Application of a New Physical Model of Expandable Casing Technology in Mitigation of Wellbore Leaks


Application of a New Physical Model of Expandable Casing Technology in Mitigation of Wellbore Leaks

CETI 13-020

Authors: D. Kupresan, Craft & Hawkins Department of Petroleum Engineering, LSU; J. Heathman, Shell Exploration & Production; M. Radonjic, Craft & Hawkins Department of Petroleum Engineering, LSU

Volume 1, Number 5

The unique casing expansion model was designed and developed for experimental investigation of the potential remedial impact of expandable casing technology on wellbore cement integrity compromised by microannular gas migration behind the casing. Remediation of gas migration and surface casing leaks poses a great challenge for the oil and gas industry.

Wellbore cements can undergo one or more forms of failure during the life of a well, such as debonding at the cement/formation and cement/casing interface, fracturing and defects within cement matrix. Failures and defects within cement will ultimately lead to fluids migration, resulting in inter-zonal fluid communication, necessary remediation operations and premature well abandonment. 

Experiments described in this paper used an original bench-scale physical model to simulate a mechanical manipulation of a previously-cemented casing in field-like conditions. During the expansion of the casing/formation cemented annulus, increase in applied expansion forces and significant alterations in cement structure were observed. Pre- and post-expansion multi-rate flowthrough experiments with nitrogen gas were run on composite samples with a pre-manufactured microannulus. After expansion of the pipe with an 8% expansion ratio cone, gas flow through the microannulus was successfully sealed. 

This novel study provides insights into the effects of mechanical manipulation of pipe on microannulus remediation and consequently how volume reduction of hydrated cement impacted the properties of the cement sheet under expansion.


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