A PLUG FOR WELL DRILLING PROCESS PROVIDED WITH MANDREL FORMED FROM DEGRADABLE MATERIAL

摘要

This boring plug is provided with: (a) a mandrel formed from a degradable material; (b) a pair of rings positioned on the outer-circumferential surface perpendicular to the axial direction of the mandrel, one or both of the rings being formed from a degradable material; and (c) one or more ring-shaped rubber members capable of expanding in diameter and positioned between the pair of rings. It is preferable for the degradable material of the plug to be one with a mass reduction rate of 5-100% after immersion in water for 72 hours at 150°C. This boring method is characterized in that part or all of the boring plug degrades after filling the bored hole by using the boring plug.