some offshore oil-gas field at normal-temperature. This study has verified the viscous deformation of unconsolidated sand is the main factor to affect the shrinkage of horizontal hole. The deformation of horizontal hole was analyzed with considering the visco-elastoplastic deformation of the surrounding rock. The shrinkage rate of the horizontal hole was calculated with FLAC3D with considering the influence of in-situ stress,mud density and rheological parameter, and the safety drilling cycle determine is determined based on the shrinkage rate of the horizontal hole.