Scholarly record

TECHNOLOGY OF REAMING BEFORE RUNNING CASING UNDER PERMAFROST CONDITIONS

Rinat Atlasov, Maria Nikolaeva, PhD in Engineering sciences Revo Skryabin

Abstract

Drilling in permafrost is accompanied by a risk of specific complications related to the disturbance of temperature conditions. The risk imposes certain restrictions on the use mud motors, depths of installation of conductor pipe and surface casing, temperature of the circulation fluid, timing of cement curing etc. This article discusses a technology of additional reaming and reciprocating the wellbore just before running casing, which is based on the properties of cryogenic rocks. Conducted an analysis of technical and technological risks before the run of casing string in the permafrost conditions, identified the main reasons for casing failure. The authors propose a technical device that provides a means of combining the stages of reaming and the wiper trip. Analysis of the caliper log before and after adding the gauge stabilizer into the bottomhole assembly suggests that a so-called "wiping effect" arises in the dynamics of the proposed device. The effect is due to the fact that though not having cutting and shearing qualities of standard stabilizers, proposed smooth-walled device kneads and grinds the roughnesses and protrusions on the borehole wall. This is facilitated by a reduced angle of impact on the borehole walls along with a significantly larger contact area.

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