Conducting emergency operations in wells with narrowed zones in the production string

Abstract

The article provides information that the production string along the entire length consists of casing pipes of the same type-size with different wall thicknesses, in some cases thicker in the upper part, relatively less thick in the lower part; on the reduction of the inner diameter with some methods of restoring the tightness of casing strings. Conducting emergency operations in such wells stopped during operation by milling the emergency ends or their annulus, as a necessary measure, with milling cutters of a smaller diameter causes even greater deformation of the emergency ends up to breaks. And also for catching the wider lower part of the production string eccentrically located or leaning against the wall of the pipe, due to the impossibility of using a centering device – funnels, down-laid fishing tools without a centering device, although they freely pass through the narrowed zone of the production string located above the emergency end, due to the impossibility of covering with a bell, as well as directing the pipe rod into the inner surface of the fishing pipe, fishing work is unsuccessful. In these cases, the use of an eccentric sub in the assembly of the bottom of the drill string, the use of a milling cutter of the smallest diameter ensures the milling of the emergency end located below the narrowed zone, with a milling cutter of the required diameter corresponding to the inner diameter of the production string, and also provides the possibility of catching an emergency pipe without a centering device. Information about the design features and their advantages in the relevant downhole conditions is given. Keywords: emergency end; milling cutters; fishing tools; BHA; eccentric sub.