In the South Sulige gas field, a casing leak was discovered after a velocity string production failure caused well SNXXX-02 to be killed because of water traveling from the formation into the wellbore through the casing leak. This high productivity well urgently needed casing leak remediation to restart production.
Instead of a conventional casing patch approach to repair casing leakage, an innovative solution using an epoxy resin system was applied to recover wellbore integrity and return the well to production. In addition, the resin system does not create casing diameter reduction or restriction during the next velocity installation. However, operational histories and field performance in terms of the capability to mill resin inside 3 1/2-in. casing were rare. This paper discusses a case study of applying the epoxy resin system, a rigless operation using fiber-optic coiled tubing (FOCT) to detect a leak, and then squeezing the epoxy resin using coiled tubing (CT) followed by milling-out after its solidification.
The remediation's effectiveness was determined and examined using qualified wellbore pressure testing; this is the first successful application of an epoxy resin in the South Sulige gas field. The recovery of wellbore integrity helped the operator restart production and maintained the wellbore with no ID restriction for ease of the following velocity string installation.
Most of the wells in the South Sulige gas field are tubingless directional wells with 3 1/2-in. production casing. Implementing a velocity string was widely used as a deliquification method during production.
A casing patch was the primary solution to repair casing leakage in this area. This integrated service of detecting the casing leakage point and applying the epoxy resin presents a new method of well remediation for the operator.