A major Middle East Operator has adopted a new type of solid expandable tubular technology to isolate shallow aquifers as well as fractured formations. The technology is based on a steel wired balloon expanding a stainless steal into the well bore. The simplicity of the technology combined with a significantly increased expansion ratio has opened a whole range of new applications to materialize low cost wells. This paper will outline the two trial wells in which the technology was applied, review the benefits of expandable tubulars for these applications as well as looking in candidate selection. Particular emphasis is given on the Operator's experience with the technology.
Isolation of shallow aquifers and fractured formations while drilling has been a major challenge for many years in Oman. The requirement for zonal isolation of the shallow aquifers is often compromised by the total losses encountered. Often a cocktail of chemicals followed by multiple cement jobs are used to achieve the objective. The latter can be costly not to mention the extra time incurred and HSE exposure. Also failure to isolate aquifers also increases the risk of cross flow between fractured formations what has been a significant contributor towards free water corrosion of the surface casing strings as well as subsequent issues referring to un-cemented casing strings in thermal wells.
Inflating a sleeve into the formation has proved successful in terms of installation reliability, isolation of fractures and isolation of shallow aquifers. Well configuration based on expandable tubular solutions have improved well delivery times what is making this expandable technology a strong case for wells to be drilled in the coming years.